A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation
Edition: Model Aviation - 1979/01
Page Numbers: 10, 11, 12, 13, 14, 15, 93, 94
A I innovations terms porting ABC Dykes haust timing squish etc know ever cycle engines ii ad article howe ruiew design o try explain thu beginners can nces various engi ew newest ne out last couple Fhe basic design mc much since Al gin gin design Wart modified r exhaust adept tuned pipes Made Bill Wismewski Roger Theobald 1966 new engines celled TWA 15 Early bar stock version left cast crankcase production version right Dominated FAt Speed flying until 1972 cycle mean piston traverses extreme other bot torn dead center BDC Top dead center TDC vice versa other words complete revolution crankshaft results two cycles twocycle engine fires revolution four-cycle engine such big auto en gine fires other revolution Perhaps familiar four-cycle engine its parts accessories such cams valves oil pump etc Lets explain four-cycle sequence first piston top exhaust stroke As piston starts downward exhaust valve closed camshaft intake valve opened fresh charge air fuel drawn through carburetor manifold After piston reaches bottom stroke starts back up intake valve closes fuel-air charge com pressed piston travels up TDC during second cycle spark plug fires piston near top dead center combustion forces pis ton down BDC power stroke exhaust valve opens gases forced out piston comes up during fourth cycle en tire sequence repeated four cycles intake com pression power exhaust occur during two complete revolutions crankshaft have neglected such things valve timing ignition timing because dont think would help explain cycles four-cycle engines burn air fuel mixture lubricating oil must contained crankcase pumped splashed around moving parts can see four-cycle engine needs such things oil pump cam shaft valves distributor magneto ignition two-cycle engines have very few moving parts just piston assembly conrod crankshaft maybe rotary valve rear intake engine has intake exhaust openings instead camshaft ports opened closed proper time piston reciprocates up down Intake air fuel come crankcase through January 1979 11 Two views engine started Schnuerle Revolution K&8 Torpedo 1 5RS made Bill Wianiewalci 1964 clearly demon strated superiority Schnuerle boost porting Engine affectionally called wart because bypass lumps crankcase the crankshaft lubrica cystioi four-kengint ton bottom dead cci explain way double power draw force up crankshaft rotates 12 Model Aviation upward intake rotary piston moves past byj creates negative crankcase negative charge air through th venturi effect draws air Meanwhile previou fuel cylinder bc piston beglow plug piston tothe stroke Inertia forces sshaft rotating past top dea *combustion gases start the power stroke int carburetor intake hole As piston goes up creates negative pressure crankcase valve opens allows fuel air come downward movement piston creates positive pressure closes reed valve seals crankcase Intake timing cannot controlled intake restricted engine will also run either direction efficient rotary valves Bypass port timing exhaust port timing again usually expressed units degrees crankshaft rotation shown Fig 3 As piston comes down TDC exhaust port opens some time before piston reaches BDC re mains open until piston again comes up close Likewise bypass port opens closes same way except opens later closes sooner Most mod ern engines have exhaust timing ap proximately 14O bypass timing approximately 1200 means port stays open shaft rotates through indicated angle Racing engines burn ing high-nitro fuels can use advanced exhaust timing since nitro burns faster alcohol Some have much 1500 exhaust timing Engines using tuned pipes use very radical exhaust timing 1650 ented long ago different ones cause gases flow patterns called loop scavenging cross scavenging Some names given porting arrange ments Schnuerle Curtis Laminar flow Refer Fig 4 have drawn schematic sketches different porting arrangements Loop scavenging Fig 4-b used large slow speed two-cycle diesel engines suitable -speed model engines can see gases come near exhaust port loop up cylinder Fig 4-c shows cross scavenging used model engines years have built Cross scavenging means bypass port op posite side cylinder exhaust port baffle piston top deflects incoming charge fuel air un ward cylinder position Porting Arrangements look engines built different manufacturers engines built same manu facturer see variations can see carburetors front rear exhausts side rear front different engine configurations mostly due different porting arrangements relationship between bypass ports exhaust ports greatly affects v cylinder Most porting its have names oat U still inOs Cross s ouve Perry carb orckplate t enough fuel ts have made using cur iem helped very ii n baffled s dead space t scavenging inco pment Mr Per fqme said e will discu nss-scavenged en id about 20 ye y Dooling K&l ic ones used Lelers manufac tg different rovement 1960 Juares Ga patent wo-stroke engines type scat ir flow di 14M g mcau -air mlxi yin ignition ten fuel s t K go pn ising t L 4-i Eric Lister knowledgeable en gineer read respect has examining families airfoils Re cently reviewed really famous Grant X-8 developed interest ing derivatives various purposes analysis shows Charlies great air foil notably used KG right respect parameters laid down eminent authorities Erics anal ysis accurate What says true Also true Charlie Grant devel oped X-8 running pencil around outlines trout Letters Editor continued page 9 pattern machine ban items makes situation seems like few valid ways bring average flier event Im referring specifically Novice dont see being controlled prob lem Look pattern itself ict rules time altitude maneuvers direc tion etc one-design type model stagnation personified different pat tern designs available novice use pipes retracts high priced engines restricts entry Now concerning Schnuerle en gines. what about ones Perry directional porting believe ten-point reduction anyone chooses nonconventional engine would fair realistic approach what could evolve Restrict radios using 4 channels 8 channels available what. just use 4 Add 10 points fixed gear model has retracts leave locked down place same bonus Add 10 points conventional engine sub tract 10 Schnuerle PDP other trick engine Ban tuned pipes nov ice event see no need radical change Novice class simply needs opened up some allow participation year year decline entries shows its sick dead feel sure what have discussed will bring comments both pro con must try find consensus opinion work solution matter Ben J Garrett Brownwood TX prefer sit out leav ing people fly Pattern make answer editor impression Novice Advanced Expert Master classes created deal formidable problem minor portion fliers having such supreme flying skills others would compete Gar rett raises another criticismtho related Novice Enlightened comment will welcome About Engines/Lee continued page 15 complicated simple porting arrangements Perry Directional Porting PDP shown Fig 4-h consists two narrow bypass ports near exhaust port directed away exhaust port can used Schnuerle porting cross porting reduce unscavenged dead space near center piston Mechanical Improvements Quite eflec tive advances have made met allurgy used modern engines Pistons instance now machined out 2024-T35 bar stock rather die cast aluminum some forged out same similar alloys 2024 harder stronger has much greater hot strength die casting alloys result power due increased ri gidity greater lifetime due better wearing properties Connecting rods also made 2024-T35 aluminum forged shot-peened increase strength eliminate stress concentra tions Heads machined same alloy give greater resistance warpage better heat transfer Crankshafts made casehardened high-strength alloy steels Modern plating techniques allow aluminum parts such backplates January 1979 93 r IF YOU BUILD FIBERGLASS MODELS YOU NEED PFC brilliant white polyester resin putty form PEG made levelling dents dips ripples chips other imperfections fiberglass parts PEG non-sagging fast setting feathers out zero thickness peeling flaking can filed drilled sanded its completely fuel proof Use PEG filling repairing reinforcing bonding shaping making fillets build anything made fiberglass need PEG A Division Pettit Paint co Inc KhhlypuNy MEN 36 Pine Street Rockaway NJ 07860 J nickle chrome plated greater wear resistance Almost crankcases die cast investment cast aluminum heat treated maximum strength piston rings used made high strength centrifugal cast iron used combination chrome plated steel sleeve Almost ideas first used Control Line Speed engines quest superior performance contin uous process Extremely high-nitro con tent fuels devilishly hard engine components ever stronger alloys design improvements developed success such work amply demon strated todays large RC engines develop over one-half horse power 10% nitro fuels run hun dreds hours before parts wear out destruct Most small engines 19 displacement less have cast iron pistons freemachining leaded steel sleeves com bination works very well cast iron wear resistant exhibits low friction cast iron heavy however almost impossible balance larger dis placement engine try use material piston reason engines 40 displacement larger have aluminum pistons ABC ABCD several manufacturers now make what called ABC engines letters stand Aluminum Brass Chrome mean engine has lapped aluminum piston chromeplated brass sleeve aluminum piston special alloy containing 19 22 per cent silicon alloy has much lower coefficient expansion regular aluminum alloys fact brass ex pands aluminum heated proper sleeve piston clear ances maintained operating conditions concept first used Super tigre 65 29 engines about ten years ago believe Dick Hall Huntsville Alabama provided information low-expansion aluminum alloy Mr Garofali worked out technique brass sleeve use racing engines lapped lightweight low-friction pis ton gave tremendous increase horse power side benefits excellent life time elimination long break-in requirements ABC sleeve piston expensive however since high sil icon alloy piston must cast chrome plating difficult hone assembly tolerances very critical reduce some costs some manufacturers made ABCD engines letters ABCD mean Aluminum Brass Chrome Dykes ring combination piston alloy either high silicon aluminum casting 2024-T35 aluminum Instead being lapped piston fitted single compression ring special type called Dykes ring Most piston rings spring loaded against walls cylinder tension creates friction drag continually piston goes up down Dykes ring however fits bore no tension depends combustion pressure force against wall sealing seals gas pressure high floats during remainder stroke great reduction friction Different rings shown Fig 5 may some differences idling characteristics between lapped ABC en gine ringed engine doubt would much detriment would guess such differences would caused change compression idling speeds Perhaps ringed piston leaks slightly low rpm low compression engines seem idle better high com pression ones theory could proven easily measuring com pression high low speeds Combustion Chambers Various combus tion chamber shapes shown Fig 6 Years ago bothered preigni tion went high compression fuels containing 50% nitro flat-top piston eliminated problem now can run extremely high com pression ratios up 80% nitro racing events successful high performance combustion chamber shape shown Fig 6-d used Supertigre engines years Wing span 67The Cuellist 2 40 has Wing chord 14seen designed Total wag area 7g5upeasy-to-f y ann safe Fse age engla 54sanding twin engined Stab lizer span 27H C mooni Combining Veric n tO Velegant appearance Hoc engine 23- 40with simple atrLcturO ta Gear F ann rerractidea tne moceler Ceanne 45w reiIwho has progrenano Control functionstnroga usaa lorons hiecatortrainers pattern Thrott e Redderow wing sport pa Coast act Ba sa 0acazea 35a67 Ins cc onwanaa ann coast oct 05 photos ac aced K acludes Deca balsa anaped pa ta ha owoon plywood a 00 pee ens Owa e d F y ng ght 6 8 05 now used Schnuerle-ported en gines distance top pis ton glow plug has great effect upon engine performance because affects tem perature engine plug other chamber shapes have tried flat area around periphery called squish band set come very close piston top stroke squishes fuel-air charge domed combustion chamber high tur bulence increased efficiency trumpet chamber shown Fig 6-f works very well used extensively Cox Rossi high-performance en gines Some hop-up experts modify squish-band chamber shown Fig 6-e claim better performance really doubt think can get iden tical better performance setting head clearance optimum compres sion ratio weather has great effect racing engines can usually correct variations weather changing compression ratio good tachometer necessary measure engine rpm vary clearance must know what rpm engine should turn required performance Sport RC engines affected weather changes compression adjustments rarely needed ends part next month will cover tuned pipes general descriptions several new engines market Spirits/Aycock continued page 24 Use 6-32 nylon bolts blind nuts hold place use nylon bolts allows gear knock off super hard landing instead tearing up bottom fuselage Epoxy maple wing blocks gussets place Square up wing fuselage drill holes wing dowels bolts See left off block front fuselage Tap blocks nylon bolts Now add forward fuselage block epoxy Install wing dowels Sand shape fuse lage fairing front end spinner Coat engine tank area resin epoxy Weight point should 15 94 Model Aviation