tee Flight Indoor Bud Tenny ANOTHER really big show has already noted elsewhere 1981 Indoor Nats will held West Baden IN super-site atrium Northwood Institute Nats will followed another Peanut Grand Prix annual fly-in National Indoor Model Airplane Society NIMAS Nats will lead off really wild week activity day test flying three days competition Peanut Grand Prix will give Peanut Scale fliers another crack other both relatively normal events far-out fun events spring fevered imagination John Martin Miami all-Indoor club Miami Indoor Airplane Model Association MIAMA Whats SNART Finally NIMAS winds up week-long festivities holding Sixth NIMAS Annual Record Trials SNART year meet furnishes change pace modelersmostly NIMAS members limited group competition events have AMA record status unusual fliers compete against existing records instead against other activity called NIMAS Index winning scores computed dividingthe actual flight time existing record time result winner may flying Ornithopter second place model may Novice Pennyplane comes about flight times compared record time Ornithopter flight may have boosted AMA record 5% score 105 Pennyplane flight may have just under existing record score 995 995% record time other competition may include nonAMA events head-to-head competition usual manner unusual format Index competition gives another dimension fliers strategy does have get best possible flight model has decide several events expertise strongest An unexpected by-product Index flying much less cut-throat normal competition Everyone flies pretty much mood strikes everyone enjoys activity Indoor wood selection things enhances challenge Indoor modeling build models fly better weighing less time required build model might expect before tries course Indoor models built various fix tures improve accuracy con struction make job handling small pieces balsa easier takes time build fixtures Once fixtures particular design have built block time removed building time real chunk time involved building models agonizing choice wood use However since Indoor classes have no minimum weight rules strength wood models great importance structure built really prime wood might up 25% lighter same strength What strong wood Balsa wood comes incredible range density less four pounds per cubic foot over 15 pounds per cubic foot very light balsa tends quite stiff compared similar weight higher density balsa two extremes strength materials structureswe can consider some given force applied structure will cause break course whole story Glass apparently very strong must exert relatively high force against example rim drinking giass before breaks key item stiffness since giass apparently does bend deform noticeably before breaks does yield glass probably will shatter tiny pieces similar plastic utensil may mash flat under much less force still break Which stronger giass plastic copy practical stand point either container far stronger needs to fulfill intended purpose bring ing liquid lips Neither extra strength nor stiffness either container has meaning until some unusual event mere fall floor probably will destroy glass plastic item will bounce harmlessly around crushing force could permanently distort plastic spoiling its ability quench thirst 66 Model Aviation Two simple balsa fixtures weight make tester spar stiffness see column Atinydollsclou-iespsn useu rora ciamp stiffness-tester thin balsa liner glued clothespin cushion piece wood being tested photos Tenny Continued page 135 piassic ruier iss raisea graauations nave nigniignsea wHin magic marerj rurnisnes vertical reference marker aid measuring deflection balsa strip being tested oldest modeling Free Flight clubs United States Thanks Russ James Fresno GMAC passing along invitation neighborhood September 26-27 stop have go part $3000 jackpot National Free Flight Society NFFS has just announced recipients Free Flight Hall Fame awards 1981 awards given individuals have contributed different ways development continuity FF model aiplane activities USA throughout world Maxwell Bassett revolution man challenged 1932 rules competition flying model aircraft powered internal com bustion engines events previously flown rubber-powered craft developed successful competition models easily successfully built thousands William L Effinger developer manu facturer tremendous variety award-winning kits can forget mark left hobby Berkeley models Duke Fox developer manufacturer engines priced within financial reach modelers have competitive potential started trend hoC fuels use today Joe Lucas deceased real expert/teacher writer subject model airplanes during 1 920s Chicago area authored columns newspapers magazines also won 1926 1928 Mulvihill event Joe Ott American youth 1930s 1 940s new him aeronautical expert Model kits made company could found hobby shops hardware stores dime stores etc Developer simplified model-assembly techniques awards will made NFFS 1981 AMA Nationals Seguin TX August 6 730 pm FF Indoor/Tenny Continued page 66 Bock Indoor models appears stiff ness rather ultimate strength may well important balsa build Indoor models largely true However con sider model never shrug offmore stress imposed flight loads could built very lightly very us have touch needed handle Indoor model twice strong needs could magically appear flight fully wound being touched human hands Another factor type ceiling site condition air super-light very stiff model quite possibly will survive flights under condi tions especially high drift brings out steering balloon problem very stiff structure can rather easily bent beyond its limit during rafter bounce steering attempt usually model shatters Let bend Suppose model bit flexible may well last much longer stiff model So can get flexible model still light strong answer use heavier moredensebalsabelieveitornot Hereshow use example six-pound wood instead four-pound wood make cross section wood enough smaller structure weight same before Now some what simplified since balsa varies density strength overall quality Before cutting spar sheet balsa examine sheet under magnifying glass NORTHERN CALIFORNIAS LARGEST1 DISCOUNT HOBBY SHOPI well FUELyouI New high film strength lubricant creased power engine lifeI Iquality ingredients IJto cut varnish I II II II II II II II II II II II IHOURS Monday thru weonesooy v ju-o ju inursoay C rrioay vJu-auuI L rday930-600 Sunday 1200-500 riD QQ4_ MaiW1735 bqa at04t7SSQ4NEO675QTC695 QUADRAQUADRAQUADRAQUADRAQUADRA INVERTED MII~iEfi UPRIGNT-iNVERTD dNVERTED MUFFLER UPRIGHTINVERTED UPRIGHT MUFFLER TwinTwa TubeeSinai TubeSinale TubTube 2135 OMUET V SCALE INSTRUMENT KITS OIeIOIO 112 di.575 SIIdia750 IlflO die660 330 QMfIT2 2250 QMTTS 30 t 15 MUFFLERS QMIST 30 5 MUFFLERS 2295 Max 302095Max 30US br 31UUbra 91Is. MakI 15 335 MakI 15 1905 a. ea 2005 nuat leading dualem avallabIe ORDER DIRECT Add 10% peetage hanilng CaIN residents add 6% tax Check Cod accepted card number date wIth VISA MASTER CARD looking tiny cracks discolorations run perpendicular grain wood defects called compression cracks occur tree falls across another ground areas weaker un damaged wood wing spar cut sheet may break compression cracks Can test wood somehow Go head class Photo 1 shows piece spar wood being tested stiffness stand left holds balsa strip given height above table top scale set end balsa strip weight hung strip amount deflection caused weight can measured course absolute measurement identical testing must performed candidate strip results compared can judge stiffness spars cut various sheets balsa After awhile get feel what required both strength standpoint stiff ness standpoint Note test does locate stress points soft points wood compression cracks may have over looked find type defect cut test strip balsa sheet appears best Hold strip ends force bow deep curve Soft areas wood will show up strip bends smaller radius will snap compression cracks created stress point nicking wood cut strip will fail stress point can make tester Photo 2 shows closeup clamp holds strip testing clamp tiny dolls clothespin glued stand look closely can see thin strip wood -in long has glued inside clamp jaw strip avoids damage strip being tested spread ing clamp force over wide area being soft balsa strip bottom clamp inset level top bar also supports strip Photo 3 shows closeup scale cheap plastic ruler has darkened top graduation marks marker pen Note ruler molded calibration marks higher surrounding plastic An engraved ruler would have sunken marks can filled similar marker material highlighted strip glued balsa strip tight slide fit groove built up thin balsa strips Another use tester Note tester shown Figure 1 can also used match prop half-spars deflection same major bend axis prop will likely flare equally under high torque Without equal flare prop will wobble under high torque waste some energy motor Test halfspar several weights hung two three points along spar compare results Take enough time make good records compare future prop spars ones stiff ness Such careful testing essential being able build props either very similar vary widely enough give choice different flares different conditions Bud Tenny P 0 Box 545 Richardson TX 75080 Chipmunk Mods/Petro Continued page 74 equipment tray compartment fuel tank 5-mm epoxy provides good bonding surface adhering servos receiver fuel tank recesses thin servo mounting tape Study pictures see engine mount fitted will have bit cut try eyeball engineering call Use sand paper bevel outside edges engine mount close fit inside walls electric motor mount will assure good tight joint epoxied permanently place Fit mount about two degrees downthrust degree right thrust Care getting offset will result better flying ship lot less trim problem Install blind nuts mount proper place inverting engine little tip coat entire mount Hot Stuff Super T drill holes mounting screws blind nuts Coat insides drilled holes will have fuel-proof mount drop Hot Stuff around flanges blind nuts will keep pushing out Screw engine onto mount insert position Check see plastic needs removed front moulded motor mount may take little trimming crankshaft housing have clearance Remove engine mount liberally coat front sides mount Hobbypoxy Formula 2 install mount final position previously should have roughened inside surface moulded plastic mount better epoxy adhesion As epoxy curing make certain proper thrust offset maintained Wing Ailerons absolute must model because designed fly rudder does very well would shame come far enjoy benefits ailerons slick axial rolls impres sive reverse Cuban eights Heres UC OLD THE NEW FIREBALL GLOW PLUGS ARE LEAKPROOF AND BLOWOUT PROOF EVEN FOR THE NEW MONSTER ENGINES BUT THEY ARE STILL THE OLD PRICE OF $170 WRITE NOW! SWANSON PO Box 151 WayneNA 07470 136 Model Aviation Cuts Coverite & Monokote better other longer blade Lasts much CURVED PROTECTCOVER &TABLETLETSYOU TRIMITIN YOUR POCKET COVERITE 420 Babylon Rd Horsham Pa100
Edition: Model Aviation - 1981/07
Page Numbers: 66, 135, 136
tee Flight Indoor Bud Tenny ANOTHER really big show has already noted elsewhere 1981 Indoor Nats will held West Baden IN super-site atrium Northwood Institute Nats will followed another Peanut Grand Prix annual fly-in National Indoor Model Airplane Society NIMAS Nats will lead off really wild week activity day test flying three days competition Peanut Grand Prix will give Peanut Scale fliers another crack other both relatively normal events far-out fun events spring fevered imagination John Martin Miami all-Indoor club Miami Indoor Airplane Model Association MIAMA Whats SNART Finally NIMAS winds up week-long festivities holding Sixth NIMAS Annual Record Trials SNART year meet furnishes change pace modelersmostly NIMAS members limited group competition events have AMA record status unusual fliers compete against existing records instead against other activity called NIMAS Index winning scores computed dividingthe actual flight time existing record time result winner may flying Ornithopter second place model may Novice Pennyplane comes about flight times compared record time Ornithopter flight may have boosted AMA record 5% score 105 Pennyplane flight may have just under existing record score 995 995% record time other competition may include nonAMA events head-to-head competition usual manner unusual format Index competition gives another dimension fliers strategy does have get best possible flight model has decide several events expertise strongest An unexpected by-product Index flying much less cut-throat normal competition Everyone flies pretty much mood strikes everyone enjoys activity Indoor wood selection things enhances challenge Indoor modeling build models fly better weighing less time required build model might expect before tries course Indoor models built various fix tures improve accuracy con struction make job handling small pieces balsa easier takes time build fixtures Once fixtures particular design have built block time removed building time real chunk time involved building models agonizing choice wood use However since Indoor classes have no minimum weight rules strength wood models great importance structure built really prime wood might up 25% lighter same strength What strong wood Balsa wood comes incredible range density less four pounds per cubic foot over 15 pounds per cubic foot very light balsa tends quite stiff compared similar weight higher density balsa two extremes strength materials structureswe can consider some given force applied structure will cause break course whole story Glass apparently very strong must exert relatively high force against example rim drinking giass before breaks key item stiffness since giass apparently does bend deform noticeably before breaks does yield glass probably will shatter tiny pieces similar plastic utensil may mash flat under much less force still break Which stronger giass plastic copy practical stand point either container far stronger needs to fulfill intended purpose bring ing liquid lips Neither extra strength nor stiffness either container has meaning until some unusual event mere fall floor probably will destroy glass plastic item will bounce harmlessly around crushing force could permanently distort plastic spoiling its ability quench thirst 66 Model Aviation Two simple balsa fixtures weight make tester spar stiffness see column Atinydollsclou-iespsn useu rora ciamp stiffness-tester thin balsa liner glued clothespin cushion piece wood being tested photos Tenny Continued page 135 piassic ruier iss raisea graauations nave nigniignsea wHin magic marerj rurnisnes vertical reference marker aid measuring deflection balsa strip being tested oldest modeling Free Flight clubs United States Thanks Russ James Fresno GMAC passing along invitation neighborhood September 26-27 stop have go part $3000 jackpot National Free Flight Society NFFS has just announced recipients Free Flight Hall Fame awards 1981 awards given individuals have contributed different ways development continuity FF model aiplane activities USA throughout world Maxwell Bassett revolution man challenged 1932 rules competition flying model aircraft powered internal com bustion engines events previously flown rubber-powered craft developed successful competition models easily successfully built thousands William L Effinger developer manu facturer tremendous variety award-winning kits can forget mark left hobby Berkeley models Duke Fox developer manufacturer engines priced within financial reach modelers have competitive potential started trend hoC fuels use today Joe Lucas deceased real expert/teacher writer subject model airplanes during 1 920s Chicago area authored columns newspapers magazines also won 1926 1928 Mulvihill event Joe Ott American youth 1930s 1 940s new him aeronautical expert Model kits made company could found hobby shops hardware stores dime stores etc Developer simplified model-assembly techniques awards will made NFFS 1981 AMA Nationals Seguin TX August 6 730 pm FF Indoor/Tenny Continued page 66 Bock Indoor models appears stiff ness rather ultimate strength may well important balsa build Indoor models largely true However con sider model never shrug offmore stress imposed flight loads could built very lightly very us have touch needed handle Indoor model twice strong needs could magically appear flight fully wound being touched human hands Another factor type ceiling site condition air super-light very stiff model quite possibly will survive flights under condi tions especially high drift brings out steering balloon problem very stiff structure can rather easily bent beyond its limit during rafter bounce steering attempt usually model shatters Let bend Suppose model bit flexible may well last much longer stiff model So can get flexible model still light strong answer use heavier moredensebalsabelieveitornot Hereshow use example six-pound wood instead four-pound wood make cross section wood enough smaller structure weight same before Now some what simplified since balsa varies density strength overall quality Before cutting spar sheet balsa examine sheet under magnifying glass NORTHERN CALIFORNIAS LARGEST1 DISCOUNT HOBBY SHOPI well FUELyouI New high film strength lubricant creased power engine lifeI Iquality ingredients IJto cut varnish I II II II II II II II II II II II IHOURS Monday thru weonesooy v ju-o ju inursoay C rrioay vJu-auuI L rday930-600 Sunday 1200-500 riD QQ4_ MaiW1735 bqa at04t7SSQ4NEO675QTC695 QUADRAQUADRAQUADRAQUADRAQUADRA INVERTED MII~iEfi UPRIGNT-iNVERTD dNVERTED MUFFLER UPRIGHTINVERTED UPRIGHT MUFFLER TwinTwa TubeeSinai TubeSinale TubTube 2135 OMUET V SCALE INSTRUMENT KITS OIeIOIO 112 di.575 SIIdia750 IlflO die660 330 QMfIT2 2250 QMTTS 30 t 15 MUFFLERS QMIST 30 5 MUFFLERS 2295 Max 302095Max 30US br 31UUbra 91Is. MakI 15 335 MakI 15 1905 a. ea 2005 nuat leading dualem avallabIe ORDER DIRECT Add 10% peetage hanilng CaIN residents add 6% tax Check Cod accepted card number date wIth VISA MASTER CARD looking tiny cracks discolorations run perpendicular grain wood defects called compression cracks occur tree falls across another ground areas weaker un damaged wood wing spar cut sheet may break compression cracks Can test wood somehow Go head class Photo 1 shows piece spar wood being tested stiffness stand left holds balsa strip given height above table top scale set end balsa strip weight hung strip amount deflection caused weight can measured course absolute measurement identical testing must performed candidate strip results compared can judge stiffness spars cut various sheets balsa After awhile get feel what required both strength standpoint stiff ness standpoint Note test does locate stress points soft points wood compression cracks may have over looked find type defect cut test strip balsa sheet appears best Hold strip ends force bow deep curve Soft areas wood will show up strip bends smaller radius will snap compression cracks created stress point nicking wood cut strip will fail stress point can make tester Photo 2 shows closeup clamp holds strip testing clamp tiny dolls clothespin glued stand look closely can see thin strip wood -in long has glued inside clamp jaw strip avoids damage strip being tested spread ing clamp force over wide area being soft balsa strip bottom clamp inset level top bar also supports strip Photo 3 shows closeup scale cheap plastic ruler has darkened top graduation marks marker pen Note ruler molded calibration marks higher surrounding plastic An engraved ruler would have sunken marks can filled similar marker material highlighted strip glued balsa strip tight slide fit groove built up thin balsa strips Another use tester Note tester shown Figure 1 can also used match prop half-spars deflection same major bend axis prop will likely flare equally under high torque Without equal flare prop will wobble under high torque waste some energy motor Test halfspar several weights hung two three points along spar compare results Take enough time make good records compare future prop spars ones stiff ness Such careful testing essential being able build props either very similar vary widely enough give choice different flares different conditions Bud Tenny P 0 Box 545 Richardson TX 75080 Chipmunk Mods/Petro Continued page 74 equipment tray compartment fuel tank 5-mm epoxy provides good bonding surface adhering servos receiver fuel tank recesses thin servo mounting tape Study pictures see engine mount fitted will have bit cut try eyeball engineering call Use sand paper bevel outside edges engine mount close fit inside walls electric motor mount will assure good tight joint epoxied permanently place Fit mount about two degrees downthrust degree right thrust Care getting offset will result better flying ship lot less trim problem Install blind nuts mount proper place inverting engine little tip coat entire mount Hot Stuff Super T drill holes mounting screws blind nuts Coat insides drilled holes will have fuel-proof mount drop Hot Stuff around flanges blind nuts will keep pushing out Screw engine onto mount insert position Check see plastic needs removed front moulded motor mount may take little trimming crankshaft housing have clearance Remove engine mount liberally coat front sides mount Hobbypoxy Formula 2 install mount final position previously should have roughened inside surface moulded plastic mount better epoxy adhesion As epoxy curing make certain proper thrust offset maintained Wing Ailerons absolute must model because designed fly rudder does very well would shame come far enjoy benefits ailerons slick axial rolls impres sive reverse Cuban eights Heres UC OLD THE NEW FIREBALL GLOW PLUGS ARE LEAKPROOF AND BLOWOUT PROOF EVEN FOR THE NEW MONSTER ENGINES BUT THEY ARE STILL THE OLD PRICE OF $170 WRITE NOW! SWANSON PO Box 151 WayneNA 07470 136 Model Aviation Cuts Coverite & Monokote better other longer blade Lasts much CURVED PROTECTCOVER &TABLETLETSYOU TRIMITIN YOUR POCKET COVERITE 420 Babylon Rd Horsham Pa100
Edition: Model Aviation - 1981/07
Page Numbers: 66, 135, 136
tee Flight Indoor Bud Tenny ANOTHER really big show has already noted elsewhere 1981 Indoor Nats will held West Baden IN super-site atrium Northwood Institute Nats will followed another Peanut Grand Prix annual fly-in National Indoor Model Airplane Society NIMAS Nats will lead off really wild week activity day test flying three days competition Peanut Grand Prix will give Peanut Scale fliers another crack other both relatively normal events far-out fun events spring fevered imagination John Martin Miami all-Indoor club Miami Indoor Airplane Model Association MIAMA Whats SNART Finally NIMAS winds up week-long festivities holding Sixth NIMAS Annual Record Trials SNART year meet furnishes change pace modelersmostly NIMAS members limited group competition events have AMA record status unusual fliers compete against existing records instead against other activity called NIMAS Index winning scores computed dividingthe actual flight time existing record time result winner may flying Ornithopter second place model may Novice Pennyplane comes about flight times compared record time Ornithopter flight may have boosted AMA record 5% score 105 Pennyplane flight may have just under existing record score 995 995% record time other competition may include nonAMA events head-to-head competition usual manner unusual format Index competition gives another dimension fliers strategy does have get best possible flight model has decide several events expertise strongest An unexpected by-product Index flying much less cut-throat normal competition Everyone flies pretty much mood strikes everyone enjoys activity Indoor wood selection things enhances challenge Indoor modeling build models fly better weighing less time required build model might expect before tries course Indoor models built various fix tures improve accuracy con struction make job handling small pieces balsa easier takes time build fixtures Once fixtures particular design have built block time removed building time real chunk time involved building models agonizing choice wood use However since Indoor classes have no minimum weight rules strength wood models great importance structure built really prime wood might up 25% lighter same strength What strong wood Balsa wood comes incredible range density less four pounds per cubic foot over 15 pounds per cubic foot very light balsa tends quite stiff compared similar weight higher density balsa two extremes strength materials structureswe can consider some given force applied structure will cause break course whole story Glass apparently very strong must exert relatively high force against example rim drinking giass before breaks key item stiffness since giass apparently does bend deform noticeably before breaks does yield glass probably will shatter tiny pieces similar plastic utensil may mash flat under much less force still break Which stronger giass plastic copy practical stand point either container far stronger needs to fulfill intended purpose bring ing liquid lips Neither extra strength nor stiffness either container has meaning until some unusual event mere fall floor probably will destroy glass plastic item will bounce harmlessly around crushing force could permanently distort plastic spoiling its ability quench thirst 66 Model Aviation Two simple balsa fixtures weight make tester spar stiffness see column Atinydollsclou-iespsn useu rora ciamp stiffness-tester thin balsa liner glued clothespin cushion piece wood being tested photos Tenny Continued page 135 piassic ruier iss raisea graauations nave nigniignsea wHin magic marerj rurnisnes vertical reference marker aid measuring deflection balsa strip being tested oldest modeling Free Flight clubs United States Thanks Russ James Fresno GMAC passing along invitation neighborhood September 26-27 stop have go part $3000 jackpot National Free Flight Society NFFS has just announced recipients Free Flight Hall Fame awards 1981 awards given individuals have contributed different ways development continuity FF model aiplane activities USA throughout world Maxwell Bassett revolution man challenged 1932 rules competition flying model aircraft powered internal com bustion engines events previously flown rubber-powered craft developed successful competition models easily successfully built thousands William L Effinger developer manu facturer tremendous variety award-winning kits can forget mark left hobby Berkeley models Duke Fox developer manufacturer engines priced within financial reach modelers have competitive potential started trend hoC fuels use today Joe Lucas deceased real expert/teacher writer subject model airplanes during 1 920s Chicago area authored columns newspapers magazines also won 1926 1928 Mulvihill event Joe Ott American youth 1930s 1 940s new him aeronautical expert Model kits made company could found hobby shops hardware stores dime stores etc Developer simplified model-assembly techniques awards will made NFFS 1981 AMA Nationals Seguin TX August 6 730 pm FF Indoor/Tenny Continued page 66 Bock Indoor models appears stiff ness rather ultimate strength may well important balsa build Indoor models largely true However con sider model never shrug offmore stress imposed flight loads could built very lightly very us have touch needed handle Indoor model twice strong needs could magically appear flight fully wound being touched human hands Another factor type ceiling site condition air super-light very stiff model quite possibly will survive flights under condi tions especially high drift brings out steering balloon problem very stiff structure can rather easily bent beyond its limit during rafter bounce steering attempt usually model shatters Let bend Suppose model bit flexible may well last much longer stiff model So can get flexible model still light strong answer use heavier moredensebalsabelieveitornot Hereshow use example six-pound wood instead four-pound wood make cross section wood enough smaller structure weight same before Now some what simplified since balsa varies density strength overall quality Before cutting spar sheet balsa examine sheet under magnifying glass NORTHERN CALIFORNIAS LARGEST1 DISCOUNT HOBBY SHOPI well FUELyouI New high film strength lubricant creased power engine lifeI Iquality ingredients IJto cut varnish I II II II II II II II II II II II IHOURS Monday thru weonesooy v ju-o ju inursoay C rrioay vJu-auuI L rday930-600 Sunday 1200-500 riD QQ4_ MaiW1735 bqa at04t7SSQ4NEO675QTC695 QUADRAQUADRAQUADRAQUADRAQUADRA INVERTED MII~iEfi UPRIGNT-iNVERTD dNVERTED MUFFLER UPRIGHTINVERTED UPRIGHT MUFFLER TwinTwa TubeeSinai TubeSinale TubTube 2135 OMUET V SCALE INSTRUMENT KITS OIeIOIO 112 di.575 SIIdia750 IlflO die660 330 QMfIT2 2250 QMTTS 30 t 15 MUFFLERS QMIST 30 5 MUFFLERS 2295 Max 302095Max 30US br 31UUbra 91Is. MakI 15 335 MakI 15 1905 a. ea 2005 nuat leading dualem avallabIe ORDER DIRECT Add 10% peetage hanilng CaIN residents add 6% tax Check Cod accepted card number date wIth VISA MASTER CARD looking tiny cracks discolorations run perpendicular grain wood defects called compression cracks occur tree falls across another ground areas weaker un damaged wood wing spar cut sheet may break compression cracks Can test wood somehow Go head class Photo 1 shows piece spar wood being tested stiffness stand left holds balsa strip given height above table top scale set end balsa strip weight hung strip amount deflection caused weight can measured course absolute measurement identical testing must performed candidate strip results compared can judge stiffness spars cut various sheets balsa After awhile get feel what required both strength standpoint stiff ness standpoint Note test does locate stress points soft points wood compression cracks may have over looked find type defect cut test strip balsa sheet appears best Hold strip ends force bow deep curve Soft areas wood will show up strip bends smaller radius will snap compression cracks created stress point nicking wood cut strip will fail stress point can make tester Photo 2 shows closeup clamp holds strip testing clamp tiny dolls clothespin glued stand look closely can see thin strip wood -in long has glued inside clamp jaw strip avoids damage strip being tested spread ing clamp force over wide area being soft balsa strip bottom clamp inset level top bar also supports strip Photo 3 shows closeup scale cheap plastic ruler has darkened top graduation marks marker pen Note ruler molded calibration marks higher surrounding plastic An engraved ruler would have sunken marks can filled similar marker material highlighted strip glued balsa strip tight slide fit groove built up thin balsa strips Another use tester Note tester shown Figure 1 can also used match prop half-spars deflection same major bend axis prop will likely flare equally under high torque Without equal flare prop will wobble under high torque waste some energy motor Test halfspar several weights hung two three points along spar compare results Take enough time make good records compare future prop spars ones stiff ness Such careful testing essential being able build props either very similar vary widely enough give choice different flares different conditions Bud Tenny P 0 Box 545 Richardson TX 75080 Chipmunk Mods/Petro Continued page 74 equipment tray compartment fuel tank 5-mm epoxy provides good bonding surface adhering servos receiver fuel tank recesses thin servo mounting tape Study pictures see engine mount fitted will have bit cut try eyeball engineering call Use sand paper bevel outside edges engine mount close fit inside walls electric motor mount will assure good tight joint epoxied permanently place Fit mount about two degrees downthrust degree right thrust Care getting offset will result better flying ship lot less trim problem Install blind nuts mount proper place inverting engine little tip coat entire mount Hot Stuff Super T drill holes mounting screws blind nuts Coat insides drilled holes will have fuel-proof mount drop Hot Stuff around flanges blind nuts will keep pushing out Screw engine onto mount insert position Check see plastic needs removed front moulded motor mount may take little trimming crankshaft housing have clearance Remove engine mount liberally coat front sides mount Hobbypoxy Formula 2 install mount final position previously should have roughened inside surface moulded plastic mount better epoxy adhesion As epoxy curing make certain proper thrust offset maintained Wing Ailerons absolute must model because designed fly rudder does very well would shame come far enjoy benefits ailerons slick axial rolls impres sive reverse Cuban eights Heres UC OLD THE NEW FIREBALL GLOW PLUGS ARE LEAKPROOF AND BLOWOUT PROOF EVEN FOR THE NEW MONSTER ENGINES BUT THEY ARE STILL THE OLD PRICE OF $170 WRITE NOW! SWANSON PO Box 151 WayneNA 07470 136 Model Aviation Cuts Coverite & Monokote better other longer blade Lasts much CURVED PROTECTCOVER &TABLETLETSYOU TRIMITIN YOUR POCKET COVERITE 420 Babylon Rd Horsham Pa100