Don Jehlik POWER SYSTEMS Ive remarked failure pay attention to un derstand details affect perfor mance source frustration types modelers obvious principle power modeling often overlooked Total performance depends attention details Problem what details dont pretend know way approach problem goal ensure satisfactory result break problem manage able bits acquire ability master bit put bits together achieve optimum performance Lets discuss some problems involved mounting engine type model First engine machine performs work Work per formed result combustion confined chamber Heat pressure stresses heat transfer mechanical conversion combustion energy mechanical forces part un derstanding nature engine lets make engine bit easier work engine vibrates pro duces heat power needs mounted such way will job intend Second what engineers call Dimensional Metrology science fitting things together will per form intended Looking prob lem engines point view bottom surfaces engine mounting lugs must mate perfectly surface placed dont lugs will forced change shape slightly bolted mount resulting stress will actually affect performance engine Heres happens piece metal mounting lugs stressed pattern stresses viewed special optical techniques shows lines stress extend lugs influence almost metal mass crankcase What happens crankcase moves engine runs moves back forth upper part cyl inder rotates slightly addition new stress introduced improper mounting changes pattern motion engine attempts relieve dynamic stresses running results changes running fits worked hard achieve breaking engine probable reduction power Metal Mounts Never assume metal mount engine flat sim ple matter sure will need sheet plate glass about thick scrap can obtained local glass shop 12 X 12 will sure plate glass because plate ground flat sheet 220 wet dry sandpaper some light oil rest supplies needed Place sandpaper glass plate wet oil Slowly evenly rub motor mount surface over paper until has matte finish Clean thoroughly Carefully set engine mount lightly push front rear lug lugs lift off mount slightest both lugs mount flat true Occasionally lugs wont seat true mount Examine bottom sur face lugs carefully dents bumps make surface uneven can removed fine file lightly rubbing file mount Drilling Tapping necessary 58 Model Aviation No matter what event fly proper mounting engines will pay handsome dividends engine its mount dont mate perfectly serious distortion loss performance can result merely tightening mounting bolts Never assume metal mount flat drill tap metal mount engine sure holes cen tered correctly drilled squarely engine properly aligned Surest way use drill press special jig hold mount pan Precision drilling tapping will covered future column metal mount attached model same fit flat-no stress principle applies mount stressed bolted model some stresses can affect engine engine vibration will unequally transmitted mount model Resulting stress can cause mount bolts Continued page 102 mount rests precisely flat sand paper after mating surface polished RC-type mounts plywood firewall mounting surface also must sanded flat Text also makes suggestions mounting beams Checking fit between engine lugs metal engine mount Requirements wood mounts detailed article March1978 59 must engine luga absolutely flat same condition applies mounts metal pan Using light oil 220-W-or-D sandpaper over plate glass author smooths off pan metal engine mount being rubbed slowly evenly over sandpaper achieve matte finish preparations carefully controlled engine hits same rpm ship stand drilling tapping metal mount make sure holes centered correctly drilled squarely engine properly aligned Note shiny surface surface trued up THE *wv/ IN TERNAI7 YO LM1ODEL ER loosen model structure weaken case RC-type mounts two approaches work well First sure back mount perfectly flat lapping carefully sand firewall sure mounting sur face also flat Second after mounting holes drilled model cut piece mylar wrap larger back mount finger coat mount surface model quick set epoxy bolt mount model mylar between lot work involved above operations results noted engine runs exactly same rpm model did test stand Wood Mounts did have time set up photos wood mounts column three important conditions satisfy First metal mounts flat matching surfaces Second stress free mounting Third durable mounting Heres suggestion flat wood mounts whether bearer type ply wood profile type put fiberglass sur face mount Before placing motor bearers model hold both bearers side side sand flat glass plate case bearers pre-constructed cross braces ladder style before installation model assemble first sand flat Next lay piece mylar glass plate cut piece regu lar weight fiberglass cloth slightly larger mount surface Using polyester slow setting epoxy brush rub resin sparingly until cloth wet throughout put thin coat mount surface Place mount wet cloth put weight until set Trim excess fiberglass razor saw file sand paper drill engine lugs have two separate bearers point bolt engine bearers before bonding model will enable retain perfect alignment engine mount build profile mount semble stub bearers balsa profile core b sand flat both sides glass plate c bond lightweight glass cloth both sides back point least 1 behind bellcrank mount lightly sand fiberglass surface flat d bond plywood doubler re peat steps b c using regular weight boat cloth instead lightweight procedure produces laminated structure durable actually creases speed profiles order 5 mph over less rigid struc ture reduction amount vibration transmitted wing/fuse lage joint reduces tendency crack greatly extends life reliability model Thats column Next month Ill discuss engine environment model fuel systems Don Jehlik 438A Schweer Dr Star Ri 1 Hawthorne NV89415 FF Duration/Meuser continued page 50 Greg Hutchison Chula Vista Calif set Senior Cat II record 834 topping own previous record set month earlier William Morgan Fresno Calif set Open Cat record 4000 using Supertigre 19 powered Satellite 450 annual all-hydro Gathering Ducks meet Gridley Calif John Drobshoff set Open -A Cat ROW mark 1114 Hydro-Star ROW kit market Also July Darryl Stevens set Junior Cargo record 60 ounces Nats August two California Seniors set Cat II Gas records Tim Young put up Supertigre 15-powered Bye Centennial designed father Lou Class B 1647 Fred Cal houn Jr put up K&B 21-powered modified Satellite 588 1500 102 Model Aviation .- * AT TROL CAT Engine Technique/Jehlik continued page 59 127
Edition: Model Aviation - 1978/03
Page Numbers: 58, 59, 102
Don Jehlik POWER SYSTEMS Ive remarked failure pay attention to un derstand details affect perfor mance source frustration types modelers obvious principle power modeling often overlooked Total performance depends attention details Problem what details dont pretend know way approach problem goal ensure satisfactory result break problem manage able bits acquire ability master bit put bits together achieve optimum performance Lets discuss some problems involved mounting engine type model First engine machine performs work Work per formed result combustion confined chamber Heat pressure stresses heat transfer mechanical conversion combustion energy mechanical forces part un derstanding nature engine lets make engine bit easier work engine vibrates pro duces heat power needs mounted such way will job intend Second what engineers call Dimensional Metrology science fitting things together will per form intended Looking prob lem engines point view bottom surfaces engine mounting lugs must mate perfectly surface placed dont lugs will forced change shape slightly bolted mount resulting stress will actually affect performance engine Heres happens piece metal mounting lugs stressed pattern stresses viewed special optical techniques shows lines stress extend lugs influence almost metal mass crankcase What happens crankcase moves engine runs moves back forth upper part cyl inder rotates slightly addition new stress introduced improper mounting changes pattern motion engine attempts relieve dynamic stresses running results changes running fits worked hard achieve breaking engine probable reduction power Metal Mounts Never assume metal mount engine flat sim ple matter sure will need sheet plate glass about thick scrap can obtained local glass shop 12 X 12 will sure plate glass because plate ground flat sheet 220 wet dry sandpaper some light oil rest supplies needed Place sandpaper glass plate wet oil Slowly evenly rub motor mount surface over paper until has matte finish Clean thoroughly Carefully set engine mount lightly push front rear lug lugs lift off mount slightest both lugs mount flat true Occasionally lugs wont seat true mount Examine bottom sur face lugs carefully dents bumps make surface uneven can removed fine file lightly rubbing file mount Drilling Tapping necessary 58 Model Aviation No matter what event fly proper mounting engines will pay handsome dividends engine its mount dont mate perfectly serious distortion loss performance can result merely tightening mounting bolts Never assume metal mount flat drill tap metal mount engine sure holes cen tered correctly drilled squarely engine properly aligned Surest way use drill press special jig hold mount pan Precision drilling tapping will covered future column metal mount attached model same fit flat-no stress principle applies mount stressed bolted model some stresses can affect engine engine vibration will unequally transmitted mount model Resulting stress can cause mount bolts Continued page 102 mount rests precisely flat sand paper after mating surface polished RC-type mounts plywood firewall mounting surface also must sanded flat Text also makes suggestions mounting beams Checking fit between engine lugs metal engine mount Requirements wood mounts detailed article March1978 59 must engine luga absolutely flat same condition applies mounts metal pan Using light oil 220-W-or-D sandpaper over plate glass author smooths off pan metal engine mount being rubbed slowly evenly over sandpaper achieve matte finish preparations carefully controlled engine hits same rpm ship stand drilling tapping metal mount make sure holes centered correctly drilled squarely engine properly aligned Note shiny surface surface trued up THE *wv/ IN TERNAI7 YO LM1ODEL ER loosen model structure weaken case RC-type mounts two approaches work well First sure back mount perfectly flat lapping carefully sand firewall sure mounting sur face also flat Second after mounting holes drilled model cut piece mylar wrap larger back mount finger coat mount surface model quick set epoxy bolt mount model mylar between lot work involved above operations results noted engine runs exactly same rpm model did test stand Wood Mounts did have time set up photos wood mounts column three important conditions satisfy First metal mounts flat matching surfaces Second stress free mounting Third durable mounting Heres suggestion flat wood mounts whether bearer type ply wood profile type put fiberglass sur face mount Before placing motor bearers model hold both bearers side side sand flat glass plate case bearers pre-constructed cross braces ladder style before installation model assemble first sand flat Next lay piece mylar glass plate cut piece regu lar weight fiberglass cloth slightly larger mount surface Using polyester slow setting epoxy brush rub resin sparingly until cloth wet throughout put thin coat mount surface Place mount wet cloth put weight until set Trim excess fiberglass razor saw file sand paper drill engine lugs have two separate bearers point bolt engine bearers before bonding model will enable retain perfect alignment engine mount build profile mount semble stub bearers balsa profile core b sand flat both sides glass plate c bond lightweight glass cloth both sides back point least 1 behind bellcrank mount lightly sand fiberglass surface flat d bond plywood doubler re peat steps b c using regular weight boat cloth instead lightweight procedure produces laminated structure durable actually creases speed profiles order 5 mph over less rigid struc ture reduction amount vibration transmitted wing/fuse lage joint reduces tendency crack greatly extends life reliability model Thats column Next month Ill discuss engine environment model fuel systems Don Jehlik 438A Schweer Dr Star Ri 1 Hawthorne NV89415 FF Duration/Meuser continued page 50 Greg Hutchison Chula Vista Calif set Senior Cat II record 834 topping own previous record set month earlier William Morgan Fresno Calif set Open Cat record 4000 using Supertigre 19 powered Satellite 450 annual all-hydro Gathering Ducks meet Gridley Calif John Drobshoff set Open -A Cat ROW mark 1114 Hydro-Star ROW kit market Also July Darryl Stevens set Junior Cargo record 60 ounces Nats August two California Seniors set Cat II Gas records Tim Young put up Supertigre 15-powered Bye Centennial designed father Lou Class B 1647 Fred Cal houn Jr put up K&B 21-powered modified Satellite 588 1500 102 Model Aviation .- * AT TROL CAT Engine Technique/Jehlik continued page 59 127
Edition: Model Aviation - 1978/03
Page Numbers: 58, 59, 102
Don Jehlik POWER SYSTEMS Ive remarked failure pay attention to un derstand details affect perfor mance source frustration types modelers obvious principle power modeling often overlooked Total performance depends attention details Problem what details dont pretend know way approach problem goal ensure satisfactory result break problem manage able bits acquire ability master bit put bits together achieve optimum performance Lets discuss some problems involved mounting engine type model First engine machine performs work Work per formed result combustion confined chamber Heat pressure stresses heat transfer mechanical conversion combustion energy mechanical forces part un derstanding nature engine lets make engine bit easier work engine vibrates pro duces heat power needs mounted such way will job intend Second what engineers call Dimensional Metrology science fitting things together will per form intended Looking prob lem engines point view bottom surfaces engine mounting lugs must mate perfectly surface placed dont lugs will forced change shape slightly bolted mount resulting stress will actually affect performance engine Heres happens piece metal mounting lugs stressed pattern stresses viewed special optical techniques shows lines stress extend lugs influence almost metal mass crankcase What happens crankcase moves engine runs moves back forth upper part cyl inder rotates slightly addition new stress introduced improper mounting changes pattern motion engine attempts relieve dynamic stresses running results changes running fits worked hard achieve breaking engine probable reduction power Metal Mounts Never assume metal mount engine flat sim ple matter sure will need sheet plate glass about thick scrap can obtained local glass shop 12 X 12 will sure plate glass because plate ground flat sheet 220 wet dry sandpaper some light oil rest supplies needed Place sandpaper glass plate wet oil Slowly evenly rub motor mount surface over paper until has matte finish Clean thoroughly Carefully set engine mount lightly push front rear lug lugs lift off mount slightest both lugs mount flat true Occasionally lugs wont seat true mount Examine bottom sur face lugs carefully dents bumps make surface uneven can removed fine file lightly rubbing file mount Drilling Tapping necessary 58 Model Aviation No matter what event fly proper mounting engines will pay handsome dividends engine its mount dont mate perfectly serious distortion loss performance can result merely tightening mounting bolts Never assume metal mount flat drill tap metal mount engine sure holes cen tered correctly drilled squarely engine properly aligned Surest way use drill press special jig hold mount pan Precision drilling tapping will covered future column metal mount attached model same fit flat-no stress principle applies mount stressed bolted model some stresses can affect engine engine vibration will unequally transmitted mount model Resulting stress can cause mount bolts Continued page 102 mount rests precisely flat sand paper after mating surface polished RC-type mounts plywood firewall mounting surface also must sanded flat Text also makes suggestions mounting beams Checking fit between engine lugs metal engine mount Requirements wood mounts detailed article March1978 59 must engine luga absolutely flat same condition applies mounts metal pan Using light oil 220-W-or-D sandpaper over plate glass author smooths off pan metal engine mount being rubbed slowly evenly over sandpaper achieve matte finish preparations carefully controlled engine hits same rpm ship stand drilling tapping metal mount make sure holes centered correctly drilled squarely engine properly aligned Note shiny surface surface trued up THE *wv/ IN TERNAI7 YO LM1ODEL ER loosen model structure weaken case RC-type mounts two approaches work well First sure back mount perfectly flat lapping carefully sand firewall sure mounting sur face also flat Second after mounting holes drilled model cut piece mylar wrap larger back mount finger coat mount surface model quick set epoxy bolt mount model mylar between lot work involved above operations results noted engine runs exactly same rpm model did test stand Wood Mounts did have time set up photos wood mounts column three important conditions satisfy First metal mounts flat matching surfaces Second stress free mounting Third durable mounting Heres suggestion flat wood mounts whether bearer type ply wood profile type put fiberglass sur face mount Before placing motor bearers model hold both bearers side side sand flat glass plate case bearers pre-constructed cross braces ladder style before installation model assemble first sand flat Next lay piece mylar glass plate cut piece regu lar weight fiberglass cloth slightly larger mount surface Using polyester slow setting epoxy brush rub resin sparingly until cloth wet throughout put thin coat mount surface Place mount wet cloth put weight until set Trim excess fiberglass razor saw file sand paper drill engine lugs have two separate bearers point bolt engine bearers before bonding model will enable retain perfect alignment engine mount build profile mount semble stub bearers balsa profile core b sand flat both sides glass plate c bond lightweight glass cloth both sides back point least 1 behind bellcrank mount lightly sand fiberglass surface flat d bond plywood doubler re peat steps b c using regular weight boat cloth instead lightweight procedure produces laminated structure durable actually creases speed profiles order 5 mph over less rigid struc ture reduction amount vibration transmitted wing/fuse lage joint reduces tendency crack greatly extends life reliability model Thats column Next month Ill discuss engine environment model fuel systems Don Jehlik 438A Schweer Dr Star Ri 1 Hawthorne NV89415 FF Duration/Meuser continued page 50 Greg Hutchison Chula Vista Calif set Senior Cat II record 834 topping own previous record set month earlier William Morgan Fresno Calif set Open Cat record 4000 using Supertigre 19 powered Satellite 450 annual all-hydro Gathering Ducks meet Gridley Calif John Drobshoff set Open -A Cat ROW mark 1114 Hydro-Star ROW kit market Also July Darryl Stevens set Junior Cargo record 60 ounces Nats August two California Seniors set Cat II Gas records Tim Young put up Supertigre 15-powered Bye Centennial designed father Lou Class B 1647 Fred Cal houn Jr put up K&B 21-powered modified Satellite 588 1500 102 Model Aviation .- * AT TROL CAT Engine Technique/Jehlik continued page 59 127