MAKING COMPOSITE O fall parts models take beating landing gear doors rank right up near top especially true fly grass runways Control Line circles have tried ways make parts bulletproof Making gear doors plywood instead balsa helped few layers lightweight cloth helped still wanted better solution problem Since fly grass time constantly repairing cracks chipped paint delicate parts Once crack developed oil soaked successive repair difficult Most models near-scale types using bare wires wasnt solution looking either During construction Spitfire February 1998 MA decided tiy molding gear doors see would end constant repairing wooden counterparts worked well easy dont think Ill ever dn other way until something better comes along two years competition havent touch up paint Start bending gear wires model upside-down use four-foot straightedge true-up tracking vertical angles important doing now lot easier trying later Temporarily install wheels wires test roll sure gear arent too far forward back prop clearance adequate Its lot work now time itnot after molding completed Make leg wire goes wing long possible prevent rotation models thick airfoils lot easier models thin airfoils bending wire along rib centerline may provide strength Make part wire least 40% leg length should very durable Wing-mounted gear always vulnerable proper engineering will help prevent unnecessary repairs down road What good bulletproof doors gear breaks wing wires trued engineered properly wing structure make up left- right-hand gear doors attach wires use plywood various thicknesses doors glue wires cyanoacrylate CyA other thin materials glues will work also use split 1/4 dowel simulate large-diameter oleo struts assemblies will plugs making molds should have details rivets oil seals braces etc want have final gear door Scale models can really add extra details such hydraulic lines scissors Put smooth finish plugs youre ready make molds Spend much time necessary because once youre done can make unlimited number beautifullydetailed gear assemblies almost no time idea May 1998 37 GEAR U Windy Urtnowski DOORS h, h WI Ann snnnnh Hardwood plug has wire running down its center Details carved plug will reflected final molded part Auto primer gives plug grain-free finish Open-face RTV rubber mold has captured scale details original wooden plug Note simulated scissor understand would have make detailed doors either way hut now can make additional sets minutes part understanding molding operation time spent well-finished plug well worth model damaged crash new gear doors can molded minutes much easier re-detailing new wooden parts Make small balsa box top sure have least clearance around edges wire inserted through box bottom gear door secured place top box now ready molding rubber Ive experimented molding materials over years opinion Dow-Corning RTV III far best material used make molds parts always release need no mold release agents whatsoever call molds soft molds opposed making polyester epoxy hard molds require draft angles mold-release agents Using material guarantees success newcomerit really easier looks Mix hardener rubber per directions Mix slowly youll get air bubbles Mix thoroughly long after think have mixed well enough Pour slowly avoid air bubbles fill box until top surface RTV III level plug Allow mold cure 24 hours gently remove plug cavity should exactly like gear door plug Insert original wire mold youre ready pour gear door its details Tip Roughen wire file Dremel cutoff wheel will pass through resin can use polyester resin actual casting prefer West System #105 epoxy resin #206 hardener Make paste mixing some mixed resin Cab-O-Sil paint mold using flux brush stiff-bristle paint brush Fill mold epoxy have left can dye epoxy color choose dyed epoxy color zinc oxide paint wore away edges would have scale weathered look finished parts mold will good plug can fix imperfections sanding repairing thick mix Cab-O-Sil resin usually paint parts molded way further work using Sig dope matches model mix own pigments Sig Lite-Coat clear get authentic scale colors want use pigments body shop supply house intended acrylic lacquer Mix pigments thinner first Sig dope gives color choices especially youre trying replicate scale paint scheme Now can pour spare set gear doors keep anyone know building same model two modelers making identical P-S ls example can mold cowl other can mold gear doors can pour extra parts partner have enjoyed molding unique parts Spitfire Seafire enjoyable friendships exchanges technology have developed since started using medium modeling Ed Gallagher deserves special thanks help project extremely pleased fellow modelers voted Spitfire winner 1996 Concours award 1996 Nats Seafire won 1997 Concours awardone five models ever awarded perfect score 20 pointsand Im sure molded gear doors other molded parts helped am always happy share information have fellow modelers can help drop line also videotaped making parts can get copy tape $1S &H y Urtnowski 96 Elliott P1 Rutherford NJ 07070 201 896-8740 Resin E-Glass Cab-O-Sil Dow-Coming RTV III tech help Florida Glue Products 4015 Georgia Ave West Palm Beach FL 33405 407 833-1863 800 771-1863 Satin-weave cloth resin carbon fiber tech help Aerospace Composites George Sparr 14210 Doolittle Dr San Leandro CA 94577 510 352-2022 Resin Tech manual & catalog free West Systems Gougeon Brothers Box 908 Bay City MI 48707-0908 517 684-7286 Great catalog tips how-to videos Fiberglast 1944 Neva Dr Dayton OH 45414 Info tech help advice Experimental Aircraft Assn Box 3086 Oshkosh WI 54903-3086 38 Model Aviation l balsa box becomes container RTV rubber mold box left place assure mold integrity Finished composite doors maintain scale detail yet thinner lighter durable wooden counterparts Sources
Edition: Model Aviation - 1998/05
Page Numbers: 37, 38
MAKING COMPOSITE O fall parts models take beating landing gear doors rank right up near top especially true fly grass runways Control Line circles have tried ways make parts bulletproof Making gear doors plywood instead balsa helped few layers lightweight cloth helped still wanted better solution problem Since fly grass time constantly repairing cracks chipped paint delicate parts Once crack developed oil soaked successive repair difficult Most models near-scale types using bare wires wasnt solution looking either During construction Spitfire February 1998 MA decided tiy molding gear doors see would end constant repairing wooden counterparts worked well easy dont think Ill ever dn other way until something better comes along two years competition havent touch up paint Start bending gear wires model upside-down use four-foot straightedge true-up tracking vertical angles important doing now lot easier trying later Temporarily install wheels wires test roll sure gear arent too far forward back prop clearance adequate Its lot work now time itnot after molding completed Make leg wire goes wing long possible prevent rotation models thick airfoils lot easier models thin airfoils bending wire along rib centerline may provide strength Make part wire least 40% leg length should very durable Wing-mounted gear always vulnerable proper engineering will help prevent unnecessary repairs down road What good bulletproof doors gear breaks wing wires trued engineered properly wing structure make up left- right-hand gear doors attach wires use plywood various thicknesses doors glue wires cyanoacrylate CyA other thin materials glues will work also use split 1/4 dowel simulate large-diameter oleo struts assemblies will plugs making molds should have details rivets oil seals braces etc want have final gear door Scale models can really add extra details such hydraulic lines scissors Put smooth finish plugs youre ready make molds Spend much time necessary because once youre done can make unlimited number beautifullydetailed gear assemblies almost no time idea May 1998 37 GEAR U Windy Urtnowski DOORS h, h WI Ann snnnnh Hardwood plug has wire running down its center Details carved plug will reflected final molded part Auto primer gives plug grain-free finish Open-face RTV rubber mold has captured scale details original wooden plug Note simulated scissor understand would have make detailed doors either way hut now can make additional sets minutes part understanding molding operation time spent well-finished plug well worth model damaged crash new gear doors can molded minutes much easier re-detailing new wooden parts Make small balsa box top sure have least clearance around edges wire inserted through box bottom gear door secured place top box now ready molding rubber Ive experimented molding materials over years opinion Dow-Corning RTV III far best material used make molds parts always release need no mold release agents whatsoever call molds soft molds opposed making polyester epoxy hard molds require draft angles mold-release agents Using material guarantees success newcomerit really easier looks Mix hardener rubber per directions Mix slowly youll get air bubbles Mix thoroughly long after think have mixed well enough Pour slowly avoid air bubbles fill box until top surface RTV III level plug Allow mold cure 24 hours gently remove plug cavity should exactly like gear door plug Insert original wire mold youre ready pour gear door its details Tip Roughen wire file Dremel cutoff wheel will pass through resin can use polyester resin actual casting prefer West System #105 epoxy resin #206 hardener Make paste mixing some mixed resin Cab-O-Sil paint mold using flux brush stiff-bristle paint brush Fill mold epoxy have left can dye epoxy color choose dyed epoxy color zinc oxide paint wore away edges would have scale weathered look finished parts mold will good plug can fix imperfections sanding repairing thick mix Cab-O-Sil resin usually paint parts molded way further work using Sig dope matches model mix own pigments Sig Lite-Coat clear get authentic scale colors want use pigments body shop supply house intended acrylic lacquer Mix pigments thinner first Sig dope gives color choices especially youre trying replicate scale paint scheme Now can pour spare set gear doors keep anyone know building same model two modelers making identical P-S ls example can mold cowl other can mold gear doors can pour extra parts partner have enjoyed molding unique parts Spitfire Seafire enjoyable friendships exchanges technology have developed since started using medium modeling Ed Gallagher deserves special thanks help project extremely pleased fellow modelers voted Spitfire winner 1996 Concours award 1996 Nats Seafire won 1997 Concours awardone five models ever awarded perfect score 20 pointsand Im sure molded gear doors other molded parts helped am always happy share information have fellow modelers can help drop line also videotaped making parts can get copy tape $1S &H y Urtnowski 96 Elliott P1 Rutherford NJ 07070 201 896-8740 Resin E-Glass Cab-O-Sil Dow-Coming RTV III tech help Florida Glue Products 4015 Georgia Ave West Palm Beach FL 33405 407 833-1863 800 771-1863 Satin-weave cloth resin carbon fiber tech help Aerospace Composites George Sparr 14210 Doolittle Dr San Leandro CA 94577 510 352-2022 Resin Tech manual & catalog free West Systems Gougeon Brothers Box 908 Bay City MI 48707-0908 517 684-7286 Great catalog tips how-to videos Fiberglast 1944 Neva Dr Dayton OH 45414 Info tech help advice Experimental Aircraft Assn Box 3086 Oshkosh WI 54903-3086 38 Model Aviation l balsa box becomes container RTV rubber mold box left place assure mold integrity Finished composite doors maintain scale detail yet thinner lighter durable wooden counterparts Sources