Radio Control: Jets

RADIO CONTROL JETS AMA TURBINE RULE CHANGE October 1998 AMAs Executive Council approved AMA Safety Committees recommendations allow thrust increase single-turbine engines new rule reads Total aircraft static thrust shall exceed 35 pounds regardless number engines static thrust dry weight ratio aircraft must within 05 09 means whole new generation turbine engines attendant large model aircraft will upon us starting year AMT Olympus rated lower 35 pounds thrust available new Golden West/Turbomin 1000 turbine rated 34 pounds thrust will available time read both engines will probably AMA-recognized have done well keeping safety oriented As result have entrusted greater power Lets enjoy keep trust Turbine Inlets Ducts evaluating turbine engines watching perform field am beginning comprehend importance consequences inlet duct design As engineer have available equations properly size flowfields column intended technical looking flying experiences gets grasp significance relative design values first illustration JPX engine F-16 Top Gun 1993 ducting open-fuselage sort sized aft nozzle opening net power extremely marginal Still memorable certainly benchmark occasion real initiation model turbine movement US same engine sized flowpath Kent Nogys Viper noticeably cleaner airframe demonstrated very strong performance top speed well above 200 mph slightly year later BVM Bob Violett Models famous philosophy area ruling flowpath analytical sizing applied results undeniable jump available power performance Turbine Committee saw same type result before after design improvements incorporated tailpipe Golden West-powered Terminator Closing tailpipe diameters proper dimensions increased installed power appreciably As observe turbine installations meets might begin notice different levels performance Sometimes true different installations same engine aircraft Overall turbines excitingthey sound right pack lot power small package offer performance exceeding fansexcept perhaps takeoff just seems some installations optimally designed deliver better results can easily distinguish real performers instance BVM models factory ducting representative airplanes already designed speed ducting shrouds inlets also optimized Recent introduction CAT April1999 117 Turbinetime AMT turbine hatches really close over fuel tanks largest turbine left end AMT Olympus Column Golden West/Turbomin 1000 turbine engine rated 34 notes static thrust limit now 35 pounds pounds thrust AMT Olympus will available year Crow Aviation Inc fleet sport airplanes shows same attention design detail resulting performance way little disappointed JPX installation BVM Maverick used standard fan inlet mated oversized shroud followed well-made tailpipe sized JPX factory specifications Power takeoff climbout very strong Top speed seemed limited primarily because oversized inlets resulting drag Maverick no slouch top speed level between 175-180 mph speed Out dive speeds significantly higher case results good airframe designed sustain speeds three four pounds heavier turbine fuel load Airframe loads way up turns takes discipline fly jet model would real jet jerk around turns model helps keep loading within marginal design limits configuration case pilots skills also limited speed ability just keep up unrecognized blessing time speed selfregulated installation design power lower speeds extra drag offset power higher speeds new Maverick old Turbinetime resurrected AMT Mercury turbine now flying new tailpipe designed fabricated installed AMT US factory Static thrust now up JPXs 12 pounds AMTs 15 pounds thrust Dry weight well above 17 pounds leading believe old readings JPX low side never trust cheap spring scales can bet Mavericks performance up up Takeoff like drag racer 0-60 mph about 2 seconds Climbout vertical right after retracting gear flaps Boy exciting Top speed flat level 180-185 mph Wait minute Thats significant increase large inlets drag increase speed quickly absorbs significant power increase small increase top speed comparison same engine Bandit demonstrating flat level speeds well above 200 mph Initially doesnt make sense Bandit three four pounds heavier especially larger fuel load Its larger has marginally lower drag BVM might debate has facts Bandit does have optimized smaller inlets both have same factory-optimized tailpipes Maverick can out-accelerate out-climb Bandit Bandit can outrun Maverick case Maverick limitations perfect couldnt handle speed neither could its fan duct designed airframe Tailpipe sizing reduces unnecessary thrust loss Large inlets induce extra drag limiting top speed vertical performance need speed optimize everything design speed resulting loads converting ducted-fan models large inlets inhibit excessive speeds thats thats bad hope learn observation Maverick makes superior airplane us average fliers Fifty-six ounces fuel result 6l/27 minutes flight time mostly 1/22/3 throttle producing 140-160 mph speeds bet BVM could fit conformal fuel 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