Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.
Issue link: http://experimenter.epubxp.com/i/271000
16 Vol.3 No.3 / March 2014 BOB ROGERS' LONE STAR MUSTANG II I thought to myself, "The only thing I see that provides a hint that I'm looking at an airplane are all the blue anodized aircraft-style hose fi ttings." Yet it all seems to work. Bob said that he aims for 43 to 45 inches of manifold pres- sure for takeof and said the turbo provides 30 inches of boost up to 17,000 feet. His other engine management target is to keep the engine coolant below 200°F. Bob said the Mazda engine exhaust noise is muffled when it's routed through the turbine wheel of the turbocharger, but "it does have its own unique sound." The exhaust note is so unusual that it always causes heads to turn when the en- gine is powered up. Bob estimated the installed engine, RD-1 redrive, and propeller weight at 360 pounds. Engine fuel-air mixtures are managed by reference to a visual-style mixture indicator mounted on the upper left corner of the instrument panel. An RWS EC-2 Program- ming and Control Module (PCM) incorporates two separate engine controllers. The PCM controller allows Bob to fine- tune the fuel-air mixtures, richen the programmed mixture for cold starts, and manually select either the A (primary) or B (secondary) engine control unit as needed for opera- tion or troubleshooting. It's mounted on the lower instru- ment panel. The PCM units control the timing and length of opening of the fuel injectors (two on each rotor—one for low-speed ops and both for ops above 16 inches MAP) and the tim- ing of the firing of the ignition coils. The coils are made by Delco and are used on many GM products, including the Corvette engine. The PCM references data from a crank angle sensor, an outside air temperature sensor, and an en- gine manifold pressure sensor. Engine fuel-air mixtures are optimized during flight using either a fuel-air gauge with an oxygen sensor probe and/or a conventional exhaust gas temperature probe. Bob installed an aftermarket knock sensor to detect the onset of detonation. He told of calling his neighbor Tom over to hit the engine with a hammer during one knock sensor testing session. After he was satisfi ed, he wired the sensor to sound an audio alert through the audio panel whenever knock (incipient detonation) takes place. Bob admitted that he'd heard the warn- ing once or twice at really high power settings. PILOT-DEPENDENT OPERATION A row of toggle switches is aligned along the upper right edge of the panel. These switches give Bob the option to select and test Battery Contactor 1 or 2, Alternator 1 or 2, Fuel Pump 1 or 2, and the primary fuel injectors or the secondary injectors on rotors 1 and 2. All these options are tested prior to fl ight. An- other switch temporarily disables each set (leading or trailing) of spark plugs on the rotors. This step is similar to testing the magnetos on a conventional aircraft engine. During takeof Bob moves all switches to the up position. After an explanation of the switches, Bob told me about "another neat thing I did." This man enjoys showing of the culmination of his work. He showed me the aural and lighted annunciator system he built. The system sends a tone to the avionics audio panel and turns on a panel-mounted light if any of several engine parameters are out of limits, including low water, fuel, oil, and voltage. N62BT rolled out of Frank Waggoner's paint shop glistening under new paint featuring a silver base coat with red and blue accent stripes. A galloping mustang sporting the colors of the Texas fl ag adorns the vertical stabilizer and rudder. Bob has logged more than 80 hours since March 18, 2009, when N62BT first flew. "I haven't had any problems," Bob added. I asked him if in hindsight he would have done anything differently. "If someone came to me for advice and I were to look back, I'd tell them to put in a Lycoming engine," said Bob. "I had to deal with a lot of uncertainties and if your time counts for anything, putting in the Mazda is just as costly as the Lycoming even though this engine works great," he continued. Bob logged many hours in rental fl eet airplanes before the fi rst fl ight in his Mustang II. He couldn't be happier with the result of his years of building. "It's a fun airplane to fl y; it re- sponds like it's reading your mind," he said. Links to various product suppliers: www.princeaircraft.com/default.aspx www.rotaryaviation.com/ www.youtube.com/watch?v=krEfY8OixqI fi rst fl ight Steve Ells (www.EllsAviation.com) has worked on airplanes since 1966. He holds an A&P;, IA, Commercial, with ME and Instrument ratings. He has written for the Cessna Pilots Association, the Aircraft Owners and Pilots Association, the Experimental Aircraft Association, and is pres- ently on staff at the Cessna Flyer and Piper Flyer magazines. He fl ies "Papa," a 1960 Piper Comanche and lives in California and Ohio with his wife Audrey. Photography by Tyson Rininger E A A E X P _ M a r 1 4 . i n d d 1 6 EAAEXP_Mar14.indd 16 3 / 3 / 1 4 1 0 : 3 0 A M 3/3/14 10:30 AM