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
THE POWERPL ANT The idea to use the two-rotor Mazda 13B engine seemed like a good idea at the time, Bob said. "I bought an old RX-7 for $1,000, took out the engine, and sold the car as salvage for $800." He figured that since a brand-new 13B engine cost about $4,000 and since maintenance costs would be less expensive, he'd come out ahead. "I originally thought I would be able to burn auto fuel," Bob said. However, acts by Congress mandating the blending of ethanol in auto fuel ended that option. REAL WORLD SOLUTIONS PRODUCTS Since the takeoff and cruise rpm of the rotary engine is too high for direct drive of the propeller, Bob installed an RD -1 redrive, also known as a propeller speed reduction unit (PSRU), from Tracy Crook's Real World Solutions (RWS). Crook retired in 2013, but manufacture of the unit may be assumed by CG Products. The redrive's 2.176-to-1 ratio results in a prop speed of 2,757 rpm at maximum 6,000 engine rpm. A 68-inch diameter (84-inch pitch), two- blade, carbon-fiber P-Tip prop from Prince Aircraft turns in left-hand rotation due to a rotation reversal by the RD -1 gearbox. RWS also provided the engine control units, the dual fuel pumps, and the apex seal lubrication system. Bob explained that the stock method of using engine oil to lubricate the apex seals eventually results in carbon buildup in the combustion chambers. Bob chose to install an RWS system that lubes these seals with two-stroke oil, which doesn't carbonize under high temperatures. In addition to the apex lubrication system, Bob also had to fi t the coolant radiator, two stock Mazda oil coolers, two ignition systems for the dual spark plugs fi tted to each rotor, dual alternators, an Aviation Develop- ment Corp. oil fi ltering system, and a bunch of warning sensors under the cowling. One of the best features of the custom-made cowling is the wide engine access doors. When Bob opened the left door, EAA Experimenter 15 Bob measures to determine the engine mount spacing needed to keep the aircraft within the Mustang's weight-and-balance envelope. E A A E X P _ M a r 1 4 . i n d d 1 5 EAAEXP_Mar14.indd 15 3 / 3 / 1 4 1 0 : 3 0 A M 3/3/14 10:30 AM