By Frederick A. Johnsen
Wait — what? A twin-engine RV? Only at AirVenture. Or wherever it flies, for that matter. It’s the only one going.
Jim and Ginger Tomaszewski of Clayton, Georgia, flew their stunning and diminutive TwinJAG to Oshkosh where it generates a lot of buzz. This airframe began life as a single-engine RV-6A quick-build kit in the 1990s. After flying it as a single for nine years, Jim, EAA Lifetime 590427, who has flown everything from Aztecs to DC-8s, “decided to turn it into a twin-engine.”
Jim said he kept the systems simple — each engine feeds from its own gas tank with no tank transfer between the two. “I didn’t want fuel going through the cabin,” he explained.
He figured out performance on one engine, including the potential loss of one engine on takeoff. Jim limits the airplane to runways at least 3,500 feet long, he said, to give enough room for aborting a takeoff if sufficient single-engine airspeed has not been achieved. But at speed, “I get about 200 feet a minute on one engine,” he added.
An experimental amateur-built category aircraft, the TwinJAG RV uses a pair of Corvair engines. But Jim is quick to point out these horizontal six-cylinder powerplants are far from their automotive origins, with aviation-grade parts including new crankshafts making them viable for flight. He coaxes a 175 mph cruising speed from these engines.
Jim figures the TwinJAG has an endurance of about three and a half to four hours. “Problem is, I have a two-and-a-half hour butt,” he added.
Jim Tomaszewski is not an engineer by trade, but he studied up on what such a radical conversion should entail. His self-taught plans and calculations proved to be about 95 percent correct when reviewed by a couple of trusted engineers, he said. “My wife says I put the ‘mental’ in experimental,” he quipped.
The new nose contains a baggage shelf. He figures on a 650-pound load capability for the TwinJAG. “That’s real close to what it was as a single.” During the conversion to a twin, Jim used a modified RV-10-style nose gear. And the cockpit went from a simple steam-gauge layout to a glass cockpit IFR airplane. He said it makes a stable IFR platform with a two-axis autopilot.
He likes what the TwinJAG offers as an IFR cross-country transport. His mantra for the project is: Simplicity plus redundancy equals reliability. And the name TwinJAG? That’s for Jim And Ginger, of course.