“Honey, I shrunk the Baron.”
That’s a line that Jim Tomaszewski could have used when he finally told his wife about his latest project — except they didn’t have a Baron.
What they did have was a single-engine RV-6A kit plane that Tomaszewski built in the mid-1990s. However, he and his wife, Ginger, like to go places and their single-engine tricycle-gear sport plane did not offer the redundancy he wanted in a cross-country traveling machine.
As chief pilot for a major executive jet charter service based on Long Island, New York, Tomaszewski is accustomed to having at least two engines.
“Simplicity plus redundancy equals reliability” is his motto, and with only 500 hours of single engine flight time spread out over 39 years and 20,000 hours in the air, Tomaszewski wanted a double-breasted twin.
So, rather than buying a multi-engine plane for traveling, he decided to convert his existing RV-6A.
“This project resulted from too many nights in a hotel room,” explained the charter pilot, who flies Gulfstreams and other top-tier private jets.
He ended up with more than 100 drawings before starting the conversion. To make sure he was on the right track with his proposed modifications, Jim consulted with a famous aircraft designer whom he does not wish to name.
Although always supportive of her husband, Ginger just rolls her eyes when talking about the major conversion project, which took 10 years to complete.
“Jim put the ‘mental’ in experimental,” she says with a laugh. “I thought he was crazy!”
To acknowledge his wife’s patient support, Tomaszewski named the plane Twin JAG, which stands for Jim and Ginger.
The converted plane has almost the same dimensions as a Wing Derringer, which was a light two-seat twin originally designed in 1958 by John Thorpe. After being certified, only 12 were produced prior to bankruptcy in 1982.
Modifications of Tomaszewski’s RV included increasing its wingspan. However, in order to decrease the plane’s roll rate and make it more stable for IFR operations, he did not increase the length of the ailerons.
Further modifications included a larger RV-9 vertical stabilizer and rudder and a “chopped” RV-10 nose gear to handle the additional weight of two engines.
Since Tomaszewski is not a fan of reduction gears like Rotax engines have, he chose a pair of modified Corvair direct drive air-cooled 120-horsepower car engines to power the plane.
“When I attended one of William Wynne’s FlyCorvair forums at Oshkosh, I knew immediately that I had found the right engines for my plane,” he recalls.
Wynne has been modifying the six cylinder horizontally-opposed 1960s-vintage Corvair engines for aircraft use since 1989 and his mods include many new parts and a special fifth bearing to handle the prop loads.
After making his decision, Tomaszewski attended Wynne’s “Corvair College,” where he built and ran both engines on a test stand.
“My Corvair engines run quiet and smooth,” he adds. “They are compact, simple, and powerful and I’ve not had even the first bit of trouble with them.”
For simplicity, Tomaszewski chose ground-adjustable non-feathering Sensenich fixed pitch props. And, as a simple and clever way to stop a prop from windmilling if he loses an engine, he installed a cable-activated bicycle brake caliper.
A custom-built burl wood panel features a two-screen Dynon Skyview system, along with a Garmin 430W for IFR. A two-axis autopilot, electric trim, heated seats, and a baggage compartment in the nose combine to make the plane a great traveling machine.
“We don’t fly long legs because my ‘butt range’ is only about two and a half hours,” explains Tomaszewski. “We like stopping at small airports because that’s part of the fun of general aviation. The plane draws attention wherever we go and we like showing it to people.”
The modified RV was finished and first flew as a twin in August 2018. A 40-hour Phase 1 flight test program was required just like any new Experimental plane and it has now accumulated over 80 hours.
“I was not looking for more speed and it flies exactly like my RV-6A did with a Lycoming O-320 and fixed pitch prop,” says Tomaszewski.
“Although this project checked every box and then some, it is not a commercial venture,” he adds.
The plan was to bring the unique plane to EAA AirVenture Oshkosh last year. However, the cancellation of the 2020 show meant a delayed debut in 2021. Since Jim and Ginger like to attend AirVenture in their camper, the plane is not likely to be back to Oshkosh any time soon.
The Twin JAG drew a steady stream of curious lookers at AirVenture, where it was tied down in the Homebuilt area close to the FlyCorvair booth. Interestingly, most people did not immediately see its RV-6A heritage.
Twin JAG specs
Empty weight: 1,600 pounds
Gross Weight: 2,250 pounds
Useful Load: 650 pounds
Cruise speed: 175 mph
Climb rate: 1,000 feet per minute
Single engine climb rate: 300 feet per minute
Stall speed: 67 mph clean, 64 mph dirty
Fuel capacity: 54 gallons
Fuel burn 14 gph in cruise
Range: 3.5 to 4 hours
Jim posted this video to YouTube last year:
Are there plans that can be purchased to build the Twin JAG? If so, where and how much? What should I budget to build it not including avionics?
at the end of the day i dont care what kind of engines you use they both not going to fail at the same time when you are flying over the everglades its nice to have that second fan out there you never miss the water till the well runs dry…….
I don’t know why he did this rebuild… it defies logic, performance, and the financial aspect. No real efficiency and perhaps more danger if an engine goes out… I am dumbfounded…
Weird on one hand and cool on the other. Twice the engines to overhaul with all the performance of the original. Redundancy in case of failure tho. I guess if that floats his boat.
Very interesting! Be interested in the engine out performance, single engine stall speed. Thx!
Was George Wing not the designer of the “Wing Derringer”?
Nope! Read your history books.
So, he traded one, 80 year old designed engine for 2, 60 year old design engines….and didn’t get any more performance. ?
Are 2 old engines more reliable than one old engine ? Or, is there now twice the probability of an engine failure ?
Why not just add another O-320.? He already had one.!
Upgrading to an EFI and electronic ignition system would bring the engines up to 2020 vintage.
He did not replace one 80 year old with two 60 year olds.
The Wynne engines are updated to be much more reliable.
Also, by building his own engines he does not need to be an A&P to repair them himself.
Not everyone has hundreds of thousands of dollars for aviation. If you do, good for you.
Let’s see… Build it yourself and LEARN for $13,000 each, or plunk down $30,000 each (times two) for an engine that requires an A&P. This is why more home built aircraft are registered with the FAA every year than certified.
Finally, take a few minutes and read on the Flycorvair.com web site and you will see that these engines are well thought out, reliable, and built by, and for home builders every day.
Get a valve stuck on a Lycoming or Continental. See what that costs you to repair.
And how long are you not flying, but still paying…
Then see how often valves stick on a Corvair, and how much more affordable they are to both build and repair.
Didnt I read someplace that lycoming did the design of the Corsair engine for GM?
Those are decisions you can make when you design, build and fly your own design.