Big Frog Diesel Racer – A Different Kind of Green

There are only 10 Nemesis NXT racers in the world, and one happens to be in France, getting tuned up to compete in this year’s Reno Air Races in about 10 weeks.  On display last month at the Paris Air Show, the lightweight, carbon-fiber racer lacked the usual Lycoming IO-540 engine, a six-cylinder powerplant that cruises the 1,500 pound two-seater at 325 miles per hour.

Aviation International News Online’s Olivia Saucier reported, “The Big Frog racer is getting attention for more than just its tongue-in-cheek patriotic name. The French aircraft is the first carbon-fiber race plane to run on a Diesel engine powered purely by jet-A fuel. And it is turning heads here at the Le Bourget show.

“Big Frog is the brainchild of three pilots–Frank Doyen, Mario Soave and Willy Gruhier – who dreamed up the project in 2005. They wanted to prove that a high-performance aircraft with a Diesel engine could win the prestigious Reno National Championship Air Races, which take place every September in the Nevada desert.”

Big Frog combines the NXT with an SMA SR305-230 engine, which uses less fuel, produces fewer emissions and has no lead in its go-juice.  Environmentally, all it lacks is a bio-Diesel sponsor.  The SMA powerplant is four cylinders, compared to the Lycoming’s six, has 235 fewer cubic inches than the 540, and in stock trim, puts out only 230 horsepower.  The team is working on cooling, turbocharging and exhaust to pump that output up to “not something we will make public,” Big Frog team leader Franck Doyen told Ms. Saucier.

One factor that will help is the overall low weight of the airplane, 330 pounds lighter than its competitors.  The combination of light weight and presumably formidable horsepower will be a big “X” factor in the race.  No French entry has won since 1936, and no  Diesel-powered craft has ever been entered in the Sport Class in which this NXT will fly.

According to Ms. Saucier’s report, the team’s goal is to fly faster than 300 knots, with an average speed of 280 knots. The Sport Class category regularly sees speeds upwards of 350 knots.

They will have big ambitions to achieve.  Jon Sharp’s IO-540 NXT had a record year in 2009, before he and his wife left the sport to care for Mrs. Sharp’s ailing mother.  “The Team had its best year ever in the thirty plus years of racing at Reno in 2009 by setting a “record a day”.  Records were broken each time the plane was on the course, with a qualifying record of 412+ MPH. The Team followed up the Qualifying record with heat race records each day raising the bar form 393+ MPH, to 399+ Mph, to 406+ MPH in the final heat race. This only to be topped by the sizzling Super Sport Gold Race Championship speed of 407+ MPH!”

A dozen skilled team members and the backing of big sponsors such as Dassault Systèmes, financial backers such as PICY Development, and piloting by Christophe Delbos and founder Willy Gruhier, may enable Big Frog to be a big surprise for Reno’s 200,000 spectators.

As 100 octane low lead fuel becomes more scarce, and in some places, illegal, Diesel fuel will take on new prominence.  The military is moving toward more “heavy fuel” engines, airlines already rely on Jet-A, and both are investigating the promise of renewable sources for Diesel oil.

A nostrum heard in high-speed circles is that racing always leads to improvements in products offered to the general public.  The drive to win leads to leaps forward in technology, and perhaps some of those leaps will show up in private aircraft in the near future.

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