GP-5 Super Sport Racer Debuts at Reno
By Tim Kern, for EAA
George Periera’s Chevy-powered GP-5, originally conceived as an Unlimited racer, debuted at Reno this week. Photo by Tim Kern
September 15, 2010 — George Periera, designer of such aircraft as the Osprey and GP-4, wanted to try his hand at a Reno Unlimited racer, and figured that a small, light aircraft could do the job at least as well as the big warbirds that dominated the class. So in the mid-1990s, he laid out his design, the GP-5, around a pilot who was 6-2, figuring that would be big enough for most (and realizing that he, himself, is that height).
That plane, the GP-5, debuted at Reno this year, creating quite a buzz when first seen on the ramp.
Engine choice was influenced by the availability of low-frontal-area, low-cost aftermarket “small block Chevy” parts; material was to be wood. Periera set to work to make the smallest racer he could.
Test pilot (and the most-experienced Reno racer, with over 200 races so far) Dave Morss made the first flight, and GP-5 development began.
However, the Reno Air Race Association and the Unlimited Class unexpectedly raised the minimum weight of Unlimited race planes to 4,500 pounds to block Thunder Mustangs and other small, high-performance machines from entering the class. They didn’t know about Periera’s airplane (or David Rose’s nearly ready and similarly light Unlimited project), but the rule change made the GP-5 useless as an Unlimited.
Within a couple years, the Super Sport Class broke from the successful and growing Sport Class, giving, one-off designs (Sport requires five sales of “identical” airframes) and single-seaters a place to race.
Builder George Backovich literally built, well, everything! Even items like the throttle quadrant are hand-made. The engine parts are standard “hot rod” items, blended into a 448-inch near-square package, with 10.6:1 compression, turning a 2:1 Geshwender Hy-Vo drive and M-T prop. Everything to make it all go into the airplane was hand-made. Inventiveness is apparent everywhere, but no more so than in the half-moon oil tank. “We wanted the weight up front,” said Periera.
With Lee Behel on the stick and fighting prop governor adjustment problems initially, early informal timing put the speeds at just over 320mph. (Tests back home have already exceeded 350 knots, Periera said.) Further development has to wait for a new engine, though; early on this week, the aluminum Chevy “started making metal” and the GP-5 now sits in the Sport Hangar, awaiting disassembly and the trailer ride back to California.
Look for a full feature on the GP-5 in a future issue of Sport Aviation. There is a lot of “wonderful” in this machine, and we’ll show it to you.