Plane & Pilot
Tuesday, July 23, 2013

The Sound Of Thunder

For those seeking a more economical alternative to the max performance of a P-51, the Thunder Mustang should satisfy your inner need for speed

The Thunder was the long-term dream of Dan Denney, a designer from Idaho who made his initial reputation by designing and building the experimental Kitfox. This small Rotax-powered fabric-covered folding-wing, store-it-in-your-garage two-seat taildragger was wildly successful, and Denney built and sold over 1,000 kits before selling the company and initiating his concept of a 3⁄4-scale all-composite P-51.

Denny began R&D on the Thunder Mustang project outside Nampa, Idaho, in the early 1990s and had a flying prototype by the mid-1990s. The resulting airplane was a near-perfect Mustang copy, but with a fuselage scaled down to 3⁄4 of the Mustang's, and wings reduced to 5⁄8 scale. Wingspan and area are reduced disproportionately, since the Thunder weighs only about a third of the original North American fighter. (Denny also told me the cockpit is two-and-a-half inches wider than scale. You can reduce the size of the airplane, but you can't shrink the pilots.)

The heart of the Thunder Mustang is Ryan Falconer's remarkable all-aluminum V12 engine. Falconer traces his engine expertise back to Roger Penske, Andy Granatelli and Galles Racing. His engines have won the Indianapolis 500 and have become standards for the Can-Am and Trans-Am racing series, and his company, RF Industries, has been building high-performance competition auto and boat engines for the last 30 years.

When Denney came to Ryan Falconer 20 years ago and proposed that the new Thunder Mustang would be the perfect vehicle for an aviation application of the Falconer V12, Falconer agreed and set to work redesigning the engine for aviation application.

In some respects, Falconer's 600-cubic-inch power plant is reminiscent of a dramatically scaled-down Rolls-Royce Merlin, though the new mill is much lighter, significantly modernized and fitted with dual FADEC systems. Unlike the original airplane's supercharged Merlin, however, the Falconer V12 is normally aspirated, typically configured to deliver optimum power at a density altitude of 5,000 feet rather than sea level. More than coincidentally, that's the elevation of Stead Field in Reno, Nev., site of the annual Reno Air Races.

The engine is redlined at 4,500 rpm, geared down 2.8 times to produce 1,607 revs at the prop. The stock propeller is a four-blade composite 94-inch diameter MT, though some builders, primarily race pilots, have switched to a three-blade Hartzell that forsakes the original Mustang look, but offers slightly less drag and better speed. Racer John Parker has turned laps of 330 knots at Reno in his airplane, Blue Thunder, and currently holds the world speed record for normally aspirated piston aircraft at better than 333 knots.

Labels: Piston Singles


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