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Aviation History
1991
1991 - 3364.PDF
- 7-^<: COUNTER-ROTATING EVOLUTION N .il .....-" "TOU^&S^W' The Pond Racer is simply the best pair of engines for the job followed by the slickest frame that could point them and a pilot in the right direction *& Bob Pond has built a machine from scratch, with Rutan structure and with modified automotive power, to challenge the piston aircraft world speed record, monopolised until now by warbirds. Guy Norris describes the intense technology being applied to this sporty dream. Photographs by Craig Schmitman. cc T: hat's not just a hot new airplane you're looking at out there...it could be the beginning of a revolution," said the Reno air race goer. The roar of engines grew and all eyes strained to pick out the diminutive shape of the new Pond Racer speeding against the Nevada backdrop and its "war- bird" competitors. Seconds later, disaster threatened as flames erupted from the port engine cowl ing, and pilot Rick Brickert was forced to nurse the smoking aircraft to an early landing. The incident, in mid-September, underscored two points; the Pond Racer has vast potential for speed — it qualified easily for the races at 348kt (400mph or644km/h) — and it showed that far more development work was needed. GENESIS Flying the aircraft at Reno was the realisa tion of a three-year-old dream for its owner, former US Navy pilot and aircraft collector, Bob Pond. As the owner/operator of more than 20 restored Second World War combat aircraft ("warbirds"), he objects to the high mortality rate of these rare machines through racing. "It disturbed me to see these historic fighter-planes, of which there are precious few left in the world, disman tled and modified for air racing, never to be the same again. Each year we are losing an irreplaceable part of our aviation history." To offset the "unnatural wastage" of warbirds, Pond believes that purpose-built racing aircraft using state-of-the-art manu facturing and propulsion technology could be used for air racing in the future. Pond floated the concept with round-the- world Voyager pilot Dick Rutan at the Experimental Aircraft Association's Oshkosh show, and in 1988 contracted Rutan's brother Burt's Scaled Composites company to design and produce a proto type. Dick Rutan later became chief test pilot and managing director of Bob Pond Racing, set up to develop the aircraft. In the requirements issued in a statement of work from Pond in October 1987, it also emerged that meeting the target of replacing warbirds would bring other targets within reach. "The design goal is a new aircraft, using state-of-the-art aerodynamics, struc tures and propulsion, that can capture a new piston world speed record and have adequate performance to ensure a clear margin of victory over current Reno compe titors," says the Mojave, California-based design company. DESIGN CONCEPTS To meet Pond's requirements, several pro posed configurations were developed and analysed. As a baseline for performance against which to judge the various concepts, Scaled Composites began with a clean sheet and set the rules for the perfect racer. Using a computer program, the com pany's design team drew possible paths around the Reno race course showing the theoretical, but impossible, shortest dis tance to be 14.8km (8nm). The computer drew an arc through three pylons to show the turn radius required to navigate around the three tightest corners of the race course. The path was then modified using a spline curve fit, and some smoothing added to produce a tight path around the course. The computer showed that the distance was then 15.2km, with a minimum turn radius of 2,480ft (756m) around pylons one and two. To make this turn at 435kt would require g levels of about 6.8 — much too high for modified warbirds without a major loss of airspeed. More typical paths showing a distance of 15.8km required less ambitious g levels of between 3.5 and 4. The team then considered the difference between two aircraft, each capable of 435kt, but one able to sustain 6.8g and the other 4g. The apparent lap speed for the first was 407kt, for the second, 425kt. This is. a lap difference of 18kt or 3s at the same ground speed. "If an aircraft can be built with lower induced drag while taking the tight path, it can fly the course faster even with the same top speed," says the company. Typical Reno warbirds such as the North American P-51 Mustang, Grumman F8F Bearcat, Vought F4U Corsair, Hawker Sea Fury and occasional Lockheed P-38 Light ning have wings that are larger than neces- 28 FLIGHT INTERNATIONAL 25 December, 1991 - 7 January, 1992
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