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The Red Baron RB-51
Complying with the hot rodders premise, there ain't no replacement for displacement, the Red Baron racing team produced a race plane that, unfortunately never reached it's true potential. Based on a successful racing P-51D Mustang, Ed Browning, owner of the Red Baron Racing team purchased the aircraft in 1973. At this stage considerable airframe modifications had already been performed including clipping the wings and a highly modified cockpit canopy. Still retaining the Merlin for power, Browning campaigned the aircraft through 1974. At the end of racing for the year, Browning enlisted the help of Pete Law and Bruce Boland, two Lockheed engineers familiar with the unlimited racing scene, to modify the aircraft for Griffon power. A stockpile of former RAF Griffon 58's from Shackletons were purchased along with De Havilland/Rotol six bladed contra rotating propellers. Boland and Law totally redesigned the P-51 from the firewall forward incorporating new engine mounts cowling etc. Due to the additional length of the Griffon compared to the V-1650-9, the firewall was moved aft by 9 inches. This also helped preserve the correct centre of gravity without resorting to additional weight. Although the standard P-51 radiator ducting was retained, incorporating front to rear flow instead of the standard cross flow modified the radiator. Even with the improved radiator, heat rejection would have been inadequate therefore spray bars were incorporated. At high engine temperatures, water was sprayed onto the radiator, intercooler/aftercooler and oil cooler cores. This explains the steam trail issuing from most race planes. Starting out with a basic Griffon 58 from a Shackleton, Randy Scoville, the brilliant engine builder who built the Red Baron engines used a Griffon 64 crankshaft because of the additional counter weights on this unit, and Griffon 57 connecting rod and piston assemblies. It was felt that two stage supercharging would be essential. Consequently, a Griffon 64 blower was grafted onto the -58 crankcase. Severe space restraints would not allow the use of the -64 carburettor, therefore the intake elbow from a Mk. XIX Spitfire was modified and turned 180 degrees resulting in down draught induction. A Bendix PR-58 carburettor from a C series Pratt and Whitney R-2800 was mounted on top of the modified intake elbow. Thanks to experience working with this carburettor, it was not difficult to reflow the PR-58 for Griffon requirements. A large airscoop on top of the cowling supplied induction air. The camshafts were modified by grinding the base circle thus yielding additional lift although interestingly the timing was left stock. The profile was modified to allow a gentler lift off the seat and a similarly gentler closing for both intake and exhaust valves. Fuel was 115/145 PN with water/methanol ADI (anti detonation injection). ADI was injected at the rate of 1/2 pound for each pound of fuel burned. Propeller modifications included removing 6 inches from the tip of each blade, re-twisting the blades and modified governor springs and bob weights for increased rpm. Test flying brought to the surface handling problems which were not satisfactorily resolved for several years. Worst among them was a serious dutch roll tendency at high speed. Resolution of this characteristic required the manufacture of a totally new vertical stabilizer. As can be expected engine problems also abounded including the failure of connecting rods, one being due to a faulty rod bolt. More seriously, persistent failure of the blower gears plagued the team. The gears were custom made units that could not stand the loads being imposed upon them; power requirements for the supercharger would be in excess of 400 horsepower. Loss of the blower drive would still allow the engine to run naturally aspirated and produce enough power to effect a safe landing. By 1979 the aircraft was sufficiently well developed to make an attempt on the worlds air speed record for piston driven aircraft. In August the aircraft was flown to Tonapah, Nevada but the hoped for 100 degree temperatures never materialized. The early attempts were frustrated by numerous problems including a failed connecting rod and turbulence. On August 14, 1979 conditions were far from ideal but as good as they were going to get in the foreseeable future. Steve Hinton, the well known, brilliant race pilot took the Red Baron out with an air temperature of 68 degrees and broke the existing record with an average 499.018 mph, frustratingly close to exceeding 500. With further engine development and ideal conditions, the RB-51 could have exceeded 525 mph. 110 inches manifold pressure at a modest 2,850 rpm was used for the record attempts. The engine was potentially capable of 3,900 horsepower. Steve Hinton related to me that each additional 50 rpm yielded another 5 inches of manifold pressure. Coolant temperature was held to 100 degrees C and oil was kept at 80 degrees C. With the record in hand the aircraft was prepared for Reno, '79. During the final Gold Race with Steve Hinton in second place the old nemesis of blower gear failure occurred. This time however things went from bad to worse to catastrophic. Broken pieces of gear jammed the pressure oil pump resulting in rapid engine failure due to a failed rod. Steve could not get the prop feathered resulting in the contra prop acting as a massive air brake. The ensuing crash landing in the desert resulted in a huge fireball and total destruction of the aircraft but miraculously, Steve came out of it alive albeit seriously injured. Thus the final chapter was written on an aircraft that never saw it's true potential realized.