Presentation Date: November 18, 1999
Stu Eberhardt
Racing P-51 at Reno Air Show Racing P-51 at Reno Air Show. Talks about his experiences as an Unlimited Air Racing pilot at Reno. Stu shares a real 'down to earth' point of view of unlimited pylon racing and answers questions that you always wondered about.
"Merlin's Magic at Reno"
"My claim to fame is we have never, ever been beaten by an airplane that is a match
or a slower airplane. Usually we end up beating a faster airplane."
Since Stu Eberhardt's Air Force career ended, his life and his family's have remained intertwined with aviation. In addition to years of flying for the airlines, there has been something called Unlimited pylon air racing. At the Golden Gate Wing's November meeting Stu spoke of his involvement in the world's fastest motor sport, and showed a tape of his 1996 win in Reno's Unlimited Silver Race.
Air racing was the rage in the 1930s, a time when new designs, powerful engines, and daring fliers came together to compete in national contests. The aircraft - - Wedell-Williams, GeeBee, Travel Air Mystery Ship - - are icons of aviation's Golden Age. After World War Two, a new generation of "warbird" held the spotlight of Unlimited pylon racing, until Bill Odom's 1949 fatal crash of Beguine in Columbus, Ohio. In 1964, unlimited pylon racing, requiring only a piston-powered engine in the aircraft, returned. Since then Stead, a former Air Force base near Reno, Nevada has been the capital of air racing.
Eberhardt notes the dominating aircraft since the return of racing have been WWII fighters, notably the North American Mustang and Grumman Bearcat. Twice a Hawker Sea Fury has taken the title and once a Chance-Vought Corsair with a P&W 4360 engine. In the meantime, all three hand-made racers designed to win Reno have been lost, as have their pilots. Eberhardt says the best way to explain that phenomenon is that racing requires a great deal of endurance. World War II aircraft had to be durable.
One reason the P-51 has been a perennial favorite at Reno, beyond its airfoil and fuselage shape, is the power plant. "The outstanding feature of a Merlin engine is its supercharger. During the -30s and -40s the leading supercharger designers and builders were the British."
Preliminaries
Eberhardt says Reno is a week-long challenge. Living in a hotel and working in a 60' by 60' area of asphalt that is the pit. Three days of practice and qualifications and four days of racing. Of the 42 planes entered in the Unlimited class, 27 will get paid. Pilots must be commercial or better, with second class medical and pass a check ride with formation flying and course-racing with a check pilot, and some emergency procedure. Maneuvers include a half roll and back without losing altitude, showing the ability to escape from another aircraft's vortices using only ailerons, no rudder.
Clothing is a parachute, helmet and oxygen - - breathing protection from smoke in the event your plane's engine blows. The aircraft also must pass rigid technical inspection for safety..
The Unlimited course at Stead is 8.35 miles around. Races are held three-a-day in heats on Thursday, Friday and Saturday - - nine airplanes per race - - with the championships on Sunday. Stu says after taking off, the race planes form into a group around a T-33 jet chase plane, before entering the course somewhere around Pylon Three. Eberhardt calls it ,"a big game of chicken to see who can get first to number four. Because the first guy there has the advantage."
"The P-51 is not a particularly good diving airplane. It's very fast in level flight but it doesn't come downhill fast." Eberhardt described the modifications of his P-51 to make it more competitive. "We take the three feet off each wingtip when we go racing and we put short ailerons on. We put a low-profile canopy on it."
The Mustang
Stock power in a P-51 is 61 inches of mercury for manifold pressure, at 3000 rpm. The military version had a 67 inch war emergency power setting. 'What we do is race my airplane at 85 (inches) and 33 (-hundred rpm). When I beat Howard that year, I was going 90 and 34, which resulted in some very expensive repairs to the engine."
Stu charted the settings crews at Reno have incrementally boosted to raise aircraft performance around the course, along with the costs per lap of modifying and running the planes - -
Manifold pressure Revs. per minute Cost of mod/operations per lap
61 inches 3000 rpms $100
85 inches 3300 rpms $300
100 inches 3500 rpms $1,000
Merlin's Magic is now being overhauled, with Eberhardt planning to run it at 100 inches and 3500 rpm. For the week of racing at Reno, with practice runs, qualifications, and all the races - - you fly about 40 laps. At the lowest power setting, a lap costs about $100 - - fuel, maintenance, spark plugs, and so forth. That's the price of over-boosting the Rolls Royce Merlin engine. Stu says, "The big boys are going to 120 (inches). They're going to Reno with three engines."
Fuel - - Running at speeds around 400 miles an hour makes for high manifold pressures so high the Merlin will pre-detonate with conventional fuels, and Eberhardt says it wouldn't get half way around the course without blowing apart. Anti-detonation injection, or ADI, is the mixture of water and alcohol, injected into the supercharger to cool the engine. According to Stu, Rolls Royce says 100 degrees Celsius is the onset of detonation, which is why the cockpit has an induction temperature gauge. The ADI system on Merlin's Magic is made by Pratt & Whitney and is off of a DC-6.
Stu explains why fuel for this modified warbird is both 115 and 145 octane. "When you take off and join up, you're running at relatively low power. In the Mustang you have two fuel tanks, one in the left wing and one in the right. If we would run the join-up at this power, we'd have fouled plugs before the race started. In fact this used to happen to us. So what we did is carry low-lead in one tank and 145 in the other, and that way the plugs aren't fouled."
He also says it's pretty simple why Merlin's Magic doesn't run with nitrous oxide. Injected into an aircraft engine in short spurts, the gas brings bursts of extra power. "Because nitrous carries its own oxygen, it doesn't have to go through the normal carburetion system. And the engine is operating in a completely untested area, and that's where they blow up, We can't afford to blow up engines."
Running the Race
"Unlimited races occur in the late afternoon. Coming around pylon eight and nine (on the north side of the course) you're almost at a ninety-degree bank. You look at the pylon and see two shadows, your airplane and you see this other guy, so you can tell how he's doing. Of course, when you roll the wings level, if you see his prop spinner from your peripheral vision, he's probably going to get you."
Stu says your concentration should be outside of the windshield, looking at the next pylon. "So when you go around a pylon, you see a shadow of your airplane, the liquid-cooled Mustang has a door that opens and closes to regulate the temperature. If that door is opening as you see your shadow, your engine's overheating. You like to go around corners and not see the shadow of the door opening."
Eberhardt runs his P-51 on a "daily flight plan" - - the same power setting for each entire race of the day, as long as the engine's running well. Stu says he keeps his left hand on the canopy rail, holding both the throttle and the prop controls in place against the airframe's vibrations.
Propwash is a fact of life at Reno. Generally, says Eberhardt, if you're flying next to another airplane, if you see any part of the fuselage, you'll be clear of propwash. "But the problem is the course gets very dirty and you really can't tell who's halfway around ahead of you." Eberhardt told of one race in which his plane was dragged into a left roll by propwash. He used both hands to keep from rolling further left, only to drift out of that propwash and violently roll to the right. Stu says one of Lyle Shelton's pet phrases when he was regularly winning was, "I like being out in front. It's clean air."
Cutting pylons, appearing through the barrel atop the pole to a spotter down below, means a penalty of 3 seconds per cut times the total number of laps in the race. For example, a single cut over a six lap race would be an 18 second penalty. In twelve years of racing, Eberhardt says he has a perfect record of running the course. "I've never cut a pylon. But I've come so close. My son meets me (after a race) and the first thing I ask him is were there any pylon cuts?."
Emergencies
Eberhardt has never blown an engine in Merlin's Magic , but during a race in 1997, the plane lost its carburetor. "There are eight #7 studs that hold the carburetor on the airplane. What had occurred is I think it happened gradually, because the engine was losing power on the last lap, and I noticed things weren't going so good. When I looked at the instruments, everything was in the green. But the airplane was losing power, and when I finished the race and came by the home pylon, the engine quit just liked you turned the mags off. And, did it get quiet."
There was an extremely strong wind out of the south, which helped Stu climb immediately to 2500 feet above the airport and was down to 225 knots airspeed. He chose one of the runways which is closed for all but emergency traffic, then had to make a decision whether or not to lower the plane's landing gear. It was an important decision because if he didn't make the runway, he'd need gear up to belly-in on the desert. "When I came around, it appeared it was going to be nip and tuck, so I held the gear, I didn't put gear or flaps down. And I disappeared behind a hill, and people thought I was going to land on the desert. But just as I came up on the threshold, I saw I was going to make it, I put the gear down and just before I touched down the light turned green."
Stu says he looked up and couldn't see the end of the runway because of some T-hangars. He called Steve Hinton in the safety plane and asked if, at 200 knots, he had enough runway left, to which Hinton answered, "Plenty."
A few years ago, Eberhardt had one of his most startling racing experiences. At the start of one race, the rudder trim tab went into flight control flutter, a condition which can destroy an airplane. In this case, Stu was coming into the chute, wingtip to wingtip with eight other planes, when everything started shaking. The shaking was so violent, Stu thought the engine had blown. He pulled the throttle back and when it all smoothed out, eased the throttle forward again. Right next to Merlin's Magic was Lefty Gardner, and as Eberhardt began catching up with the rest of the aircraft, Lefty noticed Stu's mount was flying with only half the rudder intact. Eberhardt remembers Lefty saying something like, "Hey there are parts flying off your airplane."
Stu says, "And, I'm looking around and wondering who that poor guy is." Stu now races without a rudder trim tab, and with the shorter wings, without aileron trim tabs.
With the high cost of modifying and maintaining aircraft for the Unlimited Races, as well as costs for crew room and board during the week at Reno, sponsorship has become the key to even competing in the Gold category. And, in the dozen years Stu Eberhardt has raced at Reno, he has actually made money - - a claim not every pilot and crew can make.