How Reno Racers Keep Their Cool
At the Reno air races, pilots know that to go fast, you have to stay cool. That’s where Pete Law comes in.
- By Preston Lerner
- Air & Space magazine, September 2012
(Page 3 of 6)
In the F-104, air passes through a heat exchanger submerged in water. The water cools the air for air conditioning in the cockpit before boiling off into steam. Greenamyer wanted to use a similar boil-off system in his Bearcat. Only instead of cooling air, he wanted to cool engine oil, just as the Me 209 had done. By bathing the oil cooler in a cold fluid, Greenamyer figured he could get rid of the two scoops in the airplane’s wings designed to provide cold air to the system. Eliminating the air scoops would reduce some aerodynamic inefficiency known as cooling drag.
Law immediately understood the concept of boil-off cooling, but he knew nothing about piston-engine aircraft. Luckily, Bruce Boland, a structural engineer he’d befriended on his first day at the Skunk Works, was a warbird fanatic. “He ate, slept, and dreamed old airplanes, especially Grummans,” Law says. “He was intimately familiar with them, and it was his lifelong dream to work on them. His hero airplane was the Bearcat.” The two formed a partnership.
Law engineered the boiler system, but instead of using water, he used ADI fluid—a 50-50 mix of water and methanol—because it cooled the oil to a lower temperature than water alone. (The unit reduced cooling drag so well that the resulting gain in airspeed was the equivalent of giving the engine an additional 200 horsepower.) Meanwhile, Boland upgraded the aerodynamic qualities of the airplane by slicking up the airframe. Flying the modified Bearcat, Greenamyer blitzed the Unlimited competition at Reno in 1965. And 1966. And 1967. And 1968. In August 1969, he flew the Bearcat to a world speed record of 483 mph. (The Fédération Aéronautique Internationale later re-calculated the speed to 482.464 mph, but the recalculation had no impact on the record.) A month later, he lapped the entire field at Reno. With nobody left to beat, Greenamyer told Law, “You and Bruce have to go off and start helping the other guys.”
His suggestion was not quite as altruistic as it sounds. Greenamyer knew that racers, fans, and, most important of all, sponsors would lose interest if the same guy won all the time. For the races to survive, they had to be competitive.
Greenamyer’s Bearcat was later enshrined in the National Air and Space Museum. Law and Boland became the Lennon and McCartney of the Unlimited air racing community. “Systems by Pete Law, Aerodynamics by Bruce Boland” was the legend painted on the fuselage of Strega, the nine-time Gold winning P-51 Mustang, but it could have been affixed to virtually every competitive entry at Reno. Red Baron, Dago Red, Dreadnought, Stiletto, Tsunami, Miss America, Rare Bear, Jeannie, Furias, Super Corsair, Mr. Awesome, Critical Mass—their fingerprints were on each of them. Boland died in 1995. “There isn’t a day that goes by that I don’t think of him,” Law says.
Wednesday, Day Three
Heat is the enemy of engines. The problem is especially acute at Reno because more power generates more heat. Back in the 1930s, aircraft engineers began cooling engines by injecting a mixture of water and methanol through a water regulator into the combustion chamber. This prevented a potentially catastrophic event—the detonation of the fuel-air mixture in each cylinder ahead of spark-plug ignition. Early, unwanted detonation, often accompanied by a death rattle known as engine knock, produces a spike in heat so extreme it can melt the aluminum on a piston. The cooling system enabled pilots to use more manifold pressure and more fuel in the air-fuel mixture that runs an engine; both translated into extra power. By the end of World War II, ADI systems were fitted to most high-performance fighters and bombers. These days, at Reno, all of the fast guys “go wet,” or run ADI.
Shortly after Law got involved in air racing, Greenamyer introduced him to Al DiMauro, the owner of Aircraft Carburetor in Burbank, California. “Al taught me everything there was to know about carburetors and water regulators,” Law says. He learned his lessons so well he began refurbishing and modifying units for DiMauro. And when DiMauro retired in 1978, Law essentially took over the part of the business that supplied the units for airplane and hydroplane racing. For an overhauled carburetor or water regulator, Law charges around $200. Law doesn’t do much hands-on carburetor work himself these days, but he remains a major supplier of ADI systems, based on water regulators that are nearly as old as he is. An ADI regulator can run as much as a grand, but, as Law told Sport Aviation editor Jack Cox in 1986, “When I sell a water-injection system, it’s warranted for life, effectively, and I come with the warranty.” At the races, his charges depend on the time he spends with a team to test and tune the cooling systems: anywhere from $50 to a couple hundred—enough, he says, to pay for his motel and meals while he’s there.
One of Law’s first customers was storied P-51 builder Dave Zeuschel, who sought his expertise in 1971. Unlike the air-cooled radial engine that Law had been working with in Greenamyer’s Bearcat, the Mustang was powered by a water-cooled V-12, so it needed an air inlet to cool the radiator. Law theorized that he could reduce the size of the scoop—and the consequent cooling drag—by spraying water into the face of the radiator. So he laboriously drilled dozens of tiny holes into quarter-inch stainless steel tubing and mounted this so-called spray bar in front of the radiator. Working with Zeuschel, he added deflector tabs and, later, injector nozzles to better atomize the water droplets. The spray bars were so effective that pretty much everybody copied them.