7 March 1961: Launched over Silver Lake, a dry lake bed near the California/Nevada border, at 10:28:33.0 a.m., Pacific Standard Time, test pilot Major Robert M. White, U.S. Air Force, flew the number two North American Aviation X-15 hypersonic research rocketplane, 56-6671, to Mach 4.43 (2,905 miles per hour/4,675 kilometers per hour) and 77,450 feet (23,607 meters), becoming the first pilot to exceed Mach 4.
This was the first flight for the number two X-15 with the Reaction Motors XLR99-RM-1 engine, which was rated at 57,000 pounds of thrust (253.55 kilonewtons).
The flight plan called for a burn time of 116 seconds, an altitude of 84,000 feet (25,603 meters) and a predicted maximum speed of Mach 4.00. The actual duration of the engine burn was 127.0 seconds. Peak altitude was lower than planned, at 77,450 feet (23,607 meters). The longer burn and lower altitude translated into the higher speed.
The total duration of the flight, from the air drop from the Boeing NB-52B Stratofortress carrier, 52-008, to touchdown at Edwards Air Force Base, was 8 minutes, 34.1 seconds.
7 March 1945: At Morton Grove, Pennsylvania, Frank Nicholas Piasecki, founder (along with Harold Venzie) of the P–V Engineering Forum, made the first flight of the PV-3, a prototype for the first successful tandem rotor helicopter. The United States Navy designated the new helicopter XHRP-X. Two additional prototypes, designated XHRP-1, Bu. Nos. 37968 and 37969, were ordered. The original aircraft, a proof-of-concept aircraft, made its final flight in May.
Because of the arrangement of the fuselage, which allowed vertical clearance between the fore and aft rotors, the helicopter was popularly known as “the Flying Banana.” Internally, like many engineering test aircraft, the XHRP-X was called “the dog ship.”
Frank Piasecki was the first pilot to be licensed by the C.A.A. as a helicopter pilot.
The PV-3 was designed to be flown by two pilots and be capable of carrying 10 passengers. The fuselage was 47 feet, 2 inches (14.376 meters) long. Each of the three-bladed rotors were 41 feet (12.497 meters) in diameter. The overall height was 13 feet, 11 inches (4.242 meters). The helicopter had an empty weight of 4,279 pounds (1,941 kilograms), and gross weight of 6,420 pounds (2,912 kilograms). The helicopter had fixed tricycle landing gear with castering wheels.
The PV-3 was powered by an air-cooled, supercharged, 971.930-cubic-inch displacement (15.927 liter) Continental-built Wright Whirlwind (R-975), a nine-cylinder radial engine rated at 450 horsepower, mounted in the rear fuselage. A transmission transferred power from the engine to two driveshafts running along the top of the fuselage, to remote gearboxes, which in turn, drove the two main rotors. The rotors turned in opposite directions with each canceling the torque effect of the other. No tail (anti-torque) rotor was required, as in single-rotor helicopters. Without a tail rotor, which can absorb as much as 30% of the engines’ power, all the power can be put directly into lift and thrust, making the aircraft much more efficient.
The helicopter had a cruise speed of 100 miles per hour (161 kilometers per hour) and maximum speed of 110 miles per hour (177 kilometers per hour). Its range was 300 miles (483 kilometers).
The XHRP-1 was ordered into production as the HRP-1 and HRP 2. They were operated by the U.S. Marine Corps and U.S. Coast Guard. Including the prototypes, 28 of the helicopters were built.
The “Flying Banana” concept was later seen in the Piasecki H-21 Work-Horse, which first flew in 1952.
The Boeing CH-47F Chinook, which is currently in production, is a direct descendant of Frank Piasecki’s PV-3.