4 August 1960: NASA research test pilot Joseph Albert Walker set an unofficial world speed record when he flew the number one North American Aviation X-15, 56-6670, to 2,195 miles per hour (3,532.5 kilometers per hour). This was the 18th flight of the X-15 Program. It was 56-6670’s eighth flight and Walker’s fourth X-15 flight. The purpose of this test was to gradually increase the rocket plane’s speed toward its design limit.
Airdropped from the Boeing NB-52A Stratofortress mothership, 52-003, over Silver Lake, near the California-Nevada border, at 08:59:13.0 a.m., PDT, Walker fired the X-15’s two Reaction Motors XLR11-RM-13 rocket engines for 264.2 seconds. The X-15 accelerated to Mach 3.31 and climbed to a peak altitude of 78,112 feet (23,810 meters). [The two XLR11s were used as an interim powerplant until the Reaction Motors XLR99 was ready. The combined thrust of both LR11s was only slightly more than the idle thrust of the XLR99.]
Walker touched down on Rogers Dry Lake at Edwards Air Force Base, California, after a flight of 10 minutes, 22.6 seconds.
Joe Walker with X-15 56-6670 on Rogers Dry Lake. (NASA)
A U.S. Air Force Sikorsky H-5F lifts off during the Korean War. (U.S. Air Force)
4 August 1950: During the Battle of the Pusan Perimeter, wounded soldiers were evacuated from the battlefield by helicopter for the first time when a Sikorsky H-5F of Detachment F, 3rd Emergency Rescue Squadron,¹ Air Rescue Service, United States Air Force, flew Private 1st Class Claude C. Crest, Jr., U.S. Army, from the Sengdang-ni area to an Army hospital. By the end of combat in 1953, 21,212 soldiers had been medevaced by helicopters.
Only the second military helicopter, the H-5 was frequently flown overloaded and outside of its center of gravity limits. The helicopter was not armed, though the pilot normally carried an M1911 .45-caliber semi-automatic pistol, and the crewman, a .30-caliber M1 Carbine.
Eleven commercial Sikorsky S-51 helicopters had been purchased by the Air Force in 1947 and designated R-5F. This was later changed to H-5F. It was a four-place, single-engine helicopter, operated by one pilot. The cabin was built of aluminum with Plexiglas windows. The fuselage was built of plastic-impregnated plywood, and the tail boom was wood monocoque construction. The main rotor consisted of three fully-articulated blades built of metal spars and plywood ribs, covered with two layers of fabric. (All metal blades soon became available.) The three bladed semi-articulated tail rotor was built of laminated wood. The main rotor turned counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right.) Its normal operating range was 175–195 r.p.m. The tail rotor was mounted on the helicopter’s left side in a pusher configuration. It turned clockwise as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.)
Sikorsky S-51 three-view drawing with dimensions. (Sikorsky Historical Archives)
The helicopter’s fuselage was 41 feet, 1¾ inches (12.541 meters) long. The main rotor had a diameter of 48 feet, 0 inches (14.630 meters) and the tail rotor diameter was 8 feet, 5 inches (2.565 meters),² giving the helicopter an overall length of 57 feet, ½ inch (17.386 meters) with rotors turning. It was 12 feet, 11–3/8 inches (3.947 meters) high. The tricycle landing gear had a wheel base of 10 feet, 1 inch (3.073 and the tread was 12 feet, 0 inches (3.658 meters). The S-51 had an empty weight of 4,050 pounds (1,837 kilograms) and maximum gross weight of 5,300 pounds (2,404 kilograms) below 1,000 feet (305 meters) MSL.³ Fuel capacity was 100 gallons (379 liters).
The H-5F was powered by an air-cooled, supercharged, 986.749-cubic-inch-displacement (16.170 liter) Pratt & Whitney R-985 AN-5 (Wasp Jr. T1B4 ) which was placed in the fuselage behind the crew compartment with the crankshaft vertical. The R-985-AN-5 was a direct-drive, nine-cylinder radial engine with a compression ratio of 6:1. It required 91-octane aviation gasoline and was rated at 450 horsepower at 2,300 r.p.m., Standard Day at Sea Level. The R-985 AN-5 was 48.00 inches (1.219 meters) long, 46.25 inches (1.175 meters) in diameter and weighed 684 pounds (310.3 kilograms) with a magnesium crankcase.
The H-5F had a maximum speed (VNE) of 107 knots (123 miles per hour/198 kilometers per hour). Range was 275 miles (443 kilometers). The service ceiling was 14,800 feet (4,511 meters). The absolute hover ceiling was 3,000 feet (914 meters).
Sikorsky H-5, Korea. (U.S. Air Force)
¹ Reorganized as the 3rd Air Rescue Squadron 10 August 1950.
² An 8 foot, 9 inch (2.667 meter) all-metal two-blade tail rotor assembly became standard with the H-5G, and was available to retrofit earlier helicopters.
³ The maximum gross weight had to be reduced 150 pounds (68 kilograms) for each additional 1,000 feet of altitude.
LZ 4 floating out of its hangar on Lake Constance, 0600, 4 August 1908. (Bain News Service/Library of Congress)
4 August 1908: Ferdinand Adolf Heinrich August Graf von Zeppelin, to demonstrate the capabilities of his airship, LZ 4, departed from its floating hangar on Lake Constance at 6:22 a.m., 4 August 1908, on a planned 24-hour round trip down the Rhine to Basel, Strasbourg and Mainz, then back to Stuttgart, a distance of approximately 435 miles.
LZ 4 leaves the hangar on Lake Constance, 6:05 a.m., 4 August 1908.Zeppelin LZ 4 over Lake Constance. (Archiv der Luftschiffbau Zeppelin GmbH)
LZ 4 was 136 meters (446 feet, 2 inches) long and 12.95 meters (42 feet, 6 inches) in diameter. Buoyancy was provided by hydrogen contained in 17 rubberized cotton gas bags inside the dirigible’s rigid structure. The total volume of the airship was 15,008 cubic meters (530,003 cubic feet). It was propelled by two Daimler engines, producing 105 horsepower each, and driving three-bladed propellers. Its maximum speed was 48 kilometers per hour (29.8 miles per hour).
McDonnell Douglas YF-15A-1-MC Eagle, 71-0280, with McDonnell Douglas RF-4C Phantom II chase plane, in flight near Edwards AFB. (U.S. Air Force)
3 August 1972: During a 45-minute test flight at Edwards Air Force Base, the McDonnell Douglas YF-15A-1-MC Eagle prototype, 71-0280, went supersonic for the first time, reaching Mach 1.5.
An air-superiority fighter, the F-15 entered service with the United States Air Force in 1975. More than 1,500 fighter, two-seat trainer, and two-seat F-15E Strike Eagle fighter-bombers have been built by McDonnell Douglas and Mitsubishi. It is operated by allied air forces around the world and is expected to remain in front line service until 2025.
McDonnell Douglas F-15C Eagle. (Defense Media Network)
Major Robert M. White, U.S. Air Force, is greeted by his 7-year-old son, Greg, after his record-setting flight into space. “Boy, that was a ride.” (LIFE Magazine)
3 August 1962: Following his record-setting flight into space aboard an X-15 hypersonic research rocketplane, 17 July 1962, Major Robert M. White, U.S. Air Force, was featured with a cover photograph on the LIFE Magazine issue for the week of 3 August 1962. LIFE was the most prestigious news magazine of its time.
This was the first time that a manned aircraft had gone higher than 300,000 feet (91,440 meters). It was also the first flight above 50 miles (80.47 kilometers). For that achievement, Bob White became the first X-15 pilot to be awarded U.S. Air Force astronaut wings. His 314,750-foot altitude (95,936 meters) also established a Fédération Aéronautique Internationale (FAI) world altitude record, which will probably never be broken.
To qualify, a new record would have to exceed White’s altitude by at least 3%, or more than 324,419 feet (98,882.9 meters). As the FAI-recognized boundary of Space is the Kármán line (100 kilometers, or 328,083.99 feet), any prospective challenger would have to hit a very narrow band of the atmosphere.
Command Pilot Astronaut insignia, United States Air Force
Major White had been the first pilot to fly faster than Mach 4, Mach 5 and Mach 6. He was the first to fly over 200,000 feet (60,960 meters), then over 300,000 feet (91,440 meters). He was a graduate of the Air Force Experimental Test Pilot School and flew tests of many aircraft at Edwards before entering the X-15 program. He made at total of sixteen X-15 flights.
In this photograph, Lieutenant Robert M. White is on the right, with Lieutenant F. Mark Johnson (left) and Major Lee G. Mendenhall (center), all of the 354th Fighter Squadron, 355th Fighter Group. Lieutenant Johnson’s fighter, Sweet “Dosey” II, is a North American Aviation P-51D-10-NA Mustang, 44-14089. (Little Friends)
A P-51 Mustang fighter pilot in World War II, Bob White was shot down on his 52nd combat mission in February 1945 and captured. He was held as a prisoner of war until the war in Europe came to an end in April 1945. White was recalled to active duty during the Korean War and was assigned to a fighter squadron stationed in Japan. Later, he flew 70 combat missions over North Vietnam in the Republic F-105 Thunderchief supersonic fighter bomber, including leading the attack against the Paul Doumer Bridge at Hanoi, 11 August 1967, for which he was awarded the Air Force Cross.
Colonel Robert M. White, United States Air Force, Deputy Commander for Operations, 355th Tactical Fighter Wing, Takhli RTAFB, 1967, with other Republic F-105 Thunderchief pilots. Colonel White is the third from the left. (U.S. Air Force)
Colonel White next went to Wright-Patterson Air Force Base, Ohio, where he was director of the McDonnell Douglas F-15 Eagle systems program. He then returned to Edwards Air Force Base, California, as commander of the Air Force Flight Test Center. White was promoted to Major General in 1975.
General White retired from the U.S. Air Force in 1981. He died 17 March 2010.
Major Robert M. White, U.S. Air Force, with a North American Aviation X-15 on Rogers Dry Lake, 1961. (NASA)
