At the left, Boeing NB-52A 52-003 carries X-15 56-6670 while on the right, NB-52B 52-008 carries X-15 56-6671. (NASA)
4 November 1960: This photo shows one of the four attempts NASA made at launching two X-15 aircraft in one day. This attempt occurred November 4, 1960.
None of the four attempts was successful, although one of the two aircraft involved in each attempt usually made a research flight.
In this case, Air Force test pilot Major Robert A. Rushworth flew X-15 #1, 56-6670, on its sixteenth flight to a speed of Mach 1.95 and an altitude of 48,900 feet (14,905 meters).
North American Aviation X-15A-2 56-6671 on Rogers Dry Lake. In addition to the lengthened fuselage and external tanks, the nose wheel strut is longer and the windshields have been changed to an oval shape. A wheeled dolly supports the aft end of the rocketplane. (NASA)
3 November 1965: Major Robert A. Rushworth made the first flight of the modified X-15A-2 rocketplane, Air Force serial number 56-6671. After a landing accident which caused significant damage to the Number 2 X-15, it was rebuilt by North American Aviation. A 28-inch (0.71 meter) “plug” was installed in the fuselage forward of the wings to create space for a liquid hydrogen fuel tank which would be used for an experimental “scramjet” engine that would be mounted on the the ventral fin. The modified aircraft was also able to carry two external fuel tanks. It was hoped that additional propellant would allow the X-15A-2 to reach much higher speeds.
The first flight with the new configuration was an “envelope expansion” flight, intended to test the handling characteristics of the X-15A-2, and to jettison the tanks (which were empty on this flight) to evaluate the separation and trajectory as they fell away from the rocketplane in supersonic flight.
Boeing NB-52A Stratofortress 52-003, The High and Mighty One, with North American Aviation X-15A-2 56-6671 mounted to the pylon under its right wing. The external propellant tanks have been brightly painted to aid tracking after they are jettisoned. (U.S. Air Force)
The X-15A-2 was dropped from the Boeing NB-52A Stratofortress 52-003, over Cuddeback Lake, 37 miles (60 kilometers) northeast of Edwards Air Force Base in the Mojave Desert of southern California. This was the only time during the 199-flight X-15 Program that this lake was used as a launch point.
The X-15 was released at 09:09:10.7 a.m., PST. Bob Rushworth ignited the Reaction Motors XLR99-RM-1 rocket engine and it ran for 84.1 seconds before its fuel supply was exhausted. This engine was rated at 57,000 pounds of thrust (253.549 kilonewtons).
The X-15 climbed to 70,600 feet (21,519 meters) and reached Mach 2.31 (1,514 miles per hour/2,437 kilometers per hour.)
The test flight went well. The external tanks jettisoned cleanly and fell away. The recovery parachute for the liquid oxygen tank did not deploy, however, and the tank was damaged beyond repair.
Rushworth and the X-15A-2 touched down on Rogers Dry Lake after a flight of 5 minutes, 1.6 seconds.
North American Aviation YF-100A Super Sabre 52-5754 during a speed record attempt at the Salton Sea, 29 October 1953. (San Diego Air and Space Museum Archives)
29 October 1953: Lieutenant Colonel Frank Kendall (“Pete”) Everest, United States Air Force, flew a new prototype air superiority fighter, North American Aviation’s YF-100A Super Sabre, serial number 52-5754, over the 3 kilometer and 15 kilometer courses at the Salton Sea, in the Colorado Desert of southeastern California.
Flying four runs over the short course, Everest averaged 757.75 miles per hour (1,219.48 kilometers per hour). Although this was 4.80 miles per hour (7.725 kilometers per hour) faster than the FAI record set three weeks earlier by Lieutenant Commander James B. Verdin, U.S. Navy, with a Douglas XA4D-1 Skyray,¹ it was not fast enough to establish a new world record under FAI rules, which required that a new record exceed the previous record by 1%.
Lieutenant Colonel Frank Kendall Everest, Jr., United States Air Force.
Next came four speed runs over the 15-to-25 kilometer course. All runs were made with the Super Sabre flying within 100 feet (30 meters) of the ground. The official Fédération Aéronautique Internationale (FAI) average speed was 1,215.298 kilometers per hour (755.151 miles per hour)—0.99 Mach. ²
The course at the Salton Sea was used because its surface lies 235 feet (72 meters) below Sea Level. The denser air causes undesired transonic effects to occur at lower speeds, but the higher air temperatures help to delay them, allowing the pilot a greater margin of control during the speed record runs.
Lieutenant Colonel Frank K. Everest and the North American Aviation YF-100A Super Sabre, 52-5754, 29 October 1953. (San Diego Air and Space Museum Archives)
Frank Kendall (“Pete”) Everest, Jr., was born 10 Aug 1920, at Fairmont, Marion County, West Virginia. He was the first of two children of Frank Kendall Everest, an electrical contractor, and Phyllis Gail Walker Everest. Attended Fairmont Senior High School, Fairmont, West Virginia, graduating in 1939. He studied at Fairmont State Teachers College, also in Fairmont, West Virginia, and then studied engineering at the University of West Virginia in Morgantown.
Pete Everest enlisted as an aviation cadet in the United States Army Air Corps at Fort Hayes, Columbus, Ohio, 7 November 1941, shortly before the United States entered World War II. His enlistment records indicate that he was 5 feet, 7 inches (1.703 meters) tall and weighed 132 pounds (59.9 kilograms). He graduated from pilot training and was commissioned as a second lieutenant, Air Reserve, 3 July 1942.
Lieutenant Frank Kendall Everest, Jr. (schultzy)
2nd Lieutenant Everest married Miss Avis June Mason in Marion, West Virginia, 8 July 1942. they would have three children.
He was promoted to 1st Lieutenant, Army of the United States, 11 November 1942. He was assigned as a Curtiss-Wright P-40 Warhawk pilot, flying 94 combat missions in North Africa, Sicily and Italy. He was credited with shooting down two German airplanes and damaging a third. Everest was promoted to the rank of Captain, 17 August 1943.
Pete Everest with his Curtiss-Wright P-40 Warhawk, North Africa, circa 1943.
In 1944, Everest was returned to the United States to serve as a flight instructor. He requested a return to combat and was then sent to the China-Burma-India theater of operations where he flew 67 missions and shot down four Japanese airplanes. Everest was appointed commanding officer of the 29th Fighter Squadron (Provisional), 5th Fighter Group (Provisional) at Chihkiang, China, in April 1945. He was himself shot down by ground fire in May 1945. Everest was captured by the Japanese and suffered torture and inhumane conditions before being freed at the end of the war. He was promoted to the rank of major, 1 July 1945. He was returned to the United States military 3 October 1945.
Following World War II, Major Everest was assigned as a test pilot at Wright-Patterson Air Force Base, Ohio, before going west to the Air Force Flight Test Center at Edwards Air Force Base, California.
Major Everest was returned to the permanent rank of first lieutenant, Air Corps, 19 June 1947, with date of rank retroactive to 3 July 1945.
At Edwards, Pete Everest was involved in nearly every flight test program, flying the F-88, F-92, F-100, F-101, F-102, F-104 and F-105 fighters, the XB-51, YB-52, B-57 and B-66 bombers. He also flew the pure research aircraft, the “X planes:” the X-1, X-1B, X-2, X-3, X-4 and X-5. Pete Everest flew the X-1B to Mach 2.3, and he set a world speed record with the X-2 at Mach 2.9 (1,957 miles per hour, 3,149.5 kilometers per hour) which earned him the title, “The Fastest Man Alive.” He was the test pilot on thirteen of the twenty X-2 flights.
In 1957, Lieutenant Colonel Everest was awarded the Harmon Trophy “for the most outstanding international achievements in the arts and/or science of aeronautics for the preceding year,” and also received the Octave Chanute Award “for an outstanding contribution made by a pilot to the art, science and technology of aeronautics.”
Major Frank Kendall Everest, Jr., U.S. Air Force, with the Bell X-2 supersonic research rocketplane, on Rogers Dry Lake at Edwards AFB, California, 1956. (U.S. Air Force)
Frank Everest returned to operational assignments and commanded a fighter squadron, two combat crew training wings, and was assigned staff positions at the Pentagon. On 20 November 1963, Colonel Everest, commanding the 4453rd Combat Crew Training Squadron, flew one of the first two operational McDonnell F-4C Phantom II fighters from the factory in St. Louis, Missouri, to MacDill Air Force Base, Tampa, Florida.
In 1965, Pete Everest was promoted to the rank of brigadier general. He was assigned as commander of the Aerospace Rescue and Recovery Service. General Everest retired from the Air Force in 1973 after 33 years of service.
Shortly after he retired from the Air Force, on 5 April 1973, Sikorsky Aircraft appointed General Everest its Chief Test Pilot. The manufacturer was developing the S-70 Black Hawk and S-76 commercial helicopters at the time.
During his military career General Everest was awarded the Air Force Distinguished Service Medal; Legion of Merit with two oak leaf clusters (three awards); Distinguished Flying Cross with two oak leaf clusters (three awards); Purple Heart; Air Medal with one silver and two bronze oak leaf clusters (seven awards); Air Force Commendation Medal with one oak leaf cluster (two awards); Presidential Unit Citation with two bronze oak leaf clusters (three awards); Air Force Gallant Unit Citation; Prisoner of War Medal; American Campaign Medal; European-African-Middle Eastern Campaign medal with four bronze stars; Asiatic-Pacific Campaign Medal with two bronze stars; World War II Victory Medal; National Defense Service Medal; Armed Forces Expeditionary Medal; Vietnam Service Medal; Air Force Longevity Service Award with one silver and two bronze oak leaf clusters (seven awards); Air Force Small Arms Expert Marksmanship Ribbon; and the Republic of Vietnam Campaign Medal with 1960– device. General Everest was rated as a Command Pilot, and a Basic Parachutist.
Brigadier General Frank Kendall Everest, Jr. United States Air Force (Retired), died at Tucson, Arizona, 1 October 2004 at the age of 84 years.
Brigadier General Frank Kendall Everest, Jr., United States Air Force
The North American Aviation F-100 Super Sabre was designed as a supersonic day fighter. Initially intended as an improved F-86D and F-86E, the “Sabre 45” soon developed into an almost completely new airplane.
The Super Sabre had a 49° 2′ sweep to the leading edges of the wings and horizontal stabilizer. The total wing area was 385.2 square feet (35.79 square meters). The wings had an angle of incidence of 0°, with no twist or dihedral. The ailerons were placed inboard on the wings and there were no flaps, resulting in a high stall speed in landing configuration. The horizontal stabilizer was moved to the bottom of the fuselage to keep it out of the turbulence created by the wings at high angles of attack. The F-100A had a distinctively shorter vertical fin than the YF-100A. The upper segment of the vertical fin was swept 49° 43′.
There were two service test prototypes, designated YF-100A, followed by the production F-100A series. The first ten production aircraft (all of the Block 1 variants) were used in the flight testing program.
The F-100A Super Sabre was 47 feet, 1¼ inches (14.357 meters) long with a wingspan of 36 feet, 6 inches (11.125 meters). With the shorter vertical fin, the initial F-100As had an overall height of 13 feet, 4 inches (4.064 meters), 11 inches (27.9 centimeters) less than the YF-100A.
North American Aviation Chief Test Pilot George S. Welch in the cockpit of the YF-100A, 52-5754, at Los Angeles International Airport. (North American Aviation, Inc.)
The F-100A had an empty weight of 18,135 pounds (8,226 kilograms), and its maximum takeoff weight was 28,971 pounds (13,141 kilograms). It had an internal fuel capacity of 744 gallons (2,816 liters) and could carry two 275 gallon (1,041 liter) external fuel tanks.
The new air superiority fighter was powered by a Pratt & Whitney Turbo Wasp J57-P-7 engine. The J57 was a two-spool axial-flow turbojet which had a 16-stage compressor section (9 low- and 7 high-pressure stages) and a 3-stage turbine (2 high- and 1 low-pressure stages). Its continuous power rating was 8,000 pounds of thrust (35.586 kilonewtons). The Military Power rating was 9,700 pounds (43.148 kilonewtons) (30-minute limit). Maximum power was 14,800 pounds (43.148 kilonewtons) with afterburner (5-minute limit). The engine was 20 feet, 9.7 inches (6.342 meters) long, 3 feet, 3.9 inches (1.014 meters) in diameter, and weighed 5,075 pounds (2,303 kilograms). Later production aircraft used a J57-P-39 engine, which had the same ratings.
North American Aviation YF-100 Super Sabre 754 parked on the dry lake at Edwards Air Force Base, California. (U.S. Air Force)
The Super Sabre was the first U.S. Air Force fighter capable of supersonic speed in level flight.
The YF-100A had a maximum speed of 660 miles per hour (1,062 kilometers per hour) at 43,350 feet (13,213 meters). During testing, 52-5754 reached Mach 1.44 in a dive. The service ceiling was 52,600 feet (16,033 meters). Range with internal fuel was 422 miles (679 kilometers).
North American Aviation YF-100A Super Sabre 52-5754 over Edwards Air Force Base, California, 25 May 1953. (North American Aviation, Inc.)
The production F-100 was armed with four M39 20 mm autocannons, capable of firing at a rate of 1,500 rounds per minute. The ammunition capacity of the F-100 was 200 rounds per gun.
North American Aviation built 199 F-100A Super Sabres at its Inglewood, California, plant before production shifted to the F-100C fighter bomber variant. Approximately 25% of all F-100As were lost in accidents.
North American Aviation YF-100A Super Sabre 52-5754 banks away from a chase plane during a flight test. (U.S. Air Force)
Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype North American Aviation XP-86. (U.S. Air Force)
14 October 1947: Twenty minutes before Captain Charles E. (“Chuck”) Yeager broke the sound barrier with a Bell X-1 rocketplane, North American Aviation Chief Test Pilot George S. Welch put the swept-wing XP-86 prototype, serial number 45-59597, into a shallow dive from 37,000 feet (11,278 meters) and accelerated. In direct violation of orders from the Secretary of the Air Force to not do so, Welch broke the “sound barrier.”
Witnesses on the ground heard the distinctive “B-BOOM” double-shock as the aircraft exceeded the speed of sound. Welch was the first to observe “Mach jump” as the airspeed indicator momentarily indicated higher due to the compression of air in front of the aircraft.
Estimates are that the XP-86 reached Mach 1.02–1.04 on this flight.
George S. Welch with his MG T-series sports car and North American Aviation XP-86 45-59597. (Unattributed)
Major William J. Knight, United States Air Force, with the North American Aviation X-15A-2, 56-6671. (U.S. Air Force)
3 October 1967: The 188th flight of the X-15 Program was the 53rd for the Number 2 aircraft, 56-6671. It had been extensively modified by North American Aviation to an X-15A-2 configuration following a landing accident which had occurred 9 November 1962. The fuselage was lengthened 28 inches (0.711 meters) to accommodate a liquid hydrogen fuel tank for a scramjet engine that would be added to the ventral fin, a new tank for additional hydrogen peroxide to generate steam for the rocket engine turbo pump, and external propellant tanks to allow the rocketplane to reach higher speeds and altitudes. The entire surface of the X-15 was covered with an ablative coating to protect the metal structure from the extreme heat it would encounter on this flight.
Minor issues delayed the takeoff but finally, after they were corrected, and with Pete Knight in the X-15’s cockpit, it was carried aloft under the right wing of Balls 8, a Boeing NB-52B Stratofortress, 52-008.
At 45,000 feet (13,716 meters) over Mud Lake, Nevada, the X-15 was droppeded at 14:31:50.9 local time. Knight fired the Reaction Motors XLR99-RM-1 rocket engine and began to climb and accelerate. After 60 seconds, the ammonia and liquid oxygen propellants in the external tanks was exhausted, so the the tanks were jettisoned to eliminate their weight and aerodynamic drag.
The X-15A-2 climbed to 102,100 feet (31,120 meters) and Pete Knight leveled off, still accelerating. After 140.7 seconds of engine burn, Knight shut the XLR99 down. He noticed that thrust seemed to decrease gradually and the X-15 continued to accelerate to 6,630 feet per second (2,021 meters per second), or Mach 6.72.
North American Aviation X-15A-2 56-6671 is carried to launch altitude under the right wing of the Boeing NB-52B Stratofortress 52-008. The scramjet is attached to the ventral fin. (U.S. Air Force)North American Aviation X-15A-2 56-6671 immediately after being released from the mothership, Boeing NB-52B Stratofortress 52-008, Balls 8, over Mud Lake, Nevada, 3 October 1967. The steam trail is hydrogen peroxide used to power the rocket engine turbopump. (U.S. Air Force)The X-15A-2’s XLR99-RM-1 rocket engine ignites after release from the mothership, Balls 8, 3 October 1967. (U.S. Air Force)
Shock waves from the dummy scramjet mounted on the ventral fin impinged on the fin’s leading edge and the lower fuselage, raising surface temperatures to 2,700 °F. (1,482 °C.) The Inconel X structure started to melt and burn through.
Pete Knight entered the high key over Rogers Dry Lake at 55,000 feet (16,764 meters) and Mach 2.2, higher and faster than normal. As he circled to line up for Runway One Eight, drag from the scramjet caused the X-15 to descend faster and this set him up for a perfect approach and landing. Because of heat damage, the scramjet broke loose and fell away from the X-15.
Knight touched down after an 8 minute, 17.0 second flight. His 4,520 mile per hour (7,274 kilometers per hour) maximum speed is a record that still stands.
Firefighters cool down the ventral fin of the North American Aviation X-15A-2 56-6671 after its final landing on Rogers Dry Lake, 3 October 1967.(U.S. Air Force)
The X-15A-2 suffered considerable damage from this hypersonic flight. It was returned to North American for repairs, but before they were completed, the X-15 Program came to an end. This was 56-6671’s last flight. It was sent to the National Museum of the United States Air Force where it is part of the permanent collection.
In a ceremony at the White House, President Lyndon B. Johnson presented the Harmon International Trophy to Major William J. Knight.
The Harmon International Trophy at the Smithsonian Institution National Air and Space Museum. (NASM)