29 June 1965: At 10:21:17.6 PDT, Captain Joe H. Engle, United States Air Force, flying the Number Three North American Aviation X-15A-3 research rocketplane, 56-6672, was air-dropped from the NB-52B Stratofortress mothership, Balls 8, over Delamar Dry Lake in Nevada. This was the 138th flight of the X-15 Program, and Joe Engle’s 12th. He fired the Reaction Motors XLR99-RM-1 engine for 81.0 seconds and accelerated to Mach 4.94 (3,432 miles per hour, 5,523 kilometers per hour). The X-15 climbed to an altitude of 280,600 feet (85,527 meters, 53.14 miles). He touched down at Edwards Air Force Base after 10 minutes, 34.2 seconds of flight. His parents were at Edwards to witness his flight.
Captain Engle qualified for Astronaut wings on this flight, the third and youngest Air Force pilot to do so.
Command Pilot Astronaut insignia, United States Air Force
From 1963 and 1965, Joe Engle made 14 flights in the three X-15s. After leaving the X-15 Program, he was assigned to the Apollo Program, the only NASA astronaut with prior spaceflight experience. He was the back-up Lunar Module pilot for Apollo 14 and he was the designated LM pilot for Apollo 17 but was replaced by Harrison Schmidt when Apollo 18 was cancelled. Next he went on to the Space Shuttle Program. He was a Mission Commander for the Enterprise flight tests and for Columbia‘s second orbital flight, during which he became the only pilot to manually fly a Mach 25 approach and landing. Finally, he commanded the Discovery STS 51-1 mission.
Joe Engle retired from the Air Force in 1986. He was then promoted to the rank of Major General and assigned to the Kansas Air National Guard. He has flown at least 185 aircraft types and accumulated 14,700 flight hours, with 224 hours in space.
Captain Joe H. Engle, U.S. Air Force, with the North American Aviation X-15A-2, 56-6671, at Edwards Air Force Base, California, 1965. (NASA)
27 June 1963: At 09:56:03.0 PDT, Major Robert A. Rushworth, United States Air Force, flying the Number Three North American Aviation X-15 research rocketplane, 56-6672, was air-dropped from the NB-52B Stratofortress mothership, Balls 8, over Delamar Dry Lake in Nevada.
This was the 87th flight of the X-15 Program, and Bob Rushworth’s 14th.
North American Aviation X-15 56-6672 immediately after being dropped by the Boeing NB-52 Stratofortress. (NASA)
Rushworth fired the Reaction Motors XLR99-RM-1 engine for 80.1 seconds and accelerated to Mach 4.89 (3,425 miles per hour, 5,512 kilometers per hour). The X-15 climbed to an altitude of 285,000 feet (86,868 meters, 53.98 miles). Rushworth touched down at Edwards Air Force Base after 10 minutes, 28.0 seconds of flight.
Major Rushworth qualified for Astronaut wings on this flight, the second X-15 pilot to do so.
From 1960 and 1966, Bob Rushworth made 34 flights in the three X-15s, more than any other pilot.
Command Pilot Astronaut insignia, United States Air Force
Jean L. Ziegler in the cockpit of Bell X-2 46-675 after landing on Rogers Dry Lake, at Edwards Air Force Base, California, 27 June 1952. (NASA)
27 June 1952: The Bell X-2 research rocketplane, with company test pilot Jean Leroy (“Skip”) Ziegler at the controls, was airdropped from a “mothership,” a Boeing B-50A-5-BO Superfortress, 46-011, over Edwards Air Force Base, California. This was the first flight of the X-2 Program, and was an unpowered glide flight for pilot familiarization.
On touch down, the nose wheel collapsed and the aircraft slid across the dry lake bed, but was not seriously damaged.
Two X-2 rocketplanes, serial numbers 46-674 and 46-675, were built by the Bell Aircraft Corporation, which has also built the X-1 series. The second X-2 was the first one to fly.
Bell Aircraft Corporation test pilot Jean Leroy (“Skip”) Ziegler standing next to the Bell X-2 rocket plane on Rogers Dry Lake, California, after the first glide flight, 27 June 1952. The nose wheel collapsed on landing. (NASM)
The X-2 was a joint project of the U.S. Air Force and NACA (the National Advisory Committee for Aeronautics, the predecessor of NASA). The rocketplane was designed and built by Bell Aircraft Corporation of Buffalo, New York, to explore supersonic flight at speeds beyond the capabilities of the earlier Bell X-1 and Douglas D-558-2 Skyrocket. In addition to the aerodynamic effects of speeds in the Mach 2.0–Mach 3.0 range, engineers knew that the high temperatures created by aerodynamic friction would be a problem, so the aircraft was built from Stainless Steel and K-Monel, a copper-nickel alloy.
The Bell Aircraft Corporation X-2 was 37 feet, 10 inches (11.532 meters) long with a wingspan of 32 feet, 3 inches (9.830 meters) and height of 11 feet, 10 inches (3.607 meters). Its empty weight was 12,375 pounds (5,613 kilograms) and loaded weight was 24,910 pounds (11,299 kilograms).
Bell X-2 46-675 on its transportation dolly at the NACA High Speed Flight Station, Edwards Air Force Base, California, 1952. (NASA)
The X-2 was powered by a throttleable Curtiss-Wright XLR25-CW-1 rocket engine that produced 2,500–15,000 pounds of thrust burning alcohol and liquid oxygen. Rather than use its limited fuel capacity to take off and climb to altitude, the X-2 was dropped from a modified heavy bomber as had been the earlier rocketplanes. The launch altitude was 30,000 feet (9,144 meters). After the fuel was exhausted, the X-2 glided to a touchdown on Rogers Dry Lake at Edwards Air Force Base.
A four-engine Boeing B-50A Superfortress bomber, serial number 46-011, was modified as the ”mothership.” A second Superfortress, B-50D-95-BO 48-096, was also modified to carry the X-2, and was redesignated EB-50D. During the flight test program, the X-2 reached a maximum speed of Mach 3.196 (2,094 miles per hour, 3,370 kilometers per hour) and a maximum altitude of 126,200 feet (38,466 meters).
On 12 May 1953, less than one year after the first glide flight, Skip Ziegler was in the cockpit of 46-675 while it was being carried on a captive test flight aboard the B-50A Superfortress. An internal explosion destroyed the X-2 and killed Ziegler and another crewman aboard the mothership. The rocketplane fell into Lake Ontario and neither it nor Ziegler’s body were ever recovered. The Superfortress was able to land, but was so badly damaged that it never flew again.
Jean Leroy “Skip” Ziegler, with the Bell X-5 at Edwards Air Force Base, 1952. (LIFE Magazine via Jet Pilot Overseas.)
Bob White exits the cockpit of an X-15 on Rogers Dry Lake. (NASA)
23 June 1961: Major Robert Michael White, United States Air Force, became the first pilot to exceed Mach 5 in an aircraft. This was the 38th flight of the X-15 Program. Flights during this phase incrementally increased the speed and altitude of the X-15 up to its design limits of Mach 6 and 250,000 feet (76,200 meters).
The second North American Aviation X-15A, 56-6671, was air-dropped from the NB-52A Stratofortress mothership, 52-003, over Mud Lake, Nevada at 2:00:05.0 p.m., Pacific Daylight Time (21:00 UTC). White fired the Reaction Motors XLR99-RM-1 engine for 78.7 seconds, reaching Mach 5.27 (3,603 miles per hour, 5,799 kilometers per hour) and climbed to 107,700 feet (32,827 meters). 10 minutes, 5.7 seconds after being dropped from the B-52, White touched down on Rogers Dry Lake at Edwards Air Force Base.
Bob White was the first pilot to exceed Mach 4, Mach 5 and Mach 6. He also flew an X-15 to an altitude of 314,750 feet (95,936 meters), qualifying for U.S. Air Force astronaut wings.
After leaving the X-15 program, Major White flew 70 combat missions in the Republic F-105D Thunderchief fighter bomber during the Vietnam War. He lead the attack against the heavily-defended Paul Doumer Bridge in Hanoi, 11 August 1967, for which he was awarded the Air Force Cross.
Major General White retired from the U.S. Air Force in 1981. He died 10 March 2010.
56-6671 is in the collection of the National Museum of the United States Air Force. The mothership, 52-003, is on display at the Pima Air and Space Museum, Tucson, Arizona.
Lieutenant Russell L. Maughan, Air Service, United States Army (FAI)
23 June 1924: Lieutenant Maughan took off from Mitchel Field, Long Island, New York, at 3:58 a.m., Eastern Time, and flew across the country to land at Crissy Field, at the Presidio of San Francisco, California at 9:46 p.m., Pacific Time. His airplane was a Curtiss XPW-8 Hawk, serial number A.S. 23-1201, McCook Field Project Number 295. He covered a distance of 2,670 miles (4,297 kilometers) in 21 hours, 47 minutes. Maughan’s actual flight time was 20 hours, 48 minutes. He averaged 128.37 miles per hour (206.59 kilometers per hour).
His Dawn-To-Dusk transcontinental flight took place on a mid-summer day in order to take advantage of the longer hours of daylight, and he flew from East to West, to follow the advancing Sun across the sky.
Major General Mason Matthews Patrick, Chief of the Air Service, with Lieutenant Russell L. Maughan, 8 July 1924. (Library of Congress)
Lieutenant Maughan made stops at McCook Field, Dayton, Ohio; St. Joseph, Missouri; North Platte, Nebraska; Cheyenne, Wyoming and Salduro Siding, Utah. The stop at Dayton took 1 hour, 20 minutes when a mechanic over-tightened a fuel line fitting and damaged it. When he arrived at “Saint Joe,” the grass field was wet from rains, restricting his takeoff weight. Unable to carry a full load of fuel, he took off with a reduced load and then made a previously unplanned stop at North Platte, Nebraska, where he topped off his fuel tank.
Planned route of Maughan’s Dawn-to-Dusk transcontinental flight. (U.S. Air Force)
Russell Maughan was an experienced combat pilot and test pilot. He had been awarded the Distinguished Service Cross for his actions during World War I, and he had competed in numerous air races and had set several speed records.
Lieutenant Russell L. Maughan with his Curtiss PW-8 Hawk A.S. 24-204, 10 June 1924. (National Air and Space Museum)
The airplane flown by Lieutenant Maughan was the fourth production Curtiss PW-8 Hawk, a single-place, single-engine biplane fighter, serial number A.S. 24-204, McCook Field project nuymber P-361. It was modified by the Curtiss Aeroplane and Motor Company at its Long Island, New York, factory. Curtiss removed the fighters’s two .30-caliber machine guns and added 100 gallons (378.5 liters) to the airplane’s standard fuel capacity of 77 gallons (291.5 liters).
The Curtiss PW-8 Hawk was powered by a water-cooled, normally-aspirated 1,145.111-cubic-inch-displacement (18.765 liter) Curtiss D-12 dual overhead cam (DOHC) 60° V-12 engine, which was developed by Arthur Nutt, based on the earlier Curtiss K-12 which had been designed by Charles B. Kirkham. The D-12 had four valves per cylinder and a compression ratio of 5.7:1. It was rated at 415 horsepower at 2,000 r.p.m., and 460 horsepower at 2,300 r.p.m. During testing, it produced a 475 horsepower at 2,320 r.p.m. using a 50/50 mixture of 95-octane gasoline and benzol. The D-12 was a right-hand tractor direct-drive engine. It turned a two-bladed, fixed-pitch, forged aluminum propeller designed by Dr. Sylvanus A. Reed. The Curtiss D-12 was 56¾ inches (1.441 meters) long, 28¼ inches (0.718 meters) wide and 34¾ inches (0.882 meters) high. It weighed 678.25 pounds (307.65 kilograms).
The PW-8 had a cruise speed of 136 miles per hour (219 kilometers per hour) and maximum speed of 171 miles per hour (275 kilometers per hour) at Sea Level. The airplane’s service ceiling was 20,350 feet (6,203 meters) and its range was 544 miles (875 kilometers).
In the early years of military aviation, pilots undertook various dramatic flights to create public awareness of the capabilities military aircraft. Of this transcontinental flight, Maughan said, “The real reason for my flight across the United States in the sunlight hours of one day was that the chief of the Air Service wanted to show Congress just how unprotected are the people of the Pacific Coast.”
The Curtiss PW-8 Hawk, A.S. 24-204, was damaged beyond repair when it nosed over while landing on a muddy field at Selfridge Field, Michigan, 11 May 1926.
