Tag Archives: Rocketplane

25 April 1956

Lieutenant Colonel Frank K. Everest, U.S. Air Force, with a Bell X-2 at Edwards Air Force Base. Colonel Everest is wearing a capstan-type partial pressure suit for protection at very high altitude. (U.S. Air Force)
Lieutenant Colonel Frank K. Everest, U.S. Air Force, with a Bell X-2 at Edwards Air Force Base. Colonel Everest is wearing a David Clark Co. T-1 capstan-type partial-pressure suit for protection at very high altitude. (U.S. Air Force)

25 April 1956: At Edwards Air Force Base, California, test pilot Lieutenant Colonel Frank Kendall (“Pete”) Everest, United States Air Force, was airdropped from a Boeing EB-50D Superfortress in the Bell X-2 supersonic research rocket plane, serial number 46-674. This was the tenth flight of the X-2 program, and only the third powered flight.

For the first time, Everest fired both chambers of the Curtiss-Wright XLR25 rocket engine. On this flight, the X-2 reached Mach 1.40 and 50,000 feet (15,240 meters). It was the first time an X-2 had gone supersonic.

Bell X-2 46-674 in flight over Southern California, circa 1955–56. (NASA Photograph ET–128)
Bell X-2 46-674 in flight over Southern California, circa 1955–56. (NASA Photograph ET–128)

The X-2 was a joint project of the U.S. Air Force and NACA (the National Advisory Committee on 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-II 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).

The X-2 was powered by a throttleable two-chamber Curtiss-Wright XLR25-CW-1 rocket engine that produced 2,500–15,000 pounds of thrust (11.12–66.72 kilonewtons)

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. A four-engine Boeing B-50D-95-BO Superfortress bomber, serial number 48-096, was modified as the drop ship and redesignated EB-50D.

Bell X-2 46-674 on final approach. (NASA)

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.

Two X-2 rocketplanes were built. The second X-2, 46-675, was destroyed during a captive flight, 12 May 1953. The explosion killed Bell test pilot Skip Ziegler and Frank Wolko, an engineer aboard the B-50A mothership. The B-50 made an emergency landing but was so badly damaged that it never flew again.

The X-2 reached a maximum speed of Mach 3.196 (2,094 miles per hour/3,370 kilometers per hour) and maximum altitude of 126,200 feet (38,466 meters).

Boeing EB-50D Superfortress 49-096 with a Bell X-2 (U.S. Air Force)
Boeing EB-50D Superfortress 48-096 with a Bell X-2 (U.S. Air Force)

The EB-50D was a highly modified four-engine Boeing B-50D-95-BO Superfortress long range heavy bomber, engineered to carry research aircraft to high altitudes before releasing them for a test flight. The B-50 was an improved version of the World War II B-29A Superfortress.

Boeing B-50D-95-BO (S/N 48-096) in flight. (U.S. Air Force photo)
Boeing B-50D-95-BO Superfortress 48-096 prior to modification to an EB-50D X-2 carrier. (U.S. Air Force/Bill Pippin Collection, 1000aircraftphotos.com)
Boeing B-50D-90-BO Superfortress 48-096 prior to modification to an EB-50D X-2 carrier. (U.S. Air Force)
Boeing B-50D-95-BO Superfortress 48-096 prior to modification to an EB-50D X-2 carrier. (U.S. Air Force)
Boeing B-50D-95-BO Superfortress 48-096 prior to modification to an EB-50D X-2 carrier. (U.S. Air Force)

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 teh University of Wesst 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.

Everest married Miss Avis June Mason in Marion, West Virginia, in 1942.

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.

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. 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.

After the war, 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.

Everest was returned to the permanent rank of first lieutenant, Air Corps, 19 June 1947, with date of rank retroactive to 3 July 1945.

Major Frank Kendall Everest, Jr., U.S. Air Force, with a Bell X-1 supersonic research rocketplane, 46-062, circa 1950. (mach-buster.co.uk)

At Edwards, he 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.

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 via Jet Pilot Overseas)

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 to MacDill Air Force Base.

In 1965, Pete Everest was promoted to the rank of brigadier general. He was commander of the Aerospace Rescue and Recovery Service. He retired from the Air Force in 1973 after 33 years of service. He later worked as a test pilot for Sikorsky Aircraft.

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, United states Air Force
Brigadier General Frank Kendall Everest, Jr., United States Air Force. (U.s. Air Force)

© 2018, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

25 January 1946

Jack Valentine Woolams, Chief Experimental Test Pilot, Bell Aircraft Corporation. (John Trudell/Ancestry)

25 January 1946:¹ Near Pinecastle Army Airfield, Bell Aircraft Corporation Senior Experimental Test Pilot Jack Woolams made the first unpowered flight of the XS-1 supersonic research rocketplane, 46-062.

46-062 was the first of three XS-1 rocketplanes built by Bell for the U.S. Army Air Corps to explore flight at speeds at and beyond Mach 1, the speed of sound. It had rolled out of Bell’s plant at Buffalo, New York, on 27 December 1945. The rocket engine, which was being developed by the Reaction Motors Co., was not ready, so the experimental aircraft was carrying ballast in its place.

Jack Woolams with Bell XS-1 46-063. (Niagara Aerospace Museum)

The XS-1 was to be air-dropped from altitude by a modified heavy bomber, so that its fuel could be used for acceleration to high speeds at altitude, rather than expended climbing from the surface. Bell manufactured B-29 Superfortresses at its Atlanta, Georgia, plant and was therefore very familiar with its capabilities. A B-29 was selected as the drop ship and modified to carry the rocketplane in its bomb bay.

Boeing B-29-96-BW Superfortress 45-21800 carries a Bell XS-1 rocketplane. (Bell Aircraft Museum)

Pinecastle Army Airfield was chosen as the site of the first flight tests because it had a 10,000 foot (3,048 meter) runway and was fairly remote. There was an adjacent bombing range and the base was a proving ground for such aircraft as the Consolidated B-32 Dominator. (Today, Pinecastle A.A.F. is known as Orlando International Airport, MCO.)

Bell XS-1 46-062 was placed in a pit at Pinecastle A.A.F. so that the B-29 drop ship in the background could be positioned over it. (NASA)
Bell XS-1 46-062 was placed in a pit at Pinecastle A.A.F. so that the B-29 drop ship in the background could be positioned over it. (NASA)

The B-29 carrying the XS-1 took off from Pinecastle at 11:15 a.m., and began its climb to altitude. Woolams was in the forward crew compartment. As the bomber reached approximately 10,000 feet (3,048 meters), he entered the bomb bay and climbed down into the cockpit of the research aircraft. At the drop altitude, the B-29 was flying at 180 miles per hour (290 kilometers per hour) with the inboard propellers feathered and flaps lowered to 20°.

The XS-1 dropped away smoothly. Woolams flew the rocketplane to a maximum 275 miles per hour (443 kilometers per hour) indicated air speed during this first glide test. He described the rocketplane as, “solid as a rock, experiencing absolutely no vibration or noise. At the same time, it felt as light as a feather during maneuvers due to the lightness, effectiveness an nice balance between the controls.” Woolams described the visibility from the cockpit as “not good, but adequate.”

The duration of the first glide flight was about ten minutes. Woolams misjudged his approach to Pinecastle and landed slightly short of the runway, on the grass shoulder. The XS-1 was undamaged.

The conclusion of Woolams’ test flight report is highly complementary of the experimental airplane:

11.  Of all the airplanes the writer has flown, only the XP-77 and the Heinkle [sp] 162 compare with the XS-1 for maneuverability, control relationship, response to control movements, and lightness of control forces. Although these impressions were rather hastily gained during a flight which lasted only 10 minutes, it is the writer’s opinion that due to these factors and adding to them the security which the pilot feels due to the ruggedness, noiselessness, and smoothness of response of this airplane, it is the most delightful to fly of them all.

—PILOT’S REPORT, Flight #1, by Jack Woolams

Jack Woolams made ten glide flights with 46-062, evaluating its handling characteristics and stability. The aircraft was returned to Bell to have the rocket engine installed, and it was then sent to Muroc Army Airfield in the high desert of southern California for powered flight tests. (Muroc was renamed Edwards Air Force Base in 1949.)

Bell X-1 46-062 was later named Glamorous Glennis by its military test pilot, Captain Charles E. Yeager, U.S. Army Air Corps. On 14 October 1947, Chuck Yeager flew it to Mach 1.06 at 13,115 meters (43,030 feet). Today it is on display at the Smithsonian Institution National Air and Space Museum.

The Bell XS-1, later re-designated X-1, was the first of a series of rocket-powered research airplanes which included the Douglas D-558-II Skyrocket, the Bell X-2, and the North American Aviation X-15, which were flown by the U.S. Air Force, U.S. Navy, NACA and its successor, NASA, at Edwards Air Force Base to explore supersonic and hypersonic flight and at altitudes to and beyond the limits of Earth’s atmosphere.

An X-1 under construction at teh Bell Aircraft Corporation plant, Buffalo, New York. (Bell Aircraft Corporation)
An X-1 under construction at the Bell Aircraft Corporation plant, Buffalo, New York. (Bell Aircraft Corporation)

The X-1 has an ogive nose, similar to the shape of a .50-caliber machine gun bullet, and has straight wings and tail surfaces. It is 30 feet, 10.98 inches (9.423 meters) long with a wing span of 28.00 feet (8.534 meters) and overall height of 10 feet, 10.20 inches (3.307 meters). Total wing area is 102.5 square feet (9.5 square meters). 46-062 was built with a very thin 8% aspect ratio wing, while 46-063 had a 10% thick wing.

The fuselage cross section is circular. At its widest point, the diameter of the X-1 fuselage is 4 feet, 7 inches (1.397 meters). The empty weight is 6,784.9 pounds (3,077.6 kilograms), but loaded with propellant, oxidizer and its pilot with his equipment, the weight increased to 13,034 pounds (5,912 kilograms).

Front view of a Bell XS-1 supersonic research rocketplane at the Bell Aircraft plant, Buffalo, New York. (Bell Aircraft Museum)

The X-1 is powered by a four-chamber Reaction Motors, Inc., XLR11-RM-3 rocket engine which produced 6,000 pounds of thrust (26,689 Newtons). This engine burns a mixture of ethyl alcohol and water with liquid oxygen. Fuel capacity is 293 gallons (1,109 liters) of water/alcohol and 311 gallons (1,177 liters) of liquid oxygen. The fuel system is pressurized by nitrogen at 1,500 pounds per square inch (103.4 Bar).

The X-1 was usually dropped from a B-29 flying at 30,000 feet (9,144 meters) and 345 miles per hour (555 kilometers per hour). It fell as much as 1,000 feet (305 meters) before beginning to climb under its own power.

The X-1’s performance was limited by its fuel capacity. Flying at 50,000 feet (15,240 meters), it could reach 916 miles per hour (1,474 kilometers per hour), but at 70,000 feet (21,336 meters) the maximum speed that could be reached was 898 miles per hour (1,445 kilometers per hour). During a maximum climb, fuel would be exhausted as the X-1 reached 74,800 feet (2,799 meters). The absolute ceiling is 87,750 feet (26,746 meters).

Bell X-1 46-062 on the dry lake bed at Muroc Army Airfield, circa 1947. (NASM)

The X-1 had a minimum landing speed of 135 miles per hour (217 kilometers per hour) using 60% flaps.

The X-1 was designed to withstand an ultimate structural load of 18g.

There were 157 flights with the three X-1 rocket planes. The number one ship, 46-062, Glamorous Glennis, made 78 flights. On 26 March 1948, with Chuck Yeager again in the cockpit, it reached reached Mach 1.45 (957 miles per hour/1,540 kilometers per hour) at 71,900 feet (21,915 meters).

The third X-1, 46-064, made just one glide flight before it was destroyed 9 November 1951 in an accidental explosion.

The second X-1, 46-063, was later modified to the X-1E. It is on display at the NASA Dryden Research Center at Edwards Air Force Base. Glamorous Glennis is on display at the Smithsonian Institution National Air and Space Museum, next to Charles A. Lindbergh’s Spirit of St. Louis.

Bell X-1, 46-062, Glamorous Glennis, on display at the National Air and Space Museum, Washington, D.C. (NASM)
Bell X-1 46-062, Glamorous Glennis, on display at the National Air and Space Museum, Washington, D.C. (NASM)

Jack Valentine Woolams was born on Valentine’s Day, 14 February 1917, at San Francisco, California. He was the second of three children of Leonard Alfred Woolams, a corporate comptroller, and Elsa Mathilda Cellarius Woolams. He grew up in San Rafael, California, and graduated from Tamalpais School in 1935. He then studied at The University of Chicago at Chicago, Illinois.

After two years of university study, Woolams entered the Air Corps, U.S. Army, as an aviation cadet, in 1937. He trained as a pilot at Kelly Field, San Antonio, Texas. On graduation, 16 June 1938, he was discharged as an aviation cadet and commissioned as a second lieutenant, Air Reserve. He was assigned to Barksdale Army Air Field, Louisiana, where he flew the Boeing P-26 and Curtiss P-36 Hawk.

On 10 February 1939, Lieutenant Woolams was one of three Air Corps officers thrown into the waters of Cross Lake, near Shreveport, Louisiana, when the boat, owned by Woolams, capsized in 4 foot (1.2 meters) waves. Woolams and Lieutenant J.E. Bowen were rescued after 4 hours in the water, but the third man, Lieutenant Wilbur D. Camp, died of exposure.

Lieutenant Woolams transferred from active duty to inactive reserve status in September 1939 in order to pursue his college education at The University of Chicago, where he was a member of the Alpha Delta Phi (ΑΔΦ) fraternity. While at U. of C., he played on the university’s football and baseball teams, and was a member of the dramatic society. Woolams graduated 18 July 1941 with a Bachelor of Arts (A.B.) degree in Economics.

Mr. and Mrs. Jack V. Woolams, 16 June1941. (Unattributed)

Jack Woolams married Miss Mary Margaret Mayer at the bride’s home in Riverside, Illinois, 16 June 1941. They would have three children. Miss Mayer was also a 1941 graduate from the University of Chicago. She had been Woolams’ student in the Civilian Pilot Training Program.

Woolams became a production test pilot for the Bell Aircraft Corporation at Buffalo, New York. He test flew newly-built Bell P-39 Airacobra fighters. As he became more experienced, he transitioned to experimental testing with the P-39, P-63 King Cobra, and the jet-powered P-59 Airacomet.

Jack Valentine Woolams, Chief Experimental Test Pilot, Bell Aircraft Corporation, circa 1946. (Niagara Aerospace Museum)

On 28 September 1942, Jack Woolams flew a highly-modified Bell P-39D-1-BE Airacobra, 41-38287, from March Field, near Riverside, California, to Bolling Field, Washington, D.C., non-stop. The duration of the flight was approximately 11 hours. The modifications were intended to allow P-39s to be flown across the Pacific Ocean to Hawaii and on to the Soviet Union for delivery under Lend Lease.

During the summer of 1943, Woolams flew the first Bell YP-59A Airacomet, 42-108771, to an altitude of 47,600 feet (14,508 meters) near Muroc Army Air Field in California.

On 5 January 1945, Woolams was forced to bail out of a Bell P-59A-1-BE, 44-22616. He suffered a deep laceration to his head as he left the airplane. He lost his flight boots when the parachute opened, and on landing, had to walk barefoot through knee-deep snow for several miles to a farm house. The deep snow prevented the company’s ambulance from reaching Woolams. Bell Aircraft president Lawrence D. Bell sent the company’s second prototype Bell Model 30 helicopter, NX41868, flown by test pilot Floyd Carlson, to transport a doctor, J.A. Marriott, M.D., to the location. Another Bell test pilot, Joe Mashman, circled overhead in a P-63 King Cobra to provide a communications link. Later, an ambulance was able to get through the snow to take Woolams to a hospital.

Wreckage of Bell P-59A-1-BE Airacomet 44-22616. Jack Woolams bailed out of this airplane 5 January 1945. (Niagara Aerospace Museum)

He was scheduled to  make the first powered flight in the XS-1 during October 1946.

Jack Woolams was killed Friday, 30 August 1946, when his red Thompson Trophy racer, Cobra I, a modified 2,000-horsepower Bell P-39Q Airacobra, crashed into Lake Ontario at over 400 miles per hour. His body was recovered by the U.S. Coast Guard four days later.

Bell Aircraft Corporation experimental test pilots Jack Woolams and Tex Johnston with their modified Bell P-39Q Airacobras, Cobra I and Cobra II. (Niagara Aerospace Museum)

¹ This article was originally dated 19 January 1946. There were known discrepancies as to the date of the first flight from various reliable sources. Recently discovered test flight reports, provided to TDiA by Mr. Roy T. Lindberg, Historian of the Niagara Aerospace Museum, Niagara Falls, New York, have confirmed that the date of the first flight was actually 25 January 1946. The article has been been revised accordingly, as well as to incorporate new information from these reports. TDiA is indebted to Mr. Lindberg for providing this and other documentation.

© 2018, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

North American Aviation, Inc., X-15A Hypersonic Research Rocketplane

Rollout AFFTC History Office
North American Aviation, Inc., X-15A-1, 56-6670, at Los Angeles Division, October 1958. (Air Force Flight Test Center History Office)

20 December 1968: After 199 flights, the National Aeronautics and Space Administration cancelled the X-15 Hypersonic Research Program. A 200th X-15 flight had been scheduled, but after several delays, the decision was made to end the program. (The last actual flight attempt was 12 December 1968, but snow at several of the dry lakes used as emergency landing areas resulted in the flight being cancelled.)

The X-15A rocketplane was designed and built for the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA, the predecessor of NASA) by North American Aviation, Inc., to investigate the effects of hypersonic flight (Mach 5+). Design work started in 1955 and a mock-up had been completed after just 12 months. The three X-15s were built at North American’s Los Angeles Division, at the southeast corner of Los Angeles International Airport (LAX), on the shoreline of southern California.

The first flight took place 8 June 1959 with former NACA test pilot Albert Scott Crossfield in the cockpit of the Number 1 ship, 56-6670.

While earlier rocketplanes, the Bell X-1 series, the the Douglas D-558-II, and the Bell X-2, were airplanes powered by rocket engines, the X-15 was a quantum leap in technology. It was a spacecraft.

Like the other rocketplanes, the X-15 was designed to be carried aloft by a “mothership,” rather than to takeoff and climb to the test altitude under its own power. The carrier aircraft was originally to be a Convair B-36 intercontinental bomber but this was soon changed to a Boeing B-52 Stratofortress. Two B-52s were modified to carry the X-15: NB-52A 52-003, The High and Mighty One, and NB-52B 52-008, Balls 8.

From 8 June 1959 to 24 October 1968, the three X-15s were flown by twelve test pilots, three of whom would qualify as astronauts in the X-15. Two would go on to the Apollo Program, and one, Neil Alden Armstrong, would be the first human to set foot on the surface of the Moon, 20 July 1969. Joe Engle would fly the space shuttle. Four of the test pilots, Petersen, White, Rushworth, and Knight, flew in combat during the Vietnam War, with Bob White being awarded the Air Force Cross. Petersen, Rushworth and White reached flag rank.

One pilot, John B. (“Jack”) McKay, was seriously injured during an emergency landing at Mud Lake, Nevada, 9 November 1962. Another, Michael James Adams, was killed when the Number 3 ship, 56-6672, went into a hypersonic spin and broke up on the program’s 191st flight, 15 November 1967.

North American Aviation, Inc. X-15A 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA)
North American Aviation, Inc., X-15A-1 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA Image E-5251)

Flown by a single pilot/astronaut, the X-15 is a mid-wing monoplane with dorsal and ventral fin/rudders and stabilators. The wing had no dihdral, while the stabilators had a pronounced -15° anhedral. The short wings have an area of 200 square feet (18.58 square meters) and a maximum thickness of just 5%. The leading edges are swept to 25.64°. There are two small flaps but no ailerons. The entire vertical fin/rudder pivots for yaw control.

Above 100,000 feet (30,840 meters) altitude, conventional aircraft flight control surfaces are ineffective. The X-15 is equipped with a system of reaction control jets for pitch, roll and yaw control. Hydrogen peroxide was passed through a catalyst to produce steam, which supplied the control thrusters.

The forward landing gear consists of a retractable oleo strut with steerable dual wheels and there are two strut/skids at the rear of the fuselage. The gear is retracted after the X-15 is mounted on the NB-52 and is extended for landing by its own weight.

 North American Aviation X-15A 56-6672 touches down on Rogers Dry Lake. (NASA)
North American Aviation, Inc., X-15A-3 56-6672 just before touch down on Rogers Dry Lake. (NASA Image E-7469)

The rocketplane’s cockpit featured both a conventional control stick as well as side-controllers. It was pressurized with nitrogen gas to prevent fires. The pilot wore an MC-2 full-pressure suit manufactured by the David Clark Company of Worcester, Massachusetts, with an MA-3 helmet. The suit was pressurized below the neck seal with nitrogen, while the helmet was supplied with 100% oxygen. This pressure suit was later changed to the Air Force-standardized A/P22S.

X-15A cockpit with original Lear Siegler instrument panel. (NASA)
X-15 cockpit with original Lear Siegler instrument panel. (NASA image E63-9834)

The X-15 is 50.75 feet (15.469 meters) long with a wing span of 22.36 feet (6.815 meters). The height—the distance between the tips of the dorsal and ventral fins—is 13.5 feet (4.115 meters). The stabilator span is 18.08 feet (5.511 meters). The fuselage is 4.67 feet (1.423 meters) deep and has a maximum width of 7.33 feet (2.234 meters).

Since the X-15 was built of steel rather than light-weight aluminum, as are most aircraft, it is a heavy machine, weighing approximately 14,600 pounds (6,623 kilograms) empty and 34,000 pounds (15,422 kilograms) when loaded with a pilot and propellants. The X-15s carried as much as 1,300 pounds (590 kilograms) of research instrumentation, and the equipment varied from flight to flight. The minimum flight weight (for high-speed missions): 31,292 pounds (14,194 kilograms) The maximum weight was 52,117 pounds (23,640 kilograms) at drop (modified X-15A-2 with external propellant tanks).

Initial flights were flown with a 5 foot, 11 inch (1.803 meters)-long air data boom at the nose, but this would later be replaced by the “ball nose” air sensor system. The data boom contained a standard pitot-static system along with angle-of-attack and sideslip vanes. The boom and ball nose were interchangeable.

Neil Armstrong with the first North American Aviation X-15A, 56-6670, on Rogers Dry Lake after a flight, 1960. His hand is resting on the rocketplane's ball nose sensor. (NASA)
NASA Research Test Pilot Neil A. Armstrong with the first North American Aviation X-15A, 56-6670, on Rogers Dry Lake after a flight, 1960. His right hand is resting on the rocketplane’s ball nose sensor. (NASA Image E60-6286)

The X-15s were built primarily of a nickel/chromium/iron alloy named Inconel X, along with corrosion-resistant steel, titanium and aluminum. Inconel X is both very hard and also able to maintain its strength at the very high temperatures the X-15s were subjected to by aerodynamic heating. It was extremely difficult to machine and special fabrication techniques had to be developed.

Delays in the production of the planned Reaction Motors XLR99 rocket engine forced engineers to adapt two vertically-stacked Reaction Motors XLR11-RM-13 four-chamber rocket engines to the X-15 for early flights. This was a well-known engine which was used on the previous rocketplanes. The XLR11 burned a mixture of ethyl alcohol and water with liquid oxygen. Each of the engines’ chambers could be ignited individually. Each engine was rated at 11,800 pounds of thrust (58.49 kilonewtons) at Sea Level.

Two Reaction Motors Division XLR11-RM-5 four-chamber rocket engines installed on an X-15. (NASA)
Two Reaction Motors Division XLR11-RM-13 four-chamber rocket engines installed on an X-15. The speed brakes of the ventral fin are shown in the open position. (NASA)

The Reaction Motors XLR99-RM-1 rocket engine was throttleable by the pilot from 28,500 to 60,000 pounds of thrust. The engine was rated at 50,000 pounds of thrust (222.41 kilonewtons) at Sea Level; 57,000 pounds (253.55 kilonewtons) at 45,000 feet (13,716 meters), the typical drop altitude; and 57,850 pounds (257.33 kilonewtons) of thrust at 100,000 feet (30,480 meters). Individual engines varied slightly. A few produced as much as 61,000 pounds of thrust (271.34 kilonewtons).

The XLR99 burned anhydrous ammonia and liquid oxygen. The flame temperature was approximately 5,000 °F. (2,760 °C.) The engine was cooled with circulating liquid oxygen. To protect the exhaust nozzle, it was flame-sprayed with ceramic coating of zirconium dioxide. The engine is 6 feet, 10 inches (2.083 meters) long and 3 feet, 3.3 inches (0.998 meters) in diameter. It weighs 910 pounds (413 kilograms). The Time Between Overhauls (TBO) is 1 hour of operation, or 100 starts.

Thiokol Reaction Motors Division XLR-RM-1 rocket engine. (U.S. Air Force)
Thiokol Corporation Reaction Motors Division XLR99-RM-1 rocket engine. (U.S. Air Force)

The XLR99 proved to be very reliable. 169 X-15 flights were made using the XLR99. 165 of these had successful engine operation. It started on the first attempt 159 times.

The highest speed achieved during the program was with the modified number two ship, X-15A-2 56-6671, flown by Pete Knight to Mach 6.70 (6,620 feet per second/4,520 miles per hour/ kilometers per hour) at 102,700 feet (31,303 meters). On this flight, the rocketplane exceeded its maximum design speed of 6,600 feet per second (2,012 meters per second).

The maximum altitude was reached by Joe Walker, 22 August 1963, when he flew 56-6672 to 354,200 feet (107,960 meters).

The longest flight was flown by Neil Armstrong, 20 April 1962, with a duration of 12 minutes, 28.7 seconds.

North American Aviation X-15A-1 56-6670 is on display at the Smithsonian Institution National Air and Space Museum. X-15A-2 56-6671 is at the National Museum of the United States Air Force.

A North American Aviation F-100 Super Sabre chase plane follows NB-52A 52-003 prior to launch of an X-15. (NASA)
A North American Aviation F-100 Super Sabre chase plane follows NB-52A 52-003 prior to launch of an X-15. (NASA)

Recommended reading:

Always Another Dawn: The Story of a Rocket Test Pilot, by A. Scott Crossfield and Clay Blair, Jr., The World Publishing Company, Cleveland and New York, 1960

At The Edge Of Space, by Milton O. Thompson, Smithsonian Institution Press, 1992

X-15 Diary: The Story of America’s First Spaceship, by Richard Tregaskis, E.F. Dutton & Company,  New York, 1961; University of Nebraska Press, 2004

X-15: Exploring the Frontiers of Flight, by David R. Jenkins, National Aeronautics and Space Administration http://www.nasa.gov/pdf/470842main_X_15_Frontier_of_Flight.pdf

The X-15 Rocket Plane: Flying the First Wings into Space, by Michelle Evans, University of Nebraska Press, Lincoln and London, 2013

Screen Shot 2016-06-07 at 21.18.14
North American Aviation, Inc., X-15A-2 56-6671 accelerates after igniting its Reaction Motors XLR99-RM-1 rocket engine (NASA)

© 2016, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

12 December 1953

Bell X-1A 48-1384 in flight. The frost band on the fuselage shows the location of the cryogenic propellant tank. (U.S. Air Force)

12 December 1953: On its tenth flight, U.S. Air Force test pilot Major Chuck Yeager flew the Bell X-1A rocket plane to Mach 2.44 (1,621 miles per hour/2,609 kilometers per hour) at 74,700 feet (22,769 meters), faster than anyone had flown before.

After the rocket engine was shut down, the X-1A tumbled out of control—”divergent in three axes” in test pilot speak—and fell out of the sky. It dropped nearly 50,000 feet (15,240 meters) in 70 seconds. Yeager was exposed to accelerations of +8 to -1.5 g’s. The motion was so violent that Yeager cracked the rocketplane’s canopy with his flight helmet.

Yeager was finally able to recover by 30,000 feet (9,144 meters) and landed safely at Edwards Air Force Base.

Yeager later remarked that if the X-1A had an ejection seat he would have used it.

Bell Aircraft Corporation  engineers had warned Yeager not to exceed Mach 2.3.

Major Charles E. Yeager, U.S. Air Force, seated in the cockpit of the Bell X-1A, 48-1384, circa 1953. (U.S. Air Force)

The following is from Major Charles E. Yeager’s official post-flight report:

“After a normal drop at 31,000 feet, chambers #4, #2, and #1 were ignited and [the] airplane was accelerated up to .8 Mach number. A flight path was formed holding .8 Mach number up to 43,000 feet where chamber #3 was ignited and the airplane accelerated in level flight to 1.1 Mach number. A climb was again started passing through 50,000 feet at 1.1 Mach number, 60,000 feet at 1.2 Mach number and a push-over was started at 62,000 feet. The top of the round-out occurred at 76,000 feet and 1.9 Mach number. The airplane was accelerated in level flight up to 2.4 [2.535 indicated] Mach number where all of the rocket chambers were cut. The flight path was very normal and nothing uneventful [sic] happened up to this point. After the engine was cut, the airplane went into a Dutch roll for approximately 2 oscillations and then started rolling to the right at a very rapid rate of roll. Full aileron and opposite rudder were applied with no effect on the rate of roll of the airplane. After approximately 8 to 10 complete rolls, the airplane stopped rolling in the inverted position and after approximately one-half of one second started rolling to the left at a rate in excess of 360 degrees per second, estimated by the pilot. At this point the pilot was completely disoriented and was not sure what maneuvers the airplane went through following the high rates of roll. Several very high ‘g’ loads both positive and negative and side loads were felt by the pilot. At one point during a negative ‘g’ load, the pilot felt the inner liner of the canopy break as the top of his pressure suit helmet came in contact with it. The first maneuver recognized by the pilot was an inverted spin at approximately 33,000 feet. The airplane then fell off into the normal spin from which the pilot recovered at 25,000 feet.”

Flight test data from Yeager's 12 December 1953 flight superimposed over a photograph of the bell X-1A. (NASA)
Flight test data from Yeager’s 12 December 1953 flight superimposed over a photograph of the Bell X-1A. (NASA)

The following is a transcript of radio transmissions during the flight:

Yeager: Illegible [inaudible]—gasping—I’m down to 25,000 over Tehachapi. Don’t know
whether I can get back to the base or not.
Chase (Ridley): At 25,000 feet, Chuck?
Yeager: Can’t say much more, I got to (blurry—save myself).
Yeager: I’m—(illegible)—(Christ!)
Chase (Ridley): What say, Chuck?
Yeager: I say I don’t know if I tore anything up or not but Christ!
Chase (Murray): Tell us where you are if you can.
Yeager: I think I can get back to the base okay, Jack. Boy, I’m not going to do that any more.
Chase (Murray): Try to tell us where you are, Chuck.
Yeager: I’m (gasping)…I’ll tell you in a minute. I got 1800 lbs [nitrogen] source pressure.
Yeager: I don’t think you’ll have to run a structure demonstration on this damned thing!
Chase (Murray): Chuck from Murray, if you can give me altitude and heading, I’ll try to check you from outside.
Yeager: Be down at 18,000 feet. I’m about—I’ll be over the base at about 15,000 feet in a minute.
Chase (Murray): Yes, sir.
Yeager: Those guys were so right!
Yeager: Source pressure is still 15 seconds, I’m getting OK now.
Yeager: I got all the oscillograph data switches off. 4 fps camera off, it’s okay.
Bell Truck: Jettison and vent your tanks.
Yeager: I have already jettisoned. Now I’m venting both lox and fuel. Leaving hydrogen peroxide alone.
Bell Truck: Roger.
Yeager: I cut it, I got—in real bad trouble up there.
Yeager: Over the base right now, Kit, at 14,500 feet.
Chase (Murray): I have you.

A North American F-86E-10-NA Sabre chase plane, 51-2848, follows the Bell X-1A as it glides toward Rogers Dry Lake. (NASA)
A North American F-86E-10-NA Sabre chase plane, 51-2848, follows the Bell X-1A as it glides toward Rogers Dry Lake. (NASA)

In his autobiography, Always Another Dawn, NACA test pilot Albert Scott Crossfield wrote:

Probably no other pilot could have come through that experience alive. Much later I asked Yeager, as a matter of professional interest, exactly how he regained control of the ship. He was vague in his reply, but he said he thought that after he reached the thick atmosphere, he had deliberately put the ship into a spin.

“A spin is something I know how to get out of,” he said. “That other business— the tumble—there is no way to figure that out.”

. . . Yeager received many accolades. I didn’t begrudge him one of them. If ever a pilot deserved praise for a job well done, it was Yeager. After that X-1A episode, he never flew a rocketplane again.

Always Another Dawn: The Story of a Rocket Test Pilot, by A. Scott Crossfield with Clay Blair, Jr., The World Publishing Company, Cleveland and New York, Chapter 19 at Pages 183–184.  

Bell X-1A 48-1384 (U.S. Air Force)

The Bell X-1A, 48-1384, was an experimental rocket-powered high-speed, high-altitude research aircraft. It was one of four second-generation X-1s (including the X-1B, X-1D and X-1E), specifically designed to investigate dynamic stability at speeds in excess of Mach 2 and altitudes greater than 90,000 feet. It was a mid-wing monoplane with retractable tricycle landing gear. The airplane was 35 feet, 6.58 inches (10.835 meters) long with a wingspan of 30 feet, 6 inches (9.296 meters) and overall height of 10 feet, 2.37 inches (3.261 meters). The wheelbase, measured from the nose wheel axle to the main wheel axle, was  13 feet, 5.13 inches. (4.093 meters). The main wheel tread was 4 feet, 3 inches (1.295 meters). The X-1A design gross weight was 10,668 pounds (4,839 kilograms).

The X-1A was powered by a single Reaction Motors XLR11-RM-5 rocket engine with four independent combustion chambers. The XLR11 was fueled with ethyl alcohol and liquid oxygen. It produced 6,000 pounds of thrust (26.689 kilonewtons).

The Bell X-1A made its first flight 14 February 1953 with Bell test pilot Jean Ziegler in the cockpit. It reached its highest speed, Mach 2.44 on Flight 10. Its highest altitude was 90,440 feet (27,566 meters) on its 24th flight. On 8 August 1955, while still on board its B-50 drop ship, the X-1A suffered an external explosion. The rocketplane was jettisoned and destroyed when it hit the desert floor.

© 2016, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

20 November 1953

NACA test pilot Scott Crossfield in the cockpit of the Douglas D-558-II Skyrocket after his record-setting flight, 20 November 1953. (NASA) 20 November 1953: At Edwards Air Force Base, California, NACA’s High Speed Flight Station test pilot Albert Scott Crossfield rode behind the flight crew of the Boeing P2B-1S Superfortress as it carried the Douglas Aircraft Company D-558-II Skyrocket supersonic research rocketplane to its launch altitude. As the four-engine bomber climbed through 18,000 feet (5,486 meters), Crossfield headed back to the bomb bay to enter the Skyrocket’s cockpit and prepare for his flight.

The Douglas D-558-II was Phase II of a U.S. Navy/Douglas Aircraft Company/National Advisory Committee on Aeronautics joint research project exploring supersonic flight. It was a swept-wing airplane powered by a single Reaction Motors LR8-RM-6 four-chamber rocket engine. The Skyrocket was fueled with alcohol and liquid oxygen. The engine was rated at 6,000 pounds of thrust (26.69 kilonewtons) at Sea Level.

There were three Phase II aircraft. Originally, they were also equipped with a Westinghouse J34-W-40 turbojet engine which produced 3,000 pounds of thrust (13.35 kilonewtons) and the Skyrockets took off from the surface of Rogers Dry Lake. Once the D-558-II reached altitude, the rocket engine was fired for the speed runs. As higher speeds were required, the program shifted to an air launch from a B-29 (P2B-1S) “mothership”. Without the need to climb to the test altitude, the Skyrocket’s fuel load was available for the high speed runs.

NACA 144. a Douglas D-558-II Skyrocket, Bu. No. 37974, on Rogers Dry Lake. (NASA)
NACA 144. a Douglas D-558-II Skyrocket, Bu. No. 37974, on Rogers Dry Lake. (NASA)

The D-558-II was 42.0 feet (12.80 meters) long, with a wingspan of 25.0 feet (7.62 meters). The leading edge of the wing was swept at a 35° angle and the tail surfaces were swept to 40°. The aircraft weighed 9,421 pounds (4,273 kilograms) empty and had a maximum takeoff weight of 15,787 pounds (7,161 kilograms). It carried 378 gallons (1,431 liters) of water/ethyl alcohol and 345 gallons (1,306 liters) of liquid oxygen.

The mothership, NACA 137, was a Boeing Wichita B-29-95-BW Superfortress, U.S. Air Force serial number 45-21787. It was transferred to the U.S. Navy, redesignated P2B-1S and assigned Bureau of Aeronautics number 84029. Douglas Aircraft modified the bomber for its drop ship role at the El Segundo plant.

Douglas D-558-II Skyrocket, Bu. No., 37974, NACA 144, is dropped from the Boeing P2B-1S Superfortress, Bu. No. 84029, NACA 137. (NASA)
Douglas D-558-II Skyrocket, Bu. No. 37974, NACA 144, is dropped from the Boeing P2B-1S Superfortress, Bu. No. 84029, NACA 137. (NASA)

Going above the planned launch altitude, the Superfortress was placed in a slight dive to build to its maximum speed. At the bomber’s critical Mach number (Mcr), the Skyrocket was just above its stall speed. At 32,000 feet (9,754 meters), Crossfield and the Skyrocket were released. The rocketplane fell for about 400 feet (122 meters) until the rocket engine ignited and then it began to accelerate.

Crossfield climbed at a steep angle until he reached 72,000 feet (21,946 meters), and then leveled off. Now in level flight, the D-558-II accelerated, quickly passing Mach 1, then Mach 1.5. Crossfield pushed the nose down and began a shallow dive. The Skyrocket, still under full power, built up speed. As it passed through 62,000 feet (18,998 meters) the Skyrocket reached its maximum speed, Mach 2.005, or 1,291 miles per hour (2,078 kilometers per hour).

Scott Crossfield and the Douglas D-558-II Skyrocket, with their support team: two North American F-86 Sabre chase planes and the Boeing P2B-1S Superfortress mothership, at the NACA High Speed Flight Station, Edwards Air Force Base, California, 1 January 1954. (NASA)
Scott Crossfield and the Douglas D-558-II Skyrocket, with their support team: two North American F-86 Sabre chase planes and the Boeing P2B-1S Superfortress mothership, at the NACA High Speed Flight Station, Edwards Air Force Base, California, 1 January 1954. (NASA)

Scott Crossfield was the first pilot to fly an aircraft beyond Mach 2, twice the speed of sound. During his career as a test pilot, he flew the Douglas D-558-II, the Bell X-1, Bell X-2 and North American X-15. He made 112 flights in rocket-powered aircraft, more than any other pilot.

NACA Test Pilot Albert Scott Crossfield on Rogers Dry Lake. (NASA)
NACA Test Pilot Albert Scott Crossfield on Rogers Dry Lake. (NASA)

© 2016, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather