Convair XB-58 55-0660 in its original paint scheme. (Unattributed)
11 November 1956: At Fort Worth, Texas, Convair’s Chief Test Pilot, Beryl Arthur Erickson, takes the first prototype XB-58, serial number 55-0660, on its first flight.
“Pilot B.A. Erickson is interviewed by NBC after a flight as part of a B-58 Press Show Demonstration. July 10, 1957″—Code One
The B-58 Hustler was a high-altitude Mach 2 strategic bomber which served with the United States Air Force from 1960 to 1970. It was crewed by a pilot, navigator/bombardier and a defensive systems operator, located in individual cockpits. The aircraft is a delta-winged configuration similar to the Convair F-102A Delta Dagger and F-106 Delta Dart supersonic interceptors.
The Hustler is 96 feet, 10 inches (29.515 meters) long, with a wing span of 56 feet, 10 inches (17.323 meters) and an overall height of 31 feet 5 inches (9.576 meters). The fuselage incorporates the “area rule” which resulted in a “wasp waist” or “Coke bottle” shape for a significant reduction in aerodynamic drag. The airplane’s only control surfaces are two “elevons” and a rudder, and there are no flaps.
The B-58’s delta wing has a total area of 1,542.5 square feet (143.3 square meters) and the leading edges are swept back at a 60° angle. The wing has an angle of incidence of 3° and 2° 14′ dihedral (outboard of Sta. 56.5).
The B-58A had an empty weight of 51,061 pounds (23161 kilograms), or 53,581 pounds (24,304 kilograms) with the MB-1 pod. The maximum takeoff weight was 158,000 pounds (71,668 kilograms).
Convair XB-58 Hustler 55-0660. (U.S. Air Force)
The B-58A was powered by four General Electric J79-GE-5 axial-flow afterburning turbojet engines, suspended under the wings from pylons. This was a single-shaft engine with a 17-stage compressor and 3-stage turbine. It had a Normal Power rating of 9,700 pounds of thrust (43.148 kilonewtons). The Military Power rating was 10,000 pounds (44.482 kilonewtons), and it produced a maximum 15,600 pounds (69.392 kilonewtons) at 7,460 r.p.m., with afterburner. The J79-GE-5 was 16 feet, 10.0 inches (5.131 meters) long and 2 feet, 11.2 inches (0.894 meters) in diameter. It weighed 3,570 pounds (1,619 kilograms).
Convair XB-58 Hustler 55-0660 rotates during a high-speed taxi test. (Code One)
The bomber had a cruise speed of 544 knots (626 miles per hour/1,007 kilometers per hour) and a maximum speed of 1,147 knots (1,320 miles per hour/2,124 kilometers per hour) at 67,000 feet (20,422 meters). The B-58A had a combat radius of 4,225 nautical miles (4,862 statute miles/7,825 kilometers). Its maximum ferry range was 8,416 nautical miles (9,685 statute miles/15,586 kilometers).
Convair XB-58 55-0660 carrying at jettisonable fuel/weapon centerline pod. (U.S. Air Force)
The B-58 weapons load was a combination of Mark 39, B43 or B61 thermonuclear bombs. The weapons could be carried in a jettisonable centerline pod, which also carried fuel. The four of the smaller bombs could be carried on underwing hardpoints. There was a General Electric M61 20 mm rotary cannon mounted in the tail, with 1,200 rounds of ammunition, and controlled by the Defensive Systems Officer.
FAI altitiude record setting Convair B-58A-10-CF 59-2456, showing the bomber’s weapons capability. (U.S. Air Force)
116 were built and they served the Strategic Air Command until January 1970 when they were sent to Davis-Monthan AFB, Tucson, Arizona for long-term storage.
Convair XB-58 55-0660 was transferred to Kelly Air Force Base, Texas, 15 March 1960, for use as a ground instruction airframe. It was scrapped some time later.
Convair XB-58 55-0660 touches down on the runway following a test flight. (Unattributed)
Sikorsky YH-19 49-2012 first flight, Bloomfield, Connecticut, 10 November 1949. (Sikorsky, a Lockheed Martin Company)
10 November 1949: At Bloomfield, Connecticut, Dimitry D. (“Jimmy”) Viner, a nephew of Igor Sikorsky and chief test pilot for the Sikorsky Aircraft Corporation, made the first flight of the prototype Sikorsky S-55 helicopter, serial number 55-001, which the U.S. Air Force had designated YH-19 and assigned serial number 49-2012.
Five YH-19 service test aircraft were built. Two were sent to Korea for evaluation in combat. As a result, the United States Air Force placed an initial order for 50 H-19A Chickasaw helicopters. (It is customary for U.S. Air Force and U.S. Army helicopters to be named after Native American individuals or tribes, though there are exceptions.) This was quickly followed by orders for 264 H-19B helicopters.
Sikorsky YH-19 49-2014 in Korea, circa 1951. (U.S. Air Force)
The United States Navy ordered 118 S-55s which were designated HO4S-1 and HO4S-3. The U.S. Coast Guard bought 30 HO4S-1G and HO4S-3Gs configured for rescue operations. The U.S. Marine Corps purchased 244 HRS-1, HRS-2 and HRS-3 helicopters. The U.S. Army ordered 353 H-19C and H-19D Chickasaw utility transports. The remaining 216 Sikorsky-built helicopters were S-55, S-55C and S-55D commercial models.
Cutaway illustration of the Sikorsky S-55/H-19/HO4S/HRS. Note the rearward-facing, angled placement of the radial engine. (Sikorsky Historical Archives)
The S-55 was flown by two pilots in a cockpit placed above the passenger/cargo compartment. The most significant design feature was moving the engine from directly under the main rotor mast to a position at the front of the helicopter. Installed at an angle, the engine turned a drive shaft to the main transmission. The engine placement provided space for a large passenger/cargo compartment. The aircraft was constructed primarily of aluminum and magnesium, with all-metal main and tail rotor blades.
The main rotor consisted of three fully-articulated blades built of hollow aluminum spars, with aluminum ribs. Spaces within the blade were filled with an aluminum honeycomb. The blades were covered with aluminum sheet. The hollow spars were filled with nitrogen pressurized to 10 p.s.i. An indicator at the blade root would change color if nitrogen was released, giving pilots and mechanics an indication that the spar had developed a crack or was otherwise compromised. The main rotor turned counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right.) Flapping hinges were offset from the main rotor axis, giving greater control response and effectiveness. 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 helicopter’s fuselage was 42 feet, 2 inches (12.852 meters). The main rotor had a diameter of 53 feet, 0 inches (16.154 meters) and tail rotor diameter was 8 feet, 8 inches (2.642 meters), giving the helicopter an overall length with all blades turning of 62 feet, 2 inches (18.948 meters). It was 13 feet, 4 inches (4.064 meters) high. The landing gear tread was 11 feet (3.353 meters). The S-55 had an empty weight of 4,785 pounds (2,173 kilograms) and maximum takeoff weight of 7,200 pounds (3,271 kilograms). Fuel capacity was 185 gallons (698 liters).
The YH-19 was powered by an air-cooled, supercharged 1,343.804-cubic-inch-displacement (22.021 liter) Pratt & Whitney R-1340-57 (Wasp S1H2) 9-cylinder radial engine mounted at a 35° angle in the fuselage forward of the crew compartment. This was a direct-drive engine which had a Normal Power rating of 550 horsepower at 2,200 r.p.m. to 8,000 feet (2,438 meters), and 600 horsepower at 2,250 r.p.m. for Take Off.
Later production S-55 commercial and H-19/HO4S and HRS military helicopters used an air-cooled, supercharged 1,301.868-cubic-inch (21.334 liter) Wright Aeronautical Division 871C7BA1 Cyclone 7 (R-1300-3) 7-cylinder radial engine with a compression ratio of 6.2:1. The R-1300-3 was also a direct-drive engine, but was rated at 700 horsepower at 2,400 r.p.m., Normal Power, and 800 horsepower at 2,600 r.p.m. for Take-Off. Both engines incorporated a large cooling fan to circulate air around the cylinders. The R-1300-3 was 49.68 inches (1.261 meters) long, 50.45 inches (1.281 meters) in diameter, and weighed 1,080 pounds (490 kilograms).
Sikorsky Aircraft Corps. YH-19 49-2012 (c/n 55-001) shown with engine “clam shell” doors open. This allowed excellent access to the engine for maintenance. (Sikorsky Historical Archives)
The S-55 had a maximum speed of 95 knots (109 miles per hour, 176 kilometers per hour) at Sea Level. The helicopter’s hover ceiling in ground effect (HIGE) was 7,875 feet (2,400 meters) and out of ground effect (HOGE) is 4,430 feet (1,350 meters). The service ceiling was 11,400 feet (3,475 meters) and range was 405 miles (652 kilometers).
Sikorsky Aircraft Corporation built 1,281 S-55-series helicopters. Another 477 were built under license by Westland Aircraft Ltd., Société Nationale des Constructions Aéronautiques du Sud-Est (SNCASE) and Mitsubishi Heavy Industries.
49-1012 is in the collection of the Smithsonian Institution National Air and Space Museum.
The first of five YH-19 service test helicopters, 49-2012, is on display at the Smithsonian Institution National Air and Space Museum. (NASM)Dimitry D. Viner, circa 1931
Дмитро Дмитрович Вінер (Dimitry Dimitry Viner) was born in Kiev, Ukraine, Imperial Russia, 2 October 1908. He was the son of Dimitry Nicholas Weiner and Helen Ivan Sikorsky Weiner, a teacher, and the sister of Igor Ivanovich Sikorsky.
At the age of 15 years, Viner, along with his mother and younger sister, Galina, sailed from Libau, Latvia, aboard the Baltic-American Line passenger steamer S.S. Latvia, arriving at New York City, 23 February 1923.
“Jimmy” Viner quickly went to work for the Sikorsky Aero Engineering Company, founded by his uncle, Igor Sikorsky.
Dimitry Viner became a naturalized United States citizen on 27 March 1931.
Viner married Miss Irene Regina Burnett. The had a son, Nicholas A. Viner.
A Sikorsky YR-5A flown by Jimmy Viner with Captain Jack Beighle, hoists a crewman from Texaco Barge No. 397, aground on Penfield Reef, 29 November 1945. (Sikorsky Historical Archive)
On 29 November 1945, Jimmy Viner and Captain Jackson E. Beighle, U.S. Army, flew a Sikorsky YR-5A to rescue two seamen from an oil barge which was breaking up in a storm off of Fairfield, Connecticut. This was the first time that a hoist had been used in an actual rescue at sea.
Jimmy Viner made the first flight of the Sikorsky S-51 prototype on 16 February 1946, and in 1947, he became the first pilot to log more than 1,000 flight hours in helicopters.
Dimitry Dimitry Viner died at Stratford, Connecticut, 14 June 1998, at the age of 89 years.
Dimitry D. (“Jimmy”) Viner with a Sikorsky S-51, the civil version of the R-5. (Sikorsky Historical Archive)
9 November 1962: Flight 74 of the X-15 Program was the Number Two aircraft’s 31st flight. X-15 56-6671 was carried aloft by Balls 8, the Boeing NB-52B Stratofortress, 53-008, for launch over Mud Lake, Nevada. NASA test pilot John Barron (“Jack”) McKay was to take the rocketplane to 125,000 feet at Mach 5.5 to investigate the stability and handling of the X-15 with the lower half of the ventral fin removed, and to investigate aerodynamic boundary layer phenomena.
North American Aviation X-15 56-6671 under the right wing of a B-52 Stratofortress at 45,000 feet. (NASA)
The B-52 mothership dropped Jack McKay and the X-15 right on schedule at 10:23:07.0 a.m., local time, from an altitude of 45,000 feet (13,716 meters) and speed of approximately 450 knots (833 kilometers per hour). McKay advanced the throttle to ignite the Reaction Motors XLR99-RM-1 rocket engine. It fired immediately but when McKay advanced the throttle for the full 57,000 pounds of thrust, the engine remained at just 30%.
The X-15 could have flown back to Edwards Air Force Base, about 200 miles (320 kilometers) to the south, but with the engine not responding to the throttle, it was uncertain that it would continue running. The decision was made to make an emergency landing at Mud Lake.
Having reached a peak altitude of 53,950 feet (16,444 meters) and Mach 1.49 (1,109 miles per hour/1,785 kilometers per hour), Jack McKay continued to circle the lake burning off propellants as he lost altitude. The engine was shut down at 70.5 seconds. McKay positioned the aircraft for landing as he continued to dump unused propellant and liquid oxygen, but a considerable amount remained on board.
As he neared touchdown, he tried to lower the flaps but they did not deploy. The X-15 touched down on the dry lake bed at 296 miles per hour (476.4 kilometers per hour), 66 miles per hour (106 kilometers per hour) faster than normal.
Duration of the flight from air launch to touchdown was 6 minutes, 31.1 seconds.
The high speed and extra weight caused the X-15’s rear skids to hit harder than normal. When the nose wheels hit, a rebound effect placed even higher loads on the rear struts. At the same time, with the elevators in an extreme nose-up position, the higher aerodynamic loads pushed the skids deeper into the lake bed. This higher loading caused the left rear strut to collapse. The X-15 rolled to the left and the left elevator dug into the lake bed. This caused the aircraft to start sliding to the left. Jack McKay jettisoned the canopy and as the right wing tip dug into the surface, the X-15 flipped over and came to rest upside down.
A Piasecki H-21 rescue helicopter lands near the overturned X-15 at Mud Lake, 9 November 1961. (NASA)The X-15 rolled over when the left landing skid collapsed because of the high-speed, overweight emergency landing at Mud Lake, Nevada. Jack McKay was trapped in the cockpit and suffered serious spinal injuries. (NASA)The Number Two X-15, 56-6671, lies upside down and severely damaged at Mud Lake, Nevada, 9 November 1962. (NASA)
McKay was seriously injured. He was trapped in the upside down X-15 and was in danger from the vapors of the ammonia propellants and liquid oxygen. An H-21 rescue helicopter hovered overhead to blow the vapor away.
Prior to the flight, an Air Force C-130 had brought a fire engine and crew to standby at Mud Lake, returned to Edwards and picked up a second fire engine and its crew, then remained airborne should an emergency landing be made at another intermediate dry lake.
These propositioned emergency assets were able to rescue McKay and to transport him to the hospital back at Edwards.
McKay eventually recovered sufficiently to return to flight status, but ultimately his injuries forced him to retire.
The Number Two X-15 was severely damaged. It was taken back to North American and was rebuilt into the X-15A-2, intended to reach speeds up to Mach 8. It would be more than a year and a half before it flew again.
North American Aviation X-15A-2 56-6671, after a 19-month repair, redesign and modification program. The fuselage was lengthened, additional propellant and reaction control tanks installed internally, the nose wheel and rear landing skid struts lengthened, and external tanks installed. (NASA)
Major Robert M. White was the first pilot to exceed Mach 4, Mach 5, and on 9 November 1961, he flew to Mach 6.04. (U.S. Air Force)
9 November 1961: Major Robert M. White, U.S. Air Force, became the first pilot to fly faster than Mach 6 when he flew the number two North American Aviation X-15 hypersonic research rocketplane, 56-6671, to Mach 6.04.
This was the 45th flight of the X-15 program, and Bob White’s 11th flight. The purpose of this test flight was to accelerate 56-6671 to its maximum velocity, to gather data about aerodynamic heating at hypersonic speeds, and to evaluate the rocketplane’s stability and handling.
Boeing NB-52A Stratofortress 52-003 carries a North American Aviation X-15 piloted by Major Bob White. (NASA)
The X-15 was carried to approximately 45,000 feet (13,716 meters) while mounted to a pylon under the right wing of the “mothership,” a Boeing NB-52B Stratofortress, 52-008, nicknamed Balls 8. White was dropped over Mud Lake, Nevada, approximately 200 miles (322 kilometers) north of Edwards Air Force Base. Once clear of the B-52, he ignited the Reaction Motors XLR99-RM-1 rocket engine, and with it producing 57,000 pounds of thrust (253.549 kilonewtons) at full throttle, the X-15 accelerated for 86.9 seconds. The rocketplane reached a peak altitude of 101,600 feet (30,968 meters). Its speed was Mach 6.04 (4,094 miles per hour/6,589 kilometers per hour).
White stated in his post-flight report, “When I leveled off at about 101,000 feet, I made a little downward pressure [on the control stick], because I didn’t want to be climbing. I remember . . . going along watching that [Mach] meter reading roughly 6,000 feet per second,[and] saying to myself, ‘Go, go, go, go!’ We did just crack it, because we knew that bringing all the proper things together, we could or should get just about Mach 6.”
In order to achieve the goal, the flight plan called for pushing the LR-99 to the point of exhaustion instead of manually shutting down the engine at an arbitrary point. White said, “The shutdown seemed to be a little bit different this time, compared with a shutdown by closing the throttle. It seemed to occur over a longer time interval.”
— The X-15 Rocket Plane: Flying the First Wings into Space, by Michelle Evans, University of Nebraska Press, Lincoln and London, 2013, Chapter 3 at Page 87.
The number two North American Aviation X-15, 56-6671, is dropped from the Boeing NB-52A Stratofortress, 52-003. The XLR99 rocket engine is just igniting. Frost from the cryogenic fuels coats the fuselage. (NASA)
“The airplane really did get hot on those flights. Temperatures in excess of 1,300 °F. were recorded. Parts of the airplane glowed cherry red and softened up a bit during those flights. The airplane got so damned hot that it popped and banged like an old iron stove. It spewed smoke out of its bowels and it twitched like frog legs in a skillet. But it survived.”
— At the Edge of Space: The X-15 Flight Program, by Milton O. Thompson, Smithsonian Institution Press, Washington, 1992, at Page 98.
North American Aviation X-15 56-6671 accelerates after the XLR99 engine is ignited. (NASA)
As the X-15 decelerated through Mach 2.4, the right side windshield shattered, leaving it completely opaque. On Bob White’s previous flight, the left windshield had also broken. Fortunately, in both cases, only the outer layer of the dual pane glass broke. The reduced visibility made the approach difficult to judge, but White made a successful landing, touching down on Rogers Dry Lake after a flight of 9 minutes, 31.2 seconds duration.
The number three North American Aviation X-15 rocketplane, 56-6672, just before touchdown on Rogers Dry Lake. A Lockheed F-104 Starfighter chase plane escorts it. The green smoke helps the pilots judge wind direction and speed. Frost on the X-15’s belly shows residual propellants in the tanks. (NASA)The shattered windshield of X-15 56-6671, 9 November 1961. (NASA)
A P-51 Mustang fighter pilot in World War II, Robert M. 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. 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.
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, then over 300,000 feet. He made at total of sixteen X-15 flights.
Major Robert M. White, U.S. Air Force, with one of the three North American Aviation X-15s on Rogers Dry Lake, 1961. (NASA)
After leaving the X-15 program, Bob White returned to operational duties. 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. He next went to Wright-Patterson AFB where he was director of the F-15 Eagle systems program. He returned to Edwards AFB 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 10 March 2010.
A North American Aviation support crew deactivates X-15 56-6671 on Rogers Dry Lake after a flight, while the mothership, NB-52A Stratofortress 52-003 flies overhead. (NASA)
The Number 2 X-15, 56-6671, broke in half when it made an emergency landing while still partially loaded with propellants. (NASA)
5 November 1959: During his fourth X-15 flight—the third in the Number Two ship, 56-6671—North American Aviation chief test pilot Albert Scott Crossfield made an emergency landing at Rosamond Dry Lake after one of the two Reaction Motors XLR11-RM-13 rocket engines exploded, causing an engine compartment fire.
The X-15 had been launched by the Boeing NB-52A Stratofortress, 52-003, at 0.82 Mach and approximately 45,000 feet (13,716 meters) over Bouquet Canyon Reservoir, about 35 miles (56 kilometers) southwest of Edwards Air Force Base. Scott Crossfield ignited both XLR11 rocket engines and began to accelerate and climb, but one of four combustion chambers of the lower engine exploded almost immediately. He shut both engines down after 11.7 seconds. Crossfield kept the rocketplane in a level attitude for the 114 seconds it took to jettison the liquid oxygen and water-alcohol propellants to lighten the X-15 for the landing. The tanks could not fully drain and the aircraft remained approximately 1,000 pounds (455 kilograms) overweight.
The X-15 approached the emergency landing site at Rosamond Dry Lake, about ten miles (16 kilometers) southwest of Edwards, while Major Robert M. White, flying a Lockheed F-104 chase plane, called out Crossfield’s distance from the dry lake and his altitude. As he neared the touch down point, Crossfield raised the X-15’s nose to decelerate.
“I lowered the skids and nose wheel, pulled the flaps, and felt for the lake bed.
“The skids dug in gently. The nose wheel slammed down hard and the ship plowed across the desert floor, slowing much faster than usual. Then she came to a complete stop within 1500 feet instead of the usual 5000 feet. Something was wrong; the skids failed, I was sure. . . Quickly I scrambled out of the cockpit. What I saw almost broke my heart. The fuselage had buckled immediately aft of the cockpit, two hundred and thirty inches back from the nose. Her belly had dragged in the sand, causing the abrupt deceleration on the lake. The rocket chambers which had exploded at launch were a shambles.”
—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, Chapter 41 at Pages 383–384.
The scene at Rosamond Dry Lake after Scott Crossfield’s emergency landing following an engine explosion. (NASA)
It was determined that the engine had exploded due to an ignition failure, a relatively simple problem not connected to the design of the X-15. But there remained the question as to why the rocketplane had broken in half. The investigation found that the rapid extension of the nose wheel strut when lowered caused the oil inside the strut to foam and vaporize, providing almost no shock absorption. This was corrected and the check list changed to lower the gear sooner.
The total duration of this flight was 5 minutes, 28.0 seconds. The peak altitude was 45,462 feet (13,857 meters) and the maximum speed was 660 miles per hour (1,062 kilometers per hour).
56-6671 was taken back to the North American Aviation plant for repair. It returned to flight operations three months later.
Test pilot A. Scott Crossfield with the damaged X-15 on Rosamond Dry Lake. (UPI/Harry Ransom Center, University of Texas at Austin)
