Tag Archives: Edwards Air Force Base

26 March 1966

Allison Engine Co. test pilot Jack l. Schweibold with teh record-setting prototype Hughes YOH-6A, 62-4213, at Edwards Air Force Base, California, 1966. (FAI)
Allison Engine Co. test pilot Jack Schweibold with the record-setting number three prototype Hughes YOH-6A Light Observation Helicopter, 62-4213, at Edwards Air Force Base, California, 1966. (FAI)

26 March 1926: Allison Engine Company test pilot Jack Schweibold flew the third prototype Hughes Aircraft Company YOH-6A Light Observation Helicopter, 62-4213, to set three Fédération Aéronautique Internationale (FAI) World Records for Distance Over a Closed Circuit Without Landing of 2,800.20 kilometers (1,739.96 miles), including an Absolute Record for Class E (Rotorcraft).¹ These records still stand.

Hughes YOH-6A 62-4213 at Edwards Air Force Base, 1966. (FAI)
Hughes YOH-6A 62-4213 at Edwards Air Force Base, 1966. (FAI)

One week earlier, 20 March 1966, Hughes Aircraft Company test pilot Jack L. Zimmerman flew the same helicopter to set another distance record of of 1,700.12 kilometers (1,056.41 miles).² One 27 March, Zimmerman would set six more world records with 62-4213.³

Jack Schweibold wrote about the record flight in his autobiography, In the Safety of His Wings (Holy Fire Publishing, DeLand, Florida, 2005). He was one of a group of military and civilian test pilots selected to attempt a series of world record flights, using the number three prototype Hughes YOH-6A, 62-4213, from 20 March to 7 April 1966.

The record attempt began at midnight to take advantage of the cold desert air. The cold-soaked YOH-6A had been fueled with pre-cooled JP-5 in order to get the maximum amount of fuel on board. In addition to the standard fuel tank, two auxiliary tanks were placed in the cabin. The helicopter was so heavy from the overload that it could not hover. Jack made a running take-off, sliding the skids across the concrete until the increasing translational lift allowed the aircraft to break free. He began a very shallow climb.

Schweibold was flying a 60 kilometer (37.28 miles) closed course, but because of the near total darkness, he flew on instruments and was guided from the ground by Air Force test range radar controllers (Spatial Positioning and Orientation Radar Tracking, call sign SPORT). Accuracy was critical. The attempt would be disqualified if the helicopter cut inside of a pylon—which Jack could not see—but if he flew too far outside, the extra distance flown would not be counted and time would be lost. The maximum range would be controlled by the amount of fuel carried in the three tanks, and by the endurance of the pilot.

Throughout the flight, Jack gradually increased the altitude, as the T-63-A-5 turboshaft would be more efficient in thinner, colder air. He was flying a precisely calculated profile, taking into consideration aerodynamic drag, the efficiency of the helicopter’s rotor system, and the performance characteristics of the engine. He had been airborne for four hours before he climbed through 10,000 feet (3,048 meters).

At 14,000 feet (4,267 meters), Schweibold was on oxygen. He continued through 20,000 feet (6,096 meters) but was having trouble staying alert. (It would later be discovered that there was a malfunction in his oxygen mask.)

On the final lap, at 22,000 feet (6,706 meters) Jack had to fly around a towering cumulus cloud and radar contact was lost. He dived to lose altitude and popped out from under the cloud about a half-mile short of the runway.

When he shut down the engine, Jack Schweibold had flown the prototype YOH-6A 2800.20 kilometers (1,739.96 statute miles), non-stop. His record still stands.

Jack set 30 FAI World Records between 1966 and 1986. 26 of these remain current.

Frederick Jack Schweibold was born at Toledo, Ohio, 8 November 1935, the son of Henry E. and Jeanette Schweibold. He attended Ohio State University and majored engineering. He had enlisted in the United States Navy Reserve in 1952 and the joined the United States Air Force in 1954 as an Aviation Cadet. Schweibold went through pilot training at Randolph Air Force Base, San Antonio, Texas, flying the T-34 and T-28. He went on to train in the B-25 at Reese Air Force Base, Lubbock, Texas. Schweibold was commissioned as a second lieutenant and received his pilot’s wings in July 1957. In  momentary decision, he selected helicopter training.

Lieutenant Schweibold flew the Sikorsky H-19B for the Air Rescue Service, assigned to Oxnard Air Force Base, California. (The airfield is now Camarillo Airport, CMA, where I first soloed, and is about ten miles away from my desk.)

After leaving the Air Force, Jack flew Sikorsky S-55s for Chicago Helicopter Service, then Bell 47s for Butler Aviation. In 1960, he was hired by the Allison Division of General Motors as a test pilot and engineer for the new 250-series turboshaft engine.

I had the good fortune to have known Jack Schweibold. I first met him through his involvement in the Helicopter Association International biennial flight instructor recertification seminars, held during the HAI’s annual convention. He kept the seminar classes on track, and in between, was always available for questions. He was the authority on Allison’s 250-series turboshaft engines, and over the years I often called him for technical information and operational advice. On top of that, Jack Schweibold was just an all-around nice guy.

U.S. Army Hughes YOH-6A prototype 62-4213 at Le Bourget, circa 1965.
U.S. Army Hughes YOH-6A prototype 62-4213 at Le Bourget, circa 1965. (R.A. Scholefield Collection)

The Hughes Model 369 was built in response to a U.S. Army requirement for a Light Observation Helicopter (“L.O.H.”). It was designated YOH-6A, and the first aircraft received U.S. Army serial number 62-4211. It competed with prototypes from Bell Helicopter Company (YOH-4) and Fairchild-Hiller (YOH-5). All three aircraft were powered by a lightweight Allison Engine Company turboshaft engine. The YOH-6A won the three-way competition and was ordered into production as the OH-6A Cayuse. It was nicknamed “loach,” an acronym for L.O.H.

The YOH-6A was a two-place light helicopter, flown by a single pilot. It had a four-bladed, articulated main rotor which turned counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right.) Stacks of thin stainless steel “straps” fastened the rotor blades to the mast and also allowed for flapping and feathering. Hydraulic dampers controlled lead-lag. Originally, there were blade cuffs around the main rotor blade roots in an attempt to reduce aerodynamic drag, but these were soon discarded. A two-bladed semi-rigid tail rotor was mounted on the left side of the tail boom. Seen from the left, the tail-rotor rotates counter-clockwise. (The advancing blade is on top.)

Overhead photograph of a Hughes YOH-6. Note the blade cuffs. (U.S. Army)
Overhead photograph of a Hughes YOH-6A. Note the blade cuffs. (U.S. Army)

The YOH-6A was powered by a T63-A-5 turboshaft engine (Allison Model 250-C10) mounted behind the cabin at a 45° angle. The engine was rated at 212 shaft horsepower at 52,142 r.p.m. (102% N1) and 693 °C. turbine outlet temperature for maximum continuous power, and 250 shaft horsepower at 738 °C., 5-minute limit, for takeoff. Production OH-6A helicopters used the slightly more powerful T63-A-5A (250-C10A) engine.

The Hughes Tool Company Aircraft Division built 1,420 OH-6A Cayuse helicopters for the U.S. Army.  The helicopter remains in production as AH-6C and MH-6 military helicopters, and the MD500E and MD530F civil aircraft.

Hughes YOH-6A 62-4213 is in the collection of the United States Army Aviation Museum, Fort Rucker, Alabama.

The third prototype YOH-6A, 62-4213, testing the XM-7 twin M60 7.62 weapons system. (U.S. Army)
The third prototype YOH-6A, 62-4213, testing the XM-7 twin M60 7.62 weapons system. (U.S. Army)

¹ FAI Record File Numbers 786, 787 and 11656

² FAI Record File Number 762

³ FAI Record File Numbers 771, 772, 9920, 9921, 9922, and 9923

© 2017, Bryan R. Swopes

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25 March 1955

John W. Konrad in the cockpit of the prototype Vought XF8U-1 Crusader, Bu. No. 138899. (Vought Heritage)
John W. Konrad in the cockpit of the prototype Vought XF8U-1 Crusader, Bu. No. 138899. (Vought Heritage)

25 March 1955: Chance Vought Aircraft Corporation experimental test pilot John William Konrad took the first prototype XF8U-1 Crusader, Bu. No. 138899, for its first flight at Edwards Air Force Base in the high desert of Southern California. The new fighter had been transported from the factory at Dallas, Texas, by truck. During the first flight, the Crusader went supersonic in level flight. It was able to maintain supersonic speeds (not only for short periods in a dive) and was the first fighter aircraft to exceed 1,000 miles per hour in level flight (1,609 kilometers per hour).

The F8U Crusader has a unique variable-incidence wing which can be raised to increase the angle of attack. This created more lift at low speeds for takeoff and landing aboard aircraft carriers, but allows the fuselage to remain fairly level for better forward visibility.

The test program went so well that the first production airplane, F8U-1 Crusader Bu. No. 140444, made its first flight just over six months after the prototype’s.

Prototype Vought XF8U-1 Crusader during a test flight, 25 March 1955. (Vought)
Prototype Vought XF8U-1 Crusader Bu. No. 138899 during a test flight, 25 March 1955. (Vought Heritage)

The Chance Vought F8U-1 was nearly identical to the prototype XF8U-1. It was a single-place, single-engine swept-wing fighter designed to operate from the United States Navy’s aircraft carriers. The F8U-1 was 54 feet, 3 inches (16.535 meters) long with a wingspan of 35 feet, 8 inches (10.871 meters) and height of 15 feet, 9 inches (4.801 meters). Its empty weight was 15,513 pounds (7,037 kilograms) and maximum takeoff weight was 27,468 pounds (12,459 kilograms).

Early production aircraft were powered by a Pratt & Whitney J57-P-12A engine. This was a two-spool, axial-flow turbojet engine with a 16-stage compressor and 3-stage turbine. The J57-P-12A was rated at 10,000 pounds of thrust (44.48 kilonewtons), and 16,000 pounds (71.17 kilonewtons) with afterburner.

The F8U-1 had a maximum speed of 733 miles per hour (1,179.7 kilometers per hour) at Sea Level and Mach 1.53 (1,013 miles per hour/1,630.3 kilometers per hour) at 35,000 feet (10,668 meters). It had a service ceiling of 42,300 feet (12,893 meters) and combat radius of 389 miles (626 kilometers).

Vought XF8U-1 Crusader parked on Rogers Dry Lake, Edwards Air Force Base. (Vought)
Vought XF8U-1 Crusader Bu. No. 138899 parked on Rogers Dry Lake, Edwards Air Force Base. (Vought Heritage)

The Vought F8U Crusader was in production from 1955 through 1964 with a total of 1,261 built in both fighter and photo reconnaissance versions. The fighter earned several nicknames: It is known as “The Last of the Gunfighters” because it was the last American fighter aircraft to be designed with guns as the primary armament. (It carried four Colt Mark 12 20-mm autocannon with 144 rounds of ammunition, each, though it could also carry AIM-9 Sidewinder air-to-air missiles.) Because of a high accident rate, the Crusader has also been called “The Ensign Killer.”

During five years of testing, Bu. No. 138899 made 508 flights. It was donated to the Smithsonian Institution in 1960. The restored prototype is now at The Museum of Flight, Seattle, Washington.

The Vought XF8U-1 has been restored by The Museum of Flight at Paine Field, Stattle, Washington. (The Museum of Flight)
The first of two prototypes, Chance Vought XF8U-1 Crusader, Bu. No. 138899, has been restored by The Museum of Flight at Paine Field, Seattle, Washington. The Crusader’s variable incidence wing is in the raised take-off/landing position. (The Museum of Flight)

John william Konrad was born 25 November 1923 at San Diego, California. He was the second of three children of  William Konrad, a salesman, and Anne E. Stensrud Konrad.

Konrad became interested in aviation at an early age, learning to fly in a Piper Cub at the age of 15.Learned to fly in a Piper J-3 Cub at San Diego, age 15. After graduating from high schhool, he enlisted as a private in the U.S. Army Air Corps at San Diego, 26 February 1943. Konrad was 5 feet, 3 inches (1.600 meters) tall and weighed 118 pounds (53.5 kilograms). He trained as a pilot and flew Boeing B-17 Flying Fortress heavy bombers with the 305th Bombardment Group (Heavy), stationed at RAF Chelveston, during World War II. He later flew Douglas C-47 Skytrains during the Berlin Airlift.

Konrad married Miss Harriet Marilyn Hastings at Clearwater, Florida, 11 February 1945. They would have two children.

Following the War, Konrad was selected for the first test pilot training class at Wright Field, then was assigned to Muroc Army Airfield (Edwards Air Force Base) in California, where he graduated from the Air Force Experimental Flight Test Pilot School, Class 51-C, 19 May 1952.

Konrad resigned from the Air Force in 1953 and joined the Chance Vought Aircraft Corporation in Dallas, Texas, as a test pilot. In addition the the XF8U-1 Crusader, he also made the first flight of the Ling-Temco-Vought A-7 Corsair II, and the experimental LTV XC-142 tiltwing V/STOL transport in 1964. He was appointed Director Test Operations in 1965. Konrad retired from Vought in 1988 after 25 years with the company.

After retiring, John Konrad continued to fly a Goodyear FG-!D Corsair with Commemorative Air Force.

John William Konrad, Sr., Captain, United States Air Force, died 20 September 2006 at Dallas, Texas. He is buried at the Dallas–Fort Worth National Cemetery.

John William Konrad. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

© 2017, Bryan R. Swopes

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24 March 1960

Joseph Albert Walker in the cockpit of North American Aviation X-15A 56-6670, after a flight, 1960. (NASA)
Joseph Albert Walker in the cockpit of North American Aviation X-15A 56-6670, after a flight, 1960. (NASA)

24 March 1960: After North American Aviation’s Chief Engineering Test Pilot, Albert Scott Crossfield, had made the first flights in the new X-15 hypersonic research rocketplane (one gliding, eight powered), NASA Chief Test Pilot Joseph Albert Walker made his first familiarization flight.

The X-15, 56-6670, the first of three built by North American Aviation, Inc., was carried aloft under the right wing of a Boeing NB-52A Stratofortress, 52-003, flown by John E. Allavie and Fitzhugh L. Fulton.

The rocketplane was dropped from the mothership over Rosamond Dry Lake at 15:43:23.0 local time, and Joe Walker ignited the Reaction Motors XLR-11 rocket engine. The engine burned for 272.0 seconds, accelerating Walker and the X-15 to Mach 2.0 (1,320 miles per hour/2,124.3 kilometers per hour) and a peak altitude of 48,630 feet (14,822.4 meters). Walker landed on Rogers Dry Lake at Edwards Air Force Base after a flight of 9 minutes, 8.0 seconds.

Joe Walker made 25 flights in the three X-15 rocket planes from 24 March 1960 to 22 August 1963. He achieved a maximum Mach number of 5.92, maximum speed of 4,104 miles per hour (6,605 kilometers per hour) and maximum altitude of 354,200 feet (107,960 meters).

Joe Walker was killed in a mid-air collision between his Lockheed F-104N Starfighter and a North American Aviation XB-70A Valkyrie near Barstow, California, 1 June 1966.

The number one ship, 56-6670, made 81 of the 199 flights of the X-15 Program. It was the first to fly, and also the last, 24 October 1968. Today, it is in the collection of the Smithsonian Institution National Air and Space Museum.

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

© 2017, Bryan R. Swopes

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22 March 1956

Boeing P2B-1S, Bu. No. 84029, at Edwards AFB, 22 March 1956. (NASA)

22 March 1956: While carrying the U.S. Navy’s Douglas D-558-II Skyrocket, problems developed aboard both the research rocketplane and the “mothership.” The modified four-engine heavy bomber, a U.S. Air Force Boeing B-29-95-BW Superfortress (which had been transferred to the U.S. Navy and redesignated P2B-1S Superfortress), had a runaway propeller on the Number 4 engine, outboard on the right wing. The propeller broke apart from excessive rotational speed, slicing through the Number 3 engine, the fuselage, and striking the Number 2 engine.

NACA research test pilot John Barron (“Jack”) MacKay, in the cockpit of the Skyrocket, had called “No drop!” because of problems with the rocketplane, but he was jettisoned so that the mothership could maintain flight and make an emergency landing.

McKay dumped the Skyrocket’s propellants and glided to the lake bed.

“Each rocket-plane pilot had worked out, in conjunction with the pilot of the mother ship, a procedure to follow if any emergency developed in either plane. Jack McKay, who had developed into a very able test pilot, and I had agreed with Butchart that if something went wrong after either of us had entered the cockpit of the Skyrocket and had closed the canopy, he would immediately jettison the rocket plane, leaving the rocket-plane pilot to look after his own hide. As a matter of fact, McKay and Butchart later ran into such an emergency. One day something went haywire in a propeller on the B-29 mother plane. As agreed, Butchart instantly cut loose the Skyrocket. A split second later the B-29 prop tore loose and cartwheeled through the space the Skyrocket had just vacated. McKay landed without difficulty; but had Butchart not cut the parasite plane loose, the prop would have ripped into its fuel tanks, causing an explosion that would have killed everyone, including McKay.”

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 21 at Pages 201–202.

The Superfortress pilots, Stanley Paul Butchart and Neil Alden Armstrong, landed the plane safely on the lake bed at Edwards Air Force Base.

Neil Armstrong would land on The Moon 13 years later.

The P2B1-S is jacked up inside a hangar at Edwards AFB so the the Douglas D-558-II Skyrocket can be loaded aboard.
The P2B1-S is jacked up inside a hangar at Edwards AFB so the the Douglas D-558-II Skyrocket can be loaded aboard. (NASA)

© 2017, Bryan R. Swopes

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20 March 1966

Test pilot Jack L. Zimmerman with the record-setting Hughes YOH-6A Light Observation Helicopter, 62-4213. (FAI)
Hughes Aircraft Division test pilot Jack L. Zimmerman with the record-setting Hughes YOH-6A Light Observation Helicopter, 62-4213. (FAI)

20 March 1966: At Edwards Air Force Base in the high desert of southern California, Hughes Aircraft Company test pilot Jack L. Zimmerman flew the third prototype YOH-6A Light Observation Helicopter, 62-4213, to set a Fédération Aéronautique Internationale (FAI) World Record for Distance Over a Closed Circuit Without Landing of 1,700.12 kilometers (1,056.41 miles).¹ Fifty-one years later, this record still stands.

One week later, Zimmerman would set six more World Records ² with the “Loach.”

Hughes YOH-6A 62-4213 at Edwards Air Force Base, 1966. (FAI)
Hughes YOH-6A 62-4213 at Edwards Air Force Base, 1966. (FAI)

The Hughes Model 369 was built in response to a U.S. Army requirement for a Light Observation Helicopter (“L.O.H.”). It was designated YOH-6A, and the first aircraft received U.S. Army serial number 62-4211. It competed with prototypes from Bell Helicopter Company (YOH-4) and Fairchild-Hiller (YOH-5). All three aircraft were powered by a lightweight Allison Engine Company turboshaft engine. The YOH-6A won the three-way competition and was ordered into production as the OH-6A Cayuse. It was nicknamed “loach,” an acronym for L.O.H.

The YOH-6A was a two-place light helicopter, flown by a single pilot. It had a four-bladed, articulated main rotor which turned counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right.) Stacks of thin stainless steel “straps” fastened the rotor blades to the hub and were flexible enough to allow for flapping and feathering. Hydraulic dampers controlled lead-lag. Originally, there were blade cuffs around the main rotor blade roots in an attempt to reduce aerodynamic drag, but these were soon discarded. A two-bladed semi-rigid tail rotor was mounted on the left side of the tail boom. Seen from the left, the tail-rotor rotates counter-clockwise. (The advancing blade is on top.)

The third prototype YOH-6A, 62-4213, testing the XM-7 minigun. (U.S. Army)
The third prototype YOH-6A, 62-4213, testing the XM-7 twin M60 7.62 mm weapons system. (U.S. Army)

The YOH-6A was powered by a T63-A-5 turboshaft engine (Allison Model 250-C10) mounted behind the cabin at a 45° angle. The engine was rated at 212 shaft horsepower at 52,142 r.p.m. (102% N1) and 693 °C. turbine outlet temperature for maximum continuous power, and 250 shaft horsepower at 738 °C., 5-minute limit, for takeoff. Production OH-6A helicopters used the slightly more powerful T63-A-5A (250-C10A) engine.

The Hughes Tool Company Aircraft Division built 1,420 OH-6A Cayuse helicopters for the U.S. Army. The helicopter remains in production as AH-6C and MH-6 military helicopters, and the MD500E and MD530F civil aircraft.

Hughes YOH-6A 62-4213 is in the collection of the United States Army Aviation Museum, Fort Rucker, Alabama.

U.S. Army Hughes YOH-6A prototype 62-4213 at Le Bourget, circa 1965.
U.S. Army Hughes YOH-6A prototype 62-4213 at Aéroport de Paris – Le Bourget, 19 June 1965.(R.A. Scholefield via AVIAFORA)

Jack Louis Zimmerman was born 1 September 1921 at Chicago, Illinois, the second of three children of Bernard Zimmerman, an electrician, and Esther Rujawski Zimmerman. He studied engineering at the University of Chicago, but left to enlist in the U.S. Army Air Corps. He graduated from flight school in 1943 and was commissioned a second lieutenant.

Lieutenant Zimmerman was sent to Freeman Field, Indiana, as part of the Army’s first class of student helicopter pilots, training on the Sikorsky R-4. On completion of training he was assigned to a Liberty ship in the western Pacific as part of a Project Ivory Soap Aviation Repair Unit.

Taking off from the Army Transport Serviceship SS Maj. Gen. Robert Olds (formerly, the Liberty ship, SS Daniel E. Garrett), Lieutenant Zimmerman’s helicopter crashed into the sea. For his heroic actions in saving a passenger’s life, he was awarded the Soldier’s Medal:

“For heroism displayed in rescuing an enlisted man from drowning on 1 November 1944. While taking off from the flight deck of the SS Daniel E. Garrett, Lieutenant Zimmerman with Private William K. Troche as passenger was forced to land at sea. Lieutenant Zimmerman at the risk of his life made several dives into the plane when his passenger had difficulty in extricating himself from the craft. When Private Troche’s life preserver failed to operate properly, Lieutenant Zimmerman supported him in the water for approximately 30 minutes and afterwards pulled him to a life preserver, which had been thrown from the ship. The heroism displayed by Lieutenant Zimmerman on this occasion reflects great credit upon himself and the military service.” —http://collectair.org/zimmerman.html

Following World War II, Jack Zimmerman was employed as a commercial pilot, and then a test pilot for the Seibel Helicopter S-4 and YH-24 light helicopters, and when the company was bought by Cessna, he continued testing the improved Cessna CH-1 and UH-41 Seneca. In 1963, Zimmerman began working as a test pilot for the Hughes Tool Company’s Aircraft Division. He retired in 1982.

Jack Louis Zimmerman died at San Diego, California, on his 81st birthday, 1 September 2002.

¹ FAI Record File Number 762

² FAI Record File Numbers 771, 772, 9920, 9921, 9922, and 9923

© 2017, Bryan R. Swopes

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