Tag Archives: Fédération Aéronautique Internationale

30 March 1939

Test pilot Hans Dieterle in the cockpit of the Heinkel He 100 V8 prototype. The airplane is unpainted and the surface seams are puttied and smoothed to reduce aerodynamic drag. (Heinkel-Flugzeugwerke)

30 March 1939: At 5:25 p.m., Ernst Heinkel Flugzeugwerke GmbH test pilot Hans Dieterle, flying a high-performance prototype fighter, the Heinkel He 100 V8, D-IDGH, entered a measured 3 kilometer course near the factory’s airfield at Oranienberg, Germany. He would attempt to set a new Fédération Aéronautique Internationale (FAI) World Record for Speed Over a 3 Kilometer Course.¹

FLIGHT described the record flight in its 20 April 1939 edition:

The F.A.I. regulations stipulate that for speed record purposes the flight must be made over a course 3 km. (1.86 miles) long. This is the distance over which the machine is timed, and while traversing it the aircraft must not exceed a height of 75 m. (264ft.). Before entering the 3,000 m. course the machine must pass through an approach 500 m. (1,640ft.) long, on which also the height must not exceed 75 m. The timing is done in two flights in each direction and the average speed of the four runs taken.

While turning at the end of of each run the pilot may fly as wide as he likes, i.e., any radius of turn may be used, but the machine must not at any time during the turn exceed a height of 400 m. (1,312ft.) Other aircraft flying at exactly 400 m. are used for checking that this stipulation is observed.

Illustration from FLIGHT article, "THE NEW SPEED RECORD," 20 April 1939 at Page 395.
Illustration of the Askania Werke AG timing system from FLIGHT article, “THE NEW SPEED RECORD,” 20 April 1939 at Page 395.
Heinkel He 100 V8 passes checkpoint B during the speed trial, 30 March 1939. (Askania Werke/FAI)
Heinkel He 100 V8 passes checkpoint B during the speed trial, 30 March 1939. (Askania Werke/FAI)

On the day of the record flight the preparations were completed at 5.15 p.m. and the aeroplanes carrying the official observers went up. Dieterle took off at 5.23 p.m. After completing his two runs in each direction he made a perfect landing 14 minutes after the start. Although the official speed of the runs could obviously not have been known to him, he must have been certain that he had beaten the record, for on leaving the machine he turned three handsprings in the exuberance of his youth (he is only 24). When the speeds had been worked out it was found that the average was 746.66 km./h (463.953 m.p.h.) The machine took only 14.464 sec. to cover the timed section.

Field Marshal Göring immediately promoted Herr Dieterle to Flight Captain: he is the youngest pilot to hold that rank in the German Luftwaffe.

FLIGHT The Aircraft Engineer, No. 1582. Vol. XXXV., Thursday, 20 April 1939, at Pages 395–396.

Dieterle’s officially-recognized World Record for Speed is 746.60 kilometers per hour (463.91 miles per hour). This exceeded the previous record which had been set by Dr.-Ing. Hermann Wurster on 11 November 1937,² flying a prototype Messerschmitt Bf 113R (Bf 109 V13), D-IPKY, by 135.65 kilometers per hour (84.29 miles per hour).

Test pilot Hans Dieterle with his wife, following the speed record flight. (Bundsarchive Bild 183-Z0414-509)
Test pilot Hans Dieterle with his wife, following the speed record flight, 30 March 1939. (Bundsarchive Bild 183-Z0414-509)

Dieterle’s new record would last less than one month, however. On 26 April 1939, Fritz Wendel flew another Messerschmitt prototype, Me 209 V1 (D-INJR) to 755.14 kilometers per hour (469.22 miles per hour).³

Heinkel He 100 V8 D-IDGH, world record-setting prototype, in overall light gray. (Heinkel Flugzeuwerke)
Right profile of Heinkel He 100 V8 D-IDGH, world record-setting prototype, in overall light gray. (Heinkel-Flugzeugwerke)

D-IDGH was the eighth He 100 prototype, V8 (Versuch 8). Two prototypes, V3 and V8, were modified for the speed record attempt. Their wingspan was shortened from the 30 feet, 10 inches (9.398 meters) of the earlier prototypes to 24 feet, 11½ inches (7.607 meters), with the wing area being reduced by about 25%. V3, D-ISVR, had a streamlined canopy, while V8 had a cut down windshield and canopy. V3 crashed during testing.

The eighth prototype,Heinkel He 100 V8, was modified for the speed record trial. It is also referred to as he 112U.
The eighth prototype, Heinkel He 100 V8, was modified for the speed record trial. It is also referred to as the  He 112U. (Heinkel-Flugzeugwerke)

He 100 V8 was equipped with a highly-modified version of the Daimler-Benz DB 601A, a liquid-cooled, direct-injected and supercharged 33.929 liter (2,075.497-cubic-inches), inverted single-“underhead”-camshaft 60° V-12 engine with four valves per cylinder and a compression ratio of 6.9:1. The supercharger was driven hydraulically. The standard production engine was rated at 970 horsepower at 2,300 r.p.m. at 12,000 feet (3,658 meters), and 1,050 horsepower at 2,400 r.p.m. for takeoff (limited by a clockwork mechanism to 1 minute), using 87-octane gasoline. The propeller reduction gear ratio was 14:9. The DB 601A was 67.5 inches (1.715 meters) long, 40.5 inches (1.029 meters) high and 29.1 inches (0.739 meters) wide. It weighed 1,610 pounds (730.3 kilograms).

Front view of Heinkel He 100 V8. Luftwaffe crosses and the identification 42C 11 are visible on the bottom of its wings. (Heinkel-Flugzeugwerke)
Front view of Heinkel He 100 V8. Luftwaffe Balkenkreuz crosses and the identification 42C 11 are visible on the bottom of its wings. (Heinkel-Flugzeugwerke)

The modified DB 601A engine installed in D-IDGH used methyl alcohol injection and produced 1,800 horsepower at 3,000 r.p.m., although its service life was just 30 minutes. It drove a three-bladed Vereinigte Deutsche Metallwerke (V.D.M.) electrically-controlled, variable-pitch propeller through a 14:9 gear reduction.

He 100 V8 was painted overall gray and carried its civil registration as well as Balkenkreuz markings with identification 42C+11. It was later painted dark blue with gray undersides and Luftwaffe markings. D-IDGH was displayed at the Deutsches Museum, Munich, Germany.

Henkel He 100 V8 displayed at the Deutsches Museum, München, Germany.
Heinkel He 100 V8 D-IDGH displayed at the Deutsches Museum, München, Germany. (LuftArchive.de)

The Heinkel He 100 was a single-place, single-engine fighter which was produced in very small numbers. It was a more complex aircraft than the Messerschmitt Bf 109, which was already in production. For example, it used a system of surface-mounted evaporative coolers in the wings, rather than radiators, in an effort to reduce drag.

The production He 100D-1 was 26 feet, 11 inches (8.204 meters) long with a wingspan of 30 feet, 10 inches (9.398 meters) and overall height of 11 feet, 10 inches (3.607 meters). It was armed with one 20 mm autocannon and two 7.92 mm machine guns.

Speed Record Poster
Speed Record Poster

¹ FAI Record File Number 8744

² FAI Record File Number 8747

³ FAI Record File Number 8743

© 2019, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather

30 March 1928

With its cowlings removed, the Fiat Aviazione AS.3 V-12 engine of a Macchi M.52 is visible. (San Diego Air and Space Museum Archive)

30 March 1928: At Venice, Italy, Regia Aeronautica Major Mario de Bernardi, flying a Macchi M.52bis, established a new Fédération Aéronautique Internationale (FAI) World Record for Speed Over a 3 Kilometer Course of 512.78 kilometers per hour (318.63 miles per hour).¹

Major de Bernardi was the first pilot to fly faster than 300 miles per hour (482.8 kilometers per hour).

Colonel Mario de Bernardi, Regia Aeronautica
Colonel Mario de Bernardi, Regia Aeronautica

The Macchi M.52bis was a specially-constructed single-place, single-engine float plane designed to compete in the Schneider Trophy Races. The airplane was 23 feet, 4¾ inches (7.131 meters) long with a wingspan of 25 feet, 9 inches (7.849 meters). It had a gross weight of 3,263 pounds (1,480 kilograms).

The M.52bis was powered by a water-cooled, normally-aspirated, 34.677 liter (2,116.138-cubic-inch-displacement) Fiat Aviazone AS.3 dual overhead camshaft (DOHC), four-valve, 60° V-12 engine. The AS.3 had four valves per cylinder and a compression ratio of 6.7:1. It produced 1,000 horsepower at 2,400 r.p.m. The design of the AS.3 was based on the Curtiss D-12, although it used individual cylinders and water jackets instead of the American engine’s monoblock castings.

Only one M.52bis was built.

¹ FAI Record File Number 11827

© 2016, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather

29 March 1923

Lieutenant Russell L. Maughan, Air Service, United States Army (FAI)
First Lieutenant Russell Lowell Maughan, Air Service, United States Army (FAI)

29 March 1923: Flying a Curtiss R-6 Racer, serial number A.S. 68564, at Wright Field, Dayton, Ohio, First Lieutenant Russell Lowell Maughan, Air Service, United States Army, set a Fédération Aéronautique Internationale (FAI) World Record for Speed of 380.75 kilometers per hour (236.59 miles per hour).¹

Flight reported:

The Fédération Aéronautique Internationale has just homologated as world’s records the following performances:

Class C (heavier than air): Greatest speed (U.S.), Lieut. Maughan on Curtiss R.6, 465 h.p. Curtiss, March 29, 1923, 380.751 kms. (236 m.p.h).

FLIGHT, The Aircraft Engineer and Airships, No. 757. (No. 26, Vol. XV.) 28 June 1923, at Page 356, Column 1

Curtiss R-6 Racer. (U.S. Air Force)

The Curtiss R-6 Racers were single-engine, single seat, fully-braced single-bay biplanes with fixed landing gear, developed from the U.S. Navy Curtiss CR. The airplane and its D-12 Conqueror engine were both built by the Curtiss Aeroplane and Motor Co., Garden City, New York.

The fuselage was a stressed-skin monocoque, built with two layers of wood veneer covered by a layer of doped fabric. The wings were also built of wood, with plywood skins and fabric-covered ailerons. Surface radiators were used for engine cooling.

The Curtiss R-6 was 19 feet, 0 inches (5.791 meters) long with a wing span of 19 feet, 0 inches (5.791 meters). It had an empty weight of 2,121 pounds (962 kilograms).

The R-6 was powered by a water-cooled, normally-aspirated 1,145.111-cubic-inch-displacement (18.765 liter) Curtiss D-12 dual overhead cam (DOHC) 60° V-12 engine, which was developed by Arthur Nutt, based on the earlier Curtiss K-12 which had been designed by Charles B. Kirkham. The D-12 had four valves per cylinder and a compression ratio of 5.7:1. It was rated at 415 horsepower at 2,000 r.p.m., and 460 horsepower at 2,300 r.p.m. During testing, it produced a 475 horsepower at 2,320 r.p.m. using a 50/50 mixture of 95-octane gasoline and benzol. The D-12 was a right-hand tractor direct-drive engine. It turned a two-bladed, fixed-pitch, forged aluminum propeller designed by Sylvanus Albert Reed, Ph.D. The Curtiss D-12 was 56¾ inches (1.441 meters) long, 28¼ inches (0.718 meters) wide and 34¾ inches (0.882 meters) high. It weighed 678.25 pounds (307.65 kilograms).

The racer had a range of 281 miles (452 kilometers) and a ceiling of  22,000 feet (6,706 meters).

Two R-6 Racers were built for the U.S. Army at a cost of $71,000, plus $5,000 for spare parts.

A.S. 68564 disintegrated in flight at the Pulitzer Trophy Race, 4 October 1924, killing its pilot, Captain Burt E. Skeel.

Curtis R-6, A.S. 68564, P-278. (FAI)
Curtiss R-6, A.S. 68564, P-278. (FAI)

Russell Lowell Maughan was born at Logan, Utah, 28 March 1893. He was the sixth of eight children of Peter Weston Maughan, an accountant, and Mary Lucinda Naef Maughan. He attended Utah Agricultural College in Logan and graduated with a bachelor of science degree in 1917.

Maughan was commissioned as a second lieutenant in the U.S. Army Signal Officers Reserve Corps, 28 May 1917. He was promoted to first lieutenant, 8 January 1918. This commission was vacated 10 September 1920 and he was appointed a first lieutenant, Air Service, United States Army, retroactive to 1 July 1920.

On 14 August 1919, Maughan married Miss Ila May Fisher at Logan, Utah. They would have three children, but divorced sometime after 1940. His son, Russell L. Maughan, Jr., would become an officer in the U.S. Air Force.

Following the War, Lieutenant Maughan became a test pilot at McCook Field, Ohio. In 1921, he was reassigned to the 91st Observation Squadron, based at the Presidio of San Francisco.

Russell L. Maughan with Curtiss R-6 Racer, at National Air Races, 1922. (Library of Congress)

On 14 October 1922, he won the Pulitzer Trophy Race at Selfridge Field, near Mount Clemens, Michigan, before a crowd of 200,000 spectators. He set two World Speed Record during the race with his Curtiss R-6: 330.41 kilometers per hour (205.31 miles per hour) over a distance of 100 kilometers, and 331.46 kilometers per hour (205.96 miles per hour) over a distance of 200 kilometers). On 29 March 1923, he set another World Speed Record, 380.75 kilometers per hour (236.587 miles per hour), again flying a Curtiss R-6.

On 23 June 1924, Lieutenant Maughan flew a Curtiss PW-8 Hawk from Mitchel Field, Long Island, New York, to the Presidio of San Francisco on the west coast of California, in an elapsed time of 21 hours, 47 minutes including refueling stops enroute. This was the “Dawn-to-Dusk Flight.” For this transcontinental flight, Maughan was awarded the Distinguished Flying Cross.

Major General Mason Patrick, Chief of the Air Service, with Lieutenant Russell L. Maughan, 8 July 1924. (Library of Congress)

On 1 October 1930, Maughan was promoted to captain. He served in the Philippine Islands from 1930 to 1935, acting as an advisor to the government until 1932. From 1932 to 1935, he served as the post operations officer. He and his family lived in Manila. They returned to the United States aboard SS Columbus, a Norddeutscher Lloyd passenger liner, arriving at New York City from Southampton, 18 August 1935.

On 16 June 1936, Captain Maughan was promoted to major (temporary). That rank was made permanent 12 June 1939. He was again promoted, this time to lieutenant colonel, 11 March 1940.

During World War II, Lieutenant Colonel Maughan commanded the 60th Transport Group, a Douglas C-47 unit, 1941–42, and then, promoted to the rank of colonel, he commanded the 51st Troop Carrier Wing , which included the 60th, as well as eight other transport groups, during Operation Torch, the Allied invasion of North Africa.

On 25 October 1946, Colonel Maughan married Lois Rae Roylance in Nevada. She was 21 years his junior. They lived in Portland, Oregon.

Maughan was discharged from the U.S. Air Force, 30 November 1947, at the U.S. Army Hospital at Valley Forge, Pennsylvania. He died at the U.S. Air Force Hospital, Lackland Air Force Base, San Antonio, Texas, 21 April 1958, at the age of 65 years.

¹ FAI Record File Number 15194: Class C, Powered Airplanes: 380.75 kilometers per hour.

© 2019, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather

27 March 1966

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

27 March 1966: At Edwards Air Force Base in the high desert of southern California, Hughes Aircraft Company test pilot Jack Louis Zimmerman flew the third prototype YOH-6A Light Observation Helicopter, 62-4213, to set six Fédération Aéronautique Internationale (FAI) World Record for Altitude and Time-to-Climb. The records were set in two sub-classes, based on the helicopter’s take-off weight. Fifty-three years later, one of these records still stands.

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

Zimmerman took the YOH-6A from the surface to a height of 3,000 meters (9,843 feet) in 4 minutes, 1.5 seconds ;¹ and to 6,000 meters (19,685 feet) in 7 minutes, 12 seconds.² The helicopter reached an altitude in level flight of 8,061 meters (26,447 feet).³  9921 remains the current record for helicopters in Sub-Class E-1b, with a takeoff weight of 500–1,000 kilograms (1,102–2,205pounds).

Beginning with a takeoff weight between 1,000–1,750 kilograms (2,205–3,858 pounds) (Sub-Class E-1c), Zimmerman took the “loach” to a height 3,000 meters (9,843 feet) in 5 minutes, 37 seconds.⁴ The helicopter reached an altitude of 5,503 meters (16,578 feet), without payload.⁵

[The field elevation of Edwards Air Force Base (EDW) is 2,210 feet (704 meters) above Sea Level. If the time-to-altitude flights had been made at nearby NAS Point Mugu (NTD) on the southern California coast, which has a field elevation 13 feet (4 meters), the times might have been significantly reduced. The air temperature at Edwards, though, was much colder.]

One day earlier, 26 March, Allison Engine Company test pilot Jack Schweibold flew the same YOH-6A  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).⁶ One week earlier, 20 March, Jack Zimmerman had 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).⁷ Fifty-three years later, these four World Records still stand.

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

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 above the axis of rotation.)

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.

¹ FAI Record File Number 9922

² FAI Record File Number 9923

³ FAI Record File Numbers 9920 and 9921

⁴ FAI Record File Number 771

⁵ FAI Record File Number 772

⁶ FAI Record File Numbers 786, 787 and 11656.

⁷ FAI Record File Number 762.

© 2017 Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather

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 1966: 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 at Edwards Air Force Base, in the high desert of southern California. From 20 March to 7 April 1966, they flew 62-4213 over a series of distances and altitudes.

Edwards Air Force Base, California, circa 1970. The runway complex is at top, center. (U.S. Department of Defense)

Jack Schweibold’s 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 of the ground. 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 Naval Reserve in 1952 and then joined the United States Air Force as an Aviation Cadet in 1954.

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. He was commissioned as a second lieutenant and received his pilot’s wings in July 1957. In a momentary decision, he selected helicopter training.

Air Rescue Service Sikorsky H-19A Chicasaw 51-3850. (AR.1999.026)

Lieutenant Schweibold flew the Sikorsky H-19B for the U.S.A.F. 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.

A Chicago Helicopter Airways Sikorsky S-55.

I had the good fortune to have known Jack Schweibold. I first met him through his involvement in the Helicopter Association International’s biennial flight instructor re-certification seminars, held during the HAI’s annual conventions. He kept the seminar classes on track, and in between, was always available for questions. Jack 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. It was a pleasure to know him.

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

© 2019, Bryan R. Swopes

Facebooktwitterredditpinterestlinkedinmailby feather