Monthly Archives: April 2025

8 April 1954

Aviation, , , , , , , , , , , , ,
De Havilland DH.106 Comet 1 G-ALYY, 1953. (Zoggavia)
De Havilland DH.106 Comet 1 G-ALYY, 1953. (Zoggavia)

8 April 1954: Suid-Afrikaanse Lugdiens (South African Airways) Flight 201, a chartered British Overseas Airways Corporation de Havilland DH.106 Comet 1, departed Rome at 1832 UTC, bound for Cairo.

The Comet, registered G-ALYY, was under the command of Captain Wilhelm Karel Mostert, with First Officer Barent Jacobus Grove, Navigator Albert Escourt Sissing, Radio Officer Bertram Ernest Webstock, and Flight Engineer August Ranwald Lagesen. Air Hostess Pamela Lucia Reitz and Flight Steward Jacobus Bruwer Kok were in the passenger compartment with the 14 passengers.

As the airliner climbed toward 35,000 feet (10,668 meters), they made several position reports. Last heard from at 1907 UTC, radioing an expected arrival time at Cairo, the Comet disintegrated in flight and fell into the Tyrrhenian Sea. Searchers found a debris field and floating bodies the next day near the volcanic island of Stromboli. All 21 persons aboard were killed.

This was the second catastrophic failure of a DH.106 in just three months. BOAC immediately grounded its entire Comet fleet, and the British Air Ministry revoked the airliner’s certificate of airworthiness. Production of the airliner at de Havilland was halted.

The first crash had been presumed to be a result of an in-flight fire, and the second, an uncontained turbine engine failure. But an extensive investigation eventually determined that the cause of both crashes was the in-flight break up of the fuselage pressure hull. “Owing to the absence of wreckage, we are unable to form a definite opinion on the cause of the accident near Naples, but we draw attention to the fact that the explanation offered for the accident at Elba [Comet G–ALYP, 10 January 1954] appears to be applicable to that at Naples.” ¹ Metal fatigue of the fuselage was caused by the repeated expansion and contraction of pressurization cycles. Cracks in the aluminum skin formed at stress points at the corners of the passenger compartment windows and then spread outward. This resulted in catastrophic explosive decompression.

Cut-away illustration of de Havilland Comet I G-ALYP by artist Laurence Dunn.

The DH.106 Comet 1 was the first production version and was very similar to the two prototypes. It can be visually identified by its square passenger windows. It was flown by a pilot, co-pilot, flight engineer and navigator. The airliner could carry up to 44 passengers.

The airplane was 93 feet (28.346 meters) long with a wingspan of 115 feet (35.052 meters) and overall height of 27 feet, 10 inches (8.484 meters). The wings were swept 20°, as measured at ¼ chord. The fuselage had a maximum outside diameter of 10 feet, 3 inches (3.124 meters), and 9 feet, 9 inches (2.972 meters) inside. The Comet 1 had an authorised maximum all-up weight of 107,000 pounds (48,534 kilograms).

The Comet I was powered by four de Havilland Engine Co., Ltd., Ghost 50 Mk.I turbojet engines. The Ghost was a single-shaft centrifugal-flow turbojet with a single-stage compressor, 10 combustion chambers and a single-stage turbine. It was rated at 5,000 pounds of thrust (22.24 kilonewtons) at 10,250 r.p.m. The Ghost 50 had a maximum diameter of 4 feet, 5 inches (1.346 meters), length of 10 feet, 1 inch (3.073 meters) and dry weight of 2,218 pounds (1,006 kilograms). When first placed in service, the engines required a combustion chamber inspection at 125 hour intervals. A complete overhaul was required every 375 hours. The Ghost was the first turbojet certified for civil airliner operations.

A de Havilland Engine Company advertisement in the Illustrated London News, circa 1950.

The Comet I had a maximum cruising speed of 490 miles per hour (789 kilometers per hour), True Air Speed, and operating altitude of 35,000 to 40,000 feet (10,668–12,192 meters). The airliner’s fuel capacity was 6,050 Imperial gallons (27,504 liters, or 7,266 U.S. gallons) giving a practical stage length of 2,140 miles (3,444 kilometers). The maximum range was 3,860 miles (6,212 kilometers).

Twelve DH.106 Comet 1 airliners were built.

The de Havilland Comet was the first commercial jet airliner and its introduction had revolutionized the industry. The two disasters were a blow from which the company never really recovered.

The first production de Havilland DH.106 Comet 1, G-ALYP, in formation with the two prototypes, G-ALVG and G-ALZK. G-ALYP also broke up in flight, 10 January 1954. (Ed Coates Collection)
The first production de Havilland DH.106 Comet 1, G-ALYP, in formation with the two prototypes, G-ALVG and G-ALZK. G-ALYP also broke up in flight, 10 January 1954. (Ed Coates Collection)

¹ MINISTRY OF TRANSPORT AND CIVIL AVIATION, CIVIL AIRCRAFT ACCIDENT. Report of the Court of Inquiry into the Accidents to Comet G–ALYP on 10th January, 1954 and Comet G–ALYY on 8th April, 1954, Part IX: THE COURT’S CONCLUSION AS TO CAUSE OF ACCIDENT, at Pages 46–47

© 2024, Bryan R. Swopes

8 April 1945

Aviation, , , , , , , , , , , , , , ,
In one of the most dramatic photographic images of World War II, “Wee Willie,” Boeing B-17G-15-BO Flying Fortress 42-31333, is going down after it was hit by antiaircraft artillery over Stendal, Saxony-Anhalt, Germany, 8 April 1945. (American Air Museum in Britain, Roger Freeman Collection.)

8 April 1945: Wee Willie, a Flying Fortress heavy bomber, left its base at Air Force Station 121 (RAF Bassingbourne, Cambridgeshire, England), on its 129th combat mission over western Europe. The aircraft commander was 1st Lieutenant Robert E. Fuller, U.S. Army Air Forces.

Wee Willie was a B-17G-15-BO, serial number 42-31333, built by the Boeing Airplane Company’s Plant 2, Seattle, Washington. It was delivered to the United States Army Air Forces at Cheyenne, Wyoming on 22 October 1943, and arrived at Bassingbourne 20 December 1943. It was assigned to the 322nd Bombardment Squadron (Heavy), 91st Bombardment Group (Heavy), 1st Air Division, 8th Air Force. The identification letters LG W were painted on both sides of its fuselage, and a white triangle with a black letter A on the top of its right wing and both sides of its vertical fin.

Boeing B-17G-15-BO Flying Fortress 42-31333, Wee Willie, December 1944. (U.S. Air Force)
Boeing B-17G-15-BO Flying Fortress 42-31333, LG W, Wee Willie, December 1944. (U.S. Air Force)

On 8 April 1945, the 322nd Bombardment Squadron was part of an attack against the locomotive repair facilities at the railroad marshaling yards in Stendal, Saxony-Anhalt Germany. The squadron was bombing through clouds using H2S ground search radar to identify the target area. Antiaircraft gunfire (flak) was moderate, causing major damage to four B-17s and minor damage to thirteen others. Two bombers from the 91st Bomb Group were lost, including Wee Willie.

The Missing Air Crew Report, MACR 13881, included a statement  from a witness:

We were flying over the target at 20,500 feet [6,248 meters] altitude when I observed aircraft B-17G, 42-31333 to receive a direct flak hit approximately between the bomb bay and #2 engine. The aircraft immediately started into a vertical dive. The fuselage was on fire and when it had dropped approximately 5,000 feet [1,524 meters] the left wing fell off. It continued down and when the fuselage was about 3,000 feet [914.4 meters] from the ground it exploded and then exploded again when it hit the ground. I saw no crew member leave the aircraft or parachutes open.

This photographic image precedes the one above. The Boeing B-17G-15-BO Flying Fortress 42-31333, Wee Willie, is engulfed in flame. The left wing has separated and is crossing over the fuselage. (American Air Museum in Britain)

The pilot, Lieutenant Fuller, did escape from the doomed bomber. He was captured and spent the remainder of the war as a Prisoner of War. The other eight crew members, however were killed.

1st Lieutenant Robert E. Fuller, O-774609, California. Aircraft Commander/Pilot—Prisoner of War

2nd Lieutenant Woodrow A. Lien, O-778858, Montana. Co-pilot—Killed in Action

Technical Sergeant Francis J. McCarthy, 14148856, Tennessee. Navigator—Killed in Action

Staff Sergeant Richard D. Proudfit, 14166848, Mississippi. Togglier—Killed in Action

Staff Sergeant Wylie McNatt, Jr., 38365470, Texas. Flight Engineer/Top Turret Gunner—Killed in Action

Staff Sergeant William H. Cassiday, 32346219, New York. Ball Turret Gunner—Killed in Action

Staff Sergeant Ralph J. Leffelman, 19112019, Washington. Radio Operator/Top Gunner—Killed in Action

Staff Sergeant James D. Houtchens, 37483248, Nebraska. Waist Gunner—Killed in Action

Sergeant Le Moyne Miller, 33920597, Pennsylvania. Tail Gunner—Killed in Action

In the third photograph of the sequence, Wee Willie has exploded and fragments of the wings and fuselage streak downward in flame. (American Air Museum in Britain, Roger Freeman Collection)

Wee Willie was the oldest B-17G still in service with the 91st Bomb Group, and the next to last B-17 lost to enemy action by the group before cessation of hostilities. The War in Europe came to an end with the unconditional surrender of Germany just 30 days later, 7 May 1945.

Boeing B-17G-15-BO Flying Fortress, LG W, “Wee Willie,” and its flight crew at Air Force Station 121, RAF Bassingbourne, 12 February 1944. The bomber is still nearly new, having flown 6 combat missions, 31 January 1943–3 February 1944, when it was damaged by anti-aircraft artllery over Wilhelmsahaven, Germany. “Wee Willie” was out of action until 20 February 1944. Standing, left to right: 1st Lt. John A. Moeller, co-pilot; 2nd Lt. Harry Lerner, navigator; S/Sgt Robert Kelley, waist gunner; S/Sgt Martin, ball turret gunner; Lt. Joe Gagliano, bombardier; 1st Lt. Paul D. Jessop, pilot. Kneeling, left to right: S/Sgt MacElroy, waist gunner; S/Sgt Shoupe, radio operator; S/Sgt Southworth, engineer/top turret gunner; and S/Sgt Joe Zastinich, tail gunner. Waist gunner S/Sgt Henry F. Osowski was wounded on the Wilhelmshaven mission and is not in this photograph. (American Air Museum in Britain)
During the 129 missions “Wee Willie” flew in its 1 year, 3 months, 20 days at war, many airmen served as its crew members. The men in this photograph are not identified, and the date it was taken is not known. A battle-scarred veteran, “Wee Willie” now has markings showing 106 missions completed. These men are representative all the aircrews who fought and died in the skies over Europe. The officer kneeling in the front row, right, has been identified as 2nd Lieutenant Jess Ziccarello, the navigator for this crew. Lieutenant Colonel Ziccarello passed away 2 October 2019 at the age of 96 years. Thanks to his son, Rick Ziccarello, for the identification. In the back row, second from right, is waist gunner Samuel McGowen. According to his nephew, Hal McGowen, he completed his 30 mission combat tour and lived until 2007. (American Air Museum in Britain)

© 2019, Bryan R. Swopes

8 April 1931

Aviation, , , , , , , ,
Amelia Earhart with Pitcairn Autogiro Co. PCA-2 #4, X760W, at Pitcairn Field, Warrington, Pennsylvania, 8 April 1931. (Purdue University)
Amelia Earhart with Pitcairn Autogiro Co. PCA-2 #4, NX760W, at Pitcairn Field, Warrington, Pennsylvania, 8 April 1931. (Purdue University)

8 April 1931: Amelia Earhart, flying a Pitcairn PCA-2 autogyro, reached an altitude of 18,415 feet (5,613 meters) ¹ over Warrington, Pennsylvania. The duration of the flight, her second of the day, was 1 hour, 49 minutes. She landed at 6:04 p.m.

A sealed barograph was carried aboard to record the altitude for an official record. Following the flight, the barograph was sent to the National Aeronautic Association headquarters in Washington, D.C., for certification.

08 Apr 1931, Pennsylvania, USA --- Original caption: Miss Amelia Earhart in two altitude tests with an autogiro plane, at the Pitcairn Airfield, Willow Grove, Pa., soars to height of 18,500 feet in the first, and surpasses that mark by 500 feet in the second. If her barographs correspond with those marks, she in all probability will have established a world record for men as well as women. She is the only woman who ever piloted one of the "windmill" types of craft. Photo shows Amelia Earhart handing Major Luke Christopher, her barograph after her first flight. --- Image by © Bettmann/CORBIS
Amelia Earhart, in the cockpit of a Pitcairn PCA-2 autogyro, handing a barograph to Major Luke Christopher, National Aeronautic Association. (© Bettmann/CORBIS)

An autogyro is a rotary wing aircraft that derives lift from a turning rotor system which is driven by air flow (autorotation). Unlike a helicopter, thrust is provided by an engine-driven propeller. The engine does not drive the rotor.

The Pitcairn Autogyro Company’s PCA-2 was the first autogyro certified in the United States. Operated by a single pilot, it could carry two passengers. The fuselage was constructed of welded steel tubing, covered with doped fabric and aluminum sheet.

Amelia Earhart with the Pitcairn PCA-2 aurtogyro, NX760W.
Amelia Earhart with a Pitcairn PCA-2 autogyro.

The PCA-2 was 23 feet, 1 inch (7.036 meters) long, excluding the rotor. The low-mounted wing had a span of 30 feet, 0 inches (9.144 meters), and the horizontal stabilizer and elevators had a span of 11 feet, 0 inches. (3.353 meters). The overall height of the autogyro was 13 feet, 7 inches (4.140 meters). The PCA-2 had an empty weight of 2,233 pounds (1,013 kilograms) and gross weight of 3,000 pounds (1,361 kilograms).

The four-bladed rotor was semi-articulated with horizontal and vertical hinges to allow for blade flapping and the lead-lag effects of Coriolis force. Unlike the main rotor of a helicopter, there was no cyclic- or collective-pitch motion. The rotor system was mounted at the top of a pylon and rotated counter-clockwise, as seen from above. (The advancing blade is on the right.) The rotor had a diameter of 45 feet, 0 inches (13.716 meters). The blades were approximately 22 feet (6.7 meters) long, with a maximum chord of 1 foot, 10 inches (0.559 meters). Each blade was constructed with a tubular steel spar with mahogany/birch plywood ribs, a formed plywood leading edge and a stainless steel sheet trailing edge. They were covered with a layer of very thin plywood. A steel cable joined the blades to limit their lead-lag travel.

The aircraft was powered by an air-cooled, supercharged, 971.930-cubic-inch-displacement (15.927 liter) Wright R-975E Whirlwind 330 nine-cylinder radial engine with a compression ratio of 5.1:1. The R-975E produced a maximum 330 horsepower at 2,000 r.p.m. at Sea Level, burning 73-octane gasoline. The engine turned a two-bladed Hamilton Standard variable-pitch propeller through direct drive. The engine weighed 635 pounds (288 kilograms).

The PCA-2 had two fuel tanks with a total capacity of 52 gallons (197 liters). It also had a 6½ gallon (24.6 liter) oil tank to supply the radial engine.

The PCA-2 had a maximum speed of 120 miles per hour (193 kilometers per hour). It had a service ceiling of 15,000 feet (4,572 meters) and a range of 290 miles (467 kilometers).

Pitcairn Autogyro Co. PCA-2 NX760W at East Boston Airport, October 1930. (Courtesy of the Boston Public Library, Leslie Jones Collection.)
Pitcairn Autogyro Co. PCA-2 NX760W at East Boston Airport, October 1930. (Courtesy of the Boston Public Library, Leslie Jones Collection.)

¹ Most sources state that Earhart set a “world altitude record” on this flight. TDiA checked with the National Aeronautic Association, which certifies aviation records in the United States. NAA has no such record in its files. Fédération Aéronautique Internationale (FAI) records show that Earhart set three world speed records in 1930, and a world distance record in 1932. She is not credited with an altitude record, or any flight record in an autogyro.

© 2019, Bryan R. Swopes

7 April 1967

Aviation, , , , , , , , , , ,
SA 340 F-WOFH (Airbus Helicopters)
Jean Boulet hovers the prototype Sud-Aviation SA 340 Gazelle, 340.001, F-WOFH, at Marignane, France, 7 April 1967. (Airbus Helicopters)

7 April 1967: The prototype Sud-Aviation SA 340 Gazelle, c/n 340.001, F-WOFH, made its first flight at Marseille–Marignane Airport with test pilot Jean Boulet. The SA 340 was a five-place, light turboshaft-powered helicopter, flown by a single pilot. It was intended as a replacement for the SA 313B/318C Alouette II and SA 316/319 Alouette III.

The prototype used the engine, drive train, tail rotor and landing skids of an Alouette II, and a new three-bladed, composite, semi-rigid main rotor, based on the four-bladed rigid rotor of the Messerschmitt-Bölkow-Blohm (MBB) Bo-105.

Sud-Aviation test pilot Jean Boulet in the cockpit of the SA 349, an experimental variant of the SA 340 Gazelle.
Sud-Aviation test pilot Jean Boulet in the cockpit of the SA 349, an experimental modification of the prototype SA 340 Gazelle, 340.001. (Airbus Helicopters)

Société nationale des constructions aéronautiques du sud-ouest (Sud-Aviation) was a French government-owned aircraft manufacturer, resulting from the merger of Société nationale des constructions aéronautiques du sud-est (SNCASE) and Société nationale des constructions aéronautiques du sud-ouest (SNCASO) in 1957. In 1970, following another merger, the company would become Société nationale industrielle aérospatiale, or SNIAS, better known as Aérospatiale. This company combined several other manufacturers such as Matra and Messerschmitt-Bölkow-Blohm to become Eurocopter, then EADS. It is now Airbus Helicopters.

The SA 340 was powered by a Turboméca Astazou IIN turboshaft which turns 42,500 r.p.m. (± 200 r.p.m.). The output shaft speed is reduced through a 7.34728:1 gear reduction.  The engine rated at 353 kW (473 shaft horsepower) continuous, or 390 kW (523 shaft horsepower) for takeoff. It is temperature-limited to 500 °C. for continuous operation, or 525 °C. for takeoff.

The main rotor assembly, mast, transmission and Turbomeca Astazou engine of the prototype SA 340 Gazelle. (Airbus Helicopters)
The main rotor assembly, mast, swash plate and pitch control links, transmission, main driveshaft and Turboméca Astazou turboshaft engine of the prototype Sud-Aviation SA 340 Gazelle, F-WOFH. (Airbus Helicopters)

F-WOFH was used to test the new fenestron anti-torque system. The conventional tail rotor was replaced with a smaller 13-bladed ducted fan contained within a large vertical fin. The fenestron had several advantages: It was safer, as it was protected from ground strikes or from ground personnel walking into it. It was more effective in producing thrust for anti-torque, though it required more engine power at a hover. It reduced the aerodynamic drag of the helicopter in forward flight, and was not subject to large displacements resulting from dissymmetry of lift. The large fin was cambered and relieved the anti-torque system during forward flight. This meant that the  helicopter could be flown following an anti-torque failure, rather than requiring an immediate emergency autorotation.

Sud-Aviation fenestron on an early production SA 341 Gazelle, c/n 1006, F-WTNV
Sud-Aviation fenestron on an early production SA 341 Gazelle, c/n 1006, F-WTNV. (Airbus Helicopters)

The Aérospatiale SA 341 Gazelle entered production in 1971, as both a military and civil helicopter. The aircraft was also produced in England by Westland.

The Gazelle the first helicopter to be certified for instrument flight with a single pilot.

The SA 341 had an overall length, with rotors turning, of 11.972 meters (39 feet, 3.34 inches). The fuselage was 9.533 meters (31 feet, 3.31 inches) long and the top of its fin was 3.192 meters (10 feet, 5.67 inches) high. The three-bladed main rotor was 10,500 meters (34 feet, 5.39 inches) in diameter, and turned clockwise as seen from above. (The advancing blade is on the left.) The rotor has a normal operating speed of  378 r.p.m., ± 12 r.p.m. (310–430 r.p.m. in autorotation. The 13-blade fenestron is enclosed in a duct in the vertical fin. The rotor has a diameter of 0.695 meters (2 feet, 3. 36 inches) and turns counter-clockwise as seen from the left. (The advancing blades are above the axis of rotation.)

The helicopter’s certified maximum gross weight is 1,800 kilograms, or 3,970 pounds.

Aérospatiale SA 341 Gazelle three-view illustration with dimensions. (Aérospatiale)

The Gazelle is powered by a Turboméca Astazou III.

Teh SA 341 has a maximum speed (Vne ) of 310 kilometers per hour (168 knots ) at Sea Level, making it the fastest light helicopter produced at the time. The helicopter is limited to a pressure altitude of 20,000 feet (6,096 meters). It can operate in temperatures from -50  to +45 °C. (-58 to 113 °F.)

Approximately 1,775 Gazelles were built between 1967 and 1996, when production ended.

Sud-Aviation SA 340.001, F-WOFH. (Airbus Helicopters)
Sud-Aviation SA 340.001, F-WOFH. (Airbus Helicopters)

© 2019, Bryan R. Swopes

6–7 April 1966

Aviation, , , , , , , , , ,
Test pilot Bob Ferry in teh cockpit of YOH-61 62-4213, with engineer Dick Lofland, before the non-stop coast-to-coast flight. (Hughes Aircraft)
Test pilot Bob Ferry in the cockpit of Hughes YOH-6A 62-4213, with engineer Dick Lofland, before the non-stop coast-to-coast flight. (Hughes Aircraft)

6–7 April 1966: Chief Test Pilot Robert G. Ferry of Hughes Tool Company’s Aircraft Division flies the number three prototype YOH-6A, 62-4213, from the company airport at Culver City, California, non-stop to Ormond Beach, Florida, a distance of 3,561.55 kilometers (2,213.04 miles). Bob Ferry set three Fédération Aéronautique Internationale (FAI) World Records for Distance Without Landing.¹ All three 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)

Bob Ferry took off at the Hughes Airport at Culver City (just north of LAX) at 2:20 p.m., Pacific Time. The aircraft twas so heavily loaded with fuel that the test pilot exceeded the engine’s torque limit by 21% just to get airborne. When he established a climb he reduced the power to “red line.” During the entire flight he kept the engine at 105% N2 (a 2% overspeed). He landed after 15 hours, 8 minutes of flight.

On 26 March 1966, 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).² 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).³ Fifty-one years later, these four World Records also still stand.

Robert George Ferry was born 29 November 1923 in Hennepin County, Minnesota, the second child of Lucius M. and Charlotte E. Ferry. He developed an interest in aviation during his teen years. Ferry earned a bachelor’s degree from Florida Southern University. He entered the U.S. Army Air Corps in 1943 and graduated from flight training at Luke Filed, Arizona, in 1945.

Ferry trained as a helicopter pilot at San Marcos Army Air Field, Texas, flying Sikorsky R-5 and R-6 helicopters. After graduation Lieutenant Ferry was assigned to Panama.

In 1947, Robert Ferry married Miss Marti Holt of Austin, Texas. They remained together for 62 years.

Bob Ferry flew 90 combat missions in helicopters during the Korean War. In 1954, he was accepted to the U.S. Air Force Experimental Test Pilot School, Class 54C, at Edwards Air Force Base. (One of Ferry’s classmates was future X-15 pilot, Robert M. White.)

Assigned as a test pilot Bob Ferry flew the McDonnell XV-1 Convertiplane compound helicopter with pressure jet rotor drive and the Bell XV-3, an experimental “tiltrotor.” On 6 January 1959, he completed the conversion from helicopter to airplane mode. He also flew the Hughes XV-9A, an experimental high-speed helicopter, which also used tip jets to drive the rotor. After six years as a test pilot at Edwards, Ferry was assigned to duties in Germany. He retired from the Air Force in 1964 with the rank of Lieutenant Colonel.

Robert G. Ferry, Chieft Test Pilot, Hughes helicopters.
Robert G. Ferry, Chief Test Pilot, Hughes Helicopters. (San Diego Union-Tribune)

In 1966, Robert Ferry became chief test pilot at the Hughes Tool Company Aircraft Division at Culver City, California. He tested the OH-6A light observation helicopter and the AH-64 Apache at the Hughes facility at Palomar Airport in north San Diego County. During this time Ferry earned a Masters Degree in Business Administration from the University of San Diego.

Bob Ferry retired from Hughes Helicopters after 18 years. He had flown approximately 10,800 hours in 125 different aircraft. About 8,000 hours were in helicopters. He had been awarded the Iven C. Kincheloe Award for 1959 by the Society of Experimental Test Pilots, the Igor I. Sikorsky International Trophy for his transcontinental record flight, and the 1967 Frederick L. Feinberg Award by the American Helicopter Society.

Lieutenant Colonel Robert G. Ferry, United States Air Force (Retired) died at his home in San Marcos, California, 15 January 2009 at the age of 85 years.

Hughes YOH-6A 62-4211 in its configuration during the three-way LOH competitive testing. (U.S. Army)
Hughes YOH-6A 62-4211, the first prototype, in its configuration during the three-way LOH competitive testing. (U.S. Army)

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 above the axis of rotation.)

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.

¹ FAI Record File Numbers 784, 785 and 11655.

² FAI Record File Numbers 786, 787 and 11656.

³ FAI Record File Number 762.

© 2019, Bryan R. Swopes