Experimental Beechcraft Model 35 Bonanza NX80040, circa 1946. (Roger Bilstein Collection, San Diego Air & Space Museum Archives)
22 December 1945: Test pilot Vern Louis Carstens made the first flight of Beech Aircraft Corporation’s new Beechcraft Model 35 Bonanza. Five prototypes were built. The first two were used as static test articles. The third prototype, NX80150, serial number 3, was the first to fly.
“. . . Wichita residents and Beech employees “lined the runway” to watch the first flight of the Beechcraft Bonanza. “The town turned out and the plant all but shut down for the occasion,” said Vern L. Carstens, retired Beech Aircraft chief test pilot who made the historic flight. From the day of its first flight, the Beechcraft V-tailed Bonanza has set industry standards for high performance single engine aircraft. The Bonanza received its type certificate on March 25, 1947. . . .”
—The Salina Journal, Salina, Kansas, Sunday, 27 December 1970, at Page 25, Columns 1–7.
The first Bonanza to fly was the number three prototype, NX80150. (San Diego Air & Space Museum Archives)
On 26 October 1946, one of the Model 35 prototypes, possibly s/n 3, was destroyed:
During a dive test to determine the maximum dive velocity, a landing gear door buckled under the air loads, causing the door to be forced open. Air was then forced into the landing gear recess on the underside of the wing, and internal pressure built up to the point where the wing failed.
—Department of Transportation, Transportation Systems Center Beech V-Tail Bonanza Task Force Report, 1985.
Harry Lawrence Reiter Jr.
Harry Lawrence Reiter, Jr., Chief Flight Research Pilot for Beechcraft, was killed when the airplane broke up and crashed 15 miles east of Wichita. An observer, Robert King, was able to escape.
The registration for NX80150 was cancelled 18 May 1948.
The Beechcraft Model 35 Bonanza is a single-engine, four-place all-metal light civil airplane with retractable landing gear. The Bonanza has the distinctive V-tail with a 30° dihedral which combined the functions of a conventional vertical fin and rudder, and horizontal tail plane and elevators.
The Model 35 was 25 feet, 2 inches (7.671 meters) long with a wingspan of 32 feet, 10 inches (10.008 meters) and height of 6 feet, 6½ inches (1.994 meters). It had an empty weight of 1,458 pounds (661 kilograms) and gross weight of 2,550 pounds (1,157 kilograms.)
An early production Beechcraft Model 35 Bonanza, NC2703V, c/n D-79. (Beech Aircraft Corporation via Larry Westin)
The first flyable prototype, NX80150, was equipped with an air-cooled, normally aspirated 289.31-cubic-inch-displacement (4.741 liter) Lycoming O-290-A horizontally-opposed 4-cylinder engine, rated at 125 horsepower at 2,600 r.p.m., and 130 horsepower at 2,800 r.p.m (five minute limit).
Prototype number four, s/n 4, NX80040, and the following production models used a more powerful air-cooled, 471.24-cubic-inch-displacement (7.72 liter) Continental Motors, Inc., E185 horizontally-opposed 6-cylinder engine. This engine was rated at 165 horsepower at 2,050 r.p.m. The Bonanza used a two-bladed electrically-controlled variable-pitch R-100 propeller with a diameter of 7 feet, 4 inches (2.235 meters), made of laminated wood.
The “V-tail Bonanza” had a maximum speed of 184 miles per hour (296 kilometers per hour) at Sea Level, and a cruise speed of 175 miles per hour (282 kilometers per hour) at 10,000 feet (3,048 meters). Its service ceiling was 18,000 feet (5,486 meters). With full fuel, 40 gallons (151.4 liters), the airplane had a range of 750 miles (1,207 kilometers).
The Beechcraft 35 was in production from 1947 to 1982. More than 17,000 Model 35s and the similar Model 36 were built.
Beechcraft Model 35 Bonanza NX80040. (Hans Groenhoff Photographic Collection, Smithsonian Institution National Air and Space Museum NASM-HGC-201)
Grumman F-14A-1-GR Tomcat Bu. No. 157980, just before its first flight, Calverton, Long Island, New York, 21 December 1970. (Northrop Grumman Corporation)
21 December 1970: At the Grumman Aerospace Corporation plant, Calverton, Long Island, New York, Chief Test Pilot Robert Kenneth Smyth and Project Test Pilot William Howard Miller took off on the very first flight of the F-14A-1-GR Tomcat, Bu. No. 157980.
The F-14 is a long-range fleet defense interceptor designed to operate from the United States Navy’s aircraft carriers. It is a two-place, twin-engine Mach 2+ fighter. The most notable feature are its variable geometry wings (“swing wings”), similar to those of the General Dynamics F-111.
A Grumman F-14A Tomcat during test flight. (U.S. Navy)
The Grumman F-14A Tomcat (Grumman has a long history of naming its fighter aircraft after various cats, e.g., Wildcat, Hellcat, Tigercat, Panther, Cougar, Tiger) is 62 feet, 8 inches (19.101 meters) long with its wingspan varying from 33 feet, 3 inches (10.135 meters) when swept fully aft (overswept), and 64 feet, 1 inches (19.510 meters) when fully extended. The airplane has an overall height of 16 feet, 0 inches (4.879 meters). It has an empty weight of 38,188 pounds (17,322 kilograms) and maximum takeoff weight of 72,566 pounds (32,915 kilograms).
The fighter was initially powered by two Pratt & Whitney JTF10A (TF30-P-412A) afterburning turbofan engines. The JTF10A is a two-spool axial-flow engine. It has a 3-stage fan section, 13-stage compressor section (6 low- and 7 high-pressure stages) and 4-stage turbine (1 high- and 3 low-pressure stages). The engine has a Maximum Continuous Power rating of 10,800 pounds of thrust (48.041 kilonewtons) at 14,300 r.p.m. (N2); Intermediate Power, 12,350 pounds (54.936 kilonewtons) at 14,800 r.p.m. (45-minute limit); and a Maximum Power of 20,900 pounds (92.968 kilonewtons) at 14,780 r.p.m., with afterburner (45-minute limit). The engine is 18 feet, 7.59 inches (5.679 meters) long, 4 feet, 2.5 inches (1.283 meters) in diameter, and weighs 3,971 pounds (1,801 kilograms).
The first Grumman F-14A Tomcat, 21 December 1970. (U.S. Naval Institute)
Cruise speed for the F-14A is 497 knots (572 miles per hour/920 kilometers per hour). It has a maximum speed of 805 knots (926 miles per hour (1,491 kilometers per hour) at Sea Level (Mach 1.22) and 1,314 knots (1,512 miles per hour/2,434 kilometers per hour) at 38,000 feet (11,582 meters) (Mach 2.29). The airplane’s service ceiling is 41,000 feet (12,497 meters), and its combat ceiling is 57,600 feet (17,556 meters) at 1,030 knots (1,185 miles per hour/1,907 kilometers per hour), Mach 1.80. The Tomcat has a combat radius of 741 nautical miles (853 statute miles/1,372 kilometers), and its maximum ferry range is 1,840 nautical miles (2,117 miles/3,407 kilometers).
The Tomcat is armed with one 20 mm General Electric M61A1 Vulcan six-barrel Gatling gun with 676 rounds of ammunition. It can carry a combination of Hughes AIM-54A Phoenix long range air-to-air missiles, as well as AIM 7E Sparrow and AIM 9H Sidewinders. The F-14 has the capability of simultaneously engaging six independent targets with the Phoenix missile. The AIM-54A is a radar-guided Mach 5 missile with a range of 115 statute miles (185 kilometers). It has a 135 pound (61.2 kilograms) proximity-fused blast fragmentation warhead.
The Grumman F-14 was in production from 1970 until 1991, in three variants, the F-14A, F-14B and F-14D. A total of 712 Tomcats were built. The fighter remained in service with the United States Navy until 2006. 79 F-14As were provided to the Imperial Iranian Air Force, prior to the Islamic revolt. An unknown number of these remain in service with the Islamic Republic of Iran Air Force.
Grumman Chief Test Pilot Robert Kenneth Smyth. (Northrop Grumman Corporation)
21 December 1916: Harry George Hawker, M.B.E., A.F.C., made the first flight of the Sopwith Camel at Brooklands Aerodrome, Surrey, England. This airplane would become the Royal Air Force’s most successful fighter of World War I.
The Sopwith Camel F.1 was a British single-place, single-engine biplane fighter, produced by the Sopwith Aviation Co., Ltd., Canbury Park Road, Kingston-on-Thames. The airplane was constructed of a wooden framework, with the forward fuselage being covered with aluminum panels and plywood, while the aft fuselage, wings and tail surfaces were covered with fabric.
The length of the Camel F.1 varied from 18 feet, 6 inches (5.639 meters) to 19 feet, 0 inches (5.791 meters), depending on which engine was installed. Both upper and lower wings had a span of 28 feet, 0 inches (8.534 meters) and chord of 4 feet, 6 inches (1.372 meters). They were separated vertically by 5 feet (1.524 meters) at the fuselage. The upper wing had 0° dihedral, while the lower wing had 5° dihedral and was staggered 1 foot, 6 inches (0.457 meters) behind the upper wing. The single-bay wings were braced with airfoil-shaped streamline wires. The overall height of the Camel also varied with the engine, from 8 feet, 6 inches (2.591 meters) to 8 feet, 9 inches (2.667 meters).
The heaviest Camel F.1 variant used the Le Rhône 180 h.p. engine. It had an empty weight of 1,048 pounds (475 kilograms). Its gross weight of 1,567 pounds (711 kilograms). The lightest was equipped with the Gnôme Monosoupape 100 horsepower engine, with weights of 882 pounds (400 kilograms) and 1,387 pounds (629 kilograms), respectively.
Front view of a Sopwith Camel F.I (Unattributed)
The first Camel was powered by an air-cooled 15.268 liter (931.72 cubic inches) Société Clerget-Blin et Cie Clerget Type 9 nine-cylinder rotary engine which produced 110 horsepower at 1,200 r.p.m. and drove a wooden two-bladed propeller. Eight different rotary engines ¹ from four manufacturers, ranging from 100 to 180 horsepower, were used in the type.
The best performance came with the Bentley B.R.1 engine (5.7:1 compression ratio). This variant had a maximum speed of 121 miles per hour (195 kilometers per hour) at 10,000 feet (3,048 meters), and 114.5 miles per hour (184 kilometers per hour) at 15,000 feet (4,572 meters). It could climb to 6,500 feet (1,981 meters) in 4 minutes, 35 seconds; to 10,000 feet (3,048 meters) in 8 minutes, 10 seconds; and 15,000 feet (4,572 meters) in 15 minutes, 55 seconds. It had a service ceiling of 22,000 feet (6,706 meters). Two other Camel variants could reach 24,000 feet (7,315 meters).
The Bentley B.R.1 rotary engine was designed by Lieutenant Walter Owen Bentley, Royal Naval Air Service (later, Captain, Royal Air Force), based on the Clerget Type 9, but with major improvements. It used aluminum cylinders shrunk on to steel liners, with aluminum pistons. The Bentley B.R.1 (originally named the Admiralty Rotary, A.R.1, as it was intended for use by the Royal Navy) was an air-cooled, normally-aspirated 17.304 liter (1,055.948 cubic inches) right-hand tractor, nine-cylinder rotary engine with a compression ratio of 5.7:1. It was rated at 150 horsepower at 1,250 r.p.m. The B.R.1 was 1.110 meters (3 feet, 7.7 inches) long, 1.070 meters (3 feet, 6.125 inches) in diameter and weighed 184 kilograms (406 pounds.) The engine was manufactured by Humber, Ltd., Coventry, England, and Vickers, Ltd., Crayford.
The instruments and armament of a Sopwith Camel from No. 4 Squadron, AFC. (Australian War Memorial)
The Camel was armed with two fixed, forward-firing .303-caliber (7.7×56mmR) Vickers machine guns, synchronized to fire forward through the propeller. These guns were modified for air cooling. Some night fighter variants substituted Lewis machine guns mounted above the upper wing for the Vickers guns. Four 25 pound (11.3 kilogram) bombs could be carried on racks under the fuselage.
The Sopwith Camel was a difficult airplane to fly. Most of its weight was concentrated far forward, making it unstable, but, at the same time making the fighter highly maneuverable. The rotary engine, with so much of its mass in rotation, caused a torque effect that rolled the airplane to the right to a much greater degree than in airplanes equipped with radial or V-type engines. A skilled pilot could use this to his advantage, but many Camels ended upside down while taking off.
Major William G. Barker, RAF, with an upside-down Sopwith Camel F.1 of No. 28 Squadron, Italy, 1918. (Library and Archives Canada)
Twelve manufacturers ² produced 5,490 Sopwith Camels between 1916 and 1920. By the end of World War I, it was becoming outclassed by newer aircraft, however it was the single most successful fighter of the war, shooting down 1,294 enemy aircraft.
One single fighter, Major William Barker’s Sopwith Aviation Co., Ltd., Camel F.1 B.6313 shot down 46 enemy aircraft, more than any other fighter in history.
It is believed that only seven Sopwith Camels still exist.
Wing Commander William George Barker, V.C., D.S.O. with Bar, M.C. with 2 Bars, Croix de Guerre, with his Sopwith Camel F.1. (Library and Archives Canada)
“This photograph of the Clipper, aloft at the mouth of the Middle River, was taken from another plane by Robert F. Kniesche, Sun staff photographer.” (The Sun (Baltimore), Vol. 196–D, Friday 21 December 1934, Page 30, Columns 3–5 )
20 December 1934: William K. (“Ken”) Ebel lifted off from Middle River, Maryland, taking the Martin M-130 “Clipper” for its first flight. The M-130 was airborne for approximately 1 hours. Flying at 1,200 feet (366 meters), it reached 160 miles per hour (257 kilometers per hour).
Three-view illustration of the Martin M-130. (Flight, The Aircraft Engineer & Airships, Vol. XXVII, No. 1361, 24 January 1935, Page 99)
NC14716, named China Clipper, was the first of three Martin M-130 four-engine flying boats built for Pan American Airways. It was used to inaugurate the first commercial transpacific air service from San Francisco to Manila in November, 1935. Built at a cost of $417,000 by the Glenn L. Martin Company in Baltimore, Maryland, it was delivered to Pan Am on October 9, 1935.
The airplane was operated by a flight crew of 6 to 9, depending on the length of the flight, plus cabin staff, and could carry 18 passengers on overnight flights or a maximum 36 passengers.
Cutaway illustration of Pan American Airways’ Martin M-130 China Clipper. (Detail from larger image. NASM SI-89-1216-A. Full image at: https://airandspace.si.edu/multimedia-gallery/7135hjpg)
The Martin M-130 was 90 feet, 10.5 inches (27.699 meters) long with a wingspan of 130 feet, 0 inches (39.624 meters). It was 24 feet, 7 inches (7.493 meters) high. The total wing area was 2,315 square feet (215 square meters), including the “sea wings”. Its maximum takeoff weight was 52,252 pounds (23,701 kilograms).
Martin M-130 under construction, 24 May 1934. (SFO Museum)
The flying boat was powered by four air-cooled, supercharged Pratt & Whitney Twin Wasp S2A5-G two-row 14-cylinder radial engines with a compression ratio of 6.7:1. They had a normal power rating 830 horsepower at 2,400 r.p.m., and 950 horsepower at 2,550 r.p.m. for takeoff. They drove three-bladed Hamilton Standard Hydromatic constant-speed propellers through a 3:2 gear reduction. The S2A5-G was 3 feet, 11.88 inches (1.216 meters) in diameter, 4 feet, 8.75 inches (1.441 meters) long, and weighed 1,235 pounds (560 kilograms).
The airplane had a cruise speed of 130 miles per hour (209 kilometers per hour) and a maximum speed of 180 miles per hour (290 kilometers per hour). The M-130’s service ceiling was 10,000 feet (3,048 meters). Its range was 3,200 miles (5,150 kilometers).
A Martin M-130, X14714, undergoing ground testing at the Glenn L. Martin Co. plant at Middle River, Maryland, 30 November 1934. (Lockheed Martin)Martin M-130 X14714, 30 November 1934. (SFO Museum)
William Kenneth Ebel was born at Orangeville, Illinois, 2 January 1899. He was the first of two sons of Willam Henry Ebel, a farmer, and Nora Agnes Rubendall Ebel.
Ken Ebel attended Heidelberg College at Tiffin, Ohio. While at Heidelberg, on 1 October 1918, he enlisted as a private in the Student Army Training Corps (S.A.T.C.). With World War I coming to an end in November, Private Ebel was discharged 20 December 1918. Ebel graduated from Heidelberg in 1921 with a bachelor of arts degree.
Ebel returned to military service, enlisting as a private in the 104th Squadron (Observation), Maryland National Guard, based at Baltimore, Maryland.
Ebel continued his college education at the Case School of Applied Science in Cleveland, Ohio. In 1923, he earned a bachelor of science degree in mechanical engineering (B.S.M.E.)
On 11 September 1923, Private Ebel was appointed an aviation cadet, graduating from primary flying school on 3 June 1924. He received a commission as a 2nd lieutenant, Officers Reserve Corps (O.R.C.), United States Army, on 12 June 1925.
Continuing to serve as a reserve officer, in 1926 Ebel went to work as an engineer for the Glenn L. Martin Company, then located in Cleveland, Ohio. As a test pilot and engineer, Ebel flew the Martin M-130 four-engine flying boar
2nd Lieutenant Ebel,still with the 104th Squadron, Maryland National Guard, was promoted to the rank of 1st lieutenant on 21 December 1928. The U.S. Army advanced his rank to 1st lieutenant, Air Corps, 15 February 1929.
On 21 October 1929, William K. Ebel married Miss Florence E. Sherck at Seneca, Ohio. They would have two children, William Kenneth, Jr., and Lydia Lynn Ebel.
While testing a Martin BM-2 dive bomber, on 11 August 1932, W.K. Ebel “leaped to safety in a parachute Friday when a bombing plane he was testing failed to come out of a spin and crashed at Dahlgren, Virginia. The plane was going through its final tests before being delivered to the navy. It was wrecked in the crash.” Ebel became Member No. 495 of The Caterpillar Club.
On Thursday, 20 December 1934, Chief Pilot Ken Ebel took the new four-engine Martin M-130 flying boat, Pan American Airways System’s Hawaii Clipper, for its first flight from Middle River, Maryland. He also made the first flight of the M-156 “Russian Clipper” in 1935.
Ebel was promoted to captain, Air Corps, on 5 January 1935. On 21 August, he delivered the new Martin Model 146 “mystery bomber” to Wright Field for evaluation by the Bombardment Board.
In 1948, Ken Ebel became director of the Airplane Division of the Curtiss-Wright Corporation in Columbus, Ohio. Soon after, Curtiss-Wright sold its airplane division to North American Aviation. In 1950, the U.S. Navy’s primary submarine builder, the Electric Boat Company, appointed Ebel as Vice Pressident of Engineering for its Canadair Ltd., aircraft manufacturing subsidiary in Montreal, Quebec, Canada. (In 1952, after acquiring Convair, the corporation reorganized as General Dynamics.
William K. Ebel
Ebel returned to the United States in 1961 and served as a consultant for General Dynamics in Washington, D.C. Ebel retired in 1963, purchasing the Mount Pleasant Orchards near Baltimore.
Mrs. Ebel died in 1968. He later married Helene H. Topping.
William Kenneth Ebel, Ph.D., died at the Greater Baltimore Medical Center, 12 July 1972.
Sikorsky XHR2S-1, Bu. No. 133732, the first Model S-56, hovers at Sikorsky Aircraft, Bridgeport, Connecticut. (Sikorsky Historical Archives)
18 December 1953: At Bridgeport, Connecticut, Sikorsky chief test pilot Dimitry D. (“Jimmy”) Viner and co-pilot James Edward Chudars made the first flight of the Sikorsky XHR2S-1 (Sikorsky Model S-56). The XHR2S-1 was a prototype assault and heavy-lift helicopter for the United States Navy and Marine Corps. It was later adopted by the U.S. Army as the H-37 Mohave.
The S-56 was a large twin-engine helicopter, following the single main rotor/tail (anti-torque) rotor configuration pioneered by Sikorsky with the Vought-Sikorsky VS-300 in 1939. The helicopter was designed to be flown by two pilots in a cockpit located above the main cabin. The two engines were placed in nacelles outboard of the stub wings which also housed the helicopter’s retractable main landing gear. Two large clam shell cargo doors and loading ramp were placed in the nose. The HR2S-1 incorporated a stability system and an automatic torque compensating tail rotor.
The S-56 series was the largest and fastest helicopter built up to that time, and remains the largest reciprocating engine helicopter ever built.
U.S. Marine Corps HR2S-1 Bu. No. 138423, the seventh production S-56 helicopter (Sikorsky Historical Archives)
The S-56 was equipped with a five blade articulated main rotor. This allowed increased lift and higher forward air speed before encountering retreating blade stall than earlier three and four blade systems. A six blade rotor system was tested, which showed further improvements, but was not adopted. The main rotor diameter was initially 68 feet (20.726 meters), but later increased to 72 feet (21.946 meters). The main rotor blades had a chord of 1 foot, 9.5 inches (0.546 meters) and used the symmetrical NACA 0012 airfoil, which was standard with American helicopters up to that time. Later in the program, the blades were lengthened and the chord increased to 1 foot, 11.65 inches (0.601 meters). The airfoil was changed to the NACA 0010.9 airfoil. These changes resulted in increased lift and higher speed. The four blade tail rotor had a diameter of 15 feet (4.572 meters). The individual blades had a chord of 1 foot, 1.5 inches (0.343 meters). As is common with American helicopters, the main rotor system turned counter-clockwise as seen from above. (The advancing blade is on the right.) The tail rotor turned counter-clockwise when viewed from the helicopter’s left side. (The advancing blade is above the axis of rotation.)
Sikorsky S-56 three-view illustration with dimensions. (Sikorsky Historical Archives)
With the longer blades installed, the helicopter’s length with rotors turning was 88 feet (26.822 meters). The fuselage had a length of 64 feet, 10.69 inches (19.779 meters), and the height was 17 feet, 2 inches (5.232 meters). The HR2S-1 had an empty weight of 21,502 pounds (9,753 kilograms), and maximum weight (overload) of 31,000 pounds (14,061 kilograms). Its fuel capacity was 1,000 U.S. gallons (3,785 liters) carried in 6 tanks located in the nacelles, wings and fuselage. It could carry 20 fully-equipped troops, or 16 litters. Its maximum cargo capacity was 10,000 pounds (4,536 kilograms).
The HR2S-1 had an automatic main rotor blade folding system, and its tail rotor pylon could be folded alongside the fuselage, reducing the length to 55 feet, 8 inches (16.967 meters) and width to 27 feet, 4 inches (8.331 meters). This allowed the helicopter to use aircraft carrier elevators and reduced storage space on the hangar deck.
Early S-56 models were powered by two air-cooled, supercharged 2,804.461 cubic inch displacement (45.957 liters) Pratt & Whitney Double Wasp R-2800-50 two-row, 18-cylinder radial engines rated at 1,900 horsepower at 2,500 r.p.m. These were upgraded in later models to R-2800-54s. These were direct drive engines with a compression ratio of 6.75:1. The R-2800-54 was rated at 2,100 horsepower at 2,700 r.p.m. to 5,000 feet (1,524 meters) for takeoff; with a normal power rating of 1,900 horsepower at 2,600 r.p.m. to 7,000 feet (2,134 meters). It required 115/145 octane aviation gasoline. Each engine was supplied with 13.3 gallons (50.35 liters) of lubricating oil. The R-2800-54 was 6 feet, 9.00 inches long (2.057 meters), 4 feet, 5.00 inches (1.346 meters) in diameter, and weighed 2,300 pounds (1,043 kilograms).
The helicopter’s engines were installed at an 80° angle to the aircraft center line, with a 12.5° upward angle to align with the main transmission input. The front of the engines faced inboard. According to Sikorsky, this unusual installation resulted in high oil consumption, and because the engines were operated at continuous high r.p.m., the time interval between engine overhauls was reduced from the normal 2,000 hours to just 350 hours.
Two U.S. Marine Corps HR2S-1 Mohave assault helicopters of Marine Helicopter Transport Squadron (HMR) 462 at Camp Pendelton, California, late 1950s. (Naval History and Heritage Command)
The production HR2S-1 had a cruise speed of 100 knots (115 miles per hour/185 kilometers per hour), and a maximum speed of 121 knots (139 miles per hour/224 kilometers per hour) at Sea Level. The helicopter’s service ceiling was 13,800 feet (4,206 meters), and its absolute hover ceiling was 5,400 feet (1,646 meters). It had a maximum rate of climb of 1,580 feet per minute (8.03 meters per second) at Sea Level, and a vertical rate of climb 950 feet per minute (4.83 meters per second), also at Sea Level. The combat radius of the HR2S-1 was 100 nautical miles (115 statute miles/185 kilometers) at 100 knots (115 miles per hour/185 kilometers per hour.)
55 HR2S-1s were delivered to the U.S. Marine Corps. The U.S. Army purchased 94 S-56s in the H-37A Mohave configuration. 90 of these were later returned to Sikorsky to be upgraded to H-37Bs. This added the automatic stabilization system of the HR2S-1, changed the variable incidence horizontal stabilizers on both side of the fuselage to a single stabilizer on top of the tail rotor pylon. Engine oil capacity was increased to 30 gallons (113.6 liters) per engine.
A total of 154 S-56s were built between 1953 and 1960.
U.S. Marines exit the front cargo doors of a Sikorsky XHR2S-1 helicopter during a demonstration at Bridgeport, Connecticut, circa 1953. The leading Marine is carrying an M1918 .30-caliber Browning Automatic Rifle (commonly known as the “B-A-R”), while those following are armed with the M1 “Garand” .30-caliber semi-automatic rifle. Note the cinematographer behind the starboard cargo door. (National Archives and Records Administration, NAID: 74241875)
From 9 through 11 November 1956, a U.S. Marine Corps HR2S-1 flown by Major Roy Lee Anderson, USMC, and Sikorsky test pilot Robert S. Decker at Windsor Locks, Connecticut, set three Fédération Aéronautique Internationale (FAI) world records for speed and payload:
On 9 November, the helicopter reached an altitude of 3,722 meters (12,211 feet) with a payload of 5,000 kilograms (11,023 pounds).¹ The following day, 10 November, it set a record for the greatest mass carried to a height of 2,000 meters (6562 feet): 6,010 kilograms (13,250 feet).² Then on 11 November, the HR2S-1 reached a speed of 261.91 kilometers per hour (162.74 mph) over a 3-kilometer (1.86 miles) course.³ For these flights, Major Anderson was awarded a third gold star in lieu of a fourth award of the Distinguished Flying Cross.
Major Roy Lee Anderson, USMC, (left) and Sikorsky test pilot Robert Stewart Decker. (Fédération Aéronautique Internationale)The world-record-setting Sikorsky HR2S-1. Note the dorsal filet. (Fédération Aéronautique Internationale)
The first flyable prototype, NX80150, was equipped with an air-cooled, normally aspirated 289.31-cubic-inch-displacement (4.741 liter) Lycoming O-290-A horizontally-opposed 4-cylinder engine, rated at 125 horsepower at 2,600 r.p.m., and 130 horsepower at 2,800 r.p.m (five minute limit).
