Tag Archives: Prototype

22 October 1955

The first of two Republic YF-105A-1-RE Thunderchief prototypes, 54-098, on Rogers Dry Lake, Edwards Air Force Base, California, 1955. (U.S. Air Force)
Republic Aviation test pilot Russell M. "Rusty" Roth. (Jet Pilot Overseas)
Republic Aviation Corporation test pilot Russell M. “Rusty” Roth. (Jet Pilot Overseas)

22 October 1955: At Edwards Air Force Base, in the high desert of southern California, Republic Aviation Corporation test pilot Russell M. (“Rusty”) Roth took the first of two prototype YF-105A-1-REs, serial number 54-098, for its first flight.

Though equipped with an under-powered Pratt & Whitney J57-P-25 interim engine, the new airplane was able to reach Mach 1.2 in level flight.

Aerodynamic improvements to the engine intakes and redesign of the fuselage to incorporate the drag-reducing “area rule,” along with the more powerful J75-P-5 turbojet engine allowed the production model F-105B to reach Mach 2.15.

The Thunderchief is the largest single-place, single-engine aircraft ever built. It was a Mach 2 fighter-bomber, designed for NATO defensive tactical nuclear strikes with a nuclear bomb carried in an internal bomb bay. The YF-105A was 61 feet, 0 inches (18.593 meters) long, with a wing span of 34 feet, 11 inches (10.643 meters) and overall height of 17 feet, 6 inches (5.334 meters). Its empty weight was 20,454 pounds (9,277 kilograms) and the Maximum Takeoff Weight (MTOW) was 41,500 pounds (18,824 kilograms).

The Pratt & Whitney Turbo Wasp JT3C (J57-P-25) was a two-spool axial-flow turbojet engine with a 16-stage compressor section (9 low- and 7 high-pressure stages) and a 3-stage turbine (1 high- and 2 low-pressure stages). The J57-P-25 had a Normal Power rating of 8,700 pounds of thrust (38.700 kilonewtons), and at Military Power produced 10,200 pounds of thrust (45.372 kilonewtons) (30-minute limit). The Maximum Power rating was 16,000 pounds of thrust (71.172 kilonewtons) with afterburner (5-minute limit). The J57-P-25 was 22 feet, 3.1 inches (6.784 meters) long, 3 feet, 3.8 inches (1.011 meters) in diameter, and weighed 5,120 pounds (2,322 kilograms).

The YF-105A’s wings were swept 45° at 25% chord. The angle of incidence was 0° and there was no twist. The wings had 3° 30′ anhedral. The total wing area was 385 square feet (35.8 square meters).

During testing, the prototype’s maximum speed was 770 knots (886 miles per hour (1,426 kilometers per hour) at 35,000 feet (10,668 meters)—Mach 1.34—and 676 knots (778 miles per hour/1,252 kilometers per hour) at Sea Level—Mach 1.02. The YF-105A’s service ceiling was 52,050 feet (15,865 meters). It’s combat radius was 950 nautical miles (1,093 statute miles/1,759 kilometers), and the maximum ferry range was 2,321 nautical miles (2,671 statute miles/4,298 kilometers).

Repiblic YF-105A 54-098 landing at Edwards Air Force Base. (San Diego Air and Space Museum Archives)
Republic YF-105A 54-098 landing at Edwards Air Force Base. (Ray Wagner Collection, San Diego Air and Space Museum Archives)

The Thunderchief was armed with a General Electric T171E2 (M61) 20 mm six-barrel rotary cannon with 1,030 rounds of ammunition. 8,000 pounds (3,629 kilograms) of bombs could be carried in an internal bomb bay or on external hardpoints. A single free-fall B28IN variable-yield thermonuclear bomb could be carried in the bomb bay.

On 16 December 1955, YF-105A 54-098 made an emergency landing at Edwards AFB after one of its main landing gear assemblies was torn off when it failed to retract during a high speed flight. The pilot, Rusty Roth, was severely injured, but he survived. The prototype was shipped back to Republic for repair, but the cost was determined to be prohibitive.

Though designed for air-to-ground attack missions, F-105s are officially credited with 27.5 victories in air combat.

833 Thunderchiefs were built by Republic between 1955 and 1964. 334 of those were lost to enemy action during the Vietnam War. The F-105 remained in service with the United States Air Force until 1980, and with a few Air National Guard units until 1983.

Republic F-105D-5-RE Thunderchief 58-1173 carrying a bomb load of sixteen 750-pound M117 general purpose bombs. (U.S. Air Force)
Republic F-105D-5-RE Thunderchief 58-1173 carrying a bomb load of sixteen 750-pound M117 general purpose bombs. (U.S. Air Force)

© 2018, Bryan R. Swopes

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21 October 1959

Gerald Huelsbeck
Gerald Huelsbeck

21 October 1959: McDonnell Aircraft Corporation test pilot Gerald (“Zeke”) Huelsbeck was killed while test flying the first prototype YF4H-1 Phantom II, Bureau of Aeronautics serial number (“Bu. No.”) 142259.

The McDonnell YF4H-1 Phantom II, Bu. No. 142259, takes off at Edwards Air Force Base during preparations for Operation Top Flight. (McDonnell Aircraft Corporation)
McDonnell YF4H-1 Phantom II Bu. No. 142259 takes off at Edwards Air Force Base during preparations for Operation Top Flight. (McDonnell Aircraft Corporation)

In October 1959 the Navy tried, a bit prematurely, for its first world record with the F4H. McDonnell test pilot Gerald “Zeke” Huelsbeck, flying near Edwards AFB, was testing various flight plans for a high-altitude zoom, looking for one to recommend to the Navy test pilot who would fly the record attempt. Huelsbeck was flying the very first F4H prototype when an engine access door blew loose, flames shot through the engine compartment, and the F4H crashed, killing Huelsbeck. (Over the next three years of the F4H-1 test program three aircraft were destroyed and three crew members died, all preparing for record flights.)

Engineering the F-4 Phantom II: Parts Into Systems by Glenn E. Bugos, Naval Institute Press, Annapolis, Maryland, 1996, Chapter 5 at Page 101.

Gerald Huelsbeck
Test Pilot Gerald Huelsbeck with a prototype McDonnell YF4H-1 Phantom II. Huelsbeck is wearing a Goodyear Mk. IV full-pressure suit. (McDonnell Aircraft Corporation)

The flight control system of the YF4H-1 was damaged by the fire and went it out of control at high speed and into a spin. Zeke Huelsbeck did eject but was too low. His parachute did not open. The prototype crashed in an open area near Mt. Pinos in the Los Padres National Forest,  Ventura County, California, about 70 miles (113 kilometers) southwest of Edwards.

McDonnell YF4H-1 Bu. No. 142259 was the first prototype Phantom II. It had first been flown by Robert C. Little at Lambert Field, St. Louis, Missouri, 27 May 1958. The Phantom II was designed as a supersonic, high-altitude fleet defense interceptor for the United States Navy. It was a two-place twin engine jet fighter armed with radar- and infrared-homing air-to-air missiles.

Gerald Huelsbeck was born in Wisconsin, 16 April 1928, the third child of Walter Andrew Huelsbeck, a farmer, and Irene M. Voigt Huelsbeck. He attended Carroll College (now, Carroll University) in Waukesha, before joining the United States Navy as a midshipman. He completed flight training at NAS Whiting Field, Florida, and was commissioned as an ensign, 2 June 1950.

In 1950, Ensign Gerald Huelsbeck married Miss Mary Jean Hillary, who had also attended Carroll College. They would have two children.

Huelsbeck was promoted to lieutenant (junior grade), 2 June 1952. Assigned as a fighter pilot during the Korean War, he flew 54 combat missions in the McDonnell F2H Banshee.

While flying in the Navy, Huelsbeck experimented with helmet-mounted cine cameras:

. . . He took a standard gun camera, added a couple of gadgets, and attached it to his helmet, The camera is electrically driven and able to take about two minutes of film with a 50-foot magazine. . . “I spent some time doing ‘hand camera’ work in Korea,” he recalls. “You know, after 54 combat missions, you don’t like to think about crashing while trying to take a picture.”

The Indianapolis Star, Vol. 53, No. 116, Tuesday, 29 September 1955, Page 4 at Columns 2–4

Lt. (j.g.) Huelsbeck in teh cocpit of a Grumman F9F. A small motion picture camera is attached to his flight helmet (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Lt. (j.g.) Huelsbeck in the cockpit of a U.S. Navy fighter. A small motion picture camera is attached to his flight helmet. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

He was serving with VF-11 at NAS Jacksonville, Florida, when he was selected for the United States Naval Test Pilot School at NAS Patuxent River, Maryland, in July 1953.

“Zeke” Huelsbeck left the Navy in 1955 to accept a position as a test pilot with the McDonnell Aircraft Corporation, St. Louis, Missouri. After several months, he was assigned as an experimental test pilot and project pilot of the F4H program.

At the time of the accident, Zeke Huelsbeck was the most experienced pilot flying the F4H.

Gerald Huelsbeck was 31 years old when he died. He is buried in New Berlin, Wisconsin.

McDonnell YF4H-1 Phantom II, Bu. No. 142259, at Lambert Field, St. Louis. (McDonnell Aircraft Corporations)
McDonnell YF4H-1 Phantom II, Bu. No. 142259, at Lambert Field, St. Louis. (McDonnell Aircraft Corporations)

© 2016, Bryan R. Swopes

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20 October 1956

Bell XH-40 55-4459 with cowlings and rear doors installed. (U.S. Army)
Bell XH-40 55-4459 with stabilizer bar, cowlings and rear doors installed. (U.S. Army)

20 October 1956: Bell Aircraft Corporation Chief Pilot Floyd W. Carlson and Chief Experimental Test Pilot Elton J. Smith made the first flight of the Bell Model 204 (designated XH-40-BF serial number 55-4459 by the United States Army) at Bell’s helicopter factory in Hurst, Texas.

The XH-40 is a six-place, turboshaft-powered light helicopter, designed with a primary mission of battlefield medical evacuation. Operated by one or two pilots, it could carry four passengers, or two litter patients with an attendant. The prototype’s fuselage was 39 feet, 3.85 inches (12.294 meters) long. The overall length of the helicopter with rotors turning was 53 feet, 4.00 inches (16.256 meters). The height (to the top of the tail rotor arc) is 14 feet, 7.00 inches (4.445 meters). The empty weight of the XH-40 was 3,693 pounds (1,675 kilograms), with a maximum gross weight of 5,650 pounds (2,563 kilograms).

Bell XH-40 first flight. (U.S. Army)
Bell XH-40 first flight. (U.S. Army)

The two blade semi-rigid, under-slung main rotor had a diameter of 44 feet, 0.00 inches (12.294 meters), and turned counter clockwise when viewed from above. (The advancing blade is on the helicopter’s right.) The blades used a symmetrical airfoil. They had a chord of 1 foot, 3.00 inches (0.381 meters) and 10° negative twist. The main rotor hub incorporated pre-coning. At 100% NR, the main rotor turned 324 r.p.m. The two blade tail rotor assembly had a diameter of 8 feet, 6.00 inches (2.591 meters). It was mounted on the left side of the pylon in a pusher configuration and turned counter-clockwise as seen from the helicopter’s left. (The advancing blade is above the axis of rotation.)

The first prototype Bell XH-40, 55-4459, hovers in ground effect. (U.S. Army)

The prototype XH-40 was powered by a Lycoming LTC1B-1 (XT53-L-1) free-turbine (turboshaft). The engine uses a 5-stage axial-flow, 1-stage centrifugal-flow compressor with a single-stage gas producer turbine and single-stage power turbine. A reverse-flow combustion section with 12 burners allows a significant reduction in the the engine’s total length. The XT53L-1 had a Maximum Continuous Power rating of 770 shaft horsepower, and Military Power rating of 825 shaft horsepower. It could produce 860 shaft horsepower at 21,510 r.p.m. At Military Power, the XT53-L-1 produced 102 pounds of jet thrust (0.454 kilonewtons). The power turbine drives the output shaft through a 3.22:1 gear reduction. The T53-L-1 is 3 feet, 11.8 inches (1.214 meters) long and 1 foot, 11.25 inches (0.591 meters) in diameter, and weighs 460 pounds (209 kilograms).

A Lycoming XT53-L-1 turboshaft engine installed on the first Bell XH-40 prototype, at Hurst, Texas, 10 August 1956. (University of North Texas Libraries, Special Collections)

The XH-40 had a maximum speed of 133 knots (153 miles per hour/246 kilometers per hour) at 2,400 feet (732 meters), and 125 knots (144 miles per hour/232 kilometers per hour) at 5,000 feet (1,524 meters). The in-ground-effect hover ceiling (HIGE) was 17,300 feet (5,273 meters) and the service ceiling was 21,600 feet (6,584 meters). The helicopter’s fuel capacity was 165 gallons (625 liters), giving it a maximum range of 212 miles (341 kilometers).

The Bell XH-40 prototype hovering in ground effect at the Bell Aircraft Company plant at Hurst, Texas. The helicopter's cowlings are not installed in this photograph. (U.S. Army)
The Bell XH-40 prototype hovering in ground effect at the Bell Aircraft Corporation helicopter plant at Hurst, Texas. The helicopter’s cowlings and doors are not installed in this photograph. (U.S. Army)

Three XH-40 prototypes were built, followed by six YH-40 service test aircraft. The designation of the XH-40 was soon changed to XHU-1.

This helicopter was the prototype of what would be known world-wide as the “Huey.” The helicopter was designated by the U.S. Army as HU-1, but a service-wide reorganization of aircraft designations resulted in that being changed to UH-1. Produced for both civil and military customers, it evolved to the Model 205 (UH-1D—UH-1H), the twin-engine Model 212 (UH-1N), the heavy-lift Model 214, and is still in production 62 years later as the twin-engine, four-bladed, glass-cockpit Model 412EPI and the UH-1Y.

Left rear quarter view of the Bell XH-40 hovering in ground effect at the Bell Helicopter Company plant at Hurst, Texas. (U.S. Army)
Left rear quarter view of the Bell XH-40 hovering in ground effect at the Bell Aircraft Corporation helicopter plant at Hurst, Texas. (U.S. Army)

Sources differ as to the date of the first flight, with some saying 20 October, and at least one saying 26 October, but most cite 22 October 1956. This individual aircraft is at the U.S. Army Aviation Museum, Fort Rucker, Alabama. The museum’s director, Robert S. Maxham, informed TDiA that, “The earliest and only historical record cards that we have on 4459 are dated 2 MAY 1958, and at that time the aircraft had 225.8 hours on it.” The Smithsonian Institution National Air and Space Museum, a generally reliable source, states the first flight was 22 October 1956.

Many sources also state the the XH-40 first flew on the same day on which Lawrence D. Bell died, which was 20 October.

The earliest contemporary news report yet discovered by TDiA, states,

On October 20, after several hours of ground running, the new Bell XH-40 helicopter was flown for the first time.

FLIGHT and AIRCRAFT ENGINEER, No. 2506, Vol. 71, Friday, 1 February 1957, Page 136, at Column 1

A rare color photograph of of a prototype Bell XH-40, hovering in ground effect. In this photo, a stabilizer bar is installed, and the synchronized elevator has end plates similar to those on Bell Model 47 helicopters. (Unattributed)

Beginning in 2015, XH-40 55-4459 was restored by Blast Off, Inc., at Atmore, Alabama. It was then returned to the Army Aviation Museum.

Bell XH-40 55-4459 ready for transport to Blast Off, Inc., 16 June 2015. (The Atmore Advance)

© 2018, Bryan R. Swopes

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17 October 1974

First flight, Sikorsky YUH-60A 73-21650 at Stratford, Connecticut, 17 October 1974. (Sikorsky, a Lockheed Martin Company)

17 October 1974: Sikorsky Chief Pilot James R. (Dick) Wright and test pilot John Dixson made the first flight of the prototype YUH-60A, 73-21650, at the company’s Stratford, Connecticut, facility. This was the first of three prototypes.

After eight months of testing, the U.S. Army selected the YUH-60A for production over its competitor, the Boeing Vertol YUH-61A. In keeping with the Army’s tradition of naming helicopters after Native Americans, the new helicopter was named Black Hawk, who was a 17th Century leader of the Sauk (or Sac) people.

Sikorsky YUH-60A 73-21650 in an early configuration, with low rotor, large-area tail rotor pylon and swept stabilator, circa 1974. (Sikorsky, Lockheed Martin Company)

The Sikorsky Model S-70 (YUH-60A) was designed to meet the requirements of the U.S. Army Utility Tactical Transport Aircraft System (UTTAS). It had a 3-man crew and could carry an 11-man rifle squad. It could be transported by a Lockheed C-141 Starlifter.

The YUH-60A had an empty weight of 11,182 pounds (5,072 kilograms) and gross weight of 16,750 pounds (7,598 kilograms). The helicopter had a structural load factor of 3.5 Gs. With 1,829 pounds (830 kilograms) of fuel, it had an endurance of 2 hours, 18 minutes.

Sikorsy YUH-60A 73-21650 (c/n 70-001), right profile. In this photograph, the prototype has been modified closer to teh production variant. The rotor mast is taller, the vertical fin has been decreased in size, the crew side window is the two-piece version. (U.S. Army Aviation Museum)
Sikorsky YUH-60A 73-21650 (c/n 70-001), right profile. In this photograph, the prototype has been modified closer to the production variant. The rotor mast is taller, the vertical fin has been decreased in size, the crew side window is the two-piece version. (U.S. Army Aviation Museum)

The YUH-60A had a four-blade fully-articulated main rotor with a diameter of 53 feet, 8 inches (16.358 meters). The blades had 18° negative twist and turned counterclockwise, as seen from above (the advancing blade is on the right) at 258 r.p.m. The blade tip speed was 725 feet per second (221 meters per second).

The four-bladed tail rotor was positioned on the right side of the tail rotor pylon in a tractor configuration. The tail rotor diameter was 11 feet (3.353 meters), and turned 1,214 r.p.m., rotating clockwise as seen from the helicopter’s left (the advancing was blade below the axis of rotation). The blade tip speed was 699 feet per second (213 meters per second). The tail rotor blades had -18° of twist. Because the Black Hawk’s engines are behind the transmission, the aircraft’s center of gravity (c.g.) is also aft. The tail rotor plane is inclined 20° to the left to provide approximately 400 pounds of lift (1.78 kilonewtons) to offset the rearward c.g.

Power was supplied by two General Electric T700-GE-700 modular turboshaft engines, rated at 1,622 shaft horsepower at 20,900 r.p.m. Np, at Sea Level under standard atmospheric conditions. The T700 has a 5-stage axial-flow, 1-stage centrifugal-flow compressor, with a 2-stage axial-flow gas producer and 2-stage axial-flow power turbine. The T700 is 3 feet, 11 inches (1.194 meters) long, 2 feet, 1 inch (0.635 meters) in diameter and weighs 437 pounds (198 kilograms). The helicopter’s main transmission was designed for 2,828 horsepower. The engines are derated to the transmission limit.

The YUH-60A had a cruise speed of 147 knots (169 miles per hour/272 kilometers per hour) at 4,000 feet (1,219 meters) and 95 °F. (35 °C.). It could climb at 450 feet per minute (2.29 meters per second) at the same altitude and air temperature.

73-21650 crashed into the Housatonic River near the Stratford plant at 9:10 a.m.,  Friday, 19 May 1978, killing all three Sikorsky employees on board, pilots Albert M. King, Jr., John J. Pasquarello, and flight engineer John Marshall.

During routine maintenance an airspeed sensor for the all-flying tailplane had been disconnected. As the Black Hawk transitioned from hover to forward flight, the all-flying tailplane remained in the hover position and forced the helicopter’s nose to pitch down to the point that recovery was impossible.

A Sikorsky YUH-60A and Boeing Vertol YUH-61A hover for the camera. (U.S. Army)
A Sikorsky YUH-60A and Boeing Vertol YUH-61A hover for the camera. (U.S. Army)

The Black Hawk has been in production since 1978. More than 4,000 of the helicopters have been built and the type has been continuously improved. The current production model is the UH-60M.

Sikorsky is a Lockheed Martin Company.

A Sikorsky UH-60M Black Hawk in flight. (Sikorsky, a Lockheed Martin Company)
Sikorsky's UH-60M Black Hawk for the U.S. Army, seen here in the Military Hangar at Sikorsky Aircraft in Stratford, Conn. Feb. 20, 2008.
Sikorsky’s UH-60M Black Hawk for the U.S. Army, seen here in the Military Hangar at Sikorsky Aircraft in Stratford, Conn. Feb. 20, 2008. (Sikorsky, a Lockheed Martin Company)

© 2018, Bryan R. Swopes

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14 October 1964

Prototype Sikorsky YCH-53A Sea Stallion, Bu. No. 151613, 14 october 1964. (Sikorsky Archives)
Prototype Sikorsky YCH-53A Sea Stallion, Bu. No. 151613, 14 October 1964. (Sikorsky Archives)

14 October 1964: The first prototype Sikorsky YCH-53A  Sea Stallion, Bu. No. 151613, made its first flight at the Sikorsky plant at Stratford, Connecticut. (Sikorsky model S-65, serial number 65001.)

The fuselage of the YCH-53A was similar in configuration to the smaller CH-3C (S-61R). It used the dynamic components from the CH-37 Mojave (S-56) and CH-54A Tarhe (S-64).

U.S. Marine Corps Sikorsky CH-53A Sea Stallion (Wikimedia)

The Sikorsky CH-53A Sea Stallion is a twin-engine heavy-lift transport helicopter operated by two pilots. It is 88 feet, 2.4 inches (26.883 meters) with rotors turning. The fuselage is 67 feet, 2.4 inches (20.483 meters) long  and 8 feet, 10 inches (2.692 meters) wide. The six-blade fully articulated main rotor is 72 feet, 2.7 inches (22.014 meters) in diameter and turns counterclockwise as seen from above. (The advancing blade is on the helicopter’s right.) Main rotor speed is 185 r.pm. The four-blade semi-articulated tail rotor has a diameter of 16 feet (4.877 meters) and is placed on the left side of the tail rotor pylon in a pusher configuration. It turns clockwise as seen from the helicopters left. (The advancing blade is below the axis of rotation.) Overall height (rotors turning) of the Sea Stallion is 24 feet, 10.8 inches (7.599 meters). The tail rotor speed is 792 r.p.m.

The CH-53A is powered by two General Electric T64-GE-6 turboshaft engines rated at 2,850 shaft horsepower, each. Performance of the CH-53D (T64-GE-413, 3,925 s.h.p) has a maximum speed (Vne) of 130 knots (241 kilometers per hour) service ceiling of 16,750 feet (5,105 meters) and range with maximum payload of 540 miles (870 kilometers)

Two YCH-53A prototypes were built, followed by 139 CH-53A Sea Stallion production models.

The CH-53 was developed into the three-engine CH-53E Super Stallion. The current production variant is the CH-53K King Stallion.

Sikorsky HH-53B 66-14428, Super Jolly Green Giant, first flight at Stratford, Connecticut, 15 March 1967. (Sikorsky Historical Archives)
Sikorsky CH-53E Super Stallion at Mojave, California, 9 September 2007. (Alan Redecki/Wikipedia)
This photograph by Alan Radecki of a Sikorsky CH-53E Super Stallion taking off at Mojave, California, 20 September 2007, is too exciting not to include. (Akradecki/Wikipedia)
Sikorsky CH-53K King Stallion at West Palm Beach, Florida, 2 March 2017. (Lance Corporal Molly Hampton, United States Marine Corps)

© 2017 Bryan R. Swopes

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