Tag Archives: Test Pilot

23 October 1934

Warrant Officer Francesco Agello, Regia Aeronautica. (FAI)
Warrant Officer Francesco Agello, Regia Aeronautica. (FAI)

23 October 1934: At Lago di Garda, Brescia, Italy, Warrant Officer Francesco Agello, Regia Aeronautica, set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a 3 Kilometer Course when he flew the Macchi Aeronautica M.C. 72 float plane, serial number MM 181, to an average speed of 709.21 kilometers per hour (440.68 miles per hour).¹

A contemporary news article described the event:

FLYING the Machi-Castoldi 72 seaplane (3,000 h.p. special 24-cyl. Fiat) at Lake Garda on Tuesday of last week, Warrant-Officer Francesco Agello, of the Italian Royal Air Force, raised his own world’s air speed record by putting up a mean speed (subject to homologation) of 709.202 km./hr. (440.677 m.p.h.) for the usual four flights. His previous record stood at 682.403 km./hr. (423.76 m.p.h.)

The weather conditions under which the attempts were made were ideal, there being just sufficient breeze to take the glassiness off the water, so assisting the takeoff. Temperature was suitable, and the air was free from bumps.

Just before 3 p.m. Agello took off and made four runs over the three-kilometre course, clocking as follows:—

[Direction]         Secs.               km./hr.          m.p.h

North-South     15 29/100        705.882        438.614
South-North     15 19.2/100     710.433        441.423
North-South     15 18.1/100     711.462        442.081
South-North     15 23.4/100     709.034        440.738

Warrant Officer Francesco Agello with his Macchi M.C.72. (FAI)
Warrant Officer Francesco Agello with his record-setting Macchi M.C.72, MM 181. (FAI)

After the successful attempt a banquet was held in the Officers’ Mess at Desenzano in Agello’s honour. The speeds were announced, and Col. Bernasconi, who is in command of the High-speed Flight, stated that Signor Mussolini had honoured Warrant-Officer Agello by promoting him to a full lieutenant.

Only a few modifications had been made to the Macchi-Castoldi since the previous attempt, chief among them being the substitution of wooden floats for the metal ones previously used.

Illustration of the Fiat AS.6 V-24 aircraft engine, right side.
Illustration of the Fiat AS.6 DOHC V-24 aircraft engine, right side. (Old Machine Press)

As is well known. the most interesting feature of the machine is the extremely unconventional power-unit, the Fiat A.S.6. The problem of frontal area for such a powerful unit as was specified was solved by placing the twenty-four cylinders (totalling in capacity over fifty litres) in two rows, forming a 60 deg. “vee,” and further, arranging them in two mechanically independent groups.

Each group has its own crank shaft, but a single crank case is used for both. The crank shafts, which rotate in opposite directions, are coupled in the centre by spur-gear reduction units, which drive two airscrew shafts. One of these shafts is hollow, and the other operates within it. The two shafts run forward through the “vee” of the front unit, and each carries an airscrew; so that there are two of the latter, close together, but revolving in opposite directions.

Each engine unit has independent camshafts (two per engine), water pump and dual Marelli magnetos, but a common induction system is used, an eight-jet carburetter being mounted behind the rear unit and mixture being drawn from it passed to the cylinders by a supercharger geared up to 20,000 r.p.m. An interesting point is that this supercharger absorbs 200 h.p., and, since it is driven by the rear engine, the blades of the front airscrew (which the rear engine drives) are given different inclination to correct for the slight difference in power.

The power units develop 3,000 h.p. at 3,200 r.p.m., and weighs 2,045lb., giving a weight per h.p. of 0.706lb. The all-up weight of the machine, with pilot and full tanks, is 6,670lb.

British equipment figured in the success, for Castrol oil and K.L.G. plugs were used.

FLIGHT, The Aircraft Engineer and Airships, No. 1349, Vol. XXVI, November 1, 1934, at Page 1152.

Warrant Officer Francesco Agello, Regia Aeronautica, with the record-setting Macchi M.C.72, 23 October 1934.
Warrant Officer Francesco Agello, Regia Aeronautica, with the record-setting Macchi M.C.72, 23 October 1934. (Historic Wings)
Left rear quarter view of the Macchi M.C.72. (FAI)
Left rear quarter view of a Macchi M.C.72. (FAI)

The Macchi-Castoldi M.C.72 was designed by Mario Castoldi for Aeronautica Macchi. It was a single-place, single-engine, low-wing monoplane float plane constructed of wood and metal. It was 8.32 meters (27 feet, 3.5 inches) long with a wingspan of 9.48 meters (31 feet, 1.25 inches) and height of 3.30 meters (10.83 feet). The M.C.72 had an empty weight of 2,505 kilograms (5,512 pounds), loaded weight of 2,907 kilograms (6,409 pounds) and maximum takeoff weight of 3,031 kilograms (6,669 pounds).

It was powered by a 50.256 liter (3,067 cubic inch) liquid-cooled, supercharged Fiat S.p.A. AS.6 24-cylinder 60° dual overhead cam (DOHC) V-24 engine with 4 valves per cylinder. The engine produced 3,100 horsepower at 3,300 r.p.m. and drove two counter-rotating metal two-bladed fixed pitch propellers with a diameter of 8 feet (2.56 meters). The counter-rotating blades cancelled the torque effect of the engine.

Surface radiators were placed on top of each wing and surface oil coolers on the floats.

Radiators were placed on the upper surface of each wing. (Aeronautica Militare)
Radiators were placed on the upper surface of each wing. (Aeronautica Militare) 
The Henry De la Vaulx Medal.
The Henry de la Vaulx Medal.

Five Macchi M.C.72 float planes had been built for the 1931 Schneider Trophy race, but problems with the Fiat AS.6 engine, which was essentially two AS.5 V-12s assembled back-to-back, prevented them from competing.

Four test pilots, including Francesco Agello, had been selected to fly the airplanes for speed record attempts. Two were killed while testing the M.C.72, and the third died when another airplane crashed. The cause of the accidents were explosions within the engines’ intake tract. Though they ran perfectly on test stands, in flight, they began to backfire, then explode.

It was discovered by Rod Banks, a British engineer who had been called in to develop a special high-octane fuel, that the Fiat engineers had overlooked the ram effect of the 400 mile per hour slipstream. This caused the fuel mixture to become too lean, resulting in predetonation and backfiring. A modification was made to the intake and the problem was resolved.

Macchi M.C.72 at Aeronautica Militare
Macchi M.C.72 MM 181 at the Museo Storico dell’Aeronautica Militare (Italian Air Force Museum) in Vigna di Valle, Italy. (Unattributed)

Francesco Agello was twice awarded the Henry De La Vaulx Medal by the Fédération Aéronautique Internationale, and also awarded the Medaglia d’oro al valore aeronautico. In part, his citation read, “A high speed pilot of exceptional courage and, after competition in difficult and dangerous test flights during the development of the fastest seaplane in the world, twice he conquered the absolute world speed record.”

Captain Agello was killed in a mid-air collision, 26 November 1942, while testing a Macchi C.202 Fogore fighter.

Medalglia d'oro al valore aeronautico
Medalglia d’oro al valore aeronautico

¹ FAI Record File Number 4497

© 2016, Bryan R. Swopes

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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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20 October 1952

Douglas X-3 (NASA)
Douglas X-3 49-2892. Rogers Dry Lake is in the background. (NASA)

20 October 1952: At Edwards Air Force Base, California, Douglas Aircraft Company test pilot William Barton (“Bill”) Bridgeman made the first test flight of the X-3 twin-engine supersonic research airplane. During a high-speed taxi test five days earlier, Bridgeman and the X-3 had briefly been airborne for approximately one mile over the dry lake bed, but on this flight he spent approximately 20 minutes familiarizing himself with the new airplane.

William Barton “Bill” Bridgeman, 1916–1968. (LIFE Magazine)

Bill Bridgeman had been a Naval Aviator during World War II, flying the Consolidated PBY Catalina and PB4Y (B-24) Liberator long range bombers with Bombing Squadron 109 (VB-109), “The Reluctant Raiders.”

Bridgeman stayed in the Navy for two years after the war, then he flew for Trans-Pacific Air Lines in the Hawaiian Islands and Southwest Airlines in San Francisco, before joining Douglas Aircraft Co. as a production test pilot. He checked out new AD Skyraiders as they came off the assembly line at El Segundo, California. He soon was asked to take over test flying the D-558-2 Skyrocket test program at Muroc Air Force Base (now, Edwards AFB.) With the Skyrocket, he flew higher—79,494 feet (24,230 meters)—and faster—Mach 1.88—than any pilot had up to that time.

Douglas X-3 parked on Rogers Dry Lake, 1956 (NASA)
Douglas X-3 parked on Rogers Dry Lake, 1956 (NASA)

The Douglas X-3, serial number 49-2892, was built for the Air Force and NACA to explore flight in the Mach 1 to Mach 2 range. It was radically shaped, with a needle-sharp nose, very long thin fuselage and small straight wings. The X-3 was 66 feet, 9 inches (20.345 meters) long, with a wing span of just 22 feet, 8.25 inches (6.915 meters). The overall height was 12 feet, 6.3 inches (3.818 meters). The X-3 had an empty weight of 16,120 pounds (7,312 kilograms) and maximum takeoff weight of 23,840 pounds (10,814 kilograms).

It was to have been powered by two Westinghouse J46 engines, but when those were unsatisfactory, two Westinghouse XJ34-WE-17 engines were substituted. This was an axial flow turbojet with an 11-stage compressor and 2-stage turbine. It was rated at 3,370 pounds (14.99 kilonewtons) of thrust, and 4,900 pounds (21.80 kilonewtons) with afterburner. The XJ34-WE-17 was 14 feet, 9.0 inches (4.496 meters) long, 2 feet, 1.0 inch (0.635 meters) in diameter and weighed 1,698 pounds (770 kilograms).

The X-3 had a maximum speed of 706 miles per hour (1,136 kilometers per hour) and a service ceiling of 38,000 feet (11,582 meters).

This view of the Douglas X-3 shows its very small wings and tail surfaces. (NASA)
This view of the Douglas X-3 shows its very small wings and tail surfaces. (NASA)

The X-3 was very underpowered with the J34 engines and could just reach Mach 1 in a shallow dive. Its highest speed, Mach 1.208, required a 30° dive. The research airplane was therefore never able to be used in flight testing in the supersonic speed range for which it was designed. Because of its design characteristics, though, it became useful in exploring stability and control problems encountered in the transonic range.

Two X-3 aircraft had been ordered from Douglas, but only one completed.

In addition to Bill Bridgeman, the Douglas X-3 was flown by Air Force test pilots Major Chuck Yeager and Lieutenant Colonel Frank Everest, and NACA High Speed Flight Station research pilot Joseph A. Walker.

NACA flight testing began in August 1954. On the tenth flight, 27 October, Joe Walker put the X-3 into abrupt left aileron rolls at 30,000 feet (9,144 meters), first at 0.92 Mach and then at Mach 1.05. Both times, the aircraft violently yawed to the right and then pitched down.

This was a new and little understood condition called inertial roll coupling. It was a result of the aircraft’s mass being concentrated within its fuselage, the torque reactions and gyroscopic effect of the turbojet engines and the inability of the wings and control surfaces to stabilize the airplane and overcome its rolling tendency. (Just two weeks earlier, North American Aviation’s Chief Test Pilot George S. Welch had been killed when the F-100A Super Sabre that he was testing also encountered inertial roll coupling and disintegrated.) A post-flight inspection found that the X-3 had reached its maximum design load. The X-3 was grounded for the next 11 months.

Joe Walker resumed flight testing the X-3 in 1955. It’s last flight was 23 May 1956. After the flight test program came to an end, the X-3 was turned over to the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.

Douglas X-3 49-2892 at the National Museum of the United States Air Force. (NASM)

© 2016, Bryan R. Swopes

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