Tag Archives: Test Flight

13 November 1942

Aviation, , , , , , , , , , , , , ,
Two Republic Aviation Corporation P-47C Thunderbolts of the 56th Fighter Group retract their landing gear after takeoff. (U.S. Air Force)
Two Republic Aviation Corporation P-47C Thunderbolts of the 56th Fighter Group retract their landing gear after takeoff. (U.S. Air Force)

13 November 1942: Lieutenants Harold E. Comstock and Roger B. Dyar were fighter pilots assigned to the 63rd Fighter Squadron, 56th Fighter Group, at Bridgeport, Connecticut. They were often sent to test new P-47 Thunderbolt fighters at the Republic Aviation Corporation factory in nearby Farmingdale, New York. According to Wikipedia:

Because of the need to manufacture airplanes quickly and the close proximity to the Republic Aviation factory, active duty pilots were used for some of the test flights of the new P-47. On 13 November 1942, Lts. Comstock and Dyar were ordered to test a new type of radio antenna on the P-47C. Lt. Comstock climbed to an indicated altitude of 49,600 feet (15,118 meters) while trying to reach 50,000 feet. Due to poor response from the controls, he decided to let the aircraft fall off rather than risk a spin. He started to dive straight down and after passing below 40,000 feet he found that his controls had frozen. He then felt a bump and was unable to move the controls as the aircraft continued to dive. Even with maximum exertion, he was unable to move the control stick so he started to roll the trim tab back and after passing below 30,000 feet, the aircraft started to pull out of the dive and he recovered between 20,000 and 25,000 feet.

Lt. Dyar started his dive and encountered the same conditions. After landing, Lt. Comstock reported what happened and the chief designer of the P-47 Thunderbolt, Alexander Kartveli, questioned Lt. Comstock at length and made numerous calculations. Republic Aviation soon issued a press release claiming that Lts. Comstock and Dyar had exceeded the speed of sound. This was picked up in the national media and also drawn in Ripley’s Believe It or Not!. Soon after the press release, the 56th Fighter Group received a telegram from Gen. Henry “Hap” Arnold that “there would be no more discussion about the dive.” The actual speed attained was probably less than the speed of sound but this speed which caused the flight controls to lock up was referred to as “compressibility.” This effect was encountered by many pilots flying in combat but training and proper procedures allowed them to recover from it. In 1959, the Air Force published “A Chronology of American Aerospace Events” and included an entry for 15 November 1942 which stated “Lts. Harold Comstock and Roger Dyar set a new speed record for airplanes when they power-dived their P-47 fighters at 725 mph from 35,000 feet over an east coast air base.” While the Air Force acknowledged the speed of 725 miles per hour, it is not known whether the P-47 could actually exceed the speed of sound in a dive. Capt. Roger Dyar was killed in action on 26 June 1943. — Wikipedia

1st Lieutenant Harold E. Comstock, 56th Fighter Group. (American Air Museum in Britain)

The Los Angeles Times reported:

Plane Diving 725 m.p.h. Surpasses Speed of Sound

Bulletlike, 12-Mile-Minute Plunge of Thunderbolt P-47 Froze Control Sticks, Intrepid Army Pilots Report

     Farmingdale, N.Y., Dec. 2. (AP)—How two Army lieutenants dived their Republic P-47 Thunderbolt fighter plane at a speed of 725 miles an hour—more than 12 miles a minute and faster than the high-altitude speed of sound—was disclosed today.

     The terrific speed—perhaps faster than any human being has traveled before—froze their control sticks, the pilots reported, causing them to resort to the use of emergency cranks to move the elevator tabs and pull their ships out of the dive.

     “My body was pushed back against the rear armor plate and I had a feeling that any second the plane was going to pull away from me and leave me stranded right there, five miles above the ground. It’s a breathless feeling, your stomach curls up; it’s something like stepping from a hot shower to a cold one,” Lieut. Roger Dyar, one of the pilots, said.

     “When I rolled back on the tabs,” Lieut. Harold Comstock said, “the plane shuddered as though it had been hit by a truck.”

     Both pilots became air cadets in 1941. Lieut. Comstock is from Fresno, Cal., and Lieut. Dyar from Lowell, O.

—Los Angeles Times, Vol. LXI, Thursday, 3 December 1942, Page 1, Columns 4 and 5

The instrument panel of a Republic P-47D-40-RA Thunderbolt in the collection of the National Museum of the United States Air Force. The Airspeed Indicator is in the second row of instruments, just left of center. Note that the maximum speed marked on the face of the gauge is 700 miles per hour. (U.S. Air Force)
The instrument panel of a Republic P-47D-40-RA Thunderbolt in the collection of the National Museum of the United States Air Force. The Airspeed Indicator is in the second row of instruments, just left of center. Note that the maximum speed marked on the face of the gauge is 700 miles per hour. (U.S. Air Force)

Almost certainly, the diving Thunderbolts did not exceed the speed of sound:

In July 1944 Major [Frederic Austin] Borsodi [Chief, Fighter Test Branch, Army Air Forces Material Command, Wright Field] made a number of full power vertical dives from 40,000 feet in a North American P-51D to assess the compressibility effects on the aircraft’s handling. He achieved a maximum Mach number of 0.86, at which point severe buffeting of the empennage was noted. . . many World War II pilots remained firmly convinced that they had taken their propeller-driven fighters supersonic in steep dives, often as local shock waves rattled their craft and caused the angle of those dives to become uncontrollably steeper. More often than not the center of lift moved aft on their wings, and Mach-induced turbulence blanketed the normal control surfaces on the tail. For the lucky ones, the descent into denser air slowed the airplane, while the higher temperatures at lower altitude meant that the Mach number for a given true airspeed was lower. Consequently, local shock waves tended to disappear. A normal recovery as from any steep dive, could usually be effected. . . the later [Supermarine] Spitfires, with a demonstrated ceiling of 45,000 feet, a much thinner wing of elliptical planform, and a lower profile liquid-cooled engine, could never register a maximum speed greater than 0.9 Mach number. That is the highest recorded speed, by a substantial margin of any propeller driven fighter. Oh yes, in the course of one such dive, on entering the denser air around 20,000 feet, the Spitfire’s propeller and much of the engine cowling parted company with the rest of the aircraft. Getting to 0.90 Mach number wasn’t easy. . . the speed of sound at sea level and 59° Fahrenheit is 761 miles per hour. At an altitude of 40,000 feet, where our standard atmosphere charts tell us that the temperature is -67° Fahrenheit, sound travels at 662 miles per hour.

— Aces Wild: The Race For Mach 1, by Al Blackburn, Scholarly Resources, Inc., Wilmington, Delaware, at Pages 6–7, 24–27.

Captain Harold E. Comstock, United States Army Air Corps. (U.S. Air Force)
Captain Harold E. Comstock, United States Army Air Corps, 1944. (U.S. Air Force)
Harold E. Comstock, circa 1940.

Harold Elwood Comstock was born 20 December 1920 at Fresno, California. He was the son of Clinton Elwood Comstock, a telephone company repairman, and Leona M. Sutherland Comstock. He graduated from Roosevelt High School in Fresno, in February 1939. Comstock then entered Fresno State College. He was a member of the F.S.C. Pilots Club and the Aero Mechanics Club.

Harold Comstock was appointed an Aviation Cadet, Air Corps, Army of the United States (A.U.S.), 10 October 1941. He was 5 feet, 10 inches (1.78 meters) tall and weighed 149 pounds (67.6 kilograms). After completing flight training, on 3 July 1942 Comstock was commissioned as a second lieutenant, Air Reserve. Comstock was promoted to first lieutenant, A.U.S., 29 May 1943. Lieutenant Comstock advanced to the rank of captain, A.U.S., on 12 March 1944, and to major, A.U.S., 17 September 1944. On 3 July 1945, Major Comstock’s permanent Air-Reserve rank was advanced to first lieutenant.

UN Y, Bunny Comstock’s P-47C-5-RE Thunderbolt, 41-6326. (American Air Museum in Britain)
Detail of artwork on P-47C 41-6326 UN-Y “Happy Warrior” assigned to Harold “Bunny” Comstock. (American Air Museum in Britain)

Harold Comstock flew two combat tours in Europe with the 56th Fighter Group during World War II. He completed his second tour as commanding officer of the group’s 63rd Fighter Squadron. He flew 138 combat missions and is officially credited with destroying 5 enemy aircraft in aerial combat, with 2 probably destroyed and 3 damaged, and another 3 destroyed on the ground.

Low on fuel after a combat mission, 1st Lieutenant Comstock’s Republic P-47C-5-RE Thunderbolt 41-6326 crashed at Lyons Farm, Mutford, Suffolk, England, 3 February 1944. (U.S. Air Force)
Harold Comstock’s P-47C, 41-6326, UN Y. (American Air Museum in Britain)
Comstock’s P-47 (American Air Museum in Britain)

During his World War II service, Major Comstock was awarded the Distinguished Flying Cross with three oak leaf clusters (four awards); the Air Medal with 11 oak leaf clusters (12 awards) and the Purple Heart.

Republic P-47 Thunderbolts of the 63rd Fighter Squadron, 56th Fighter Group, ready for takeoff at RAF Boxted. (American Air Museum in Britain)
Miss Barbara Lucille Joint, circa 1940.

Lieutenant Comstock married Miss Barbara Lucille Joint, also from Fresno, 10 June 1942 at Bridge City, Texas. They would have two children, Harold Eric Comstock, and Roger Joseph Comstock.

On 16 May 1947, Major Comstock was promoted to the rank of Lieutenant Colonel, Air-Reserve. On 10 October 1947, Comstock’s permanent military rank became fist lieutenant, Air Corps, with date of rank retroactive to 3 July 1945. When the United States Air Force was established as an independent branch of the U.S. Armed Forces, Comstock’s commission was converted. (1st Lieutenant, No. 7779.)

During the Vietnam War, Lieutenant Colonel Comstock commanded the 481st Tactical Fighter Squadron, 27th Tactical Fighter Wing from 1965 to 1968. He flew another 132 combat missions in the North American Aviation F-100D Super Sabre, and 38 as commander of an airborne command and control unit of the 7th Airborne Command and Control Squadron. Colonel Comstock’s final assignment was as commanding officer, 602nd Tactical Control Group, Bergstom Air Force Base, southeast of Austin, Texas.

Lieutenant Colonel Harold E. Comstock, U.S. Air Force, 481st Tactical Fighter Squadron, 26th Tactical Fighter Wing, with a North American Aviation F-100D-26-NA Super Sabre, 55-3623, at Cannon Air Force Base, New Mexico, 1964. (Jet Pilot Overseas)
Lieutenant Colonel Harold E. Comstock, U.S. Air Force, 481st Tactical Fighter Squadron, 26th Tactical Fighter Wing, with a North American Aviation F-100D-26-NA Super Sabre, 55-3623, at Cannon Air Force Base, New Mexico, 1964. (Jet Pilot Overseas)

Colonel Comstock retired from the Air Force on 30 September 1971. He was twice awarded the Legion of Merit, and he held the Distinguished Flying Cross with six oak leaf clusters, a Purple Heart, and 17 Air Medals.

Harold E. Comstock died at Clovis, California in 2009 at the age of 88 years. He was buried at Fresno Memorial Gardens, Fresno, California.

Republic P-47 Thunderbolt “22931,” 56th Fighter Group, RAF Kings Cliff, 11 March 1943. (American Air Museum in Britain)

The Republic P-47 Thunderbolt was the largest single-engine fighter that had yet been built. The first P-47C variant was completed 14 September 1942, only one month before Bunny Comstock’s famous dive. An early change (P-47C-1) was the addition of 8 inches (0.203 meters) to the forward fuselage for improved handling. The P-47C-5-RE was 36 feet, 1-3/16 inches (11.003 meters) long with a wingspan of 40 feet, 9-5/16 inches (12.429 meters) The overall height was 14 feet 3-5/16 inches (4.351 meters). The fighter’s empty weight was 9,900 pounds (4,490.6 kilograms) and maximum gross weight was 14,925 pounds (6,769.9 kilograms).

The P-47C was powered by an air-cooled, supercharged, 2,804.4-cubic-inch-displacement (45.956 liter) Pratt & Whitney Double Wasp TSB1-G (R-2800-21) two-row, 18-cylinder radial engine with a compression ratio of 6.65:1. The R-2800-21 had a Normal Power rating of 1,625 horsepower at 2,550 r.p.m. to 25,000 feet (7,620 meters) and a Takeoff/Military Power rating of  2,000 horsepower at 2,700 r.p.m. to an altitude of 25,000 feet (7,620 meters). A large General Electric turbosupercharger was mounted in the rear of the fuselage. Internal ducts carried exhaust gases from the engine to drive the turbocharger and the supercharged air was then carried forward to supply the engine. The engine drove a 12 foot, 2 inch (3.708 meter) diameter four-bladed Curtiss Electric propeller through a 2:1 gear reduction. The R-2800-21 was 6 feet, 3.72 inches (1.923 meters) long, 4 feet, 4.50 inches (1.340 meters) in diameter, and weighed 2,265 pounds (1,027 kilograms). Approximately 80% of these engines were produced by the Ford Motor Company. It was also used as a commercial aircraft engine, with optional propeller gear reduction ratios.

63rd Fighter Squadron P-47C-5-RE Thunderbolt 41-6325 ready for takeoff at RAF Horsham St. Faith, 16 March 1943. (American Air Museum in Britain)

The P-47C had a maximum speed in level flight of 433 miles per hour (697 kilometers per hour) at 30,000 feet (9,144 meters). The service ceiling was 42,000 feet (12,802 meters), and it could climb to 15,000 feet (4,572 meters) in 7 minutes, 12 seconds. It had a maximum range of 1,250 miles (2,012 kilometers) with external fuel tanks.

The Thunderbolt was armed with eight Browning AN-M2 .50-caliber machine guns, four in each wing, with 3,400 rounds of ammunition. It could also carry external fuel tanks, rockets and bombs. The structure of the P-47 could be described as “robust” and it was heavily armored.

602 P-47Cs were built in the five months before the P-47D entered production. A total of 15,683 Thunderbolts were built; more than any other Allied fighter type. In aerial combat it had a kill-to-loss ratio of 4.6:1. The amount of damage that the airplane could absorb and still return was remarkable. The P-47, though, really made its name as a ground attack fighter, destroying aircraft, locomotives, rail cars, and tanks by the many thousands. It was one of the most successful aircraft of World War II.

Republic P-47D-6-RE Thunderbolt 42-74742 at RAF Duxford during World War II. The maintenance technicians show the fighter's enormous size. (Daily Mail)
Republic P-47D-6-RE Thunderbolt 42-74742 at RAF Duxford during World War II. The four maintenance technicians show the fighter’s enormous size. (Daily Mail)

© 2018, Bryan R. Swopes

7 September 1965

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Bell Model 209 prototype, N209J, in flight with skids retracted. (Bell Helicopter Co.)
Bell Model 209, N209J, prototype of the AH-1G Huey Cobra attack helicopter, in flight with landing skids retracted. (Bell Helicopter Company)

7 September 1965: First flight of the prototype Bell Model 209 attack helicopter. Test pilot William Thomas (“Bill”) Quinlan was in command. The duration of the flight was twelve minutes.

The Model 209 was a private venture, built in just seven months and rolled out at Fort Worth, Texas, 2 September 1965. The prototype aircraft combined the drive system, rotors and tail boom of the production UH-1C gunship with a streamlined fuselage which placed the two pilots in tandem.

The prototype was equipped with retractable landing gear which gave the 209 increased speed, but the expense and complexity were enough that this feature was not included on production aircraft.

This helicopter would be developed into the famous AH-1G Huey Cobra.

N209J,the Bell Model 209 prototype, shown in camouflage colors. (Bell Helicopter Company)
N209J, the Bell Model 209 prototype, shown in camouflage colors. (Bell Helicopter Company)

The second prototype, AH-1G 66-15246, was used by the Army for flight testing at Edwards Air Force Base, California, from 3 April to 21 April 1967.

66-15246 had an overall length of 52 feet, 11.65 inches (16.146 meters) with rotors turning. The fuselage was 44 feet, 5.20 inches (13.433 meters) long, and it was 3 feet, 0 inches (0.914 meters) wide. The HueyCobra had a short “stub wing” with a span of 10 feet, 11.60 inches (3.343 meters). Its angle of incidence was 14°. The wing’s area was 27.8 square feet (2.6 square meters). 66-15426 had an empty weight of 5,516 pounds (2,502 kilograms) and maximum gross weight of 9,500 pounds (4,309 kilograms).

Bell Model 209, N209J, prototype of the AH-1G Cobra, with landing skids extended. (U.S. Army)

The two-bladed Model 540 “door-hinge” main rotor was 44 feet, 0 inches (13.411 meters) in diameter. The blades had a chord of 2 feet, 3 inches (0.686 meters) and 10° negative twist. The main rotor turned counter-clockwise when viewed from above. (The advancing blade is on the helicopter’s right.) Normal rotor r.p.m. (power on) was 314–324 r.p.m., and power off, 304–339 r.p.m. The minimum transient rotor speed, power off, was 250 r.p.m.

The two blade tail rotor assembly had a diameter of 8 feet, 6 inches (2.591 meters) with a chord of 8.41 inches (0.214 meters). There was no twist. 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 tail rotor pylon was cambered to allow aerodynamic forces in forward flight to “unload” the tail rotor.

Bell AH-1G Cobra three-view drawing. (U.S. Army Aviation Systems Test Activity)

The AH-1G was powered by a Lycoming LTC1K-4 (T53-L-13) turboshaft engine rated at 1,400 shaft horsepower, though it was derated to the helicopter’s transmission limit. The T53-L-13 is a two-shaft free turbine with a 6-stage compressor (5 axial-flow stages, 1 centrifugal-flow stage) and a 4-stage axial-flow turbine (2 high-pressure stages, 2 low-pressure power turbine stages). The T53-L-13 is 3 feet, 11.9 inches (1.217 meters) long, 1 foot, 11.0 inches (0.584 meters) in diameter and weighs 549 pounds (249 kilograms).

The speed of the Cobra was effected by the armament configuration, whether “clean,” light or heavy scout, or “heavy hog.” At 5,000 feet (1,524 meters), the cruise speed in the clean configuration was 138.0 knots (158.8 miles per hour, 255.6 kilometers per hour); light scout, 134.0 knots (154.2 miles per hour, 248.2 kilometers per hour); and heavy hog, 127.0 knots (146.2 miles per hour, 235.2 kilometers per hour). The maximum airspeed in level flight was 149.0 knots (171.5 miles per hour, 276.0 kilometers per hour); 144.0 knots (165.7 miles per hour, 266.7 kilometers per hour); and 136.5 knots (157.1 miles per hour, 252.8 kilometers per hour), respectively.

The limiting airspeed (VNE) was 190 knots (KCAS) (219 miles per hour, 352 kilometers per hour) below 3,000 feet (914 meters) density altitude.

In autorotation, the airspeed for the minimum rate of descent was 74.0 knots (85.2 miles per hour, 137.1 kilometers per hour) with the main rotor turning 294 r.p.m., resulting in a rate of descent of 1,750 feet per minute (8.89 meters per second).

Bell AH-1G Cobra. (U.S. Army)

The basic armament for the AH-1G Cobra was an Emerson M28 turret which could be equipped with one or two General Electric M134 Miniguns, or a combination of a Minigun with a Philco Ford M129 automatic grenade launcher, or two grenade launchers. Each Minigun was supplied with 4,000 rounds of 7.62 NATO ammunition, while a grenade launcher had 300 rounds of 40 × 53 millimeter high-velocity explosive ammunition.

Four hardpoints on the stub wing could be loaded with M18 7.62 NATO Minigun pods; XM35 pods, containing a short-barreled General Electric XM195 20 millimeter Gatling gun (a variant of the M61 Vulcan); rocket pods with seven or nineteen 2.75-inch unguided rockets.

The prototype Cobra, Bell Model 209 N209J, is in the collection of the U.S. Army Aviation Museum, Fort Rucker, Alabama, as is the second prototype, 66-15246.

© 2017, Bryan R. Swopes

7 September 1956

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Captain Iven Carl Kincheloe, Jr., United States Air Force
Captain Iven Carl Kincheloe, Jr., United States Air Force

7 September 1956: At Edwards Air Force Base, California, test pilot Captain Iven Carl Kincheloe, Jr., U.S. Air Force, flew the Bell X-2 rocketplane, serial number 46-674, to a speed of Mach 1.7 and an altitude of 126,200 feet (38,465 meters). He was the first pilot to fly above 100,000 feet (30,480 meters) and was called “The First of the Spacemen.”

The X-2 was a joint project of the U.S. Air Force and NACA (the National Advisory Committee for Aeronautics, the predecessor of NASA). The rocketplane was designed and built by Bell Aircraft Corporation of Buffalo, New York, to explore supersonic flight at speeds beyond the capabilities of the earlier Bell X-1 and Douglas D-558-2 Skyrocket. In addition to the aerodynamic effects of speeds in the Mach 2.0–Mach 3.0 range, engineers knew that the high temperatures created by aerodynamic friction would be a problem, so the aircraft was built from Stainless Steel and K-Monel, a copper-nickel alloy.

Bell X-2 46-674 on approach to land. (NASA ED06-0174)

The Bell Aircraft Corporation X-2 was 37 feet, 10 inches (11.532 meters) long with a wingspan of 32 feet, 3 inches (9.830 meters) and height of 11 feet, 10 inches (3.607 meters). Its empty weight was 12,375 pounds (5,613 kilograms) and loaded weight was 24,910 pounds (11,299 kilograms).

The X-2 was powered by a throttleable Curtiss-Wright XLR25-CW-1 rocket engine that produced 2,500–15,000 pounds of thrust (11.12–66.72 kilonewtons) burning alcohol and liquid oxygen. The engine used two rocket chambers and had pneumatic, electrical and mechanical controls. The smaller chamber could produce a maximum 5,000 pounds of thrust, and the larger, 10,000 pounds (22.24 and 44.48 kilonewtons, respectively).

Professor Robert H. Goddard, “The Father of Modern Rocketry,” authorized Curtiss-Wright to use his patents, and his rocketry team went to work for the Curtiss-Wright Rocket Department. Royalties for use of the patents were paid to the Guggenheim Foundation and Clark University. Professor Goddard died before he could also make the move to Curtiss-Wright.

Rather than use its limited fuel capacity to take off and climb to altitude, the X-2 was dropped from a modified heavy bomber as had been the earlier rocketplanes. A four-engine Boeing B-50A Superfortress bomber, serial number 46-011, was modified as the ”mothership.” A second Superfortress, B-50D-95-BO 48-096, was also modified to carry the X-2, and was redesignated EB-50D

The launch altitude was 30,000 feet (9,144 meters). After the fuel was exhausted, the X-2 glided to a touchdown on Rogers Dry Lake at Edwards Air Force Base.

The Bell X-2 carried by Boeing EB-50D Superfortress 48-096. (U.S. Air Force)
A Bell X-2 carried by Boeing EB-50D Superfortress 48-096. (U.S. Air Force)

Iven Kincheloe was awarded the Mackay Trophy for this flight. His altitude record remained unbeaten until the X-15 Project.

Iven Kincheloe stands in front of the Bell X-2 and the entire support team at Edwards Air Force Base. The "mothership" is a highly-modified Boeing EB-50D Superfortress. Chase aircraft are a North American F-86 Sabre, Lockheed T-33 Shooting Star, North American F-100 Super Sabre. The rescue helicopter is a Sikorsky H-19.
Iven Kincheloe stands in front of the Bell X-2 and the entire support team at Edwards Air Force Base. The “mothership” is a highly-modified Boeing EB-50D Superfortress. Chase aircraft are a North American F-86 Sabre, Lockheed T-33 Shooting Star, North American F-100 Super Sabre. The rescue helicopter is a Sikorsky H-19. (NASA)

© 2017, Bryan R. Swopes

15 August 1951

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William Barton Bridgeman (TIME Magazine)
William Barton Bridgeman (Boris Artzybasheff/TIME Magazine)

15 August 1951: Just 8 days after he set an unofficial world speed record of Mach 1.88 (1,245 miles per hour; 2,033.63 kilometers per hour), Douglas Aircraft Company test pilot William Barton (“Bill”) Bridgeman flew the rocket-powered United States Navy/National Advisory Committee on Aeronautics (NACA) Douglas D-558-II Skyrocket, Bu. No. 37974, to a world record altitude at Edwards Air Force Base in the high desert of Southern California.

The Skyrocket was airdropped at 34,000 feet (10,363 meters) from a highly-modified U.S. Navy P2B-1S Superfortress, Bu. No. 84029. The mother ship was a U.S. Air Force Boeing B-29-95-BW Superfortress, 45-21787, transferred to the Navy and flown by another Douglas test pilot, George R. Jansen.

Douglas D-558-II Skyrocket, Bu. No., 37974, NACA 144, is dropped from the Boeing P2B-1S Superfortress, Bu. No. 84029, NACA 137. (NASA)
Douglas D-558-II Skyrocket, Bu. No., 37974, NACA 144, is dropped from the Boeing P2B-1S Superfortress, Bu. No. 84029, NACA 137. (NASA)

The flight plan was for Bridgeman to fire the rocket engine and allow the Skyrocket to accelerate to 0.85 Mach while climbing. The Skyrocket was powered by a Reaction Motors LR8-RM-6 engine, which produced 6,000 pounds of thrust. As the rocketplane continued to accelerate to Mach 1.12, the test pilot was to pull up, increasing the angle of climb while holding an acceleration rate of 1.2 Gs. This would result in a constantly increasing angle of climb. When it reached 50°, Bridgeman was to maintain that, climbing and accelerating, until the rocket engine ran out of fuel.

Initially, the plan was to continue climbing after engine shutdown until the D-558-II was approaching stall at the highest altitude it could reach while on a ballistic trajectory. There were differing expert opinions as to how it would behave in the ever thinner atmosphere. On the morning of the flight, Douglas’ Chief Engineer, Ed Heinemann, ordered that Bridgeman push over immediately when the engine stopped.

Bill Bridgeman stuck to the engineers’ flight plan. As the Skyrocket accelerated through 63,000 feet (19,200 meters), it started to roll to the left. He countered with aileron input, but control was diminishing in the thin air. The next time it began there was no response to the ailerons. Bridgeman found that he had to lower the Skyrocket’s nose until it responded, then he was able to increase the pitch angle again. At 70,000 feet (21,336 meters), travelling Mach 1.4, he decided he had to decrease the pitch angle or lose control. Finally at 76,000 feet (23,165 meters), the engine stopped. Following Heinemann’s order, Bridgeman pushed the nose down and the D-558-II went over the top of its arc at just 0.5 G.

Bill Bridgeman. (Unattributed)
Bill Bridgeman. (Unattributed)

“In the arc she picks up a couple of thousand feet. The altimeter stops its steady reeling and swings sickly around 80,000 feet. The altitude is too extreme for the instrument to function.

“Eighty thousand feet. It is intensely bright outside; the contrast of the dark shadows in the cockpit is extreme and strange. It is so dark lower in the cockpit that I cannot read the instruments sunk low on the panel. The dials on top, in the light, are vividly apparent. There seems to be no reflection. It is all black or white, apparent or non-apparent. No half-tones. It is a pure, immaculate world here.

“She levels off silently. I roll right and there it is. Out of the tiny windows slits there is the earth, wiped clean of civilization, a vast relief map with papier-mâché mountains and mirrored lakes and seas. . . .

“It is as if I am the only living thing connected to this totally strange, uninhabited planet 15 miles below me. The plane that carries me and I are one and alone.”

—The Lonely Sky, William Bridgeman with Jacqueline Hazard, Castle and Company LTD, London, 1956, Chapter XXII at Page 268.

After the data was analyzed, it was determined that William Bridgeman and the Douglas Skyrocket had climbed to 79,494 feet (24,230 meters), higher than any man had gone before. This was the last flight that would be made with a Douglas test pilot. The rocketplane was turned over to NACA, which would assign it the number NACA 144.

A Douglas D-558-II Skyrocket, Bu. No. 37974. glides back toward Rogers Dry Lake at Edwards Air force Base. A North American Aviation F-86E-1-NA Sabre, 50-606, flies chase. Major Charles E. "Chuck" Yeager frequently flew as a chase pilot for both Bill Bridgeman and Scott Crossfield. (NASA)
A Douglas D-558-II Skyrocket, Bu. No. 37974, glides back toward Rogers Dry Lake at Edwards Air Force Base. A North American Aviation F-86E-1-NA Sabre, 50-606, flies chase. Lieutenant Colonel Frank K. “Pete” Everest and Major Charles E. “Chuck” Yeager frequently flew as chase pilots for both Bill Bridgeman and Scott Crossfield. (NASA)

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 Pacific Southwest Airlines in San Francisco, before joining Douglas Aircraft Co. as a production test pilot, testing 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.

The D-558-II Skyrocket was Phase II of a planned three phase experimental flight program. It was designed to investigate flight in the transonic and supersonic range. It was 46 feet, 9 inches (14.249 meters) long with a 25 foot (7.62 meter) wing span. The wings were swept back to a 35° angle. The Skyrocket was powered by a Westinghouse J34-WE-40 11-stage axial-flow turbojet engine, producing 3,000 pounds of thrust, and a Reaction Motors LR8-RM-6 four-chamber rocket engine, which produced 6,000 pounds of thrust. The rocket engine burned alcohol and liquid oxygen.

There were three D-558-2 Skyrockets. Between 4 February 1948 and 28 August 1956, they made a total of 313 flights. Bill Bridgeman’s speed and altitude record-setting Skyrocket, Bu. No. 37974, NACA 144, is in the collection of the Smithsonian Institution National Air and Space Museum.

Douglas D-558-2 Skyrocket, Bu. No. 37974, NACA 144. (NASA)

© 2016, Bryan R. Swopes

13 August 1976

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The prototype Bell 222 hovering in ground effect during its first flight, 13 August 1976. (Bell Helicopter TEXTRON)

13 August 1976: At the Bell Helicopter facility at Arlington, Texas, the prototype Model 222 twin-engine helicopter, registration N9988K, made its first flight. During the 42-minute flight, test pilots Donald Lee Bloom and Louis William Hartwig flew the aircraft through a series of hovering maneuvers and transitions to forward flight. A Bell spokesperson described it as, “One of the most successful prototype flights we’ve ever had.”

The prototype Bell 222 in flight with landing gear retracted, 13 August 1976. (Bell Helicopter TEXTRON)

The Model 222 (“Two Twenty-Two”) was Bell Helicopter’s first completely new helicopter since the Model 206 JetRanger series. Classified as a light twin, the aircraft was originally powered by two Lycoming LTS101-650C-3 turboshaft engines. The two-blade main rotor was similar in design to that used on the AH-1 Cobra attack helicopters. The first four prototypes were built with a T-tail configuration, but problems discovered early in the test program resulted in a change to the arrangement used in the production version.

Bell Model 222 prototypye, N9988K, in flight. Note T-tail configuration. (Bell Helicopter)
Bell Model 222 prototype, N9988K, in flight. Note T-tail configuration. (Bell Helicopter TEXTRON)

The Bell 222 is used as an executive transport, a utility transport and an aeromedical helicopter. It can carry a maximum of ten persons, and is operated with either one or two pilots. The 222 is certified for Instrument Flight Rules. The standard aircraft has retractable tricycle landing gear but the Model 222UT replaces that with a lighter weight skid gear.

The Bell Model 222 is 47 feet, 6.16 inches (14.482 meters) long with rotors turning. The helicopter has a maximum height of 14 feet, 7.25 inches (4.451 meters) with the forward main rotor blade against its droop stop. The height from ground level to the top of the vertical fin is 11 feet, 0.56 inches (3.367 meters). The helicopter’s maximum width is 11 feet, 4.0 inches (3.454 meters). The empty weight is 4,555 pounds (2,066 kilograms), and the maximum gross weight is 7,848 pounds (3,560 kilograms).

The fifth prototype Bell 222, N222BX (c/n 47005), in the 40′ × 80′ (12.2 × 24.4 meters) wind tunnel at the NASA Ames Research Center, Moffett Field, California. The man at the lower left corner of the image shows scale. (NASA)

The 222’s main rotor mast is tilted 5° forward and 1° 15′ to the left. This contributes to a higher forward air speed and counteracts the helicopter’s translating tendency in a hover.

The two-bladed, underslung, semi-rigid main rotor system rotates counter-clockwise as seen from above (the advancing blade is on the right.)and turns 324 r.p.m at 100% NR. The main rotor has a diameter of 39 feet, 9.0 inches (12.116 meters). The blades have a chord of 2 feet, 4.6 inches (7.264 meters) and are pre-coned 3° 30′. The two-bladed tail rotor is positioned on the left side of the tail boom and turns clockwise as seen from the helicopter’s left (the advancing blade is below the axis of rotation). The tail rotor’s diameter is 6 feet, 6.0 inches (1.981 meters). The blades’ chord is 10.0 inches (0.254 meters).

The Bell 222 was originally powered by two Lycoming LTS101-650C-3 engines. The LTS101 is a compact, light weight, turboshaft engine. The 2-stage compressor section has 1 axial-flow stage and 1 centrifugal-flow stage. The turbine section has 1 high-pressure gas generator stage and 1 low-pressure free power stage. The LTS101-650C-3 was has a maximum continuous power rating of 598 shaft horsepower (446 kilowatts at 49,159 r.p.m. (N1) at Sea Level, and 630 shaft horsepower (470 kilowatts) at 49,638 r.p.m. for takeoff (5-minute limit). The output shaft (N2) turns 9,545 r.p.m. With one engine inoperative (OEI), the -650C-3 is rated at 650 shaft horsepower (485 kilowatts) at 50,169 r.p.m. (30-minute limit), and a maximum 675 shaft horsepower at 50,548 r.p.m. N1/9,784 r.p.m. N2 (2½-minute limit). The LTS101-650C-3 is 1 foot, 10.6 inches (0.574 meters) in diameter, 2 feet,7.3 inches (0.795 meters) long, and has a dry weight of 241 pounds (109 kilograms).

The Bell 222 has a maximum speed of 130 knots. Its hover ceiling is approximately 9,000 feet (2,743 meters). The service ceiling is 12,800 feet (3,901 meters). The maximum range is 324 nautical miles (373 statute miles/600 kilometers).

During early production, problems were experienced with the LTS101 engines, which were also used on the Sikorsky S-76 and the Aérospatiale AS-350D A-Star. This seriously hurt the reputation and sales of all three helicopters. Bell Helicopter’s parent corporation, Textron, bought the Lycoming factory and modernized it in order to improve the engine. (The engine is now owned by Honeywell Aerospace.) Operators began to replace the two Lycoming engines with a pair of Allison 250-C30 turboshafts, and eventually Bell Helicopter modified the aircraft, marketing it as the Model 230. A four-bladed variant with a longer cabin is called the Model 430.

After the test program was completed, the first prototype, N9988K, was used as a static prop on the popular television series, “Airwolf.”

Bell 222 N34NR, an aeromedical helicopter operated by Air Angels, Inc., Bolingbrooke, Illinois. (Photograph courtesy of Chris Hargreaves)
Donald Lee Bloom

Donald Lee Bloom was born in Tulsa, Oklahoma, 23 April 1932. He was the son of Fred Miles Bloom, a telegraph operator for the Standard Oil Company, and Georgia Randolph Bloom.

Don Bloom attended the University of Houston as a Naval Reserve Officers Training Corps (NROTC) midshipman. He graduated in 1955. Bloom was commissioned as a second lieutenant, United States Marine Corps, 15 September 1955. He was assigned to pilot training at NAS Pensacola, Florida.

Lieutenant Bloom was promoted to the rank of first lieutenant, 15 March 1957. He married Miss Anne Marie Carruthers in Los Angeles, California, 5 September 1958. They would have four children, Susan, Stacy, Robert and Todd.

Lieutenant Bloom was released from active duty in 1960, and joined the Kaman Aircraft Corporation as a test pilot. In 1961, began his 29-year career as an experimental test pilot with the Bell Helicopter Company.

The first production Bell OH-58A-BF Kiowa, 68-16687. Don Bloom flight-tested this type in his investigation of Loss of Tail Rotor Effectiveness. (U.S. Army)

In 1984 the Society of Experimental Test Pilots gave its Iven C. Kincheloe Award to Don Bloom for his experimental research into the Loss of Tail Rotor Effectiveness (LTE).

After flying as a test pilot on 187 projects, Don Bloom retired from the Bell Helicopter Corporation in 1990 as Senior Experimental Test Pilot. He then worked for the Federal Aviation Administration Southwest Region as its Designated Engineering Representative Flight Test Pilot, testing aircraft for government certification. During his aviation career, Bloom flew over 14,000 hours in 102 different aircraft.

In 2011, the Federal Aviation Administration presented its Wright Brothers Master Pilot Award to Don Bloom.

Donald Lee Bloom died 18 July 2017 at Grapevine, Texas. He was buried at the Dallas-Fort Worth National Cemetery, Dallas, Texas.

Don Bloom was a project development test pilot for the Bell AH-1G Cobra. (U.S. Army)

Louis William Hartwig was born at Sherman, Iowa, 26 July 1922. He was the son of Lawrence C. Harwig and Alta May Gaughey Hartwig. He attended Bowie High Schoo in Bowie, Texas.

Lou Hartwig enlisted in the United States Army 8 September 1942. (s/n 17119277) He was assigned to the 304th and 902nd Field Artillery Battalions, 77th Infantry Division.

Lou Hartwig married Miss Katherine Elizabeth Healzer, a school teacher, at Rustburg, Virginia, 19 February 1944. They would have a son, Ronald.

Piper L-4 Grasshopper. (Harry S. Truman Library & Museum)

Hartwig was deployed to the Pacific theater of operations, 24 March 1944. He flew a Piper L-4 Grasshopper as an artillery spotter at Guam and Okinawa. He was discharged from his enlistment 18 June 1944, and commissioned a second lieutenant, 19 June 1944 (s/n O-1821011). Lieutenant Hartwig returned to the United States on 21 November 1945. He was released from active duty 24 January 1946.

Lou Hartwig was one of the early students of the Bell Aircraft Corporation’s helicopter flight school at Niagara Falls Airport, New York. The school was for experienced pilots only, and required 10–15 days to complete. Each student received a minimum 22½ flight hours in a Bell Model 47. The cost of the course was $600. Hartwig was then employed as an agriculture “crop dusting” pilot in California.

While spraying insecticide in a field near Sacramento, California, Hartwig was overcome by the poisonous chemicals and lost consciousness. The helicopter struck power lines and crashed. Hartwig was thrown from the cockpit. Crash investigators described the accident as “unsurvivable.” He spent the next 11 months in hospital.

Lou Hartwig was a test pilot for the U.S. Navy’s Bell HSL-1 ASW helicopter. (Bell Aircraft Corporation)

The Bell Helicopter Company hired Hartwig as a test pilot on 15 February 1955. One of his first projects was flight testing the Model 61, the only tandem rotor helicopter ever produced by Bell. It was used as an anti-submarine warfare helicopter by the U.S. Navy, designated HSL-1.

On 31 January 1961, Hartwig set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a Closed Circuit of 100 Kilometers Without Payload, when he flew a Bell Model 47J Ranger at an average speed of 168.36 kilometer per hour (104.61 miles per hour).¹

On 2 February 1961, Lou Hartwig flew a Bell Model 47G, N967B, to set three more FAI world records: Distance in a Closed Circuit Without Landing, 1,016.20 kilometers (631.44 miles); ² Speed Over a Closed Circuit of 500 Kilometers Without Payload, averaging 119.07 kilometers per hour (73.99 miles per hour); ³ and Speed Over a Closed Circuit of 1,000 Kilometers, 118.06 kilometers per hour (73.36 miles per hour.⁴ The Model 47G had been modified with an additional fuel tank from the earlier Model 47D-1, and curved landing skids from the Model 47J.

The Bell 533, 56-6723, in one of its many configurations. It was flown with two- and four-bladed main rotors, with and without wings, and with and without turbojet engines. (Bell Helicopter Corporation)

Lou Hartwig worked on the U.S. Army’s High Performance Helicopter project. A pre-production YH-40 Iroquois, serial number 56-6723, was modified into a winged and compound helicopter configuration, designated Model 533. Hartwig flew the helicopter to a speed of 274.6 knots (316.00 statute miles per hour/508.56 kilometers per hour). In 1971, the Vertical Flight Society gave its Frederick L. Feinberg Award to Hartwig.

Mrs. Hartwig died 10 February 1989, in San Diego, California. Lou Hartwig married his second wife, Joanne Dunning, in 1990.

Louis William Hartwig died 12 April 2016, at the age of 93 years. He was buried at the Dearborn Memorial Park, Poway, California.

¹ FAI Record File Number 986

² FAI Record File Number 983

³ FAI Record File Number 989

⁴ FAI Record File Number 990

© 2018, Bryan R. Swopes