Tag Archives: Mach 1

26 December 1948

The ç
The Lavochkin La-176 (NPO Lavochkin)

26 December 1948: Test pilot Ivan Yevgrafovich Federov (also reported as Ivan E. Fyodorov) became the first pilot in the Soviet Union to exceed Mach 1 when he flew the Lavochkin La-176 in a dive from 9,050 meters (29,692 feet) to 6,000 meters (19,685 feet).

It was first thought that the La-176’s airspeed indicator had malfunctioned, but during subsequent testing conducted the first week of January 1949, Federov repeated the dive and six times reached Mach 1.02.

The La-176 was destroyed when its canopy failed during supersonic flight. Test pilot I.V. Sokolovsky was killed.

Lavochkin La-176
Lavochkin La-176

The La-176 was a single-seat, single-engine fighter, derived from the earlier La-168. The leading edge of its wings and tail surfaces were swept at 45°. The fighter was 36 feet (10.973 meters) long with a wingspan of 28 feet, 2 inches (8.585 meters). It had an empty weight of 3,111 kilograms (6,858.6 pounds)  and loaded weight of 4,631 kilograms (10,210 pounds).

The La-176 was powered by a Klimov VK-1 centrifugal-flow turbojet, developed from the Rolls-Royce Nene. The British engines were reverse-engineered by Vladimir Yakovlevich Klimov and manufactured at Factory No. 45 in Moscow as the Klimov VK-1. The VK-1 used a single-stage centrifugal-flow compressor, 9 combustion chambers and a single-stage axial-flow turbine. It produced a maximum 26.5 kilonewtons of thrust (5,957 pounds of thrust). The VK-1 was 2.600 meters (8 feet, 6.4 inches) long, 1.300 meters (4 feet, 3.2 inches) in diameter, and weighed 872 kilograms (1,922 pounds).

The swept-wing jet had a maximum speed of 648 miles per hour (1,042.85 kilometers per hour) and a range of 621 miles (999.4 kilometers).

Armament consisted of one Nudelman N-37 30 mm cannon and two Nudelman-Suranov NS-23 23 mm cannon.

Lavochkin La-176
Lavochkin La-176

Colonel Ivan Yevgrafovich Federov (b. 23 February 1914) was a Soviet Air Force fighter pilot who fought in the Spanish civil war (where he was known as Diablo Rojo, the Red Devil), the Russo-Finish War, World War II, China and Korea. He may have shot down as many as 135 enemy airplanes. He was personally awarded the Iron Cross by Adolf Hitler, Chancellor of Germany, in 1941. His Soviet Awards include Hero of the Soviet Union, the Order of Lenin, Order of Alexander Nevsky, Order of the Red Banner, Order of the Patriotic War 1st Degree, Order of the Patriotic War 2nd Degree, and Order of the Red Star.

Colonel Ivan Yegrafovich Federov, Soviet Air Force.
Colonel Ivan Yegrafovich Federov, Soviet Air Force.

© 2016, Bryan R. Swopes

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12 December 1991: In which a Boeing 747 goes supersonic.

Evergreen International Airlines’ Boeing 747-121, N475EV, photographed at Hellinikon International Airport, Athens, Greece, 1 January 1991. The airliner has just been converted to a freighter. (Savvas Garozis)

12 December 1991: A Boeing 747 freighter operated by Evergreen International Airlines was en route from New York’s John F. Kennedy International Airport (JFK) to Tokyo, Japan, with an intermediate stop at Anchorage International Airport (ANC), Alaska, U.S.A. The 747 had a flight crew of six and no passengers.

At about 5:20 a.m., Central Standard Time (11:15 UTC), the 747 was cruising at Flight Level 310 (31,000 feet/9,449 meters) near Nakina, a small village approximately 150 nautical miles (173 statute miles/278 kilometers) northeast of Thunder Bay, Ontario, Canada.

The flight crew observed that the airplane’s Inertial Navigation System (INS) FAIL warning lights were on. Checking their instruments, they found that the 747 had entered a 90° right bank and was in a 30°–35° descent. It was rapidly losing altitude and gaining speed.

Before the crew could recover, N475EV had lost over 10,000 feet (3,048 meters) and reportedly reached 0.98 Mach in its dive. After regaining control of the 747, the crew made an emergency landing at Duluth, Minnesota, at 5:43 a.m., Central Standard Time.

On inspection, a large hole, approximately 3 feet × 15 feet (0.9 × 4.5 meters), was found in the leading edge of the right wing, inboard of the Number 3 engine. Three sheet metal panels had torn off, then struck the right horizontal stabilizer, denting its leading edge. On landing, a flap on the left wing fell off.

According to an article in the Seattle Times, an investigator for the National Transportation Safety Board confirmed that the 747 had exceeded its design speed of 0.92 Mach, but as the Flight Data Recorder had not yet been analyzed, “. . . he could not confirm reports that it reached Mach 1.25. . . .”

The Seattle Times reported the incident:

Dive! 747 In Unexplained Incident — Canada Investigating Automatic Pilot Controls After Near-Supersonic Scare

Canadian authorities are scrutinizing the automatic flight controls of a Boeing 747-100 jumbo jet after the plane inexplicably rolled 90 degrees to its right and dove two miles at near-supersonic speed.

The incident occurred last Thursday as the plane, a passenger jetliner converted to a freighter, was cruising at 31,000 feet above Nakina, Ont., on a New York-to-Anchorage flight. The jet is owned and operated by Evergreen International Airlines, based in McMinnville, Ore.

The pilots righted the craft at 22,500 feet, then made a safe emergency landing at Duluth, Minn.

None of the six Evergreen employees on board, including the three-member flight crew, was injured, according to Dave McNair, investigator for the Transporation Safety Board of Canada.

McNair said the jumbo jet’s four turbofan engines functioned properly. He said a broad investigation would take several months and will include an examination of the sophisticated computers designed to fly the plane automatically for most of the flight.

“What we’ll be doing is looking at the entire autopilot logic and any associated logic,” he said.

At some point during the incident, three large panels beneath the leading edge of the right wing tore off, leaving a 3-by-15-foot hole on the forward, inboard section of the right wing.

The panels damaged the right flap (located on the trailing edge of the wing) and dented the right-side forward edge of the horizontal tail section, according to McNair and Boeing spokesman Chris Villiers. Upon landing, part of the left flap came off, as well, Villiers said.

Authorities said it was unclear whether the panels from the right wing came loose first and, thus, precipitated the roll and dive, or if the parts shook loose as the plane careened at a 30- to 35-degree angle of descent – more than three times a normal rate of descent. McNair said age of the 21-year-old aircraft is not believed to be a factor.

The 747-100 is designed to withstand a top speed of Mach 0.92 – nine-tenths the speed of sound, or more than 500 miles per hour at that altitude. McNair said the plane reached speeds faster than that during the dive, but he could not confirm reports that it reached Mach 1.25, because precise information from the flight-data recorder was not immediately available.

Tacoma aviation safety expert John Nance, a former 747 pilot, said it is plausible that the plane would begin to disintegrate once the speed surpassed its so-called “design limit.”

Nance described modern jetliners as “metallic eggshells, very strong when used exactly as they are designed to be used; very weak when not.”

The Evergreen incident occurred on the same day that whistleblower Darrell Smith, a former Boeing 747 computer analyst, made public an internal Boeing audit outlining major flaws in a software program used by a computer that senses the position of key moving parts on the Boeing 747-400, an advanced version of the 747-100.

Boeing officials said the computer Smith reviewed on the 747-400 doesn’t exist on the 747-100. The Evergreen plane was one of the first delivered from Boeing’s Everett plant in July 1970 to Pan Am.

Even so, Smith’s allegations and the Evergreen roll-and-dive add to a string of instances over the past two years in which alleged or apparent flaws in Boeing technology have become part of a heated air-safety debate:

— Last May, an electronically controlled engine-braking device, called a thrust reverser, inexplicably deployed as a Lauda Air 767-300ER jetliner climbed away from Bangkok, instantly flipping the plane into a supersonic crash dive. All 223 on board were killed.

Authorities still do not fully understand how a stray electrical signal, vibration or some other phenomena could have deployed the reverser. Meanwhile, Boeing has steadfastly declined to answer a call by the National Transportation Safety Board to upgrade pilot instructions on what to do if a reverser warning light illuminates in the cockpit during flight. Electronic reversers are used on all Boeing jetliners delivered in the past few years – nearly 1,700 planes all told.

— Last February, Hoot Gibson, a former Trans World Airlines pilot revealed nine complaints from pilots citing major control problems on Boeing 727 jets apparently related to a random, mysterious malfunction of the autopilot computer.

Gibson has waged a 12-year battle with the NTSB and Boeing to clear his name of allegations that he caused a TWA 727 to careen dangerously from a high altitude by attempting to improperly manipulate the controls to enhance the plane’s performance. Gibson, who wrestled back control of the plane at the last minute, maintains that a flaw in the autopilot triggered the dive.

— In April 1990, the NTSB, relying on Boeing technical data and analysis, ruled that the pilots of USAir Flight 5050 made the wrong decision to abort the takeoff of a 737-400 from New York’s LaGuardia airport on Sept. 20, 1989. The pilot decided to abort takeoff when the plane lurched left because the rudder was stuck full left. (The rudder, the upright section of the tail, is supposed to be in neutral for takeoff.)

The NTSB ruled that the pilots should have noticed the stuck rudder and, in any case, should have followed through with the takeoff, even with the stuck rudder. Two passengers were killed as the plane ditched into Bowery Bay.

The ruling upset pilots who felt little credence was given to scores of reports of problems with a new type “rudder trim.” Reports from pilots said it was moving the rudder without being commanded to do so.

Copyright © 1991 Seattle Times Company, All Rights Reserved.

The Seattle Times, 19 December 1991

A year later, the Chicago Tribune reported,

Tom Cole, a spokesman at Boeing Commercial Airplane Co., said original flight tests of 747s conducted in 1969 and 1970 took 747-100 models to speeds of Mach 0.99.

In addition, Boeing knows one case in which a 747 operated by Evergreen International made an emergency descent at speeds that exceeded Mach 1, he said.

Chicago Tribune, 20 December 1992

Following the December 1991 incident, N475EV was repaired and returned to service.

This was not the first time that 19638 had been damaged:

Boeing 747 19638 (RA003) with a nose boom during flight testing, 1969. (Jeff Ohlston/Boeing)

Boeing 747-121, serial number 19638, line number RA003, had made its first flight on 11 July 1969. Boeing used the aircraft for flight and certification testing. On completion of these tests, it was to be flown to Boeing’s Renton plant to be modified to production standards, refurbished, and then delivered to the new owner, Pan American World Airways.

While landing on Runway 15 at Renton Airport, at 11:11 a.m., 13 December 1969, 19638 struck an embankment about 20 feet (6 meters) short of the runway. None the 11 Boeing employees on board were injured. The Number 3 and 4 engines were damaged and caught fire. The right landing gear was pulled backward, but held to the wing by linkages and actuators. The flaps on the right wing were damaged. The right wing’s lower surface was punctured. The fires were quickly extinguished.

A video clip of the accident is available on YouTube:

N732PA was repaired and finally delivered to Pan American on 13 July 1970. The 747 was christened Clipper Storm King. (It was later renamed Ocean Telegraph.)

Pan Am operated the airliner for nearly 21 years. It was sold to Evergreen International Airlines, 1 July 1991, and converted to an air freighter at Evergreen’s maintenance depot at Marana, Arizona. It was re-registered N475EV.

Pan American World Airways’ Boeing 747-121, N732PA, Clipper Storm King. (Aldo Bidini via Wikimedia)

Evergreen flew N475EV until it was sold to Tower Air, 13 September 1994. Under new ownership, the Boeing 747 was again re-registered, to N615FF.

The FAA registered the 747 to Kalitta Equipment LLC, 3 August 2000. The N-number did not change. The airplane’s registration was canceled 30 June 2017.

© 2018, Bryan R. Swopes

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13 November 1942

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, Bergrstom 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

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14 October 1947

Captain Charles Elwood (“Chuck”) Yeager, U.S. Air Force, with “Glamorous Glennis,” the Bell XS-1. (U.S. Air Force/National Air and Space Museum)

14 October 1947: At approximately 10:00 a.m., a four-engine Boeing B-29 Superfortress heavy bomber, piloted by Major Robert L. Cardenas, took off from Muroc Air Force Base (now know as Edwards Air Force Base) in the high desert north of Los Angeles, California. The B-29’s bomb bay had been modified to carry the Bell XS-1, a rocket-powered airplane designed to investigate flight at speeds near the Speed of Sound (Mach 1).

A Bell XS-1 rocketplane carried aloft in the bomb bay of a modified Boeing B-29-96-BW Superfortress, serial number 45-21800. (NASA)
Captain Chuck Yeager with the Bell XS-1 on Muroc Dry Lake, 1947. (Chuck Yeager collection)

Air Force test pilot Captain Charles Elwood (“Chuck”) Yeager, a World War II fighter ace, was the U.S. Air Force pilot for this project. The X-1 airplane had been previously flown by company test pilots Jack Woolams and Chalmers Goodlin. Two more X-1 aircraft were built by Bell, and the second, 46-063, had already begun its flight testing.

Captain Yeager had made three glide flights and this was to be his ninth powered flight. Like his P-51 Mustang fighters, he had named this airplane after his wife, Glamorous Glennis.

Bob Cardenas climbed to 20,000 feet (6,096 meters) and then put the B-29 into a shallow dive to gain speed. In his autobiography, Yeager wrote:

One minute to drop. [Jack] Ridley flashed the word from the copilot’s seat in the mother ship. . . Major Cardenas, the driver, starts counting backwards from ten. C-r-r-ack. The bomb shackle release jolts you up from your seat, and as you sail out of the dark bomb bay the sun explodes in brightness. You’re looking at the sky. Wrong! You should have dropped level. The dive speed was too slow, and they dropped you in a nose-up stall. . .

Cockpit of Bell X-1, 46-062, Glamorous Glennis, on display at the National Air and Space Museum. (Photo by Eric Long, National Air and Space Museum, Smithsonian Institution)

“I fought it with the control wheel for about five hundred feet, and finally got her nose down. The moment we picked up speed I fired all four rocket chambers in rapid sequence. We climbed at .88 Mach. . . I turned off two rocket chambers. At 40,000 feet, we were still climbing at .92 Mach. Leveling off at 42,000 feet, I had thirty percent of my fuel, so I turned on rocket chamber three and immediately reached .96 Mach. . . the faster I got, the smoother the ride.

“Suddenly the Mach needle began to fluctuate. It went up to .965 Mach—then tipped right off the scale. . . .”

—Brigadier General Charles E. Yeager, U.S. Air Force (Retired), Yeager, An Autobiography, by Chuck Yeager and Leo Janos, Bantam Books, New York, 1985, Pages 120, 129–130.

Chuck Yeager and flown the XS-1 through “the sound barrier,” something many experts had believed might not be possible. His maximum speed during this flight was Mach 1.06 (699.4 miles per hour/1,125.7 kilometers per hour).

Bell X-1 46-062 in flight. Note the “shock diamonds” visible in the rocket engine’s exhaust. (Photograph by Lieutenant Robert A. Hoover, U.S. Air Force)

The Bell XS-1, later re-designated X-1, was the first of a series of rocket powered research airplanes which included the Douglas D-558-II Skyrocket, the Bell X-2, and the North American Aviation X-15, which were flown by the U.S. Air Force, U.S. Navy, NACA and its successor, NASA, at Edwards Air Force Base to explore supersonic and hypersonic flight and at altitudes to and beyond the limits of Earth’s atmosphere.

The X-1 is shaped like a bullet and has straight wings and tail surfaces. It is 30 feet, 10.98 inches (9.423 meters) long with a wing span of 28.00 feet (8.534 meters) and overall height of 10 feet, 10.20 inches (3.307 meters). Total wing area is 102.5 square feet ( 9.5 square meters). At its widest point, the diameter of the X-1 fuselage is 4 feet, 7 inches (1.397 meters). The empty weight is 6,784.9 pounds (3,077.6 kilograms), but loaded with propellant, oxidizer and its pilot with his equipment, the weight increased to 13,034 pounds (5,912 kilograms). The X-1 was designed to withstand an ultimate structural load of 18g.

The X-1 is powered by a four-chamber Reaction Motors, Inc., XLR11-RM-3 rocket engine which produced 6,000 pounds of thrust (26,689 Newtons). This engine burns a mixture of ethyl alcohol and water with liquid oxygen. Fuel capacity is 293 gallons (1,109 liters) of water/alcohol and 311 gallons (1,177 liters) of liquid oxygen. The fuel system is pressurized by nitrogen at 1,500 pounds per square inch (10,342 kilopascals).

The X-1 was usually dropped from a B-29 flying at 30,000 feet (9,144 meters) and 345 miles per hour (555 kilometers per hour). It fell as much as 1,000 feet (305 meters) before beginning to climb under its own power.

The X-1’s performance was limited by its fuel capacity. Flying at 50,000 feet (15,240 meters), it could reach 916 miles per hour (1,474 kilometers per hour), but at 70,000 feet (21,336 meters) the maximum speed that could be reached was 898 miles per hour (1,445 kilometers per hour). During a maximum climb, fuel would be exhausted as the X-1 reached 74,800 feet (2,799 meters). The absolute ceiling is 87,750 feet (26,746 meters).

The X-1 had a minimum landing speed of 135 miles per hour (217 kilometers per hour) using 60% flaps.

The three X-1 rocketplanes made a total of 157 flights with the three X-1. The number one ship, Glamorous Glennis, made 78 flights. On 26 March 1948, with Chuck Yeager again in the cockpit, it reached reached Mach 1.45 (957 miles per hour/1,540 kilometers per hour) at 71,900 feet (21,915 meters).

The third X-1, 46-064, made just one glide flight before it was destroyed 9 November 1951 in an accidental explosion.

The second X-1, 46-063, was later modified to the X-1E. It is on display at the NASA Dryden Research Center at Edwards Air Force Base.

Glamorous Glennis is on display at the Smithsonian Institution National Air and Space Museum, next to Charles A. Lindbergh’s Spirit of St. Louis.

Bell X-1, 46-062, Glamorous Glennis, on display in the Milestones of Flight gallery at the National Air and Space Museum, Washington, D.C. (Photo by Eric Long, National Air and Space Museum, Smithsonian Institution)

© 2017, Bryan R. Swopes

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14 October 1947

Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype North American Aviation XP-86. (U.S. Air Force)

14 October 1947: Twenty minutes before Captain Charles E. (“Chuck”) Yeager broke the sound barrier with a Bell X-1 rocketplane, North American Aviation Chief Test Pilot George S. Welch put the swept-wing XP-86 prototype, serial number 45-59597, into a shallow dive from 37,000 feet (11,278 meters) and accelerated. In direct violation of orders from the Secretary of the Air Force to not do so, Welch broke the “sound barrier.”

Witnesses on the ground heard the distinctive “B-BOOM” double-shock as the aircraft exceeded the speed of sound. Welch was the first to observe “Mach jump” as the airspeed indicator momentarily indicated higher due to the compression of air in front of the aircraft.

Estimates are that the XP-86 reached Mach 1.02–1.04 on this flight.

George S. Welch with his MG sports car and the North American XP-86. (Unattributed)
George S. Welch with his MG T-series sports car and North American Aviation  XP-86 45-59597. (Unattributed)

© 2015, Bryan R. Swopes

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