Tag Archives: Seversky SEV-S1

21 September 1937

Jackie Cochran sits in the cockpit of the Seversky SEV-1XP, R18Y, circa September 1937. (San Diego Air & Space Museum Archives)

21 September 1937: Jackie Cochran flew the Seversky Aircraft Corporation SEV-1XP, registered R18Y, over a 3 kilometer (1.864 statute miles) course at Detroit Wayne County Airport, Romulus, Michigan. The average speed for six passes was 470.40 kilometers per hour (292.29 miles per hour). This was a new Fédération Aéronautique Internationale (FAI) world speed record.¹

The Lansing, Michigan, State Journal reported:

New York Aviatrix Smashes the Feminine World’s Speed Record at Detroit

BETTERS MARK SET BY FRENCH WOMAN

Jacqueline Cochran Averages Speed of 293.05 M.P.H. In 3-Kilometer Flight

     DETROIT, Sept. 21 (AP)—Jacqueline Cochran, New York aviatrix, averaged 293.05 miles an hour in four flights over a three-kilometer course Tuesday, bettering the women’s land plane speed record of 276.527 miles an hour established in 1934 by the late Helene Boucher of France.

     Miss Cochran made six flights, three east and three west, over the course, but only four of the flights were included in the official computation. She was timed at 304.62 miles an hour in her fastest dash, an eastward flight. Her speed on the slowest flight was 282.06 miles an hour.

     All of the flights were at altitudes of between 100 and 150 feet, thus complying with a National Aeronautics association [sic] rule that flights for records must be made below 250 feet.

     Miss Cochran flew a Seversky military pursuit demonstrator, with a 1,200 horsepower engine. The plane is of a type similar to a fleet soon to be put in use at Selfridge field, Mt. Clemens, Mich.

     “Ever since I started flying, five years ago, I’ve dreamed of doing this,” Miss Cochran said when she was notified of her record speed.

     Her record attempt, made at the Wayne county airport, was postponed four times by adverse winds. She had perfect weather conditions Tuesday.

     Airport officials said Miss Cochran’s flights were the fastest ever flown at the airport, by either a man or a woman.

The State Journal, Vol. 83, Tuesday, 21 September 1937, Page 8, Column 1

For this and her other accomplishments, Ms. Cochran was awarded the Harmon International Aviatrix Trophy by Mrs. Franklin D. Roosevelt in a ceremony in New York City, 4 April 1938.

Jackie Cochran is presented the Harmon International Aviatrix Trophy by Mrs. Franklin D. Roosevelt. (Acme)

The Seversky SEV-1XP (also called the “SEV-S1 Executive”) was the original prototype for a fly-off against the Curtiss-Wright Model 75 Hawk and Northrop 3A improved version of the P-35 fighter, which was designed by Alexander Kartveli. The P-35 was the first U.S. Army Air Corps single-engine airplane to feature all-metal construction, an enclosed cockpit and retractable landing gear.

The airplane had originally been built as a single-place, open cockpit monoplane with fixed landing gear. It was designated the Seversky II X, s/n 2, and given the experimental registration mark X18Y. In order to compete for the Army Air Corps pursuit contract of 1935, X18Y was modified into a two-place fighter with an enclosed canopy. It was armed with two machine guns mounted in the engine cowling, while a gunner sat behind the pilot with a third machine gun on a flexible mount. Still officially the Seversky II X, the company called it the SEV-2XP.

The Seversky SEV-2XP X18Y in the two-place, fixed landing gear configuration. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #: 16_006753)

In this configuration, X18Y was powered by an experimental air-cooled, supercharged, Wright Aeronautical Division GR1670A1 Whirlwind. This was a two-row, 14-cylinder radial engine with a displacement of 1,666.860 cubic inches (27.315 liters). It had a compression ratio of 6.75:1 and required 87-octane gasoline. The GR1670A1 had a normal power rating of 775 horsepower at 2,400 r.p.m., and 830 horsepower at 2,400 r.p.m. for takeoff. It drove an experimental three-bladed Hamilton Standard constant-speed propeller through a 16:11 gear reduction. The GR1670A1 was 45 inches (1.143 meters) in diameter, 52-25/32 inches (1.341 meters) long, and weighed 1,160 pounds (526 kilograms).

In mid-May 1935, Major de Seversky flew the prototype from the factory at Farmingdale, New York, toward Wright Field, Dayton, Ohio. The engine overheated, then seized, and Seversky made a forced landing on a small hilltop airfield near St. Clairsville, Ohio. X18Y suffered slight damage. A local pilot flew Seversky on to the meeting at Wright. Once there, he saw the Curtiss-Wright and Northrop competition, both single-place pursuits with retractable landing gear. The SEV-2XP was outclassed.

After repairs, on 20 June Seversky flew X18Y out of the small field and returned it to Farmingdale. It was extensively reconfigured as a single-place airplane. A new wing with retractable landing gear was installed, as were new tail surfaces. A Wright Cyclone R-1820G4 9-cylinder radial engine replaced the experimental GR1670A1. The G4 had a normal power rating of 810 horsepower at 2,100 r.p.m., and 1,000 horsepower at 2,200 r.p.m., using 87-octane gasoline. Seversky redesignated X18Y as the SEV-1XP. After a fly off with the modified prototype, the Air Corps placed an order for 100 Seversky P-35s.

Major Alexander de Seversky with SEV-1XP X18Y. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #16_006759)

Seversky continued to experiment with new engines, installing a GR-1820G5. In January 1937, a change was made to the Pratt & Whitney Twin Wasp R-1830-13, the same engine being installed in production Curtiss-Wright P-36 Hawks. This was a two-row, supercharged 14-cylinder radial engine with a normal power rating of 900 horsepower at 2,550 r.p.m. to an altitude of 10,000 feet (3,048 meters), and 1,050 horsepower at 2,700 r.p.m. for takeoff. The airplane retained the same three-bladed constant -speed Hamilton Standard propeller which had been used with the Wright Cyclone engine. It was driven through a 3:2 gear reduction.

X18Y was reconfigured as a two-place civilian transport, with a small passenger cabin below and behind the cockpit. There were two fixed windows on the left side of the fuselage, and the passenger entered through a hatch on the right side, over the wing. A Pratt & Whitney Twin Wasp SB-G was fitted. This engine was very slight smaller and weighed lest than the R-1830-13, and had a normal rating of 900 horsepower at 2,450 r.p.m. to 6,500 feet (1,981 meters), and 1,000 horsepower at 2,600 r.p.m. for takeoff.

The Seversky’s passenger compartment was accessed through a hatch on the right side of the fuselage. (San Diego Air and Space Museum Archives)

In this new configuration the SEV-1XP was called the “SEV-S1 Executive.” The experimental registration was changed to restricted: R18Y.

On 4 September 1937, R18Y was flown by Seversky’s chief test pilot, Frank Sinclair, in the cross-country Bendix Trophy Race. It carried the race number 63 on the vertical fin. Sinclair finished in fourth place, 33 minutes behind Jackie Cochran in her green Beechcraft D17W Staggerwing. He then flew R18Y in the Thompson Trophy pylon race, again finishing fourth with an average of 252.360 miles per hour (406.134 kilometers per hour).

On 27 October the SEV-1XP reverted to its experimental license number, X18Y.

Ms. Cochran continued to fly the Seversky in speed record attempts. On 3 December she flew it from Floyd Bennett Field in New York to Miami, Florida, in an elapsed time of 4:12:27.2, averaging 278.13 miles per hour (447.61 kilometers per hour).

Jackie Cochran with the Seversky “SEV-S1 Executive,” X18Y, 1937. (Cliff Henderson Collection, San Diego Air & Space Museum Archives, Catalog #: CF_09-0043)

On 9 December Jackie flew X18Y to a new U.S. national record speed of 252.875 miles per hour (406.963 kilometers per hour) over a 100-kilometer course. She was attempting to increase the her speed on 13 December, reaching an average 255.973 miles per hour (411.949 kilometers per hour).

When she landed at Miami after the record runs, the Seversky’s tail wheel began rapidly swinging from side to side. This was something that the P-35s were experiencing and a number of the fighters had been wrecked. Jackie said, “One wing was pulled off altogether and the landing gear was torn off,” she said. “The tail [wheel] had jumped its lock throwing the plane to one side.”

The SEV-1XP was damaged beyond economical repair. In less than three years it had served its purpose. Seversky would build a new airplane. X18Y’s registration was suspended 4 January 1938 and the airplane was scrapped.

Seversky SEV-1XP X18Y after a landing accident, Miami, Florida, 13 December 1937. (Los Angeles Times, Vol. LVII, Tuesday, 14 December 1937, Page 20)

¹ FAI Record File Number 12026

© 2020, Bryan R. Swopes

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3 December 1937

Alexander de Seversky and Jackie Cochran with the SEV-S1, 1937. (Cliff Henderson Collection, San Diego Air & Space Museum Archives, Catalog #: CF_09-0044)

3 December 1937: Jackie Cochran flew a Seversky SEV-S1, R18Y,¹ a variant of the P-35 fighter, from Floyd Bennett Field, Brooklyn, New York, to Miami, Florida, in 4 hours, 12 minutes, 27.2 seconds.

On the same day, Александр Николаевич Прокофьев-Северский (Alexander Nikolaievich Prokofiev de Seversky), the airplane’s designer, flew a second P-35-type airplane from New York to Havana, Cuba, in 5 hours, 3 minutes, 5 seconds.

The Miami Daily News reported:

. . . Jaqueline Cochran, 26-year-old New York woman flier, set a speed record of four hours and 12 minutes in a flight from New York City which ended at 3:21 p.m. yesterday at municipal airport. Averaging 278.13 miles an hour on her trip south, Miss Cochran beat the fastest time ever recorded either way between the two cities by eight minutes. That mark was set northbound by Howard Hughes. . .

. . . A New York-Havana non-stop flight record also was set yesterday when Maj. Alexander de Seversky flew the 1,350 miles in five hours and two minutes—two hours and one minute faster than Lieut. Commander Frank Hawks’ record of 1931. The new record-holder is expected to fly to Miami today.

Miami Daily News, Vol. XLII, No. 358, Saturday, 4 December 1937, Page 1, Column 8, and Page 2, Column 5

Jackie Cochran with the Seversky “SEV-S1 Executive,” X18Y, 1937. (Cliff Henderson Collection, San Diego Air & Space Museum Archives, Catalog #: CF_09-0043)

“. . . Sasha [de Seversky] became convinced that I could win the big New York-to-Miami air race coming up. What better rebuttal could he have than to have his plane flown 300 miles per hour [483 kilometers per hour] over a measured, timed course and to have it all done by a woman? The Army Air Forces were canceling further orders because they saw the airplane as dangerously faulty and not up to the specifications they had ordered.

“Sasha installed an extra gas tank in place of a seat for me. It wasn’t very comfortable, but what was worse was that the plane had never been test-flown with a full load of gas. I took off and discovered that the center of gravity was somewhere in the nose. God, I nearly put that plane into the bay just south of what is now Kennedy Airport. It porpoised terribly for over an hour. . .

“I did get the nose up in time to avoid a swim, but until I burned out most of the fuel in the seat tank, I really had to hold on for a rough ride—up and down the sky. From Washington  D.C., on, the situation straightened out and I got the record Sasha wanted so badly. . . .

Jackie Cochran: An Autobiography, by Jacqueline Cochran and Maryann Bucknum Brinley, Bantam Books, New York, 1987, Pages 150–151.

On five different occasions I have landed after a speed flight with less than two minutes of fuel remaining and once—on a record flight from New York to Miami—my engine went dead just as my wheels touched the runway. This was because of a risk I had not considered. When I reached the destination, a squadron of Navy planes was in formation flight over the airport and I had to circle before landing.

The Stars At Noon, by Jacqueline Cochran, Little, Brown and Company, Boston, 1954, Chapter IV at Page 72.

Jackie Cochran in the cockpit of the Seversky SEV-2S Executive, NR18Y. Note the passenger windows below and behind the cockpit. (San Diego Air and Space Museum Archives)
Seversky SEV-S1, R18Y, with Jacqueline (Jackie) Cochran in the cockpit. Note the passenger cabin, behind and below the cockpit. The airplane carries Frank Sinclair’s Bendix and Thompson Trophy race number 63 on the vertical fin. (San Diego Air & Space Museum Archives, Catalog # 15_002036)

The SEV-S1 was a civil variant of Major de Seversky’s P-35A fighter, which was the U.S. Army Air Corps’ first all-metal, single-engine airplane with an enclosed cockpit and retractable landing gear.

Designed by Alexander Kartvelishvili, the airplane had originally been built as the Seversky II X, a single-place open cockpit monoplane with fixed landing gear. It was powered by an  air-cooled, supercharged 1,666.860-cubic-inch-displacement (27.315 liter) Wright Aeronautical Division GR1670A1 Whirlwind, a two-row, 14-cylinder radial engine. The GR1670A1 had a compression ratio of 6.75:1 and was rated at 775 horsepower at 2,400 r.p.m., and 830 horsepower at 2,400 r.p.m. for takeoff, using 87-octane aviation gasoline. It drove an experimental three-bladed Hamilton Standard constant-speed propeller through a 16:11 gear reduction. The GR1670A1 was 45 inches (1.143 meters) in diameter, 52-25/32 inches (1.341 meters) long, and weighed 1,160 pounds (526 kilograms).

The Seversky II X was reconfigured as two-place monoplane fighter to compete in a fly-off at Wright Field against the Curtiss-Wright Model 75 Hawk and the Northrop 3A for the Air Corps fighter contract in 1935. The airplane was redesignated SEV-2XP and carried the registration mark X18Y.

The Seversky SEV-2XP X18Y in the two-place, fixed landing gear configuration. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #: 16_006753)

In mid May 1935, de Seversky was flying the prototype from the company’s Farmingdale, New York factory toward Wright Field, located near Dayton, Ohio. The airplane’s engine overheated and stopped. He made a forced landing at a small hilltop landing field near St. Clairsville, Ohio, during which the airplane was damaged. Several weeks were required to make repairs.

In the meantime, de Seversky had seen his competitors’ entries. Both were single place pursuits with retractable landing gear. He realized that his -2XP was completely outclassed.

The Curtiss-Wright Model 75, X17Y. This prototype would be developed into the P-36 Hawk and later, the P-40 Warhawk. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #: 16_008032)
The Northrop 3A, photographed 30 July 1935, the day it disappeared off the coast of southern California. No trace was found of it or the pilot, 1st Lieutenant Arthur Henry Skaer, Jr. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #: 16_005638)

The prototype was once again rebuilt. It was now also a single-place airplane with retractable landing gear. Designated SEV-1XP, X18Y was initially powered by a 1,823.129 cubic inch displacement (29.876 liters) 860-horsepower Wright Cyclone, which was quickly upgraded to a Wright GR-1820G4. This was also a single-row, nine-cylinder radial engine. The G4 had a compression ratio of 6.45:1 and required 87-octane aviation gasoline. It was rated at 810 horsepower at 2,100 r.p.m., and 1,000 horsepower at 2,200 r.p.m.for takeoff. The engine was 47¾ inches (1.213 meters) long, 54¼ inches in diameter, and weighed 1,210 pounds (549 kilograms). The SEV-1XP had a fuel capacity of 160 U.S. gallons (606 liters) and carried 15 gallons (57 liters) of lubricating oil.

Seversky SEV-1XP X18Y. (Seversky Aircraft Company)
Seversky SEV-1XP X18Y (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #: 16_006757)

In April 1936, X18Y’s engine was once again upgraded, this time to a Wright GR-1820G5, s/n 23233.

Major Alexander de Seversky with SEV-1XP X18Y. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #16_006759)

Another engine change came in January 1937. The Wright Cyclone was replaced by a Pratt & Whitney Twin Wasp R-1830-13, s/n 312. With the Twin Wasp, NR18Y’s designation was changed to SEV-S1. (Department of Commerce records continued to refer to it as SEV-1XP.) The -13 was a supercharged, two row, fourteen cylinder radial engine with a compression ratio of 6.7:1, requiring 91/93-octane aviation gasoline. It had a normal power rating of 900 horsepower at 2,550 r.p.m., to an altitude of 10,000 feet (3,048 meters), and 1,050 horsepower at 2,700 r,p,m for takeoff. The airplane retained the same Hamilton Standard propeller that had been used with the R-1820G5, which it drove through a 3:2 gear reduction. The R-1830-13 was 48.06 inches (1.221 meters) long, 59.25 inches (1.505 meters) in diameter, and weighed 1,370 pounds (621 kilograms).

In August 1937, the R-1830-13 was replaced by a R-1830 SB-G, s/n 112. Again, the same propeller was used. The SB-G had a normal rating of 900 horsepower at  2,450 r.p.m., to 6,500 feet (1,981 meters), and 1,000 horsepower at 2,600 r.p.m. for takeoff. 87-octane fuel was required. The SB-G had the same gear reduction ratio as the -13. It was 48.00 inches (1.219 meters) long, 55.48 inches (1.409 meters) in diameter, and weighed 1,284 pounds (582 kilograms).

On 30 August 1937, the Seversky SEV-1XP was issued a restricted registration, R18Y. As it was then configured, it had an actual empty weight of 4,390 pounds (1,991 kilograms) and gross weight of 6,290 pounds (2,853 kilograms).

Frank Sinclair, Seversky’s chief test pilot, flew R18Y in the 1937 National Air Races, held at Columbus, Ohio. Sinclair’s race number, 63, was painted on the vertical fin. On 4 September, he finished the Bendix Trophy Race from Burbank, California, to Columbus, in fourth place with a time of 11 hours, 2 minutes, winning a $2,000 prize. (Jackie Cochran flew a Beech Staggerwing in the Bendix, beating Sinclair and R18Y by 33 minutes.) Two days later, 6 September, Sinclair placed fourth in the Thompson Trophy pylon race. The Seversky averaged 252.360 miles per hour (406.134 kilometers per hour).

 The Seversky's passenger compartment was accessed through a hatch on the right side of the fuselage. (San Diego Air and Space Museum Archives) Jackie Cochran in the cockpit of the Seversky SEV-2S Executive, NR18Y. Note the passenger windows below and behind the cockpit. (San Diego Air and Space Museum Archives)
The Seversky’s passenger compartment was accessed through a hatch on the right side of the fuselage. (San Diego Air and Space Museum Archives)

On 27 October 1937, the Seversky’s registration reverted to X18Y.

Following an accident at Miami, 13 December 1937, the Department of Commerce suspended X18Y’s registration, noting “AIRCRAFT NOT APPROVED FOR RELICENSING”

It is believed that the prototype was scrapped.

¹ At that time, experimental and restricted category aircraft were prohibited from displaying the letter “N” at the beginning of their registration mark.

© 2020, Bryan R. Swopes

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