25 | May | 2025 | This Day in Aviation

1st Lieutenant James H. Doolittle, United States Army Air Corps, at the 1929 Cleveland National Air Races. Jimmy Doolittle is seen in this photograph sitting on the turtle deck of the Curtiss P-1C Hawk. (National Air and Space Museum)

25 May 1927: At Wright Field, now Wright-Patterson Air Force Base, Dayton, Ohio, First Lieutenant James H. “Jimmy” Doolittle, United States Army Air Corps, was the first pilot to successfully perform an outside loop.

Flying a Curtiss P-1B Hawk pursuit, he began the maneuver in level flight at 10,000 feet (3,048 meters), then pushed the nose down into a dive. When he reached 280 miles per hour (450 kilometers per hour), Doolittle continued to pitch the nose “down” and the airplane flew through a complete vertical circle, with the pilot’s head to the outside of the loop.

Lt. Jimmy Doolittle with a Curtiss P-1 Hawk, 4 February 1928. (NASM) — Lt. Jimmy Doolittle with a Curtiss P-1 Hawk, 4 February 1928. (National Museum of the United States Air Force)

Jimmy Doolittle attempted to repeat the outside loop at the 1929 Cleveland National Air Races, with a Curtiss P-1C Hawk, serial number 29-227. The airplane’s wings came off but Doolittle parachuted to safety. (The Curtiss P-1C used wing radiators instead of the large radiator under the nose of the P-1B. This substantially reduced the aerodynamic drag which allowed the airplane to accelerate to too high an airspeed during Doolittle’s maneuver.)

A crowd surrounds the wreckage of Jimmy Doolittle's Curtiss P-1C Hawk after it crashed during a demonstration at the 1929 Cleveland National Air Races. (Cleveland Press) — A crowd surrounds the wreckage of Jimmy Doolittle’s Curtiss P-1C Hawk after it crashed during an aerobatic demonstration at the 1929 Cleveland National Air Races. (Cleveland State University, Michael Schwartz Library, Special Collections, Cleveland Press Collection)

Jimmy Doolittle was one of America’s foremost pioneering aviators. He set many records, won air races, tested and developed new flying equipment and techniques. He was a highly-educated military officer, having earned his Bachelor of Arts from the University of California Berkeley School of Mines, and M.S and D.Sc. degrees in Aeronautical Engineering from the Massachusetts Institute of Technology. As a pioneer aviator, he won every international air race, and had been awarded every international aviation trophy. He was also the first pilot to fly completely by reference to instruments.

During the early days of America’s involvement in World War II, Lieutenant Colonel Doolittle planned and led the Halsey-Doolittle B-25 raid on Japan. He was awarded the Medal of Honor and promoted to brigadier general, and then placed in command of the Twelfth Air Force in North Africa. As a major general, he commanded the Fifteenth Air Force in the Mediterranean Theater of Operations. Lieutenant General Doolittle commanded the Eighth Air Force in England from January 1944 to September 1945. He supervised the transition of the 8th to the Boeing B-29 Superfortress and its eventual transfer to bases on Okinawa to continue the war against Japan. World War II came to an end before any of the 8th’s B-29s actually moved west.

Lieutenant General James H. Doolittle, U.S. Army Air Force (U.S. Army Photo C-2102)

After the war, Lieutenant General Doolittle was placed on the inactive list. On 4 April 1985, by Act of Congress, James H. Doolittle was promoted to General, United States Air Force, Retired.

General James Harold Doolittle is the only person to be awarded both the Medal of Honor and the Medal of Freedom. He died 27 September 1993 at the age of 96 years. He was buried at the Arlington National Cemetery, Arlington, Virginia.

Curtiss P-1B Hawk, A.C. 27-75. (U.S. Air Force)

The Curtiss P-1B Hawk was a single-engine, single-seat, single-bay biplane pursuit, an aircraft type now known as a fighter. The airplane and its D-12 Conqueror engine were both built by the Curtiss Aeroplane and Motor Co., Garden City, New York.

The P-1B was 22 feet, 10 inches (6.960 meters) long with an upper wingspan of 31 feet, 6 inches (9.601 meters). The lower wing had a span of 26 feet, 0 inches (7.925 meters), a narrower chord, and was staggered 3 feet, 2½ inches (0.978 meters) behind the upper. Both wings had significant taper with rounded tips. Their angle of incidence was 0°. The upper wing had no dihedral, while the inboard lower wing had 1°, and the outer, 5°. The total wing area was 252 square feet (23.4 square meters). The horizontal stabilizer span was 10 feet, 6.0 inches (3.200 meters) and its incidence could be adjusted from +3° to -1.5°. The vertical fin was offset 2° left of the airplane’s centerline. The overall height of the airplane was 8 feet, 10 inches (2.712 meters).

The P-1B had an empty weight of 2,105 pounds (955 kilograms), gross weight of 2,932 pounds (1,330 kilograms), and maximum weight of 3,562 pounds ( kilograms).

The P-1B was powered by a liquid-cooled, normally-aspirated, 1,145.1-cubic-inch-displacement (18.8 liter) Curtiss D-12D (V-1150-3) dual overhead cam (DOHC) 4-valve 60° V-12 engine with a compression ratio of 5.7:1. It was a direct-drive engine, rated at 415 horsepower at 2,000 r.p.m. at Sea Level, and 460 horsepower at 2,300 r.p.m. The D-12 was 58¾ inches (1.492 meters) long, 34¾ inches (0.883 meters) high and 28¼ inches (0.718 meters) wide. It weighed 680 pounds (308 kilograms). The P-1B was equipped with an aluminum Curtiss-Reed propeller with a diameter of 8 feet, 9 inches (2.667 meters).

The pursuit had a cruise speed of 127 miles per hour (204 kilometers per hour). Its maximum speed was 159.6 miles per hour (256.9 kilometers per hour) at Sea Level, and 157 miles per hour (253 kilometers per hour) at 5,000 feet (1,524 meters). It had a service ceiling of 21,400 feet (6,523 meters) and absolute ceiling of 22,900 feet (6,980 meters). Its range was 342 miles (550 kilometers).

The P-1B was armed with two fixed air-cooled Browning machine guns, one .50-caliber and one .30-caliber.

The Air Corps ordered 93 Curtiss P-1 Hawks between 1925 and 1929.

Doolittle flew a Curtiss Curtiss P-1A Hawk, 25-410, similar to the P-1B that Doolittle flew into an outside loop. (U.S. Air Force) — Curtiss P-1A Hawk, 25-410, similar in appearance to the P-1B that Doolittle flew into an outside loop. (U.S. Air Force)

Igor Ivanovich Sikorsky, 1914. (Karl Karlovich Bulla) — Igor Ivanovich Sikorsky, 1914. Sikorsky is wearing the cross of the Imperial Order of St. Vladimir. (Karl Karlovich Bulla)

25 May 1889: Ігор Іванович Сікорський (Igor Ivanovich Sikorsky) was born at Kiev, Ukraine, Russian Empire, the fifth of five children of Professor Ivan Alexeevich Sikorsky and Doctor Mariya Stefanovich Sikorskaya.

15 year-old Midshipman Igor Ivanovich Sikorksky, at lower right, with his sisters Olga, Lydia and Elena, and brother Sergei, 1904. (Sikorsky, a Lockheed Martin Company) — 15 year-old Midshipman Igor Ivanovich Sikorksky, Imperial Naval Academy, at lower right, with his sisters Olga, Lydia and Elena, and brother Sergei, 1904. (Sikorsky, a Lockheed Martin Company)

He studied at the Imperial Naval Academy, St. Petersburg, from 1903 until 1906, when he left to study engineering, first in Paris, and then at the Kiev Polytechnic Institute.

Airplane pilot Igor Sikorsky with a passenger. (RIA Novosti) — Pilot Igor Ivanovich Sikorsky with a passenger, circa 1914. (RIA Novosti)

Flying an airplane of his own design, the S-5, on 18 April 1911, he received a Fédération Aéronautique Internationale pilot’s license from L’Aéro-Club Imperial de Russie (Imperial Russian Aero Club).

Igor I. Sikorsky's FAI pilot's license. (Sikorsky Historical Archives) — Igor I. Sikorsky’s FAI pilot’s license. (Sikorsky Historical Archives)

He was chief aircraft engineer for Russko-Baltiisky Vagonny Zavod at St. Petersburg and continued to develop airplanes. In 1913, he flew the twin engine S-21 Le Grand, to which he added two more engines, and it became the Russky Vityaz.

Igor Sikorsky with one of his early biplanes.

Sikorsky S-21 in flight — Sikorsky’s S-21 in flight, 1913

Igor Sikorsky married Olga Fyodorovna Simkovich. They had a daughter, Tania. The couple soon divorced, however.

Compagnie Générale Transatlantique liner, SS La Lorraine, 11,146 gross tons. — Compagnie Générale Transatlantique liner, S.S. La Lorraine, 11,146 gross tons.

Following the October Revolution, Sikorsky emigrated to the United States. Departing Le Havre, France, aboard S.S. La Lorraine, he arrived at New York on 31 March 1919. With financial backing from composer and conductor Sergei Vasilievich Rachmaninoff, he founded the Sikorsky Aero Engineering Company at Long Island, New York, in 1924, and continued designing and building airplanes.

In 1924, Sikorsky married Elisabeth Semion, who was also born in Russia, in 1903. They would have four children. In 1928, he became a citizen of the United States of America.

Sikorsky S-39 amphibian NC54V (Civil Air Patrol)

Beginning in 1934, Sikorsky Aircraft produced the S-42 flying boat for Pan American Airways at a new plant at Stratford, Connecticut.

U.S. Navy RS-1 (Sikorsky S-41) (National Museum of Naval Aviation)

A Pan American Airways Sikorsky S-42, NC16742, moored at Honolulu, Territory of the Hawaiian Islands. (hawaii.gov/hawaiiaviation) — Pan American Airways Sikorsky S-42, NC16734, moored at Honolulu, Territory of the Hawaiian Islands. (hawaii.gov/hawaiiaviation)

Interested in helicopters since the age of 9, he directed his creative effort toward the development of a practical “direct-lift” aircraft. The first successful design was the Vought-Sikorsky VS-300. Using a single main rotor, the VS-300 went through a series of configurations before arriving at the single anti-torque tail rotor design, the VS-316A. This was put into production for the U.S. military as the Sikorsky R-4.

The prototype VS-300 helicopter clears the ground for the first time, 14 September 1939. Igor Sikorsky is at the controls. His right foot rests on the anti-torque pedal. (Sikorsky Historical Archives)

Igor Sikorsky hovers the Vought-Sikorsky VS-300. (Sikorsky, a Lockheed Martin Company) — Igor Sikorsky hovers the Vought-Sikorsky VS-300A. (Sikorsky, a Lockheed Martin Company)

On behalf of the Fédération Aéronautique Internationale, the National Aeronautic Association of the United States issued Helicopter Pilot Certificate No. 1 to Igor I. Sikorsky, 10 December 1940. (Sikorsky Historical Archives)

Igor Sikorsky hovers the VS-300 before presenting it to The Henry Ford, 7 October 1943. (Photograph courtesy of Tom Fisher, The Henry Ford. Object ID: 84.1.1660.P.B.27654)

Igor Sikorsky in the cockpit of a Sikorsky S-48 (R-5) helicopter. (Smithsonian Institution National Air and Space Museum)

The company which Igor Sikorsky founded has continued as one of the world’s biggest helicopter manufacturers. Recently acquired by Lockheed Martin, Sikorsky continues to produce the UH-60-series of Blackhawk medium helicopters, the large CH-53K King Stallion, and the civil S-76D and S-92. A variant of the S-92 has been selected as the next helicopter for the U.S. presidential air fleet, the VH-92A. This helicopter is planned to be operational by 2020.

Igor Ivanovich Sikorsky died at Easton, Connecticut, 26 October 1972 at the age of 83 years.