Vought F7U Cutlass

The Vought F7U Cutlass was a United States Navy carrier-based jet fighter and fighter-bomber of the early Cold War era. It was a tailless aircraft for which aerodynamic data from projects of the German Arado and Messerschmitt companies, obtained at the end of World War II through German scientists who worked on the projects, contributed; though Vought designers denied any link to the German research at the time. The F7U was the last aircraft designed by Rex Beisel, who was responsible for the first fighter ever designed specifically for the U.S. Navy, the Curtiss TS-1 of 1922.
Regarded as a radical departure from traditional aircraft design, the Cutlass suffered from numerous technical and handling problems throughout its short service career. The type was responsible for the deaths of four test pilots and 21 other U.S. Navy pilots. Over one quarter of all Cutlasses built were destroyed in accidents.
Design and development.
The Cutlass was Vought's entry to a U.S. Navy competition for a new carrier-capable day fighter, opened on 1 June 1945. Former Messerschmitt AG senior designer Woldemar Voigt, who supervised the development of numerous experimental jet fighters in Nazi Germany, contributed to its design with his experience in the development of the Messerschmitt P.1110 and P.1112 projects. The requirements were for an aircraft that was able to fly at at .
The design featured broad chord, low aspect ratio swept wings, with twin wing-mounted tail fins either side of a short fuselage. The cockpit was situated well forward to provide good visibility for the pilot during aircraft carrier approaches. The design was given the company type number of V-346 and then the official designation of "F7U" when it was announced the winner of the competition.
Pitch and roll control was provided by elevons, though Vought called these surfaces "ailevators" at the time. Slats were fitted to the entire span of the leading edge. All controls were hydraulically-powered.
The very long nose landing gear strut required for high angle of attack takeoffs lifted the pilot 14 feet into the air and was fully steerable. The high stresses of barrier engagements, and side-loads imposed during early deployment carrier landings caused failure of the retract cylinder's internal down-locks, causing nose gear failure and resultant spinal injuries to the pilot.
The aircraft had all-hydraulic controls which provided artificial feedback so the pilot could feel aerodynamic forces acting on the plane. The hydraulic system operated at 3000 psi, twice that of other Navy aircraft. The hydraulic system was not ready for front-line service and was unreliable.
The F7U was underpowered by its Westinghouse J34 turbojets, an engine that some pilots liked to say "put out less heat than Westinghouse's toasters." Naval aviators called the F7U the "Gutless Cutlass" and/or the "Ensign Eliminator" or, in kinder moments, the "Praying Mantis".
Testing.
None of the 14 F7U-1s built between 1950 and 1952 became approved to be used in squadron service. On 7 July 1950 Vought test pilot Paul Thayer ejected from his burning prototype in front of an airshow crowd. On 20 December 1951, the F7U-3 version took off for its maiden flight. The F7U-3 featured other engines, a stronger airframe larger by a third and extra maintenance panel for service access. Test pilot and later astronaut Walter Schirra wrote in his autobiography that he considered the F7U-3 accident prone and a "widow maker". On the positive side, test pilots found it a stable weapons platform, maneuverable, fun to fly and the strengthened airframe to be sturdy. Test pilots particularly praised its high roll rate at 570 degrees/s, three times faster than most production jets at the time.
Flight characteristics.
The Cutlass would gyrate after a stall. When Lt. Morrey Loso found himself tumbling about in the cockpit in his tumbling aircraft after a stall, he found that when he let go of the control stick to reach with both hands for the ejection handle, the Cutlass self-corrected. This meant that normal recovery procedures did not apply to the Cutlass and the result was later confirmed in wind-tunnel testing.
Operational history.
Three prototypes were ordered in 1946, with the first example flying on 29 September 1948, piloted by Vought's chief test pilot, J. Robert Baker. The maiden flight took place from Naval Air Station Patuxent River in Maryland, and was not without its problems. During testing one of the prototypes reached a maximum speed of 625 mph (1,058 km/h).
Production orders were placed for the F7U-1 in a specification very close to the prototypes, and further developed F7U-2 and F7U-3 versions with more powerful engines. Because of development problems with the powerplant, however, the F7U-2 would never be built, while the F7U-3 would incorporate many refinements suggested by tests of the -1. The first 16 F7U-3s had non-afterburning Allison J35-A-29 engines. The -3, with its Westinghouse J46-WE-8B turbojets, would eventually become the definitive production version, with 288 aircraft equipping 13 U.S. Navy squadrons. Further development stopped once the Vought F8U Crusader flew.
The F7U's performance suffered due to a lack of sufficient engine thrust; consequently, its carrier landing and takeoff performance was notoriously poor. The J35 was known to flame out in rain, a very serious fault.
The first fleet squadron to receive F7Us was Fighter Squadron 81 (VF-81) in April 1954. Few squadrons made deployments with the type, and most "beached" them ashore during part of the cruise owing to operating difficulties. Those units known to have taken the type to sea were:
In 1957, Chance Vought analysed the accident record and found that with 78 accidents and a quarter of the airframes lost in 55,000 flight hours, the Cutlass had the highest accident rate of all Navy swept-wing fighters.
The poor safety record caused Vice Admiral Harold M. “Beauty” Martin, air commander of the United States Pacific Fleet, to replace Cutlass aircraft with Grumman F9F-8 Cougars.
Blue Angels.
The Navy Flight Demonstration Squadron, the Blue Angels, flew two F7U-1 Cutlasses (BuNos 124426 & 124427) as a side demonstration during their 1953 show season in an effort to promote the new aircraft, but did not use them as part of their regular formation demonstration. Both the pilots and ground crews found the aircraft generally unsatisfactory, and it was apparent that the type was still experiencing multiple teething troubles. Among the failures were landing gear failures, hydraulic failures, engine fires while in the air and on one occasion a landing gear door fell on a spectator grandstand but through sheer luck did not injure anyone.
During the Blue Angels' first airshow appearance in 1953, pilot Lt Edward "Whitey" Feightner, the former program manager for the F7U, experienced a total loss of hydraulics on a full afterburner takeoff and steep climb. While trying to gain enough altitude for ejection he was able to stay with the aircraft until the backup system came on. He clipped trees on the end of the runway, causing the left engine to flame out. With hydraulic fluid streaming back in a bright flame, he made a hard turn and got the plane back on the runway, much to the excitement of the crowd. Later, while traveling to an airshow at Naval Air Station Glenview in Chicago, Illinois, another Blue Angel pilot, Lt Harding MacKnight, experienced an engine flameout in his Cutlass, forcing him to make an emergency landing at NAS Glenview. Traveling with him, Feightner was redirected to make his landing at Chicago's former Orchard Airpark, which had been expanded and renamed O'Hare Airport. The runway had just been completed and was covered with peach baskets to prevent aircraft from landing until it was opened. Feightner was told to ignore the baskets and land on the new runway. As a result, Feightner's F7U became the first aircraft to land on the new runway for Chicago's O'Hare International Airport.
Following these incidents, the two Cutlasses were deemed unsuitable for demonstration flying and were flown to Naval Air Station Memphis, Tennessee, where they were abandoned to become aircraft maintenance instructional airframes for the Naval Technical Training Center.
Aircraft on display.
Seven F7U-3 Cutlass aircraft are known to have survived: