Every aerospace engineer should know about this underpowered failure.
The Vought F7U Cutlass carrier-based jet fighter was one of the most unusual designs ever produced for the United States Navy (USN). Designed as the company’s entry in a 1945 carrier-based jet fighter design competition requiring capability to fly at 600 miles per hour at 40,000 feet, the aircraft featured broad-chord, low aspect ratio, swept wings, with a wing-mounted tail fin on either side of a short fuselage- resulting in a semi-tailless twin-engine jet. The cockpit was located as far forward as possible for pilot visibility.
Experience Should Have Helped
How did Vought arrive at such a novel design? German engineering. That’s right. Although at the time Vought denied any influence or even access to German aerodynamic engineers or their data, Messerschmitt and Arado engineers provided design inputs based on their experience with tailless German aircraft during the waning days of World War II. The F7U Cutlass was the last design overseen by Vought’s Rex Beisel, who designed the first Navy-specific fighter aircraft (the Curtiss/Naval Aircraft Factory TS-1 in 1922) as well as the Vought F4U Corsair.
High-pressure hydraulically actuated elevons (Vought dubbed them “ailevators”) were utilized for pitch and roll control. The wings had full span leading edge slats. The nose landing gear strut, easily the longest ever used on a Navy carrier-based aircraft, was both required for high angle of attack takeoffs and recoveries and sufficiently sturdy to accomplish its job. However, support structures such as down-locks were not up to the task and the high stresses of carrier operations caused nose gear failures- which also often caused spinal injuries to the pilots who were 14 feet up in the air when sitting on the deck.
Early Power Deficiencies
The Navy’s Bureau of Aeronautics (BuAer) ordered three XF7U prototypes in 1946. The first one flew for the first time from Naval Air Station (NAS) Patuxent River in Maryland on September 29th 1948 with Vought’s chief test pilot J. Robert Baker at the controls. The specifications for the production F7U-1s were similar to those of the prototypes. However, further testing and development of the 19 Westinghouse J34-WE-32 turbojet-powered F7U-1s built by Vought resulted in the revised F7U-2 and the F7U-3 variants. Both would be equipped with more powerful engines.
A Better Airframe But Still Lacking Thrust
At least that was the plan. At the end of the day the F7U-2 never got off the drafting board because of engine development problems. But the F7U-3 would incorporate as many improvements identified during F7U-1 flight hours as possible, resulting in a longer and stronger airframe. The first 16 F7U-3s built by Vought had non-afterburning Allison J35-A-29 engines. The remaining -3s, powered by Westinghouse J46-WE-8B afterburning turbojets, became the production standard. But that didn’t necessarily mean thrust the Cutlass pilots could trust.
Wicked Shimmies and Other Challenges
The F7U-3 Cutlass entered operational service with the US Navy with VA-66 Waldos (soon to become VF-81) in April of 1954. Eventually 13 squadrons would be equipped with Cutlasses. But operational problems were many and varied. The F7Us were all underpowered. The high-pressure hydraulic system constantly leaked. Landing gear doors had a tendency to fall off the jet. Takeoff and carrier approach performance were poor, and to make matters worse the J35 engines had a tendency to flame out when flying in rain. There were “wicked shimmies”- unpredictable crash-causing post-stall gyrations. The aircraft quickly picked up unflattering sobriquets such as “Gutless Cutlass”, “Ensign Eliminator”, and “Praying Mantis.”
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Unbreakable But Notorious
It wasn’t all bad though. F7U-3 Cutlass pilots reported that the aircraft had a high roll rate of 570 degrees per second- three times that of any other fighter at the time. The strengthened F7U-3 airframe was considered to be “unbreakable.” Evidently when the Cutlass wasn’t trying to kill the Naval Aviators at the controls, the jet was fun to fly and even “nimble.” It was found to be a stable bombing platform. But the jet was always a maintenance nightmare. No pilot ever signed off on an clean Cutlass post-flight gripe sheet.
Finding Work the Cutlass Could Do
12 Cutlass airframes were adapted for photographic reconnaissance work and given the designation F7U-3P but the camera carriers never saw operational service. A ground attack version, designated A2U-1, picked up some steam but an order for about 200 of them was cancelled after the accident rate went through the roof. The F7U-3M was capable of employing up to four Raytheon AAM-N-2 Sparrow beam-riding guided missiles. A total of 98 F7U-3Ms were built or upgraded. VA-83 Roaring Bulls became the first Navy squadron to deploy with guided missile capability in 1956. Not surprisingly though an order for 202 more F7U-3Ms was cancelled.
The Custlass Was Ahead of Its Time In More Ways Than One
Vought built a total of 320 Cutlasses (all variants). Few were flown operationally or on deployments for long before the squadrons grounded them or put them ashore for any number of faults. F7Us ended up with one of the worst safety records ever seen in Naval Aviation. Cutlasses were the cause of four test pilot deaths and the loss of a total of 21 other Naval Aviators. More than 25 percent of all operational Cutlasses were lost to accidents. F7Us accumulated some 55,000 hours of flight time with 78 accidents. The advanced design of the type was never fully sorted out and the lack of thrust or even reliability of the F7U’s engines caused many of the losses.
Another Cutlass Bites the Dust
Perhaps the most famous Cutlass mishap occurred on July 14th 1955 aboard the aircraft carrier USS Hancock (CVA-19). Lieutenant Commander Jay T. Alkire, who was at the time the executive officer of VF-124 Stingrays, settled in close drifting left and was unable to gain sufficient engine thrust to clear the round down at the end of the flight deck- the ramp. LCDR Alkire was flying BuNo 129595, side number 412, when he was killed in the mishap. Incredibly although it is often claimed that two aviation boatswain’s mates and a photographer’s mate working near the landing area at the time of the mishap were also killed, other evidence suggests only assorted injuries occurred among the deck crew.
Had a Cup of Coffee With the Blue Angels
The Navy’s Blue Angels flew a pair of Cutlasses for a portion of their 1953 show season as sort of a side attraction. The Team was flying the comparatively stodgy Grumman F9F-5 Panther at the time. The futuristic appearance of the design (and brother- it certainly looked futuristic!) made the Blue Angels Cutlass dalliance work for short while, but a series of non-fatal though serious mishaps caused the Blues to drop their Cutlasses off at NATC Memphis where they became maintenance instructional airframes- a fitting end for them.
Reputation Saved By the Next-Generation Vought Fighter
Fortunately for Vought, the F8U Crusader was in the design pipeline well before the F7U-3 became operational with the Navy. If that had not been the case the company might well have gone completely out of business after the bath they took with the F7U. The last operational Cutlasses were gone from the Navy by the end of November 1957. But there is a happy ending here. The Cutlass inspired both a car (the Oldsmobile) and a hood ornament (found on 1955 and 1956 Chevrolet Bel-Air sedans). And the Crusader…well that’s a much better story!