Vought F7U Cutlass Carrier-Borne Fighter Aircraft
Engine issues and an unenviable accident record eventually doomed the interesting Vought F7U Cutlass carrier-based fighter of the United States Navy.
Authored By Dan Alex; Content ©www.MilitaryFactory.com
The Vought F7U "Cutlass" was an American Cold War-era naval fighter and the first swept-wing USN fighter to be adopted into service as well as the first "tailless" American fighter aircraft. The type led a troubled developmental existence and an even more troubled service life to the point that only a few hundred aircraft were procured and multiple fatalities occurring during its short time in service. Its design made it as unforgettable as its track record made it forgettable - such became the legacy of the Cutlass fighter program. The aircraft inevitably received the nicknames of the "Praying Mantis", the "Ensign Eliminator" and the "Gutless Cutlass" - such was its lasting impression to pilots.
In December of 1945, the United States Navy put forth Specification OS-105 which called for a new jet-powered carrier-borne day fighter to add to its post-World War 2 ranks. The requirement specified a maximum speed of 600 miles per hour (with afterburner adding some 50mph more), a 6,500 feet-per-second rate-of-climb as well as a combat radius of 345 miles, and an operating service ceiling of 40,000 feet. Design proposals emerged from Curtiss, Douglas, Martin, McDonnell, North American, and Vought to which Vought's twin-engine, tailless offering was selected on June 25th, 1946 (as "Model V-346A"). Reportedly, Vought engineers utilized captured wartime data obtained from the German concern of Arado - famous makers of the jet-powered Ar 234 "Blitz" bomber. The Vought proposal then emerged in three prototypes under the "XF7U-1" designation and the line as a whole went on to receive the name of "Cutlass" in due time.
The Vought design was a wholly unique fighter approach for the period, lacking any true horizontal tail surfaces, instead utilizing a wide-area main wing planform with sweepback. A pair of vertical tail fins with rudder controls were fitted as normal while all other control surfaces resided on the mainplanes. The cockpit was held forward in the usual way with the pilot given good views from the elevated position - a key consideration for carrier-based aircraft on landing approaches. The twin side-by-side engine installation was aspirated by half-circle intakes to either side of the fuselage. The undercarriage was of a tricycle arrangement and fully retractable, giving the aircraft a pronounced "nose up" appearance when at rest. Indeed, the XF7U-1 stood as one of the more advanced aerodynamic design approaches to any post-war, jet-powered carrier fighter to this point in military aviation history.
Power was served through 2 x Westinghouse J46-WE-8B turbojet engines (F7U-3) developing 4,600lbs thrust (each) on dry and 6,000lbs thrust (each) with reheat (afterburner). Maximum speed reached nearly 700 miles per hour with a cruising speed closer to 565 miles per hour. Range was out to 660 miles with a service ceiling of 40,600 feet and rate-of-climb (a key carrier-based fighter consideration) of 14,420 feet-per-second. No doubt the aircraft was very fast for the intended role - superseding the USN requirements on paper .
As introduced, the F7U was an all-cannon armed aircraft fitting 4 x 20mm M3 cannons mounted just above the inlet ducts with 180 rounds afforded to a gun. It was only a later model - the F7U-3M - that introduced support for 4 x Sparrow beam-riding, medium-range air-to-air missiles under the wings. The aircraft was cleared for up to 5,500lb of external ordnance.
First flight of the line occurred on September 29th, 1948 and further testing yielded both exceptional performance as well as many technical and aerodynamic flaws. Regardless, the USN proceeded in assigning a production contract to Vought for some fourteen aircraft in the "F7U-1" guise - largely faithful to the prototype design (powered by 2 x Westinghouse J34-WE-32 engines). These proved so problematic in testing - primarily due to the temperamental and underpowered J34 engine - that these models would never achieve operational status, relegated instead as trials platforms and training. Despite the move to produce the improved "F7U-2" mark, engine issues forced an even greater redesign for the F7U-3 variant soon emerged as the definitive cutlass mark (the F7U-2 mark never entered production).
Changes in the new design included a mass collection of additional access panels to help facilitate mechanical work by ground crew and thus keep maintenance times and costs down. The canopy was enlarged and the nose redesigned several times for improved viewing out-of-the-cockpit. More powerful Westinghouse J46-WE-8 engines were selected for propulsion and the overall structure of the aircraft was reinforced for the rigors of carrier operations. The nose landing gear was also strengthened and lengthened some for greater abuse. Despite the move to the new Westinghouse engines, the initial sixteen F7U-3 examples were each delivered with non-afterburning Allison J35-29 series engines. Only subsequent F7U-3 production models arrived with their Westinghouse turbojet engines installed.
Production of the Cutlass spanned from 1948 into 1955 to which 320 total airframes were completed. These aircraft served only with the United States Navy and this for only a limited time for the line proved very accident prone due to the advanced nature of the design. Its engine did not help matters either, some known to shutdown in rainy or damp weather environments. Pilots noted the type's tricky control scheme, particularly during take-offs and landings. The F7U Cutlass went on to stock thirteen USN carrier squadrons on decks such as those belonging to the USS Ticonderoga (CVA-14), the USS Intrepid (CVA-11) and the USS Lexington (CVA-16). Formal service entry was in July of 1951 while the refined F7U-3 models did not arrive until 1954. These were then followed by the dedicated photo-reconnaissance F7U-3P variant with lengthened nose section and the missile-armed F7U-3M. Twelve examples of the P-model were obtained though none achieved operational service. M-models were seen in 98 examples built with 48 existing F7U-3 models upgraded to the new standard.
During 1956-1957, most of the F7U aircraft were already removed from frontline service within the ranks of the USN as newer, and better, alternatives became available - namely the famous Vought F8U "Crusader". As such, its short time aloft meant that the F7U series was never to see combat service in any war of the Cold War period - perhaps for the better considering its myriad of published problems. It is said that some 25% of the aircraft produced were lost to accident - a rather unforgiveable rate for a combat fighter aircraft. Even its three original prototypes were lost to crashes. The F7U series was formally retired on March 2nd, 1959. A ground attack form - this as the "A2U-1" - was proposed from the basic F7U design but an order for some 250 aircraft was eventually cancelled - again, perhaps for the better.
A preserved F7U-3M model can be seen at the National Museum of Naval Aviation in Pensacola, Florida.