Fleet Air Arm Myths, No. 3: The Supermarine Scimitar needed 1000 maintenance hours per flying hour

There have been many great British aviation manufacturers. Then there’s Supermarine, the poor man’s Blackburn, who produced a string of fair to average flying boats, one half decent piston fighter, and then a string of below par jets before being absorbed into BAC. The jets in particular started poorly with the Attacker, which for no obvious reason was a straight winged taildragger whose overall appearance screamed ‘we had one good design don’t make us change it’. This was followed by the Swift ordered as an insurance in case the Hunter didn’t perform as expected. For this Supermarine took their one ‘good’ jet design and added swept wings and a sensible undercarriage. Then we come to the Scimitar, a beast of an aircraft powered by two Avons producing around 22,000lbs of thrust while resolutely remaining subsonic. Admittedly this wasn’t completely Supermarine’s fault, although they didn’t have to listen to the Admiralty’s requirement for the aircraft to be able to conduct a free take-off from a carrier deck. As well as blown flaps this also required a much thicker wing section than was ideal for high speed flight, especially at high level where the critical Mach number made manoeuvring ‘difficult’.
Popular imagination has it that the Scimitar was also burdened with so many issues it needed 1000 maintenance man hours per flying hour. This almost sounds plausible when you consider the number of things that could go wrong with a late ‘50s aircraft. There were two Avons to leak fuel everywhere, blown flaps to malfunction, probably something resembling avionics. It does break down slightly when you introduce maths to the problem though.

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To take one example 804 NAS operated the Scimitar for 18 months from 1 Mar 1960 to 15 Sep 1961, or 563 days. During this they flew 1077 sorties for a total of 1,367 flying hours, with only one minor accident when Sub Lt J G Smith suffered a nose gear collapse when Landing on HMS Hermes. [8] 563 day is 13,512 hours, at which point the 1000 maintenance man hours per flying hour myth starts to break down. According to the myth 804 would have had to endure 1,367,000 hours of tinkering to have achieved that much flying. That’s 195,285 hours per aircraft. Or 14 people working on each aircraft every hour it isn’t flying. The compliment of 804 at this time isn’t readily available as apparently a global pandemic is the kind of easy excuse archives look for to prevent access. However, while equipped with 10 of Supermarine’s ultimate fighter, 803 NAS had around 123 personnel. [9] Ignoring any reduction in personnel due to operating fewer aircraft and subtracting the 14 officers who wouldn’t want to get in the chaps’ way while they’re working, that gives 15 maintainers per airframe on 804 NAS.
So, from the above workings the only way the Scimitar could be operated if it required 1000 maintenance hours per flying hour is if the squadrons were over manned and the workforce did nothing but fix aircraft. Even in their sleep. For those unfamiliar with the naval service they may be bastards, but they do let the workforce eat, sleep, and if they’re particularly good take leave. But what’s a more realistic figure? Well assuming weekends off, and their Lordship’s deigned to give the squadron 45 days leave over the 18 months that gives 357 days of work. Assume 8 hours a day are available for maintaining aircraft, which ignores the other duties that the navy insists are more important than fixing aircraft. In that case each maintainer would have done 2,857 hours of maintenance. Still allowing 15 maintainers per aircraft and you get a total of 42,857 hours of work on each jet for the period 804 NAS was in commission. With each aircraft averaging 195 flying hours you end up with 219 maintenance hours per flying hour as pretty much the upper limit of what’s achievable. This is still a lot, it’s around 20 times what an F-22 needs, but it’s a lot less than the figure bandied around. Which could lead you to suspect it was a glib answer given by someone who didn’t expect to be taken seriously, or the real answer was 100 hours and someone added a zero.

Bing Chandler is a former Lynx Observer and current Wildcat Air Safety Officer. If you want a Sea Vixen t-shirt he can fix you up.

[8] Eric Morgan, and John Stevens. The Scimitar File. Trowbridge: Air Britain, 2000. p137
[9] HMS Hermes Commissioning book photo. Count the people in the photo of 804 NAS.


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  1. brian

    A good & well estimated guess. I am sure certain items like; instruments, ejection seat, radar & turbine required sending the malfunctioning item off to an off site speciality maintenance unit or back to the manufacturer.

    In regards to the F35 maintenance hour per flight hour, I don’t believe anything that is published without some serious qualifications on how the numbers were calculated. Lots of mis information floating about on the F35 subject.

  2. Duker

    Some more detail is needed on the early Supermarine jets.
    “Attacker, which for no obvious reason was a straight winged taildragger ” . Straight wings were the majority of naval aircraft at the time including USN. The Attacker went into service with the RN, however there was a later swept wing version developed the 510 which first flew with tail wheels too but was soon modified to have nose undercarriage and kept the tail wheels as ‘bumpers’, which indicates why they could be useful. Remember naval aircraft of the time had some high angle of attack of takeoff ( shown in the pic) and also landing.
    Re using a fuselage design happened for Hawker Hunter to as it was developed intially from the Hawker Seahawk. First with swept wings only ( and unswept tail) and then with jet engine exhausting through the full fuselage rather than bi- furcated ducts as in the Seahawk.
    The ‘excess’ power of the Avons was needed for the flap blowing, which bleed off the compressor air and would reduce the thrust when most needed, takeoff and landing. This was one of the reasons the UK needed the extra thrust of the Spey for its Phantoms which had extra blowing, for flaps and wing leading edges.

    • skippybing

      The US Phantoms also used blown surfaces, the advantage of the Spey was that the turbofan design produced a greater, but slower, mass flow which aided low speed acceleration. The UK Phantoms were the fastest to ~400kts which obviously has its advantages getting on and off a tiny deck.
      Re the Attacker, it’s worth remembering the Soviets used the same engine to produce the MiG-15! Mike Crosley points out in ‘Up in Harm’s Way’ that the issue with tail draggers on carriers is that as the main gear generally touches down first you get an increase in angle of attack, and lift, as the tail wheel makes contact. Which is less than ideal. Tricycle aircraft have the opposite effect which is a bonus.

      • Duker

        Yes . The earlier USN Phantom version had more limited BLC or boundary layer control from blowing. The later version which the UK version was based on blowing extended to leading edges as well as well as full flap and flaperon blowing. The later J79 engine was increased thrust as well.
        The RR Nene turbojet was licensed by Pratt ( J42 and later enlarged J48 version) and was the engine in the equivalent era straight wing F9F Panther , a mainstay of the USN. The Mig version was enlarged ( Klimov VK-1) and had greater thrust.

        The Attacker developed version the later 510 was actually the first swept wing aircraft to land on a carrier, the radical for the time “tailless” USN swept wing Cutlass hadnt at the time landed on a carrier. The second 510 prototype had the nose wheel but the tail wheels retained as bumper
        Its sort of typical of UK development to chose the wrong version and stick with it inspite of it taking longer to put into service and then being obsolete at that time.

  3. tim nolan

    I recently listened to a IWM oral history by a Supermarine engineer of the time ( sorry cannot remember the name but it was fascinating). He said that the Attacker wing was pretty much that of the Spiteful and that thus the Attacker needed a tailwheel to achieve the correct incidence on take off. Maybe that then is the reason; the Attacker has been vilified for years for that tailwheel!

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