|N221, Kinkead's Supermarine S.5 (painting by author)|
In my Blog of 29.4.12, I mentioned the fatal Supermarine S.5 crash of Flt. Lieut. Samuel Kinkead, whilst making a speed record attempt. The death of this well decorated pilot is the first fatality in a Supermarine crash which might be attributed to mechanical failure and so, if for no other reason (see below), it is worthy of special consideration. Previously, Biard had survived the demise of the S.4 and both incidents reflect the increasing performance demands of the Schneider Trophy. Indeed, Mitchell, in a speech at a Rotary meeting in Southampton had given a glimpse of the feelings that he felt in connection with this sort of design work:
The designing of such a machine involved considerable anxiety because everything had been sacrificed to speed. The floats were only just large enough to support the machine, and the wings had been cut down to a size considered just sufficient to ensure a safe landing. The engine had only five hours’ duration; after that time it had to be removed and changed. In fact everything had been so cut down it was dangerous to fly. Racing machines of this sort are not safe to fly, and many times I have been thankful that it was only a single seater. The machine itself has been a source of anxiety to me right from the start, and I am pleased to know that at this moment it is safely shut up in a box.
Six weeks after the 1927 competition, De Bernardi set up a new world speed record for any type of plane at 297.8mph in the Macchi M.52, and so, the following March, the Air Ministry had the reserve S.5, N.221 (not used in Venice) “taken out of its box” and prepared for an attempt to recapture the World Absolute Air Speed record – which, it was hoped, would show the superiority of a British design.
The attempt was to be flown by Flt Lt Kinkead, who had had to retire from the previous Schneider Trophy competition in the Gloster machine. Unfortunately, the attempt was to end in tragedy – as reported in Flight on March 15, three days after the crash:
Precisely what happened is unlikely ever be fully established as the S.5 was imperfectly visible to the witnesses on the land. As we shall see later, it was asserted that Kinkead had decided to abandon the attempt because of decreasing visibility and had stalled on the landing approach; the Flight correspondent advanced another possible cause:
Equally, sun glare, coupled with an obscured horizon and a waveless sea, would have given precious little information to confirm altitude or flying attitude, so others maintained that, with the poor visibility, he misjudged his height and flew straight into the sea whilst still intent on the speed record.
(i) The possibility of a high speed stall caused by violent manoeuvres can surely be ruled as he would be doing nothing more than making minor corrections to his altitude or direction on the fatal approach run.
(ii) The possibility of a stall whilst having to make a landing approach because the visibility had deteriorated must take into account the Times’ description of his skillful landing of the S.5 on the day before the record attempt: ‘he chose an angle of glide which almost imperceptibly brought the floats nearer and nearer the water until the monoplane was just skimming the surface – a grey insect over a grey sea.'
(iii) Even if Kinkead had made a rare landing misjudgement, there seems to have been no mention of a gradual decrease in engine sound before his crash, consistent with slowing down from high speed (expected to be over 300 mph) to the necessary landing approach speed (about 100 mph); on the contrary, spectators were impressed by the sound of an approaching high-revving engine which suddenly ceased and two commentators even described his impact with the water like that of a shell.
(iv) This last explanation of the crash would seem more plausible except for the fact that most witnesses reported an unexpected change of attitude; indeed, the coroner at the inquest is reported as ‘trying to find out if there is a possible explanation of the sudden dive of the seaplane’ This is echoed in the Morning Post headline, ‘Vertical Nose-dive from 100 feet’ or The Times report that Kinkead ‘dived straight into the Solent from a height of between 100 feet and 50 feet’ and that ‘no man could have survived such a terrific impact with the water’ as the machine had ‘dived rather than flown into the sea’.
(v) It is, of course, well known how unreliable and interpretative are eye-witness accounts, especially of unexpected events, but, given the similarity of these particular reports and numerous testimonials to Kinkead's skill as a pilot, a mechanical failure rather than pilot error must thus be given particular attention. Lewis cites newspaper reports from other observers with a view from the side of ‘abnormal movement of the tail unit and fin’ (The Times) and of the aircraft ‘going at a very good speed’ when its tail developed ‘a pronounced flutter’ (the Daily Express). Biard, who was standing next to Mitchell at the time of the accident, is also quoted as being quite certain that the crash was a result of structural failure and his likely reaction at the time might have contributed to Mitchell’s distress for some time afterwards.
It should be acknowledged that the other two similar S.5 machines had successfully completed the Venice Schneider Trophy course, which involved the taking of two extremely sharp corners on each of the required seven laps whilst returning an average course speed of about 88% of the top speed available to them. Kinkead's S.5 had not been extensively tested, having been held in reserve and consequently unused in the Schneider Contest a few months earlier, but the preliminary flight on the Sunday before the fatal crash and the second mandatory flight, flown on the day of the accident, went off without any problem; however, its specially tuned engine and light fuel load might have allowed Kinkead to achieve a hitherto untested speed that brought with it unexpected structural problems.
(vi) On the other hand, some reports of a sudden engine roar at the very end must be given due consideration. No evidence of a de-coupling of engine and propeller was given at the inquest and so there thus remains the possibility that Kinkead had discovered a problem and had begun to try to get down, that he had throttled back but almost immediately poured on the power in an attempt to correct some worsening situation. As the speed of sound is slower than the speed of light, these last sounds would not be synchronous and so this aspect remains problematic.
(vii) But most problematic, in view of the various considerations above, are the findings of the RAF Court of Inquiry that the accident was ‘due to stalling of the machine’ and the verdict of the Southampton Coroner’s inquest that Kinkead’s fatal injuries were caused by diving into the sea ‘owing to lack of speed while attempting to alight’. In the latter case, it was also maintained that no evidence had been found in the wreckage to point to any physical causes for the accident although how this could be upheld in view of the extensive damage caused by impact and by the subsequent salvaging operation might perhaps only be explained by a wish to draw a discreet veil over the whole matter. (One also reads in Lewis that a file concerning the private RAF Court of Inquiry, referred to in Kinkead’s Service Record, has not survived and Hugh Trenchard, Chief of the Air Staff, had been a reluctant participant in the recent Schneider Trophy preparations as he was still very protective of his new Air Force. From another perspective, certain senior Air Ministry officials were unlikely to be happy with findings of mechanical failure as, in their case, they were in favour of continuing RAF involvement in the Schneider contests for the sake of research and development and of the prestige accruing to the British aviation industry via this blue riband event.
It is thus interesting that, at the inquest, the Inspector of Accidents, appointed by the Secretary of State for Air, felt able to assert that ‘no part of the aircraft structure or controls broke, or failed to function normally during the flight’ and that, whilst agreeing that ‘the rudder or tail of the machine was seen to be fluttering’, said that it was ‘probably the reflection of the sunlight from the rudder that gave the impression’ when the machine turned. Had a turn been necessary, it would surely have been made well before the crash site, in order to maximise the entry speed into the actual speed course, and one would in any case expect only slight movements of the rudder at the speed that Kinkead was going – producing equally slight, progressive, changes of colour tone to the rudder (but not with reference to the tail as a whole – as reported above by witnesses). And one wonders how bright was the sunlight if Kinkead had actually been attempting to land because of the worsening visibility.
* * * * *
Whilst a stall due to ‘pilot error’ remains a possible reason for the death of Kinkead, there is, to say the least, no overwhelmingly supporting evidence and, indeed, there was an article in the Times, two days after the accident:
The cause of the fatal accident ... may never be known, but it seems clear, from information that I have gathered, that the basic reason was that this gallant pilot had attained, in his initial dive on to the course [on the previous day], speed undreamt of by the most optimistic observers of the performance of this remarkable Supermarine Napier seaplane:The New York Times of March 14 included the following comment: 'It was stated tonight that Lieutenant Kinkead had been urged to content himself with beating existing records and to keep within a speed of 310 miles per hour, as the designers of the machine thought it risky to exceed that limit'.
Kinkead had preserved complete reticence as to the exact speed at which he travelled in his trial flight on Sunday morning, and no-one had realised that he had reached, on his air speed indicator, a rate of no less than 330 miles per hour. . . Kinkead was so enthusiastic after his trial flight that he said he believed he could attain probably 350 miles an hour. It should be realised that this type of monoplane had never before been flown, probably, at more than 300 miles an hour, and . . . no-one could be certain that stresses, which were within the capability of aircraft engine and propeller at 300 miles an hour, might not rise to an unexpected magnitude when the speed was increased to 350 miles an hour. . .
Perhaps one is here straying too far into the realms of speculation but it would not have been out of character for Kinkead to have taken upon himself the risk of setting a speed record that might not be broken by another country’s machine for some considerable time.
As it stands, the findings of the RAF and of the inquest can be seen as the least worst outcome for all parties except the pilot. This is an especial pity as little mention is made of the Schneider Trophy pilots when credits are given for winning the Battle of Britain and all that followed. If these pilots had not successfully flown their, frankly, dangerous aircraft, the Spitfire might not have been ready in time for the outbreak of World War Two – one notes at least D’Arcy Greig’s dedication in My Golden Flying Years ‘to all those involved with the Schneider Trophy races that helped so much in the development of the Spitfire in later years’.
It is well recognised that Mitchell’s Spitfire and its Rolls-Royce Merlin engine were ultimately a by-product of the Schneider Trophy competitions, where manufacturers were free of inhibiting Air Ministry requirements, but not enough has been said in this context about the skills of the High Speed Flight pilots who took part in this early test flying. No doubt others would have come along and accepted the risks involved but it was these pilots who led the way with their successive wins in 1927, 1929 and 1931. Of these, Kinkead’s 1927 group can be seen as the one which took the primary and most dramatic leap into the unknown. Their Flight Leader, Sqd. Ldr. L. H. Slatter spoke after the event of the skill of all his pilots but he singled out Kinkead for putting up the ‘most extraordinary show’. Thereafter Kinkead was put in command of the nucleus of the High Speed Flight retained at Felixstowe and, had he not died, he would have been in charge of the full High Speed Flight for the next competition.
It is hoped, therefore, that Kinkead will not be remembered as a pilot who was said to have died because of an error of judgement but as one willing to take the risks involved of the dangerously low speed run for the sake of national prestige and whose previous decorations were duly recorded by Flight:
For his war services he received the following decorations:- D.S.O., for attacking and dispersing a Cavalry Division in South Russia. D.S.C. for conspicuous gallantry and skill in face of enemy aerial combats. Bar to D.S.C., for attacking and bringing down an Albatross machine. Bar to D.F.C. for engaging and dispersing a large party of enemy troops in a wood.
The King has sent the following message to Sir Samuel Hoare, the Air Minister:-
“I am grieved to learn of the loss sustained by the Royal Air Force in the tragic death of Flight-Lieut. Kinkead, who had such a distinguished career in the Service. Please convey to the relatives of the gallant airman an expression of my sincere sympathy. – GEORGE. R.I.”
For reference sources, see my Blogpost: “Source Material and References" – an extended bibliography is included in my R.J.Mitchell at Supermarine; Schneider Trophy to Spitfire (details below) which also provides material for wider reading, grouped according to specific areas of interest.
More information, as well as a full account of all Mitchell's completed designs and of the man behind them, will be available in a few weeks' time:
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R.J.Mitchell at Supermarine; Schneider Trophy to Spitfire.
This is a much expanded, completely up-to-date, second edition of my earlier work with 50% more photos, and 25% more text – 380 pp. instead of 250. There are general arrangement drawings of Mitchell’s 21 main aircraft types which flew, as well as 40 other drawings. There are 24 photographs, featuring or including Mitchell, as befits the first fully detailed and, I hope, definitive account of the man and his work at Supermarine.
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