BeermatBeing a bit slow there, sorry. The constructor’s number for Erhardt’s L10 was, of course, 1055. Sorry, I am new to this.
BeermatJust out of interest – I am sure you now have this information – but the FAA TCDS for the S3H1 does indeed show max take-off power as 600HP, as opposed to rated output of 550HP – http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/8690e2dd941de2e08525670d005f9cce/$FILE/E-143.pdf
It would appear that this is quite likely a record of an engine found, but can anything possibly tie C/N 1055 to an aircraft?
BeermatBoscombe/Farnborough were aware of the problem before Feb 1939 – the crash that killed Peter Alston (who was an aerodynamicist) was during a spinning trial intended to investigate the problem. As for the turnaround time – essentially the same team designed and built the P-51 from scratch in 102 days.
There is no specific evidence about the tail either way – there is no evidence of the Americans doing anything at all, this new design just seemed to ‘appear’ if one goes by the records that have made it into secondary sources. There are papers coming out of the RAE, one in 1937 and one in 1940, that for improved spin recovery prescribe less fin/rudder area above the elevator (at least as of the 1940 report) and more unmasked rudder area (defined by a diagonal up from the trailing edge of the fully-depressed elevator) which the triangular shape and a fin further back relative to the horizontal surfaces gave – https://www.aerosociety.com/media/4839/on-the-early-history-of-spinning-and-spin-research-in-the-uk-part-2.pdf
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(The NACA came up with a report echoing these shortly after).
Hence my looking for the missing discussions and proposals specific to the Harvard II/BT-14/BC2, but they do remain elusive. While they do I am not ruling out anything, including the influence of the work being done in the UK.
BeermatIf I understand correctly, both the NA-44 and the SNJ-1 did have a metal fuselage but did NOT have the six-inch movement aft of the rudder post (and the triangular tail) in question? Please see the shot from Hagedorn, below.
I still cannot find anything demonstrating that this particular solution – the specific change to the tail – was in hand previous to February 1939. The BC-2 wasn’t ordered until October 1939.
I agree that on first reading of Hagedorn everything seems to imply earlier development, but there isn’t anything specific to support it.
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BeermatThe wing changes were important, but the thing is the tests and the theory were documented in the US at the time. They only really fixed the problem in combination with the new tail – and the very odd thing is there appears to be no documentation of these changes or the reasons why they happened.
However on this side of the pond the RAE were working on spin departure, and calculated the effects of different orientations of the elevators and rudder. The new-shape Harvard had the rudder post six inches further back relative to the horizontal surfaces, and less rudder area above the elevators – both of would have made a significant difference, at least ‘on paper’, to the aircraft’s spin recovery times.
I became interested because, while there is no sign that North American were even working in this area (instead focusing, with justification, on the wing), the Harvard II tail geometry looks like a case-study on the British theory. When you add in the almost Hollywood angle that the RAE ‘Spin Tunnel’ was presided over by Gwen Alston, who lost her husband to a spinning Harvard I in February 1939, the story becomes even more interesting. However, the big ‘hole’ in the record – who designed the new tail and when – means it remains just one possibility – hence my search for the US evidence either way.
Thanks folks.
BeermatThanks Graham. I am on the road at the mo but will answer properly later. Good stuff!
BeermatYes please! If you could look at AVIA 8/193, “Harvard: purchase from North American Aviation Inc. for use as trainer and target towing”, and note/copy any reference between 1938 and 1940 to the major modifications to the rear fuselage (especially Anglo-US correspondence and with particular regard to dates) that would be enormously helpful to something I am working on – and might help shift a view of this particular story. Many thanks in advance if you can do this (I am in Whitby now and it’s not easy for me)*.
*Getting to London, not being in Whitby..
BeermatWeston Zoyland in Somerset still has all kinds of fascinating structures easily accessible from the main road that cuts through it, via public rights of way. Just watch out for the farmer who doesn’t give a flying about rights of way and who drove out in his landrover to punch me, assuming I was a traveller on the rob (I was pulling suspicious sheet metal out of a ditch at the time, mind).
BeermatThat Dornier is really quite surprising! Are we sure that is what it is?
BeermatCharles de Gaulle won an election on June 18th 1951?
BeermatIs the 840-page ‘Aero Engineering’ a collection of the 1930’s weekly publication? If so, I would be very interested, and I will happily pay the postage. I sincerely hope you have not recycled it yet!
Matt
BeermatThe problem was visibility of what happened to an aircraft as it transitioned from the transonic (ie a high speed at which some part of the aircraft was above Mach one – which could begin at anything from 400mph to Mach 0.95 depending on shapes) and the supersonic (when all of it was). No tunnel in the world could do that 1943 to 1946, and this un-testable transition point was also exactly where the perceived ‘barrier’ was. Hence rockets etc. The Americans persisted with the manned ‘suck it and see’ approach, possibly largely for PR reasons. It’s illustrative of the doubts everyone had that they didn’t put one of their top test pilots into the X-1.. and some say it’s because one of ours was publicly earmarked for the M-52 that it was cancelled.
It comes down to what those reports – particulary ref. 6, Hutton and Gamble “High-speed wind-tunnel tests on an aircraft designed for supersonic speeds (Miles E.24/43). R. & M. 2404. July, 1945” actually said. I would be very surprised if they categorically stated anything that really justified cancellation, but if they do, that’s one less conspiracy theory.
BeermatI have just found the RAE Vickers report – it’s R&M 2835, not 2357 – that’s what threw me initially.
In fact it reads: “the Miles Company put forward a scheme for a supersonic aircraft, Ref. 1 (later known by Specification No. E.24/43). But the existence of such a proposal merely drew attention to our ignorance regarding flight conditions at and near the speed of sound, and to the need for research. Suggested research methods were the attachment of aerofoil surfaces to the tail of existing rocket missiles, the construction of a very high-speed rail track, and the dropping of heavy bodies from very high altitudes. With the gradual accumulation of knowledge it became clear that the E.24/43 was unlikely to reach sonic speed and when wind-tunnel model tests indicated the same serious loss of longitudinal stability at high subsonic speeds as was then characteristic of all existing aircraft (Ref. 6), the wisdom of continuing with this design was questioned. The decision was reached to acquire preliminary experience of flight under transonic conditions using rocket-driven pilotless scale models”.
So between us Aeronut and I have given a classic example of misinterpretation and selective use to back up a pre-conception – I apologise for seizing on ‘transonic’ and attacking the claim of ‘knowledge’ that the M-52 wouldn’t reach transonic speeds when that wasn’t what was actually said.
BeermatYes. So the ‘knowledge’ seems even more tenuous. It seems we are back to the problem of the ‘blind spot’ between Mach 0.8 and Mach 1.3 which most faciliies had at the time. It may well be the M.52 couldn’t indeed be made to ‘go transonic’.. but that was a failing of the available tunnels, not the aircraft. This situation seems to have been ‘spun’ somewhat.
BeermatSo true. Also understanding what the data is telling you (Sidney Camm and the Hurricane wing). I am not convinced that wobble on starting a run would be interpreted as instability of a design – the people running the tunnel would be professional scientists who would be experienced in the behaviour of models in their tunnel and would know what data was relevant and what wasn’t.
They would have been the source of the content of any report. Any misinterpretation of that can surely not have been accidental? I am coming across more and more examples of willful misinterpretation of aeronautical research by decision makers in British and US administrations at this time, the more I read – and the feeding back of official lines into the intro pages of RAE and NACA reports (eg. P-38 dive flaps). That line about accumilation of knowledge – not a belief or an opinion but apparently a knowledge – that it wouldn’t even reach transonic speeds suggests someone jumping on things to justify a decision already made. Especially when one considers the choice of ‘transonic’. Transonic speeds for a partucular design are those at which the flow over some part(s) of the aircraft but not all of it has a relative velocity above Mach 1, and the later an aircraft reaches transonic speed – the higher the critical Mach – the faster it will go and the easier the transition to supersonic. Might this be someone deliberately misinterpreting ‘the aircraft reaches Mach whatever without going transonic’ as ‘the aircraft won’t reach a speed at which something goes locally supersonic’.. which is an unlikely scenario when a P-40 could.
Not teaching anyone to suck eggs about the transonic stuff, btw. Just ‘showing my working’.
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