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Miles Hawk Speed Six G-ADOD

steelpillow

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Ruth Fontes was a Latin American aviator who wanted to compete in the 1935 Kings Cup air race. She had a Miles Hawk Speed Six specially built, the only one to be fitted with an 'R' series race-tuned de Havilland Gipsy Six engine. Registering it G-ADOD, she took part in the 1935 and '36 King's Cup races, in one of them under the alias of Miss R. Slow so that her brother would not realise she was competing against him.
Arthur Clouston and F.E. Tasker (a team later to become involved in record flights in a DH.88 Comet racer), then bought it to enter in the 1936 Schlesinger South African air race to Johannesburg. During the race two pistons broke and it was fitted with six standard production pistons to keep it balanced. Soon afterwards, G-ADOD was written off and only its engine was brought home. Tasker declared it worthless.

The really interesting thing about this engine is that it should not exist.

De Havilland built 12 of the special 'R' series in all, specifically for the Comet racers. One went to bench testing, one was hacked about to take an experimental propeller fitting, and by the end of 1935 the rest had all been paired up and put in the five Comets ever made. Only one pair was ever split up, those in the famous red G-ACSS Grosvenor House when its RAF incarnation as K5085 was sold for scrap, and that was a year or two after the Jo'burg race. At the time of the race, four Comets still had their racing engines while the fifth was scattered across the rugged terrain of the Sudan.

Where did Miss Fontes get her engine from, then?
And what happened to it after Tasker got fed up with looking at it?
 

avion ancien

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Is it established beyond reasonable doubt that the 'R' engine was installed ab initio for Miss Fontes, rather than being installed by Tasker and Clouston when they acquired the Speed Six from her? Also is it certain that DH built only twelve 'R' engines?
 

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avion ancien said:
Is it established beyond reasonable doubt that the 'R' engine was installed ab initio for Miss Fontes, rather than being installed by Tasker and Clouston when they acquired the Speed Six from her? Also is it certain that DH built only twelve 'R' engines?

Yes and yes.

It is known that de Havilland built a batch of twelve and, given the complexity of the castings and the short time scales involved, it is unrealistic to expect the first test engine to have been hand-made and tested beforehand.

My best guess is that they rebuilt one good engine from the two test ones, but information is thin on the ground.
 

Methuselah

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Hi;- Where is the evidence that they only built twelve.....? Which engine was the one installed in the Puss Moth Testbed....?
 

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Methuselah said:
Hi;- Where is the evidence that they only built twelve.....? Which engine was the one installed in the Puss Moth Testbed....?

I went back and checked and found I had made a mistake - only ten were ever made. The last Comet had production engines.

The number ten comes from a contemporary directory of aero engines, of which a friend sent a page to me. I do not know which one, the top of the page is cropped. I think I have seen it elsewhere too, not sure where as it's not in Ogilvy. The engine in the Puss Moth or whatever it was (no two sources seem to agree) was the first test engine and at least some of its time was spent in GDH's personal machine, carrying out tethered flights.
 

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The problem is, that I have not seen any direct evidence from credible sources of exactly how many 'R's were produced with any degree of confidence.

We know that there were six 'R's in the initial three Comets. We know that the French machine had two.
The last Comet, the very short-lived G-ADEF, was probably also fitted with 'R's - as the Ratier pneumatically-operated VP airscrews can clearly be seen in images. See here;-

http://dh88.airwar1946.nl/Comets/GADEF.htm

That's ten then, minimum. Pre-war, the only Comet fitted with DHGSSII engines was G-ACSS, after it was rebuilt by Essex Aero for Clouston, releasing two at that time in '37. One of these went into 'XF. The only known survivng unit is at Old Warden, but again, there doesn't seem to be any actual firm documentary evidence of it's history.
Added to the ten are a currently unknown number of development units. I have an image - somewhere, of the Puss/Leopard with the 'R' fitted for air-testing.
It has to be stated, that, after going to the extreme trouble of designing a new a/c specifically for the MacRoberts Race, as well as new engines, it seems absolutely inconceivable that there would be no spare engines whatsoever. It would go against DH's normally cautious, professional approach. Added to that, machines were sold abroad, to Portugal & France. Again, to have no availability of spare engines whatsoever seems possible - but highly unlikely.
I have a list which I cannot put my hand on right now, an old DH document, and I cannot remember how many were quoted - this may possibly also be the one to which you are referring too, but this was a general summary of production, compiled post war, long after the frenetic events of 1934..... Reliable..? I doubt it.

My guess is that if ten airworthy engines went into the Comets, then there would have been two to six development units.

What is a 'tethered flight'... Ground Testing..?
 

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Yes G-ADEF had Ratiers but no they were not fitted to Racing engines. According to The Western Morning News, Friday, 9 August 1935 (sorry I don't know the page), these were modified standard production engines. These would not have been suitable for the DH variable-pitch props that were fitted to the later Mk II engine, but had the same crank shaft output mounting as the R. That is why they still had Ratiers fitted.

The batch of ten allows for the two known development engines, six for the racing batch and two spares. What do you do with spare engines once the race they were built for is over? You flog 'em off in a new machine if you can, and the French duly obliged. There was nothing exceptionally incautious about that. Both the French F-ANPY and Portuguese CS-AAJ were race comets refurbished, still with their original engines. Only the second French machine, F-ANPZ, had new - the ones from the spares stock.

You must remember that the Comet and Six R were developed in a tearing hurry and many of the usual corners were indeed cut - there was no development prototype for the plane, why make more than one or two for the engine.

The photo of the "tethered" machine is not very forthcoming. Whether it was tied down or maybe flew robotically in circles like a control-line model, I don't know. It had a fuel tank strapped onto one side, presumably so as not to contaminate the machine's interior tank with high-octane fuel.

If you like I can upload an image of that unidentified directory page, would that reduce your scepticism?
 

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Obviously, the Western Morning News is not an authoritative source. The 'R's were 'modified production engines' anyway, and the hacks in a local Devon rag would be unlikely to know the difference in detail. In fact, browsing contemporary literature, often the Comets engines are often simply referred to as 'special Gipsy Sixes' - or 'High Compression Gipsy Six's' - or just 'Gipsy Six's'.
If we refer to 'Flight', the engines of G-ADEF are described on 01/08/35, p127, the engines being referred to as '...two special " Gipsy Sixes...' , which is, of course, exactly what an 'R' is - a modified Gipsy Six, whereas a SII is quite a different engine. (Different crankcase, different crankshaft, different camshaft, different pistons, different barrels, different heads, different valves etc etc....)..

The DHGSSII was certainly available in 1936, but at what exact point they first became available I'm not 100% certain. G-ADEF would have been built early in '35 - as would it's engines probably. I think it unlikely that the SII was available before spring '36. Since a standard Gipsy Six was intended for fixed-pitch airscrews, and therefore had a tapered crankshaft, we are, logically, left with the possibilities of G-ADEF's engines being R's, or much less likely, early pre-production SII's.

Propeller fitting;- Look at the 'R' at Old Warden - it's got a No.1 SBAC splined crank. Look at a standard DHGSSII - same splines. The 'R's were actually originally designed for the Bracket-Type airscrews (That's another story.), hence the No.1 SBAC splines. The only debate is as to whether or not all of the 'R's were drilled for an oilway after the decision was made to use the Ratiers instead.

The Ratiers themselves ;- Were not designed to fit the UK No.1 SBAC splines, so special adapters had to be made for them to fit the Comet's "R''s that had been designed for the new Bracket Airscrews - which had, of course, failed to be usable in time for the MacRoberts Race.

I'm always interested to see documentary data relating to UK aircraft of this period - maybe I'll recognise it as the one I have knocking around, however, if it's antecedents are unknown it's naturally of limited value.

The information on the tethered device is very interesting, as I haven't seen that.

To return to the original issue - the number of 'R's produced;- I'm not really bothered how many were produced - only that the figure is correctly recorded for posterity. For that, some authoritative source is still required. We have at least eight fitted to Comets, possibly ten if G-ADEF also had the same engines fitted, added to that is the unknown number of development engines - and spares - if any. The figure of a dozen engines has been bandied-about for as long as I can remember - but it'd be nice to see some sort of contemporary DH document to clarify the matter - which is where we came in. Even better would be to find all the serial numbers.
 

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Thank you for such a wonderfully informed commentary. I bow to the master. There is surely a place for your knowledge at the Comet Racer Project Group Facebook page: https://www.facebook.com/groups/330548433801421

I just asked there and one De Havilland history gives the production run as eight. But maybe I was right about the twelve after all, or....
 

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The c/n 34 G-ACTE in the Spanish Civil War
 

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steelpillow

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Very nice, the Miles Speed Hawks seem to have led exciting lives. But G-ACTE did not have a Gipsy Six R. G-ADOD was the only Miles Speed Hawk to be fitted with one.
 

avion ancien

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Unless I've missed something, we're still left without answers to two of the questions posed at the outset, namely:

- from where did Miss Fontes get the engine which powered G-ADOD?
- what happened to that engine after F.E.Tasker disposed(?) of it?

If my understanding is correct, Tasker was a 'money man' rather than a racing pilot or an aviation engineer, one who facilitated and financed 'raids' (sorry - I always find the French term more useful and concise than the multiple English words required to express the same concept!) rather than one who participated in them. So whilst he might have owned the remains of G-ADOD, after it crashed in Zimbabwe, and even paid to have these shipped back to the UK, would he have involved himself in assessing the post-crash value of the engine and the decision whether to keep or dispose of it? Is it not more likely that he would have delegated such tasks to those with the requisite skills? Maybe someone like Jack Cross? Food for thought, perhaps?
 

avion ancien

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Greetings, Gordy. It's nice to see you migrating from a forum that, seemingly, has had its day.
 

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I have just learnt that the Six R from G-ADOD, together with its logbook, are extant in a private collection - I have asked the appropriate questions - watch this space.

! :D

Seriously, this is extraordinary news. Shuttleworth tell me that the Six R in their collection is the one used by Alex Henshaw in his Mew Gull for his all-time class record at the 1938 King's Cup. That means it has been significantly modified by Jack Cross. So if they are right (and I have not seen the provenance of their assertion), the one you have unearthed is the only original as-manufactured Six R known to have survived.

In his book The Dangerous Skies, Clouston tells how he crashed G-ADOD in the jungle just short of his destination in the Schlesinger 1935 England-to- South Africa race, when the engine failed him. The plane was left to rot but he recovered the engine, brought it back to England with him and presented it to Tasker. The latter declared it to be worthless, and that is the last we have known of it.

On some of the other points raised above, Fontes' brother Luis had previously bought a "Gipsy Six IF" for his Speed Six G-ADGP. It was a standard Six with what racing mods DH could easily make at the time. Ruth deliberately cadged a Six R off de Havilland with the express purpose of beating him in the 1935 King's Cup; hence her subterfuge of calling herself Miss R. Slow, so that he would have no suspicions. A pair of Six Rs was definitely not available for G-ADEF in that same year. Were these two more IFs? Or were they taken a step further? The carburettor air intake can potentially tell us something. On G-ADEF the telltale side bulge of the Six I is absent, telling us that the carbs had been turned sideways, after the manner of the Six R, to take advantage of ram-air compression at 200 mph. For some reason I came to believe that G-ADGP did have the production-standard side intake, But I have not recorded my source, darn it.

Yes G-ADEF had Ratiers, but no it did not have the same spline as the Six R. It would have had either the standard DH fixed-pitch spline or, possibly, the more robust spline they were developing for the Six II with its DH-built variable-pitch props. So its Ratier adaptors would have had to be custom built for it.

More background and provenance in my new book, The Comet Racers Uncovered.
 
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steelpillow

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Oh, and on the oilway front:

All three Comets were built for the Hamilton Standard V-P props. These required a high-pressure hydraulic oil way up the centre of the crank shaft and spline.

The planned Ratier conversion included shortening the crank shaft to take the mounting plate. But by the time the Hamiltons proved unusable, there was not enough time left before the race to dismantle the engines, modify and rebuild them and have them all re-certified. Hence the last-minute development of the adapter.

According to Henshaw in The Flight of the Mew Gull, Essex Aero (Jack Cross and Jack London) had to create a new oilway for the DH variable-pitch prop, which he had to fit for the 1938 King's Cup to meet the UK-only regulation which banned the Ratier.

But how come the oilway drilled in anticipation of the Hamiltons was no longer there, when the Ratier adapter was removed? One might assume that the original oilway had been plugged, perhaps back at the pump, why could it not simply be unplugged and reconnected?

The engine had passed through the hands of the RAF, the Comet flying as K-5084, which might conceivably have something to do with it. Or perhaps Essex had had to find a new pump. One of life's little mysteries, at least for now.

And the splines. The Shuttleworth Six R has its Ratier on for display, so I can't see its spline. My knowledge is a bit limited but as I understand it the original DH fixed-pitch spline is tapered, while the V-P spline is parallel. But was the DH V-P spline copied direct from the Hamiltons, or was it a bit smaller to match the smaller props and lower engine powers in the DH range?
Is there a good online resource which details the specifications for the SBAC No.1, etc?
 
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G-ORDY

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Oh, and on the oilway front:

All three Comets were built for the Hamilton Standard V-P props. These required a high-pressure hydraulic oil way up the centre of the crank shaft and spline.

The planned Ratier conversion included shortening the crank shaft to take the mounting plate. But by the time the Hamiltons proved unusable, there was not enough time left before the race to dismantle the engines, modify and rebuild them and have them all re-certified. Hence the last-minute development of the adapter.

According to Henshaw in The Flight of the Mew Gull, Essex Aero (Jack Cross and Jack London) had to create a new oilway for the DH variable-pitch prop, which he had to fit for the 1938 King's Cup to meet the UK-only regulation which banned the Ratier.

But how come the oilway drilled in anticipation of the Hamiltons was no longer there, when the Ratier adapter was removed? One might assume that the original oilway had been plugged, perhaps back at the pump, why could it not simply be unplugged and reconnected?

The engine had passed through the hands of the RAF, the Comet flying as K-5084, which might conceivably have something to do with it. Or perhaps Essex had had to find a new pump. One of life's little mysteries, at least for now.

And the splines. The Shuttleworth Six R has its Ratier on for display, so I can't see its spline. My knowledge is a bit limited but as I understand it the original DH fixed-pitch spline is tapered, while the V-P spline is parallel. But was the DH V-P spline copied direct from the Hamiltons, or was it a bit smaller to match the smaller props and lower engine powers in the DH range?
Is there a good online resource which details the specifications for the SBAC No.1, etc

Fascinating stuff - have you thought of contacting Ratier? They are still in business (not that far from me here in France) and have an excellent museum.

I gather that the engine and airframe logbooks are with the engine from ‘DOD and I am awaiting more information.
 

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Fascinating stuff - have you thought of contacting Ratier? They are still in business (not that far from me here in France) and have an excellent museum.

I gather that the engine and airframe logbooks are with the engine from ‘DOD and I am awaiting more information.

Although the Ratier adapter was developed primarily by their M. Dreptin, he had been sent over and was working on-the-spot at Stag Lane. Also, the oilways would not have been his concern. (Another possibility there is that they were plugged, and the plugs welded in place to stop them shaking loose).

But yes, they might have some drawings brought back by Dreptin, and maybe sales ledgers, assuming such things survived the war. One of that ever-growing number of if-I-ever-have-nothing-better-to-do research subprojects.

The airframe log would be a terriffic find, too. I do hope the owner will appreciate the significance of releasing all this information.
 

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I have just learnt that the Six R from G-ADOD, together with its logbook, are extant in a private collection - I have asked the appropriate questions - watch this space.

! :D

The carburettor air intake can potentially tell us something. On G-ADEF the telltale side bulge of the Six I is absent, telling us that the carbs had been turned sideways, after the manner of the Six R, to take advantage of ram-air compression at 200 mph. For some reason I came to believe that G-ADGP did have the production-standard side intake, But I have not recorded my source, darn it.
Does this help Guy? The Mew Gull has an intake but G-ADOD doesn't. Similarly G-ADGP and the Falcon Six both have the intakes. I'm thinking that confirms 'DGP had the Gipsy Six IF but 'DOD had the Gipsy Six R.
 

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steelpillow

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Thank you. They confirm what we know of G-ADOD and G-AEKL, no question there. Ah, and I remember about G-ADGP now; Shuttleworth nowadays fly it and they say it still has its original engine (i.e. the 1F). Hence my assumption that its carbs back then were mounted the way they are now. But it would be nice to confirm that.
As an aside, which Mew Gull is behind it? I don't recognise the layout of the name on the nose (It does not quite match The Golden City).
 

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Thank you. They confirm what we know of G-ADOD and G-AEKL, no question there. Ah, and I remember about G-ADGP now; Shuttleworth nowadays fly it and they say it still has its original engine (i.e. the 1F). Hence my assumption that its carbs back then were mounted the way they are now. But it would be nice to confirm that.
As an aside, which Mew Gull is behind it? I don't recognise the layout of the name on the nose (It does not quite match The Golden City).
Not a Mew Gull behind 'DGP but a Falcon Six (G-ADLC) which had won in 1935 flown by Tommy Rose, in 1936 it was flown by C.W.A.Scott
 

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steelpillow

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Thanks again. I don't know much about the Falcon. Was it a kind of equivalent to the Vega Gull?
 

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Thanks again. I don't know much about the Falcon. Was it a kind of equivalent to the Vega Gull?
More like a Gull, 3-seater, one pilot with a bench seat for two passengers. The Merlin was a larger 4-seater version. I've flown in G-AEEG when it was the "Executive Aircraft" of Vintage Aircraft magazine back in the 1980s!
 

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