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?
 

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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.
 

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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.
 

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...the chap in the top photo standing on the right is Victor Smith.
 

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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?
 

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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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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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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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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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The latest Aeroplane (October 2021) carries a piece on the Fontes siblings. It includes various snippets and asides on the career of G-ADOD.

Its open cockpit was originally tailored around Ruth's small figure. Clouston had to have it substantially altered, and also had a new enclosed canopy fitted. He also added extra fuel tanks, which needed the undercarriage widening.

A photo with the article clearly shows the prop to be fixed pitch, which I would assume to be a Fairey-Reed. That makes this installation unique among Six Rs. So how was it mounted to the large Hamilton-Standard (aka No.1 SBAC) spline of the Six R crankshaft? DH are said to have cut down one shaft when they first trialled a Ratier, perhaps it was this one recycled with a custom adapter?

After Clouston brought the engine back from South Africa and Tasker wrote it off as worthless, it ended up with Essex Aero. That surprises me, as Essex were then a small shed near Romford in Essex and trading as Hillman and Cross. Their association with Clouston is not supposed to have begun until he engaged them to rebuild DH Comet G-ACSS later that year. In fact the ents are close enough in time that the one might well have triggered the other. More significantly, it makes one wonder who he got to modify G-ADOD when he bought it off Fontes the previous year.

Anyway, back to the engine. When Essex were liquidated and its assets sold off in 1956, it was bought by one R. C. Shelley (a known engine collector from Billericay, back in Essex again; he also had a Napier Lion, among other wonders). His collection was sold off fairly recently (following his death, I presume?), and the Six R passed to another, un-named collector.
 
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Methuselah

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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.
These engines all used the same Claudel-Hobson downdrought carburettors. This applies to the Gipsy Six, The R, the Six Series II, the Queen II and the Queen II. The only differences would have been the jets and the later engines having an AMC. The carbs were not 'turned sideways'. On some racing machines, the side-intake was replaced by an extended duct to allow the engine to breath the same air as the cooling inlet in the nose-bowl and thus reduce drag. As for the ram-air effect, this was negligible.

As for the splines - only the No.1 SBAC splines were used. There was no 'fixed-pitch spline' - and the No.1SBAC Spline was already extant. Engines intended for a fixed-pitch airscrew had a short, tapered end to the crankshaft with a keyway. Onto this, an adapter was fitted for the bolts and flanges to take a fixed-pitch airscrew. Just to confuse you further, there was available, from DH, an adapter to fit the No.1SBAC splines to allow a fixed-pitch airscrew to be fitted to either a SII or a QII et al. Thus, if you are looking at a machine with an R fitted, but using a FP airscrew, - it will have had the latter standard DH adapter fitted.
 
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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?
The SBAC Splines were a UK standard - and different to the splines used in the US.

DeHavs had already looked at all the options for VP airscrews well before the race - and that included Ratier's offerings. Having decided upon opting for Hamilton's well-proven and reliable design, the task was to shrink the Bracket airscrew design for engines much smaller than those commonly in use in the USA. Having opted for the No.1 shaft, they'd have had to make an adapter for the Ratiers, which used a much cruder mounting, intended primarily for use on engines/hubs of fixed-pitch design. Now - leaving aside oilways etc, one possibility - and it is only that - is that the existing adapters were themselves modified - and the crankshaft ends shortened. The simple reason that this shortening 'may' have been executed, was to preserve the a/c's CofG. The Ratier airscrews were by their basic design, thrown well forward. I offer this as a logical hypothesis - not a documented fact, since documentary evidence on this matter does not seem to have seen the light of day in post-war years.

Later DH engines of greater size and power used larger standard SBAC splines. The Q30's - such as Derby are fitting to their Comet, use the larger No.2 SBAC splines. The military engines - Bristols and RR etc, would have used larger versions still. Although DH's didn't produce very large capacity piston engines - they did - in the early part of the war, produce larger versions of the Bracket design - usually with three blades for Blenheims, Spitfires et al. These were superseded for multi-engined machines by the - again Hamilton-derived - DH Hydromatic type, which were fully feathering, which of course the Bracket Type were not.
 
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Methuselah said:

Great to have a knowledgeable critique here, thank you. I have to go mostly by what people write down, which is not always accurate.

Fair enough I can see that the carbs were not turned sideways. But their intake ducts were - see attached images. Also, the flame trap arrangement for the warm air inlet was rather different.

A contemporary account I came across did report that DH found the ram effect to be noticeable. I seem to recall something like 5 mph on the top speed.

The Ratier adapter was developed on-the-spot at DH by their UK representative M. Dreptin. One development crank shaft had been cut down to test the Ratier design, but by the time of the prop change all the engines had been built and certified, and there was not time to strip, modify and rebuild them all, and re-certify them, hence the adapter as a last-minute fix. Shuttleworth's Six R has one fitted; the prop only looks forward-positioned because the adapter pushes it forward. More images attached.

But I should like to know more about the SBAC spline. The Hamilton-Standard props were developed for the big American radials and the SBAC spline would not have been their standard fitting (which had a central oilway and was presumably the US spline). DH designed the R crankshaft to take those props specifically; there is no evidence of any adapters for them. Are you implying that Hamilton's must have designed specials to order, or that DH would have decided to fit spline adapters after all, or what? And was the DH SBAC adapter available in 1935 anyway, when Fontes bought her engine and the Six II was not yet available? Indeed, when was the SBAC No.1 spline defined, and why? So I am not yet clear that such an adapter would have been either available or appropriate for the engine when Fontes bought it.
 

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Methuselah

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Methuselah said:

Great to have a knowledgeable critique here, thank you. I have to go mostly by what people write down, which is not always accurate.

Fair enough I can see that the carbs were not turned sideways. But their intake ducts were - see attached images. Also, the flame trap arrangement for the warm air inlet was rather different.

A contemporary account I came across did report that DH found the ram effect to be noticeable. I seem to recall something like 5 mph on the top speed.

The Ratier adapter was developed on-the-spot at DH by their UK representative M. Dreptin. One development crank shaft had been cut down to test the Ratier design, but by the time of the prop change all the engines had been built and certified, and there was not time to strip, modify and rebuild them all, and re-certify them, hence the adapter as a last-minute fix. Shuttleworth's Six R has one fitted; the prop only looks forward-positioned because the adapter pushes it forward. More images attached.

But I should like to know more about the SBAC spline. The Hamilton-Standard props were developed for the big American radials and the SBAC spline would not have been their standard fitting (which had a central oilway and was presumably the US spline). DH designed the R crankshaft to take those props specifically; there is no evidence of any adapters for them. Are you implying that Hamilton's must have designed specials to order, or that DH would have decided to fit spline adapters after all, or what? And was the DH SBAC adapter available in 1935 anyway, when Fontes bought her engine and the Six II was not yet available? Indeed, when was the SBAC No.1 spline defined, and why? So I am not yet clear that such an adapter would have been either available or appropriate for the engine when Fontes bought it.
Accuracy is an issue. For example - even some contemporary sources have errors, as do even some of the autobiographies of people involved at the time, so on occasions, some extra digging-around is required. Official manuals and documents are the most reliable sources if relevant and available.

The inlet extension-duct was just that - it allowed the air at the front of the nosebowl to be split and some channelled-back for induction and the parasitic drag of the side intake to be eliminated. (See first photo below.).This relates to the speed-gain too, as drag increases exponentially with speed, and so losing the drag from the side intake was well worthwhile. EWP experimented with taking the intake-duct right up behind the airscrew, but I don't think they were able to measure any advantage.
The alteration to the intake manifold (See second photo below.) is the deletion of the side intake (Facing you in the upper, original config'.) and the provision of a front opening into which intake air from the nosebowl can be directed by a fabricated duct. Note the warm-air flame-trap arrangement is basically unchanged.

The different position of the centre of mass of the Ratier is significant - given the moment arm from the CofG. The DH 1000-Series spider (See third photo.) positions the airscrew disc about halfway along the splines, quite close to the front of the engine (See fourth photo.), so the difference (Perhaps 6"+ ..?) is enough, given the mass of the airscrew(s) - metal VP airscrews are heavy assemblies. The PD30/211/1 assembly weighs 70.1 Lbs - the standard spinner weighs another 7.6 Lbs - so 77.7 Lbs total. Remember you have to double the weight as there are two airscrew assemblies - so 155.4 Lbs - all well forward of the CofG. OW, Derby or KF might supply you with the W&B for the Comet so you can work out the effect on the CofG of moving that lot 6". Look again at your photo of the Ratier on the R at OW - it is a significant difference at that weight and moment arm. Did DH act on this issue...? I have no idea.

I would also point out that the 3/4 view sketch clearly shows the adapter made to fit the Ratier and the sectional sketch of the Ratier shows that there is no space for the shaft to intrude inside it. Thus - just possibly, if the CofG issue reared it's head, they may have wanted to reduce the extension and thus need to cut down the crankshaft end. Do I think on the balance (No pun intended...!) of probability that they cut the cranks down...? No.

The issue of the whys & wherefores of Jack Cross's alterations to Alex's R is quite another matter and I'll avoid further muddying the waters here.

Splines etc;- DeHavs Licensed the Hamilton design for firstly the Bracket Type airscrews, then later the Hydromatic. DH's didn't design the R's crank for these airscrews - it was effectively already the SII crankshaft. The SBAC Splines were agreed SBAC standards across the UK aviation manufacturers. Having already introduced the Gipsy Six, DH's set-out to produce an uprated version to utilise a VP airscrew which eventually became the Gipsy Six Series II - a surprisingly different engine to the SI - despite appearances. (Again - I'll avoid further muddying the waters here.). The SII was already in development when the 1934 race cropped-up. They had finished development of neither the engines, airscrews nor spinners however. The R was therefore, cobbled together from an - at that time - unfinished project. The potential for problems was compounded by uprating the new engine, then using an undeveloped and untested airscrew (It took DH's another two years to sort the SII & PD30.) - all on a new type of machine. There is an old maxim in aviation - 'Don't use a new engine type on a new type of machine'.......
All these hydraulically-operated airscrews were fed by modulated pressurised oil via the crankshaft - and the DH versions all followed the US design in that respect. The detail inside DH's spider was to the UK SBAC spline-form to suit UK engines. Forget what the Americans used, it's irrelevant - DH's never used the US splines on the Bracket Type airscrews. There was no such animal as a UK-US adapter. We are talking about a) What was made to allow the Ratiers to be retrofitted to the No.1 splines, and b) The standard DH adapter that allowed a FP airscrew to be fitted onto an SBAC splined crank end intended for a VP engine, such as a SII or QII. I've got one somewhere but I can't put my hand on it just now - anyway, it was a DH listed assembly. I think there is an illustration in the SII & QII handbooks. It's worth noting that, as this adapter slipped-over the splines, it kept the mass at the same station.

I'm not sure what year the SBAC standard for splines came into effect, but since it wouldn't have been necessary before VP airscrews arrived, I'd say early 1930's - but it's a detail anyway.

I know little about the Mmmmiles a/c and the Fontes. Pretty much all the images that I have ever seen of Speed Sixes have had FP airscrews fitted - usually FR. I have a wooden DH FP airscrew that came from Croydon and was reputed to have come from a Speed Six, but I doubt this claim, as the pitch looks too coarse. Still - it's a nice dust trap.

G-ORDY's post from 21/03/21 - and other images on the web, seems to show machines fitted with FR FP airscrews - including G-ADOD. If so - Ruth's R would have been fitted with the standard DH adapter to enable fitment of the FR airscrew - as long as the crankshaft hadn't been tampered with. Do you have any other images of Ruths machine as raced with the R fitted....?

Hope that clears things up.
 

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steelpillow

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Methuselah said:

The Hamilton V-P prop was heavier than the Ratier, which would have helped limit the difference in aircraft CG. The Comet was a bit tail-heavy and unstable anyway, except when the front tank was full, so moving the CG forwards would actually have improved its handling.

There is no Ratier adapter in either the engine or the prop sketches that I posted; one is visible in the photo of the Shuttleworth engine. It is on record that they did not cut the shafts down, and this was precisely why they came up with the adapter instead.

What is the provenance of your story that the Six II was already under development when the R was conceived? Other sources put it the other way round, that the II adopted some features developed for the R. The original Six was not type-approved until late in 1933 or early '34 and first flew in anger in the prototype DH.86 in January 1934. That was the month in which the Comet was advertised. Production of the Six II did not begin until the second half of 1935. I am sure that some features were developed with the R and II equally in mind, but to suggest that the R was a spin-off from the nascent II design requires serious evidence.

Cross's work on Henshaw's engine deserves a separate thread. However one particular aspect is highly illuminating. He had to replace the Ratier with a DH 2-position type to meet King's Cup regulations, and Henshaw describes helping him with the machining of the replacement adapter. This need for a bespoke adapter is nigh-on conclusive evidence that the R spline was different from the DH prop's and the standard DH adapater would not have fitted. It would not have fitted Fontes' R either.

Still no answer to what fitting actually was provided on the Hamilton V-Ps bought by DH for the Comet. If we follow your suggestion that it was not the spline used on the R's shaft, then what exactly was it? And timing is indeed critical. If the standard adapter was introduced with the II after Fontes bought her engine, she could not very well have had one fitted, even if it did fit.

Far and away the simplest explanation is that both the Hamiltons and the R had the American spline and that the shaft on Fontes' engine had been cut back. Close-up of her nose attached.
 

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.........
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.
.........
In Aeroplane of May 2002 there was an article about the Schlesinger 1936 race.

The article is mainly about the losers, which were most participants, including Clouston's G-ADOD
Apparently race was considered a fiasco.

Can post the article if you don't already have it.
 

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It would be useful, thanks. I have Clouston's own account in his autobiography The Dangerous Skies, but I don't suppose everybody here does.
 

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The Schlesinger Race, Aeroplane of May 2002
 

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G-ORDY

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A little late to the party here, hopefully you liked my Fontes article in Aeroplane this month.

I have discovered that The National Archives hold the certification details for both G-ADGP and G-ADOD but they have not been digitized and they are currently closed to visitors due to the pandemic! These may give a clue as to the engine installed in G-ADOD.

https://discovery.nationalarchives.gov.uk/details/r/C4014964

https://discovery.nationalarchives.gov.uk/details/r/C296009

They also have a file on full-scale Miles Hawk flap tests which I suspect is connected to the trials done at Farnborough on Ruth’s Hawk Major

https://discovery.nationalarchives.gov.uk/details/r/C2419279

One other point, I believe that the engine in G-ADGP was initially a standard Gipsy Six Srs I. It only became a 1F after it was modified post-war by Ron Paine with assistance from Frank Halford.
 

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A little late to the party here, hopefully you liked my Fontes article in Aeroplane this month.

I have discovered that The National Archives hold the certification details for both G-ADGP and G-ADOD but they have not been digitized and they are currently closed to visitors due to the pandemic! These may give a clue as to the engine installed in G-ADOD.

https://discovery.nationalarchives.gov.uk/details/r/C4014964

https://discovery.nationalarchives.gov.uk/details/r/C296009

They also have a file on full-scale Miles Hawk flap tests which I suspect is connected to the trials done at Farnborough on Ruth’s Hawk Major

https://discovery.nationalarchives.gov.uk/details/r/C2419279

One other point, I believe that the engine in G-ADGP was initially a standard Gipsy Six Srs I. It only became a 1F after it was modified post-war by Ron Paine with assistance from Frank Halford.

Thank you for those links! Sadly, "We are currently experiencing very high demand for our record copying service ... Please come back [later]."
I'll do that.
Interesting point about the Mk IF. I'd love to know the details anyway. I went to check and found the attached page from Flight supporting the 1935 end of what you say. Yet I also found one respected source online, suggesting that "all" the Speed Sixes except Ruth's had it installed - all two of them! I draw a kindly veil over their url. I await the National Archive's pleasure with interest.

By the way, do you know whether the sale of Shelley's collection was consequent on his death, or for some other reason?
 

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The collection was looked after by R C Shelley’s son, Michael, after R C had died. Michael restored the Six R to runnable condition but never ran it, he died a few years ago and that led to the sale.

The present owner was interested in some WWI engines but bought the entire collection instead.

I don’t have his name but an intermediary tells me that he will not discuss the engine or logbooks - although he would part with them on condition that G-ADOD is recreated using them as provenance.
 

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Ratier Adapter; - Here is the sketch repeated below, showing the Ratier adapter that you yourself posted only recently..... The upper image is an SI, the sketch below is an R. The adapter is specifically labelled as such on the R sketch.

Forward CG good for handling - bad for range - ask any long-haul ATPL.

Development ;- Provenance - work your way through the period issues of Flight - it's all there. Think about it - why would DH's have gone to all the huge trouble and expense of acquiring the HS Licence - only to have no engine to fit these expensively developed VP airscrews....??? Clearly, they would not. The PD30/211/1 was specifically intended for the SII - a highly modified version of the SI designed to run a VP airscrew at sustained, relatively high RPM.

The R was simply cobbled together for the race using the basic SII crank and crank-case - so it could operate the PD30, but it used the slightly modified pistons, heads and barrels of the SI - NOT the SII pistons, barrels and heads etc. Remember the SII uses totally different barrels, pistons and heads - though the rods and gudgeon pins are common. The give-away in the exhaust-ports inthe head in your illustrations - and the fact that, in 1934, DH sent standard SI engines ahead to Oz for spares. There is one recovered from Oz at Derby - in case you have any doubts. I believe it is reputed to have been used as a spares source for the ailing 'SS.
There was nothing for DH to learn from the R except a) Not to commit to deliver an experimental engine for a high-profile event under extreme pressure, & b) That the overstressed engine was very vulnerable to over-leaning. (Waller clearly looked after the R's on his Comet better, and they got him to Oz.....and back.....). In short - there is nothing in a SII carried-over from the Six R. Nada. Zilch. Basically lore.

'XF's R;- 'This need for a bespoke adapter is nigh-on conclusive evidence that the R spline was different from the DH prop's and the standard DH adapater would not have fitted.'.
No, absolutely not - but as I said - that's a separate can of worms.

'Still no answer to what fitting actually was provided on the Hamilton V-Ps bought by DH for the Comet. If we follow your suggestion that it was not the spline used on the R's shaft, then what exactly was it? And timing is indeed critical. If the standard adapter was introduced with the II after Fontes bought her engine, she could not very well have had one fitted, even if it did fit.' ;-

I did not say that the spline on the R was 'different' and no, DH's didn't buy complete HS airscrews for the Comet (Though the initial blades may have been sent over from the US - and that is precisely why they proved unusable - but that's another story.) - as I said, the US splines were different, so DH had, at the minimum, to make the spider to suit the UK splines for the 1000-Series. Remember - the deal was always for DH to manufacture under Licence for the UK and Empire market - not to buy ANYTHING from the US factory, except the design, manufacture and distribution rights.

As for the small matter of the DH FP adapter for the QII - the Dh design office will have almost certainly anticipated the possible need and drawn this part up. It's not a complex assembly. Perhaps Fontes had the first one ever - who knows - but we do know the engine will have had the No.1 Splines - and the FP FR airscrew will have needed that exact part to allow fitment. It's a detail. I also seriously doubt the c/s her R was cut-down, as it'd have been tricky to fit the adapter.

As a matter of interest, G-HEKL is flying with a unique Queen I. This was effectively a Six SII, but lacked the facility (Gear-set inside the top-covers rear accessory case.) to drive a C/S governor. This engine would have needed the exact same adapter as would have been fitted to Fontes HSS to use it's intended fixed-pitch airscrew. In fact, David Beale had to convert the engine to SII build status by fitting the required missing gears to drive the CSU for the PD30, but obviously he would no longer have needed to use an adapter with his PD30, as it would have slid directly onto the splines.

Forget the US spec' splines - Hamiltons didn't even MAKE a VP airscrew small enough to fit the Gipsies. The US splines were not used for or intended to be used by DH. Period.

Your photo seems to show a FR FP airscrew fitted to Fontes HSS BTW.
 

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Ratier Adapter; - Here is the sketch repeated below, showing the Ratier adapter that you yourself posted only recently..... The upper image is an SI, the sketch below is an R. The adapter is specifically labelled as such on the R sketch.

Have you omitted, as an attachment, the sketch to which you refer?
 

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Ratier Adapter ...
Ha! Two three-quarter drawings, each of us looking at a different one! That explains the confusion. But the callout legend on the drawing you refer to is wrong; the extension was not for the Ratier airscrew but for the (discarded) Hamilton-Standard.

Development ;- Provenance - work your way through the period issues of Flight - it's all there. Think about it - why would DH's have gone to all the huge trouble and expense of acquiring the HS Licence - only to have no engine to fit these expensively developed VP airscrews....??? Clearly, they would not. The PD30/211/1 was specifically intended for the SII - a highly modified version of the SI designed to run a VP airscrew at sustained, relatively high RPM.
You imagine I haven't done that? Oh, purr-leeze! I refer you also to The Aeroplane and the various biographies, histories and the like (Sharp's history of DH, DH's own autobiography, Taylor's biography of Halford, Ogilvy's history of the Comets, etc. etc.). I do not recognise the position you criticise. DH did not make the decision to license the H-S system until after Hagg and a colleague had gone to the US to evaluate options for the Comet. It took them a year or two to adapt it to UK needs, during which time the Comet and the R came and went in the workshops. Halford developed the Gipsy Six II expressly to take the VP props and in parallel with them - at first only the two-position props were available for the Six II, with the fully-variable props following not long after. As you say, it's all in Flight, Aeroplane and the like. There is a nice anecdote somewhere of the King's Cup (1935 I think) being intruded faintly upon by the sound of DH running bench tests on a development prop.

The R was simply cobbled together for the race using the basic SII crank and crank-case -
No, let me stop you right there. The R crank had both front and back ends different from the I and II production types. The rear changed because the starter motor was removed and other equipment substituted, requiring a different drive fitting. The front of the II shaft and casing incorporated the hydraulic oilway which had to be grafted onto the R via an external feed, and its spline was shorter.

[The R] used the slightly modified pistons, heads and barrels of the SI - NOT the SII pistons, barrels and heads etc.
Indeed. Hardly the II crankshaft either, then. In fact the pistons and a fair other selection of gubbins came from the Major C.

DH's didn't buy complete HS airscrews for the Comet (Though the initial blades may have been sent over from the US - and that is precisely why they proved unusable - but that's another story.)
Really? I'll bet you didn't get that from the pages of Flight. It is flatly contradicted by the aforementioned books and journals on my shelf - what is the provenance of you claim?

Remember - the deal was always for DH to manufacture under Licence for the UK and Empire market - not to buy ANYTHING from the US factory, except the design, manufacture and distribution rights.
What you need to remember is that the licensing deal was struck AFTER the Comet's props had been ordered; they were independent and unrelated transactions. No way did DH have either the license or the time to develop a V-P hub to mate sets of US-made blades to the R, that is just not believable without strong evidence. They had their work cut out just getting the oil supply for it in place.

You have produced no documentary evidence whatsoever, contemporary or retrospective, to counter the body of known sources on the R and support your theory of the SBAC spline and the forthcoming Six II gubbins. I am sorry, but until you do I can no longer accept such suggestions as serious.
 
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