Re: Spitfire in France, May-June 1940
 

Don't forget they were not fighters and therefore not Dowding's

Recce-Spitfires not fghters
 

Oh yes, of course I am fully aware of this but the basic aircraft was the same with a few changes to get a PR-Spit: removing the eight guns (or did they retain a few for self-defence? I don't think so.), canopy with bulges and obviously some good cameras. In theory Fighter Command's C-in-C could have refused to see several precious Spitfire-airframes (with engines) changed into unarmed recce AC. At the time (1939) Spitfires were precious few and hotly wanted by FC.

These Spits were not Fighter Command aircraft, this is true, but they could not be delivered secretly to other units than to FC squadrons without Dowding being aware of this.

Re: NUMBERS OF Spitfires in France, May-June 1940
 

- Perhaps they conned poor defenceless Dowding by asking first for two Spits only. Later they raised the number but it was too late to say "No" for the reason you mentioned.

Re: Spitfire in France, May-June 1940
 

Regards Dowding being aware of Spitfires being diverted to the PDU I would say he was fully aware. During the period in question the PDU, the parent unit Spitfires operating in France belonged to, was sub-ordinate to Fighter Command for administrative purposes. So personnel and equipment came from Dowding's Command. However, Fighter Command had no operational control over PR Spitfires in the UK or the Continent.

As to whether he agreed with this diversion of resources or even had any say I don't know. As stated previously by the time of the German invasion of France much higher authority than Dowding was taking notice of what was being achieved and resources were to be allocated accordingly whether AOC Fighter Command agreed or not.

Best regards

Andy Fletcher

Re: Spitfire in France, May-June 1940
 

I don't think that there was anything special about the supercharger on the Mk.I that would have come as any great surprise to the Germans. Indeed Hooker considered it less than ideal and his improvements were adopted on later marks. However this involved superior airflow from careful shaping not some magic gadget.

The French were given one Spitfire with an eye on issuing a significant order for them. Presumably the Germans got that one too.

Re: Spitfire in France, May-June 1940
 

X

Re: Spitfire in France, May-June 1940
 

A book about fighter aircraft engines is coming in April:

https://www.calum-douglas.com/curren...rsepower-race/

The next book is about turbocharger design:

Contents - a bit small

https://www.calum-douglas.com/contents/

Aero-engines, superchargers
 

Thanks Ed. 1st one looks quite authoritative. 2nd one too but yes, information is scarce for the moment.

As usual with anglo-american and even German authors they ignore the designs - sometimes remarkable ones - achieved in other countries. 1940 French aero-engines (Hispano-Suiza in-line engines and Gnome-Rhône radials) used in actual combat were less than ideal except for Dewoitine 520s (HP 12 Y 45) but greatly improved designs were in the pipe (in particular HP 12 Y 51 and HP 12 Z) and, as I mentioned above, would have been deployed approximately from August, 1940 on and German fighter pilots, in particular, would have been at a great disadvantage with their ol' 109s and DB 601s. See books "Les moteurs aéronautiques français" (2 volumes), Docavia IIRC. At least two new French fighter designs which existed already 1940 were able to fly faster than 700 km/h (435 mph) - Dewoitine D.551 and Bloch 157, slower than that with full military equipment (guns, ammo, etc.) - about 675 km/h but just like in all other countries improvements would have been made after the first deliveries. No doubt they were carefully looked at by the Germans (especially the superlative engines) at Lechfeld, Daimler-Benz', BMWs etc.

In the USSR as well as in Switzerland French aero-engines were used, made under license and strongly improved in the course of the years as they would have been in France too given time, reaching high power values like 1,600 ch (hp?) for the latest Soviet fighters with in-line engines (Yak, MiG). In the USSR tens of thousands of these engines, possibly well over 100,000, were produced (radials too IIRC) plus thousands in Switzerland. Their users were fully satisfied with these engines and never tried to make and use other ones. So the blindness of almost all anglo-american authors for everything which is not made "in English" or in German (they love to have these bad guys to look like heroes) is really very annoying. In particular Soviet and Swiss experts were just as good as others.

Of course I am not criticizing you Ed. You're a very knowledgeable man and ready to help. Thanks again.

Re: Spitfire in France, May-June 1940
 

I am in contact with the author of the book about aero-engines. He has spent many years in archives in Europe and elsewhere. Perhaps you can share what you know on his Facebook page.

https://www.facebook.com/TheSecretHorsepowerRace/

Your sensitivity about certain things is partly understandable and partly not.

Regards,
Ed

Re: Spitfire in France, May-June 1940
 

I'm afraid that there is a world of difference between having highly promising engines under development, or even in early production, but quite something else to get these into production and then into aircraft and then into service in significant numbers. Compare these promises (for that is what they are) with the historical development of similar engines elsewhere. For example at the same time the British had the Sabre and Vulture already flying in fighter and bomber airframes with production lines established: the Griffon and Centaurus were not so far behind. The Germans had the DB603 running... I agree that there is no reason to doubt the capabilities of the French industry, but equally there is no reason to doubt that they would have been likely to run into very similar problems as faced by other nations. And the service timescales are always longer than the ambitions.