Spitfire in France, May-June 1940

[Graham Boak]

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.

[rof120]

X

Originally Posted by Graham Boak

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.

- I believe you but in any case it was interesting to the enemy to know what exactly was hidden under the engine cowling.

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.

- That's OK for me. What mattered was the result, no matter how it was achieved. The French had an excellent supercharger (Szydlowski-Planiol) for the D.520. Are you aware that when they had to stop fighting the French were on the verge of introducing much more powerful aero-engines (made by Hispano-Suiza) with fuel injection too (like on the DB 601a engine of the Me 109). By August, 1940, French fighters, especially Dewoitine 524s etc., would have started giving the "Teutons" a licking. (Siiigh)

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

- Yes, probably. IIRC this idea was shelved because at the time the Spit airframe (or engine) could not receive any cannon and French Air HQ wanted cannon-armed fighters (they were right and the RAF wanted the same thing). I'm not sure, though. Or perhaps it was just too late.

[edwest2]

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/

[rof120]

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.

[edwest2]

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