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Greybeard · 8 November 2009, 02:22 AM

Mik,

the key point of this matter is that WWI engines DO NOT have a max power as we're accustomed with: believe it or not, they were limited BY ALLOWED RPM!

You can see graph about Salmson engine on Jane's 1919 reprint to see what i mean, for instance.

So, if we took a RAF4a or everything else at that time, probably we could get even 200 or more horsepower, but simply its mechanical resistance couldn't allow related RPM's and stresses.

As a consequence, it was matter of CONVENTIONS, like those mentioned by Dan-San about germans. Each engine had a "nominal" power that was in general, lower than power output at dynamometer, although got at rated RPM. Only exception I know was Daimler early DIII which developed 150 PS at test bench, instead of nominal 160 PS (developed then by later DIII).

According Air Ministry's Data Sheets, RAF4A developed 170 HP at 1800 RPM.

Hope this helps.

GB

8 November 2009, 02:22 AM	#6 (permalink)
Greybeard Forum Ace Join Date: Jul 2005 Location: Italy Posts: 698	Not lies, just conventions. Mik, the key point of this matter is that WWI engines DO NOT have a max power as we're accustomed with: believe it or not, they were limited BY ALLOWED RPM! You can see graph about Salmson engine on Jane's 1919 reprint to see what i mean, for instance. So, if we took a RAF4a or everything else at that time, probably we could get even 200 or more horsepower, but simply its mechanical resistance couldn't allow related RPM's and stresses. As a consequence, it was matter of CONVENTIONS, like those mentioned by Dan-San about germans. Each engine had a "nominal" power that was in general, lower than power output at dynamometer, although got at rated RPM. Only exception I know was Daimler early DIII which developed 150 PS at test bench, instead of nominal 160 PS (developed then by later DIII). According Air Ministry's Data Sheets, RAF4A developed 170 HP at 1800 RPM. Hope this helps. GB __________________ ------------------------------------------------------ It doesn't matter what we do but in what relationship we put each other while doing what we do.