Interesting graphs

retroaviation · **Posted:** Mon Dec 29, 2008 4:06 pm

A friend of mine just sent these to me. I figured y'all might find them as interesting as I did..........

Gary

Ztex · **Posted:** Tue Dec 30, 2008 2:21 pm

I don't know if i understand why there are steps in the graphs...like the P-51B in the 1944 graph...

and

This is one time I think I can get away with saying...Look at those Jugs!

Do they ever run out of power?!

ww2John · **Posted:** Tue Dec 30, 2008 2:27 pm

Once again Gary, thanks for supplying information like this.
Not meant in any way as a critique - just curious...who did the testing to come up with these charts?

retroaviation · **Posted:** Tue Dec 30, 2008 2:29 pm

I dunno.

Bill Walker · **Posted:** Tue Dec 30, 2008 2:39 pm

The steps in the graphs probably result from whatever controls were on the boost systems. This could have been simple pressure switches, or manual controls (where the pilot has a graph or table of allowable boost or some other setting versus altitude). Official test results, which these appear to be, would have to follow any required limits such as these. Merlins had a two speed gear box on the supercharger IIRC, with the pilot required to shift gears at some altitude. this would produce the type of step you see.

Modern turbochargers with proportionally controlled waste gates or inlet geometry would constantly vary maximum boost, resulting in a smoother line on the graph.

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Interesting graphs

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