Mustang P-51D pilots -- elevation cruise speeds?

[Ronald-Reagan]

My research suggests a cruise speed for the P-51D of 325 mph at 10k feet. But I've also found cruise speeds for the same aircraft listed anywhere between 275 mph and 380 mph. I assume this discrepancy is due to cruising at different altitudes. So I have a couple of questions:

1) At what altitude is the P-51D's maximum cruise speed attained?

2) Can someone give me cruise speed estimates (P-51D model) for the following altitudes?

5,000'
10,000'
15,000'
30,000'
35,000'
and 40,000'

3) And finally, how much difference would there be between cruise at those altitudes and max speed (level flight) at those altitudes?


Just trying to get a grip on intermediate P-51D performance here.


Fred B.

[Bill Greenwood]

You can look at the RARA site to get race speeds at Reno for P-51s. Rule out the cut down airframes with race engines and you find a range of about 310 mph to 360 mph. Realize that when racing these are running higher power than one would for cruise. Just as a guess take off 1/4 for lower power cruise so get about 270 mph at the lower end. I think Reno is about 5000 feet? and true airspeed increases about 2% per 1000 feet. So to cruise at 10,000 add 10% or 27 mph for a low end figure of 297 mph. The high end might be 40 mph faster.

This is sort of an educated guess, I am not at home right now and don't have a P-51 manual here. if anyone needs a Mustang ferried cross country I'd be glad to do some research!

Just as a reference, one I do know about, is my Spitfire MK IX T. At 10,000 feet, using very low power of 30 in and 1800 rpm, my speed would be about 244 mph true and the true airspeed at higher power setting of 38 inches and 2400 gives 288 mph.