p-51 and p-47

[nimrod.michaeli]

what characteristic made the p-51 fastest

what characteristic made the p-47 fastest in a dive

[Colin1]

Originally Posted by nimrod.michaeli

what characteristic made the p-51 fastest

what characteristic made the p-47 fastest in a dive

Which version of the P-51 are we talking about? WWII operational service P-51s or the later marks? There were design features that made the P-51 fast but the P-47M was faster than the contemporary P-51 at a higher altitude, something like 470mph at 32,000ft over the P-51D's 440mph at about 2,000ft lower.

There was a well-represented debate on here over which type actually was fastest in the dive, I'll see if I can find it.

[hrandy]

The Mustang had 5% to 10% less drag than contemporaries like the Spitfire, Bf 109, P-39 and P-40. There is an ongoing and sometimes acrimonious debate about why the Mustang was the most aerodynamically efficient piston engine fighter of World War II. Most people believe that it was either the laminar flow wing or the Meredith effect radiator. I don’t think we will ever know with any certainty whether it was one feature or a combination of many that resulted in the low drag and high speed of the Mustang.

At the 1944 Fighter Conference more than a dozen experienced combat pilots along with several experienced test pilots compared and rated all the then current U.S. fighters. The P-51D was rated second after the P-39G in dive acceleration and ahead of the third rated P-47D. In limit dive speed the P-51D and P-47D were rated first and equal.

[Cromwell]

Was the P47M faster than the P47N at all - I suppose it partly depended on Altitude, but I think the P47M was the fastest production version to be used in ETO or PTO.

The experimental XP-47J with a GE CH-5 turbosupercharger reached a top speed or 505 mph


P-51H among the fastest propeller fighters ever - 487 mph (784 km/h or Mach 0.74) at 25,000 ft

Originally Posted by Colin1

Which version of the P-51 are we talking about? WWII operational service P-51s or the later marks? There were design features that made the P-51 fast but the P-47M was faster than the contemporary P-51 at a higher altitude, something like 470mph at 32,000ft over the P-51D's 440mph at about 2,000ft lower.

There was a well-represented debate on here over which type actually was fastest in the dive, I'll see if I can find it.

[drgondog]

Originally Posted by hrandy

The Mustang had 5% to 10% less drag than contemporaries like the Spitfire, Bf 109, P-39 and P-40. There is an ongoing and sometimes acrimonious debate about why the Mustang was the most aerodynamically efficient piston engine fighter of World War II. Most people believe that it was either the laminar flow wing or the Meredith effect radiator. I don’t think we will ever know with any certainty whether it was one feature or a combination of many that resulted in the low drag and high speed of the Mustang.

If the often referenced (but hard to pinpoint) zero lift parasite drag number, .0163, is correct then the wind tunnel results (i.e 'no meredith thrust effect) places the Mustang around 20-25% less parastie drag - which is huge.

There really isn't much debate at all that the radiator cowling design was a significant reduction in drag, nor that the NAA laminar flow wing were major factors in reduction of parasite drag over same powered airframe (Spit), higher hp/wt airframes (109 and P-47 and 190)

At the 1944 Fighter Conference more than a dozen experienced combat pilots along with several experienced test pilots compared and rated all the then current U.S. fighters. The P-51D was rated second after the P-39G in dive acceleration and ahead of the third rated P-47D. In limit dive speed the P-51D and P-47D were rated first and equal.

Colin referenced a thread two months aga in which a couple of RAF reports were found and cited, individually, as far as dive characteristics and recommended airspeed limits. For the Mustang several dives were refenced at .85 Mach with some damage incurred. The P-47D was cited at .86.

All of these reports would be subject to some error as the speeds were post flight calculations based on STP, instrument readings and correction factors applied (presumably) for compressibility. In other words no sophisticated telemetry, just old fashioned Fluid/Aero applied physics math.

I have never seen or even heard of tactical dive trials fro P-47M/N or P-51B/H... only the above mentioned RAF tests on the Mustang IV (D) and the P-47D (with dive flaps, so post -27)

There should be no important differences in any of them as the airframe design was essentially the same, although the D had important safety design mods implemented over P-51 A/B