P-63: real performance?

[wuzak]

GregP,

I owe you an appology sir. I was having a good day yesterday until I checked our medical bills and my wife showed me what she meant by "I hit the car with the lawn mower". She ran over the push mower with the new van I just bought her. Well anyway, It was wrong of me to take it out on you. I am sorry Greg.

Now about that 437 thing. I do not know how that figure became the prime quoted/published figure for the P-51D. Memo Report No. TSCEP5E-1908 dated 6/05/45 contains the Max. figure for the P-51D-15 WITH BOMB RACKS as 442 mph/26,000 ft. at 67"Hg. Without the bomb racks add 8-12 mph. The V-1650-7 was cleared for 75"Hg a year before this report. No racks and increased boost added 14 mph to the top speed of the P-51B-15 with the V-1650-7 engine.

I am planning to post the figures for the P-63D and P-63E-1 when I get home tonight. If youall would like I could post a total comparison between the P-51D-15 and the P-63D (calculated).

See you all later, Jeff


I have seen the AIRCRAFT, MUSTANG IV (P-51D) data sheet that has the 437 figure, but that is the only official document that I have ever seen it on.

The ability to use more boost doesn't necessarily mean higher top speed.

Higher boost tends to lower the full throttle altitude. That is, a Merlin with WEP setting of +25psi boost will reach a condition of wide open throttle at a lower altitude than when running at +18psi boost. Above the altitude where full throttle and +25psi boost is achieved boost will drop off. At the full throttle height for the engine at +18psi boost, it will still be making +18psi boost.

If the full throttle height at +18psi boost is altitude A and at +25psi boost is altitude B, the plane's speed would see the biggest increase at B and below. Between B and A the speed advantage will reduce. At A and above it will remain the same.

 

[alejandro_]

I have plotted the speed measured by the NII VVS test (P-63A-10) with that of the P-63A-9 42-69417. The data are quite different, especially at sea level. A while ago I did a similar comparison with the P-39 data, and the speeds at sea level were again quite different. Manufacturers usually state a performance variation, usually 5-10% IIRC. Is there any reason why the variation should be larger at SL?

1

 

[alejandro_]

Double post, mods please delete.

 

[drgondog]

I have plotted the speed measured by the NII VVS test (P-63A-10) with that of the P-63A-9 42-69417. The data are quite different, especially at sea level. A while ago I did a similar comparison with the P-39 data, and the speeds at sea level were again quite different. Manufacturers usually state a performance variation, usually 5-10% IIRC. Is there any reason why the variation should be larger at SL?

1

SL is where the greatest density occurs and hence, the highest drag. Variations in engine performance would have an impact.

 

[CORSNING]

wuzak, you are exactly right about boosted levels.

drgondog, thanks for the explination of performance at sea level.

 

[alejandro_]

I have scanned a graph with performance data from the book America's Hundred-Thousand, one of the best references for US fighters. Soviet data does not seem to be very different from USAAF's. Note that Soviet graph specified performance for a 15 minute engine setting (military power).

 

[jmcalli2]

I have scanned a graph with performance data from the book America's Hundred-Thousand, one of the best references for US fighters. Soviet data does not seem to be very different from USAAF's. Note that Soviet graph specified performance for a 15 minute engine setting (military power).

I have a question;

Notice that the P-63D is often quoted as the fastest version, by about 20MPH. Could this be due, indirectly, to the bubble canpy sliding back-this means the induction air intake is further away from the canopy, and, I think, in much better airflow. Any ideas?
Jim

 

[wuzak]

I have a question;

Notice that the P-63D is often quoted as the fastest version, by about 20MPH. Could this be due, indirectly, to the bubble canpy sliding back-this means the induction air intake is further away from the canopy, and, I think, in much better airflow. Any ideas?
Jim

The inlet is further rearwards because the air intake goes to the auxiliary compressor, which is basically attached to the rear of a regular V-1710. Thus the intake is much further back compared.

The D probably had the most powerful version of the engine.

 

[grampi]

As I recall it made about 422 mph at best altitude (around 22,000 feet or so), climbed MUCH better than the P-51

Depends on which version of the P-51...the P-63 climbed better than the D model, probably about equal to the B/C model, but did not climb as well as the H model...

 

[jmcalli2]

The inlet is further rearwards because the air intake goes to the auxiliary compressor, which is basically attached to the rear of a regular V-1710. Thus the intake is much further back compared.

The D probably had the most powerful version of the engine.

The other reason for it being further aft is the bubble canopy on the P-63D slide back to open; it required the intake to be further aft. Still can't help but think it made a difference.

 

[Shortround6]

There were 6 different engines used in the P-63 of which one, the -47, can pretty much be ignored as it was only used in the prototype. and two others (the-133 and the -135) were used in end/postwar versions, the P-63F (2 built) and the RP-63G (32 built).
Since there were also 4 different propellers used it gets very hard to pick up differences the change in air intake would make, not saying it didn't make a difference, but without company test results specifically addressing the intake we get into speculation real quick.

 

[Dan Fahey]

The P63 was another NIH program. It would have been a far more effective ground attack aircraft. Far better than the dedicated fighters. Plus would have had the combat ability to fight back otw home! Much like the P40. It had better range than the P39 but not current long range fighters. The US was afraid the Russians would give them to the North Koreans. The French liked them in Libya and Vietnam.

 

[tomo pauk]

The P63 was another NIH program. It would have been a far more effective ground attack aircraft. Far better than the dedicated fighters. Plus would have had the combat ability to fight back otw home! Much like the P40. It had better range than the P39 but not current long range fighters. The US was afraid the Russians would give them to the North Koreans. The French liked them in Libya and Vietnam.

French liked them in Libya? Where the P-63 came from, so we can sonsider them NIH?
North Koreans in ww2? Why would the P-63 be an effective ground attack aircraft?

 

[jmcalli2]

http://www.wwiiaircraftperformance.org/P-63/P-63A_42-69417_TSCEP5E-1938.pdf

Look at the graph for the P-63D;
http://www.wwiiaircraftperformance.org/P-63/p-63-chart-bell-1400.jpg

 

[drgondog]

Look at the graph for the P-63D;
http://www.wwiiaircraftperformance.org/P-63/p-63-chart-bell-1400.jpg

Unfortunately the P-63D was never flight tested by AAF, and the Allison was notoriously flawed with WI and boost over 61-63" with WI. If Allison had EVER been able to achieve to its Marketing arm, those performance figures were 'doable'.. kinda like the Allison projections for the Xp-51J and P-82's. There were several major issues with Allison that were so onerous, that NAA was experimenting with preliminary design analysis of both the Continental and R-R in 1941 during the early flight testing of the XP-51 and Mustang I.

It is a fact that the P-63 as tested and reported upon for full scale wind tunnel tests at Langley very closely approached the P-51B for minimum Profile and parasite drag - that said, it is very doubtful that the P-63 cooling/aftercooling radiator/ducting scheme would produce significant reductions in Cooling drag in comparison to all the Merlin Mustangs.

 

[tomo pauk]

Unfortunately the P-63D was never flight tested by AAF, and the Allison was notoriously flawed with WI and boost over 61-63" with WI. If Allison had EVER been able to achieve to its Marketing arm, those performance figures were 'doable'.. kinda like the Allison projections for the Xp-51J and P-82's. There were several major issues with Allison that were so onerous, that NAA was experimenting with preliminary design analysis of both the Continental and R-R in 1941 during the early flight testing of the XP-51 and Mustang I.

Going by the manual, the P-63A was cleared for 75 in Hg with WI. The V-1710 on P-82 was supposed to run at 90 in Hg, IIRC, that will be a tall order for engine without intercooler, 6.65:1 CR, no backfire screens, new type of fuel distribution unit.
No intercooler/aftercooler on P-63.

 

[Shortround6]

Part of that question is where?

From AHT so check it out somewhere else.

Tat 75in (1800hp) started to disappear pretty quick once you left sea level. At 15,000ft the engine was good for under 1500hp using water injection. under 1400hp dry WEP and and under 1300hp Military rating (54in/12lbs)

If you are trying to make power up in the mid 20s then more power is being used up in the supercharger/s ans so more power is being made in cylinders (higher pressure and more cooling problems) that making the same power to the propeller at lower altitudes. It needed 25 gallons of water for 15 minutes which is over double the water carried by an F4U or F6F and just 5 gallons less than P-47 carried.

 

[drgondog]

Going by the manual, the P-63A was cleared for 75 in Hg with WI. The V-1710 on P-82 was supposed to run at 90 in Hg, IIRC, that will be a tall order for engine without intercooler, 6.65:1 CR, no backfire screens, new type of fuel distribution unit.
No intercooler/aftercooler on P-63.

The V-1710 was de-rated to 61" - one of the many reasons Schmued, Atwood and Kindelberger despised Allison. The Allison powered P-82 performed far under the Merlin XP-82/P-82B

 

[gjs238]

Unfortunately the P-63D was never flight tested by AAF, and the Allison was notoriously flawed with WI and boost over 61-63" with WI. If Allison had EVER been able to achieve to its Marketing arm, those performance figures were 'doable'.. kinda like the Allison projections for the Xp-51J and P-82's. There were several major issues with Allison that were so onerous, that NAA was experimenting with preliminary design analysis of both the Continental and R-R in 1941 during the early flight testing of the XP-51 and Mustang I.

It is a fact that the P-63 as tested and reported upon for full scale wind tunnel tests at Langley very closely approached the P-51B for minimum Profile and parasite drag - that said, it is very doubtful that the P-63 cooling/aftercooling radiator/ducting scheme would produce significant reductions in Cooling drag in comparison to all the Merlin Mustangs.

Would you be willing to elaborate on the Allison V-1710 issues?
Very interesting!

 

[drgondog]

Would you be willing to elaborate on the Allison V-1710 issues?
Very interesting!

Several specifics - first, even as a co-GM company, Allison failed to deliver to their own commitments with respect to delivery dates. Not only for the X73 (which flew more than six weeks after airframe completed) which only flew at all because the Army 'loaned' NAA a V-1710-39.

Second, Allison Engineering and Field Service failed repeatedly to communicate the changes made to their own product, causing NAA production issues when 'new placement' of wiring harness, etc caused re-work to the X73, then followed up by sliding deliveries of the -39 by months for the production Mustang I's.

Kindelberger started looking to the Continental and Merlin XX, including design studies, in late 1941 and had a major dust up with GM BOD over Allison's performance.

Third, despite NAA input, Allison was satisfied with their 'bolt on' second stage design, which if accepted by NAA would have resulted in a complete re-design of the fuselage to accommodate the extra length.

Fourth, the design of the second stage without backfire screens for high boost associated problems with fuel-air charge temperatures failed to deliver a reliable engine for both the XP-51J and the P-82D and Subsequent. It was a lousy engine for the XP-40Q causing several engine failures during that program also.