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Thread: P-47D performance | Forums

  1. #1
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    For reference throughout this post I have used the following test report as the basis for my conclusions:

    http://www.wwiiaircraftperformance.o...p47-26167.html

    After a rather heated discussion regarding P-47D performance on the warclouds forums ( http://www.war-clouds.com/modules.php?name=Forums&file=...topic&t=1915&start =0 ), I felt moved to conduct some testing, and have concluded that the P-47D's altitude performance with regard to top speed is somewhat excessive. The same may also be said of its low level speed performance.

    Most glaring as regards kinematic performance however would appear to be a considerable error in its rate of climb, though I have yet to conduct tests.

    In addition, the P-47D does not appear to suffer from any form of overheating at altitude, which would appear to be historically inaccurate based upon the following, taken from the Recommendations section of the report:

    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">It is recommended that pilots using these higher powers be cautioned concerning the high cylinder head temperatures and carburetor air temperatures which may be encountered in extended climbs or level flight. </div></BLOCKQUOTE>

    Irrespective of the accuracy or otherwise of actual overheating, it would appear that overheating is used in general within the sim as a device to prevent players from greatly exceeding various engine limitations (such for example as the 5 minute limitation for +25 psi operations of the Mustang III, or 67"Hg operations of the P-51B-D) despite the fact that test documentation would suggest that overheating would not in fact limit performance at high speed (see http://www.wwiiaircraftperformance.o...51h-64161.html , which cites average radiator openings of 8" corrected to give performance equivalent to a flush radiator [7¼" opening], and http://www.wwiiaircraftperformance.o...ang/tk589.html which cites a radiator adjustment to 8½" opening to provide adequate cooling at +25 psi, thus suggesting that normal engine temperatures should in fact be provided by the AUTOMATIC radiator setting in level flight even at high powers)

    As such, the P-47 appears to be something of an anomaly, which it would be nice to see corrected.

    IL2 Compare for v4.07 has been used as the source of performance graphs for convenience. However, tracks taken in v4.08 will be supplied to support the IL2C data.

    Without further ado, here is the data:

    Speed vs manifold pressure and altitude (in game via IL2C with R/L overlaid):

    http://www.war-clouds.com/modules.ph...ownload&id=485

    Climb rate vs manifold pressure and altitude (in game via IL2C with R/L overlaid):

    http://www.war-clouds.com/modules.ph...ownload&id=488

    Very long track of the P-47D being flown at 110% power with WEP until the water runs out, and then at 110% power without WEP until the fuel runs out at altitude (also demonstrates top speed capability in agreement with IL2C):

    http://www.war-clouds.com/modules.ph...ownload&id=469

    Note when viewing the above that water injection should in fact only be available for a total of 11 minutes of continuous use, at least in those blocks of P-47D fitted with 15 U.S. Gallon water tanks. See:

    http://www.zenoswarbirdvideos.com/re...aeroRV1056.ram

    *edit* JtD has updated his work, and has therefore asked me to remove his earlier test data to avoid confusion.
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  2. #2
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    For reference throughout this post I have used the following test report as the basis for my conclusions:

    http://www.wwiiaircraftperformance.o...p47-26167.html

    After a rather heated discussion regarding P-47D performance on the warclouds forums ( http://www.war-clouds.com/modules.php?name=Forums&file=...topic&t=1915&start =0 ), I felt moved to conduct some testing, and have concluded that the P-47D's altitude performance with regard to top speed is somewhat excessive. The same may also be said of its low level speed performance.

    Most glaring as regards kinematic performance however would appear to be a considerable error in its rate of climb, though I have yet to conduct tests.

    In addition, the P-47D does not appear to suffer from any form of overheating at altitude, which would appear to be historically inaccurate based upon the following, taken from the Recommendations section of the report:

    It is recommended that pilots using these higher powers be cautioned concerning the high cylinder head temperatures and carburetor air temperatures which may be encountered in extended climbs or level flight.
    Irrespective of the accuracy or otherwise of actual overheating, it would appear that overheating is used in general within the sim as a device to prevent players from greatly exceeding various engine limitations (such for example as the 5 minute limitation for +25 psi operations of the Mustang III, or 67"Hg operations of the P-51B-D) despite the fact that test documentation would suggest that overheating would not in fact limit performance at high speed (see http://www.wwiiaircraftperformance.o...51h-64161.html , which cites average radiator openings of 8" corrected to give performance equivalent to a flush radiator [7¼" opening], and http://www.wwiiaircraftperformance.o...ang/tk589.html which cites a radiator adjustment to 8½" opening to provide adequate cooling at +25 psi, thus suggesting that normal engine temperatures should in fact be provided by the AUTOMATIC radiator setting in level flight even at high powers)

    As such, the P-47 appears to be something of an anomaly, which it would be nice to see corrected.

    IL2 Compare for v4.07 has been used as the source of performance graphs for convenience. However, tracks taken in v4.08 will be supplied to support the IL2C data.

    Without further ado, here is the data:

    Speed vs manifold pressure and altitude (in game via IL2C with R/L overlaid):

    http://www.war-clouds.com/modules.ph...ownload&id=485

    Climb rate vs manifold pressure and altitude (in game via IL2C with R/L overlaid):

    http://www.war-clouds.com/modules.ph...ownload&id=488

    Very long track of the P-47D being flown at 110% power with WEP until the water runs out, and then at 110% power without WEP until the fuel runs out at altitude (also demonstrates top speed capability in agreement with IL2C):

    http://www.war-clouds.com/modules.ph...ownload&id=469

    Note when viewing the above that water injection should in fact only be available for a total of 11 minutes of continuous use, at least in those blocks of P-47D fitted with 15 U.S. Gallon water tanks. See:

    http://www.zenoswarbirdvideos.com/re...aeroRV1056.ram

    *edit* JtD has updated his work, and has therefore asked me to remove his earlier test data to avoid confusion.
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  3. #3
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    i personaly would be happy if the ingame D-22 would have the performance of the D-27!

    so we would have a Razorback and Bubbletop JUG with almost the same perfomance.
    and not two Razorbacks with almost the same performance like it is now, with the main difference of wingracks.............
    .....................................
    and before you have to ask:
    Shift + F1 will center the sight.

    Ctrl + D will remove the lenscap

    F4F and I-16 has manual landing gear only
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  4. #4
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    Check the data posted and perhaps you'll reconsider, especially considering that the razorback should have less drag than the bubble canopy version.

    IMO the "D" has excessive performance. The D-27 in game is roughly equivalent to 70" Hg with water injection, and climbs too fast into the bargain.

    Since I provide data for a variety of ratings going down to 52" Hg, you can compare the D-10 and D-22 with R/L performance data if you so wish.

    The R/L data was collected using a razorback P-47D, so I'm guessing its block number was somewhere between 22 and 25; since the serial number is known I'm sure that somebody with more knowledge of such minutiae can provide a concrete answer...

    IMO the performance of the P-47 needs to be reconsidered, especially at extreme low and high altitudes (ironically where most of them are found, either ground pounding or skywriting...). It might be more accurate to give the current D performance somewhat closer to the D-27, whilst giving the D-27 performance somewhat closer to the D-22.

    However, since I haven't examined the D-22 I can't really comment on that.

    What I can say is that the current 150 grade P-47D seems to over-perform if its performance is based upon 70" Hg; and in that case I would also point out that the report quoted above only suggests that 65" Hg be approved for service. <span class="ev_code_red">Edit - Mike Williams has just contacted me to point out that in fact 70" Hg was in fact approved for operations by 22/06/44 - see http://www.wwiiaircraftperformance.o...ess-report.pdf Thanks Mike!</span>

    Oh and BTW, the P-47D could also do with a very simple cockpit modification - the fuel placard needs to be updated from 100/130 grade to 150 grade. I'm sure that this simple change shouldn't take too long.
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  5. #5
    Interesting find if it is true. I really didn't think there was a American or British plane that was "overmodelled" except for the P-39 and maybe the Spit Mk V in rate of climb.

    I've often wondered about the SL speed of the Wildcat but don't have the data to say it is too fast...a few planes like the P-38J is too fast at sea level but too slow at altitude...kind of a trade off.

    I wonder what data Oleg modelled the P-47D after? Also interesting about the overheating...an interesting diabolical twist since none of the radiators on P&W engined aircraft actually cool the engine. They do drag/slow the aircraft down when open though.
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  6. #6
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    Mustang III was too fast for a while but it was fixed after a similar thread...
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  7. #7
    Got Spanked up high didn't you
    BPO6_PANP
    CO Birds Of Prey
    http://www.birdsofprey16thgviap.com
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  8. #8
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    Constructive...

    Now, look at the evidence, and tell me that the P-47D as modelled is correct. Otherwise STFU. Thankyou.
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  9. #9
    Very well put, thanks for the charts and data sources.

    I wish Oleg's team could model every plane according to its historical performance.

    But this looks like something impossible.

    I think you are concerned most for the climb rate of the Jug.
    If you use IL2Compare for a source to represent in-game performance, you should notice that most of the planes do climb much better.

    Take a look at La-7 for example .. Historical climb rate at sea level was 21-24m/s (according to different sources) in game
    it climbs with 27m/s.
    Bf-109G2 climbs to 5000meters in less than 4 minutes in the game, while the best time I know is 4,4min.

    So generally what we have now is somewhat accurate relative performance.

    Concerning non-overheating engine, I can mention MiG-3 AM-38. It should overheat a lot, that's even noticed in plane's description. But it doesn't at all...
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  10. #10
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BPO6_PANP:
    Got Spanked up high didn't you </div></BLOCKQUOTE>

    LOL that was Bubi that got spanked last night....but sounds true. LOL ~S~ PANP I do appreciate the testing and data tho Viper. It's always good to see good data on any ac.


    http://310thvcs.com/
    High Alt King
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