F6F-5 vs J2M3

Discussion in 'Flight Test Data' started by krieghund, Oct 19, 2010.

  1. krieghund

    krieghund Member

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    #1 krieghund, Oct 19, 2010
    Last edited: Nov 14, 2010
    As promised I finally scanned this comparison. I got it in the mid 1980's there were to be others but when I wrote the author he said he had poor reviews and decided not to do any others. I suspect he wrote the P40C vs A6M2 comparison in the early 1970s.

    Anyway enjoy
     

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  2. CliffyB

    CliffyB Member

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    Thanks for the post man! Some really neat info in there and love the photos of the captured Jack!!!!! Now does anyone make a kit of one? :twisted:
     
  3. Civettone

    Civettone Active Member

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    Only read the first half but love it. It is really the type of literature I can appreciate. No nonsense.

    I wonder though how computers and computer models in those days were accurate enough.

    Kris
     
  4. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Bill M. can answer that!
     
  5. Civettone

    Civettone Active Member

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    No one could do it better!


    (I also noticed I wrote 'how' while I meant 'if')
    Kris
     
  6. tomo pauk

    tomo pauk Creator of Interesting Threads

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    Such a simple way to talk about the complicated issues. Many thanks :)
     
  7. Gaston

    Gaston Banned

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    I dont disagree with the conclusions here, but how they were drawn: Would his method have predicted the poor turn performance of the N1K1 George, whose pilots described a severe handling problem that in hard turns could induce an unpredictable wobbly "autorotation", even with automatic flaps deployed, and that this was a major drawback of the type, so much so that the N1K1 was used mainly in boom and zoom attacks and on the vertical plane?

    I doubt it...

    Gaston
     
  8. Civettone

    Civettone Active Member

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    Interesting. Was this fixed with the N1K2-J ?


    Kris
     
  9. Glider

    Glider Well-Known Member

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    My respect for the J2M3 has increased a lot with this. I admit that I always had it as a bit of a brick in terms of agility, wrong again but thats how you learn.
     
  10. Civettone

    Civettone Active Member

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    What I also like about the Raiden and which is not mentioned is that it was a powerful but also reliable engine. The japanese had the Kasei engine already mid war but was only for their bombers, as it was too big for fighter aircraft. They succeeded in getting it into this aircraft. The other fighters like the Ki-84 and N1K2J as well as most of the projected fighters had the less reliable Homare engine.

    Kris
     
  11. Ivan1GFP

    Ivan1GFP Member

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    I believe the straight line performance of the Raiden is WAY understated here. US tests make this aircraft MUCH faster than is quoted here. TAIC 105B Data sheet on Jack 21 states 359 mph (WEP) at sea level, 417 mph (WEP) at 16,600 feet. This plane will hit 385 mph while carrying a 250 liter drop tank.

    - Ivan.
     
  12. slaterat

    slaterat Member

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    Wow, what a great article thanks for posting it.
     
  13. icepac

    icepac Member

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    One thing we should probably take with a grain of salt is the japanese pilots' opinion of the handling of the late war interceptors.

    These guys flew the zero or ki43 before transitioning into the j2m3, ki84, and N1K2 so thier opinion of the "handling" is purely by comparison to previous models flown.
     
  14. snowmobileman

    snowmobileman New Member

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    Interesting article! I know this is years old, but I noticed that the author listed the F6F-5 ceiling as 31,000', and that was a major performance detriment in his opinion. The numbers I have seen from WW2aircraftperformance list the ceiling at 38,000', give or take. That might even things out a bit...
     
  15. swampyankee

    swampyankee Active Member

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    For the gross behavior of external airflow, the models and computers were probably accurate enough if the boundary layer was reasonably well-behaved, which it should be at low-angle of attack conditions, i.e., don't trust any predictions of separation, and the drawings accurately represented the built aircraft and the drawings could be accurately digitized. For internal airflows, like cooling, the models of that time were not accurate enough to predict things like pressure losses through radiators (liquid-cooled) or cylinder baffles (air-cooled). They would also be unreliable when predicting flow over things like open wheel wells, various drags due leaks, and gun ports, all of which may cause local separation.

    The main shortcoming with the computers would be that their memory limits -- the mainframe at my college had only about 0.5 mebibytes of core (random-access memory) and about 30 mebibytes of drum (== hard disk) storage. Modern computers have much more memory and storage, so the models can be much more detailed. Their computational accuracy, from a purely numerical standpoint, was probably as good as today's (my college mainframe had 96-bit doubles), although the algorithms weren't as well-behaved under some conditions.
     
  16. Ivan1GFP

    Ivan1GFP Member

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    I believe this isn't really a poor turn performance problem as an inadequate directional stability problem.
    Yes, this problem was corrected in the N1K2-J. In fact, I suspect it was over corrected in the N1K2-J which might explain why the N1K2-J-Ko had a reduced chord fin.

    I believe the biggest problem with this report is "Garbage In == Garbage Out". The performace of J2M3 is way under what the real aircraft could do.
    The issue with F6F service ceiling is probably because it was reported for 500 fpm rather than 100 fpm.
    (Just a guess.)

    - Ivan.
     
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