A7M Reppu

Discussion in 'Aviation' started by spicmart, May 30, 2013.

  1. spicmart

    spicmart Member

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    I remember in a very old book to have read that the A7M Reppu should have been superior to all US fighters...well.
    It had a size about that of the Hellcat and about the same wing area.
    While the Americans, at least Grumman downsized their fighter airframes to get a real hot rod with the F8F
    the Japanese seem to have gone the other way around, why?
    Can't imagine how it could take on with a Bearcat other than outturning it.
    Anybody know more?
     
  2. tomo pauk

    tomo pauk Creator of Interesting Threads

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    With data available for the Reppu, it seems a controversy similar to the Hayate/SHinden/Raiden ones - the announced performance is way too low for the engine power available (with engines working as advertised) airplane size. We are to believe that Reppu was capable for 390 mph, on engine power size similar to P-47D (~ 430 mph).

    Grumman conceived F8F to be small light enough, so it would fit better on small carriers, while being to climb much better than F6F. Good as it was, F8F was unable to beat the F4U-4 and later as all-around CV fighter.
     
  3. Shortround6

    Shortround6 Well-Known Member

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    Please do NOT use the P-47 as a comparison unless you factor in a bunch of things. Like the P-47 was good NOT for 430mph at 20,000ft but more like 406mph (give or take) while using 2325hp and water injection. it could do 430mph higher up.

    The Reppu, at least the A7M2, while it had 2200hp for take-off was down to 1800hp at 6000 meters (19,685ft) (no turbo) which gives the P-47 almost a 30% power advantage.

    When figuring speed please use the power available at altitude.

    But please note that the Reppu was actually an older airplane than the Bearcat by about 1 to 1 1/2 years and was designed to be a more all round fighter than the Bearcat.
     
  4. davebender

    davebender Well-Known Member

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    6,000 meters would be a pretty common operational altitude for WWII era CV based fighter aircraft.
     
  5. Shortround6

    Shortround6 Well-Known Member

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    True but then everybody's 2000-2200hp take-off engines were down to 1650-1800hp at 6000 meters (if they were lucky) EXCEPT the P-47.

    The P-47 is a poor airplane to use a as comparison as it is about the ONLY single engine fighter that could keep it's take-off rating to 25,000 or above.
     
  6. tomo pauk

    tomo pauk Creator of Interesting Threads

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    Doh - silly me talking about Reppu as a turboed plane :oops:
     
  7. Shortround6

    Shortround6 Well-Known Member

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    A later version was planned to have a turbo but that prototype was never finished or flown. The 390mph at 6,000 meters seems to be for the A7M2 without turbo, 5 built but I don't know how many flown or how much. Several destroyed on the Ground bu US aircraft.
     
  8. davebender

    davebender Well-Known Member

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    F4U and F6F are the most likely opponents for a 1945 IJN CV based fighter aircraft. IMO that's the only comparison which really matters.
     
  9. Shortround6

    Shortround6 Well-Known Member

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    I think you rather missed the point. Tomo was trying to compare expected performance based on size and power due to the somewhat iffy performance numbers for some Japanese planes.

    The F6F and F4U are better for THIS type of comparison but for type of powerplant---power at altitude -----size of aircraft,,,,NOT just because they were the expected opponent/s.
     
  10. Aozora

    Aozora Well-Known Member

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    The A7M1 was officially clocked at 357 mph at 20,310 ft with a Nakajima NK9K Homare 22 rated at 1,570 hp at 22,475 ft
    Wingspan = 45'11⅜" area =332.173 sq ft: length =36'0⅞"
    Loaded weight = 9,722 lb: Power Loading =4.9 lb/hp
    Armament = 2 x 20mm Type 99 Mod 2 cannon, 2x 13.2mm Type 3 mg.

    A7M2 (almost identical dimensions, same wing area, armament) with Mitsubishi MK9A 1,800 hp at 19,685 ft = 390 mph: weight loaded = 10,406 lb
    so roughly the same performance as the F6F-5, albeit probably more manoeuverable - Japanese pilots commented favourably on the latter, comparing the A7M1 with the A6M when using manoeuvering flaps!
     
  11. GregP

    GregP Well-Known Member

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    #11 GregP, May 31, 2013
    Last edited: May 31, 2013
    Can't say I would agree the F8F doesn't match the F4U-4 as a fighter, but we all have our own thoughts on it. You could probably make a decent case either way.

    The A7M Reppu may have had lower performance due to several things, one being differences in propeller design. The Japanese seemed to use shorter props, as on the Raiden, than we did. That will affect speed and climb.

    Also, it is possible they weren't using quite the same octane fuel as the US Navy was using. I know the Nakajima Ki-84's they tested after the war were faster than previously reported and were fueled with out best gasoline for the tests. Seems to me there was a thread about Japanese fuel quality sometime in the recent past.

    Like some in here, I wish we had good flight test reports available for all types ...
     
  12. tomo pauk

    tomo pauk Creator of Interesting Threads

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    It took the F8F to became F8F-2 in order to equal the contemporary Corsair, the F4U-5. Despite lower drag weight, the -1 Bearcat was incapable to out-pace the F4U-4 at higher altitudes - it lacked the engine power. The analogy between P-47D and Fw-190A?

    Thanks for the data.
    Think we can see here the equivalent of the F6F here, and it ain't going to cut vs. 1945 Allied opposition, even if Japanese have had actually built Reppus in quantity.

    Yep, Japanese were quick to adopt Fowler/butterfly flaps for their fighters.
     
  13. GregP

    GregP Well-Known Member

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    #13 GregP, May 31, 2013
    Last edited: May 31, 2013
    It's funny the F8F lacked the engine power since it was running the same engine as the Corsair, just a different dash number. If I recall correctly the F4U-4 used the R-2800-18W and the F8F-2 used the R-2800-30W.

    I have the F8F-2 at 455 mph at about 20,000 feet and the F4U-4 at 446 mph at about 20,000 feet. Naturally both speeds are for clean aircraft without racks.
     
  14. Shortround6

    Shortround6 Well-Known Member

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    Not so funny when you realize that different dash numbers meant different superchargers. And different superchargers meant rather different power at altitude.

    Also different dash numbers could mean different series engines.

    The R-2800-18W was a "C" series engine with a 2 stage supercharger and the R-2800-30W was an "E" series engine with a single stage supercharger with variable speed drive. At Military rating (no water injection) the -18W had 200 more horsepower 1000ft higher. The F4U-5 used a R-2800-32W engine. Same engine?? "E" series with two stage supercharger with the parallel sidewinder impellers in the "1st" stage. Made as much power as the -18W only 7,000 ft higher or 200 HP more than the -3-W 8,000ft higher.
     
  15. GregP

    GregP Well-Known Member

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    Yah, I know the power ratings but still feel 455 mph is somewhat faster than 446 mph, though the 2% difference could easily be coverd whithin individual aircraft variance. I KNOW the F8F-2 will out climb and turn inside the F4U-4.

    I think the Corsair was better at groud attack, but the F8F was the better air superiority fighter. Many Corsair fans won't agree, and you may be one. Good thing they were on the same side, huh?
     
  16. Coyote

    Coyote Member

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    Your also talking a stock off the line first series Bearcat with a -4 Corsair. Give Grumman another year to modify the F8F and it would be better. As far as the A7M Reppu, woulda been a good fight for any of the allied fighters at the time and was a damn fine looking plane.
     
  17. Shortround6

    Shortround6 Well-Known Member

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    #17 Shortround6, May 31, 2013
    Last edited: May 31, 2013
    I don't know about being a fan but I do like to compare aircraft of the same age.

    F8F-1, first flight 21 August 1944, The first production aircraft was delivered in February 1945. Engine was either a _22W or -34W (most or all production -1s had the R-2800-34W?) with 1700hp at 16,000ft. Speed 421mph at 19,700ft ?
    F4U-4, first flight Sept 1944, The first production aircraft was delivered in December 1944. Engine was a -18W with 1800hp at 23,000ft. Speed 446mph at 26,200ft ?

    and:
    F8F-2, The first production aircraft was delivered in October 11 1947. Engine was a -30W with 1600hp at 22,000ft. Speed 447 mph at 28,000ft or 455 mph if you prefer.
    F4U-5, The first production aircraft was delivered in November 1947. Engine was a -32W with 1800hp at 30,000ft. Speed 470 mph at 26,800ft .

    It does not surprise me that a 1947 fighter can beat a 1944 fighter even with peace time development. But when comparing the 1944 versions to each other and the the 1947 versions to each other things may not be so clear cut.
     
  18. GregP

    GregP Well-Known Member

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    Decent points. I'm not too concerned about 15 -25 mph speed differences as much as which one is better when they engage.

    I'd take a Bearcat any day since once in contact, it is the better fighter. The Corsair may be able to disengage and may get shot down if he tries to do so. It would probably come down to which pilot was better or, if nearly equal, which one started in a better position. They didn't build many Bearcats, and an F8F-2 is an F8F-2, regardless of year. They were all built to the same spec.

    As you might be able to tell, the F8F-2 is my favorite piston fighter of all times with the Hawker Sea Fury running a close second. In pure looks, the Sea Fury takes the prize for me, but the Bearcat will waltz away from a Sea Fury in climb and maneuverability while the Sea Fury is faster by a small margin ... 460 mph if I recall correctly.

    I'd love to fly either one, as would probably anyone interested enough to be in here.
     
  19. Shortround6

    Shortround6 Well-Known Member

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    They were intended for somewhat different jobs.

    The F8F-1 was intended for low/medium altitude and for use on small carriers, in part replacing the FM-2.

    The F4U-4 was intended for more all round operation including higher altitudes.

    The F8F-2 was still intended for low/medium altitude although it's improved engine moved it's operational heights up.

    The F4U-5 was intended for higher altitude operation, in fact perhaps higher than some of the early jets could really manage. Although at at about 400 mph at sea level with combat power and a climb at sea level (clean) of 4800fpm with combat power it was no slouch at low altitude.
     
  20. Aozora

    Aozora Well-Known Member

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    Getting back to the A7M2, I can't help thinking that it wouldn't have been much of an improvement, if any, over the N1K2-J:

    * it was a bigger airframe, thus more wasteful of scarce resources, which Japan could not afford to waste;

    * it introduced yet another engine type into the supply chain - AFAIK the Mitsubishi MK9A was not being used in any other operational aircraft, and there is no guarantee that it would have proven to be more reliable than the NK9 Homare series;

    * it had less fire-power, with 2 cannon and 2 heavy mgs versus 4 cannon;

    * it still had no decisive performance advantage over the F6F or F4U-1, apart from manoeuverability - no doubt it would have been a handful, but with the generally superior American teamwork and tactics what ever advantage it did have would have been mostly nullified.
     

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