Does anyone have a best guess on how fast the Grumman XF5F Skyrocket was at sea level

Discussion in 'Aviation' started by pinsog, Oct 19, 2015.

  1. pinsog

    pinsog Member

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    Grumman XF5F Skyrocket, 2 1200 hp radials and supposedly 380 mph at 20,000 feet. Best guess on top speed at sea level?
     
  2. fubar57

    fubar57 Well-Known Member

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  3. pinsog

    pinsog Member

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    I had read that article, but I believe 383 at sea level is incorrect. Article says that it would "only do 383 at sea level" when at that time, I believe 383 at sea level would have been the fastest sea level aircraft in the world. Other sources give 383 at 20,000 feet which seems much more reasonable
     
  4. tomo pauk

    tomo pauk Creator of Interesting Threads

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  5. pinsog

    pinsog Member

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    Why not 380 at 20,000 get where the air is thin? It had 2400 hp. The British Whirlwind did 360 mph at sea level with 885 hp per side. Surely 1200 preside would make up some for the extra drag. I would have changed the engines to the smaller diameter Pratt and Whitneys with the 2 speed 2 stage supercharger
     
  6. tomo pauk

    tomo pauk Creator of Interesting Threads

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    #6 tomo pauk, Oct 19, 2015
    Last edited: Oct 19, 2015
    1200 HP was the take off rating. At 14000 ft, the available power was 900 HP per engine, at 20000 it dropped down to maybe 700 HP? The Whirly have had a smaller wing, that coupled with a far smaller powerplant drag meant significantly less total drag = greater speed. Also, an armed F5F will be slower than the XF5F.

    Going for even military rated Cyclones would've helped. The single stage 2-speed R-1830 further improves situation, let alone the 2-stage supercharged one. If one wants to be really naughty - stick the V-1710 on it.
    Granted, the 2-stage R-1830 and V-1710 will require some re-balancing in orcer for the CoG to remain under control.
     
  7. pinsog

    pinsog Member

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    V1710's would relegate it to the same fate as the Whirlwind, P40, P39 etc, only good for low altitude. Best guess for top speed with P&W at sea level and at 20,000 feet?
     
  8. GrauGeist

    GrauGeist Well-Known Member

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    The USAAC version, XP-50 was actually faster with it's supercharged R-1820-67/69 radials giving it a max. speed of 424mph (680kph) @ 25,000 feet (7,620m).
     
  9. pinsog

    pinsog Member

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    Do you believe those numbers? Do you believe 424 mph at 25,000? Do you believe 382 at 20,000 for the XF5F? I like the little fighter. Same basic size as a Hellcat or Corsair, more hp to begin with, and could have been ready a lot earlier than the Hellcat or Corsair. I think the XF5F could have been the fighter we needed at the beginning of the war when the Zero gave us so much trouble.
     
  10. tomo pauk

    tomo pauk Creator of Interesting Threads

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    The F5F with V-1710 would be at least as a good performer as the much vaunted Fw 187 with DB 601A; however, neither of the two never sported self sealing tanks (granted, nor did the early Japanese opposition, Zero was without those at any time). The F5F have had a lousy visibility downwards, however.
    Both engine, engine installation and airframe development of the Whirly ended abruptly, that it would not be the case for the Allison F5F had it ever entered the production. We might also recall that P-40 and Whirly were offering better or equal performance vs. Zero, bar the RoC above 20000 ft.
    As for the top speed - the unamed X5F5 was supposed to make 357-358 mph at 17300 ft (on 900 HP with ram effect). The 2-stage R-1830 will have 1000-1100 HP at ~21000 ft with ram - 380 mph? Subtract 10 mph due to armament that will be installed and it makes 370 mph, still 20 mph better than most of the Zero marks?

    The 424 mph figure for the XP-50 will require a great leap of faith. The much more streamlined P-38 needed 1500+ HP to beat the 420 mph mark, and it's powerplant drag was far smaller than that of the XP-50.
    The F5F will have a comparable drag as the F4U or F6F with 2 drop tanks?
    If we really want for the US to have better fighters early on, then there is several options I prefer more. Like a greater emphasis on the P-38 production, then jumping on the opportunity with Mustang as early as possible, while the USN/USMC might promptly develop the XF4U in a series produced fighter mostly as-is (but with: another pair of BMGs in the wing bomb bay; fuel tank under the pilot, will also mean that pilot has better visibilty over nose).
     
  11. pinsog

    pinsog Member

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    F5F had horrible visibility down left and down right, but look at that bubble canopy, visibility was great everywhere else. I would absolutely go with the P&W 2 speed, 2 stage engines over the Wright Cyclones for better altitude performance. Even fully armed it should weigh the same or less than a Hellcat or Corsair, around 4 feet shorter and about the same wing. It should still have a fantastic climb, good altitude performance, and have about the same performance as a Hellcat with better climb. I would take that in 1941-42 if I were an American fighting the Zero. 4 .50 machine guns together in the nose would be effective against anything the US had to shoot at. I think it is a great package that should have been in production before the US entered the war. The test pilot said the Spitfire came in 2nd in a fly off between them.
     
  12. GregP

    GregP Well-Known Member

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    Here's an old sketch I found years ago somewhere online:

    Grumman_XF5F.jpg

    Not all that detailed, but great to throw into a newsletter or whatever. We do a monthly newsletter for the planes of Fame volunteers.

    I think you'd probably all agree that the XF5F would be difficult to mistake for another aircraft .... it was certainly ... unusual looking, to say the least.
     
  13. pinsog

    pinsog Member

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    Greg, it was downright homely looking. But I bet a US Marine or US Navy pilot would think it was the most beautiful plane ever built if he was either outrunning, or climbing up and away from a flight of Zero's instead of getting shot down in a Wildcat or a P40
     
  14. GregP

    GregP Well-Known Member

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    #14 GregP, Oct 21, 2015
    Last edited: Oct 22, 2015
    I was thinking the same.

    It probably could roll with a Zero (almost anything could), probably could not turn with it, but could probably easily outclimb it ... maybe one and a half an early Zero's climb rate or near that.

    But 1 or 2 airfames isn't much of a fight ... the actual airframe performance ins't nearly as much of a factor as the real-world COMBAT performance of the population.

    1,000 P-51 Mustangs will absolutely KILL a MiG-15. SOMEONE will lead it just right. They might lose some, but the MiG-15 wouldn't be very welcome in the P-51 sky volume.

    They only made 1 or 2 X5F's so they were not a factor at all in real-life combat.

    COULD have been but weren't.
     
  15. Jabberwocky

    Jabberwocky Active Member

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    From information in the Flight Test Data sub-forum, - the December 1942 Navy performance data sheet - I have the following XF5F-1 speeds at normal load and R-1820-G321 engine at 1000 hp normal rating, 1200 hp take off rating:

    Sea Level: 312 mph
    4500 ft: 326 mph
    7300 ft: 324 mph
    14,000 ft: 346 mph
    20,000 ft: 352 mph

    Max speed: 358 mph at 17,300
     
  16. GregP

    GregP Well-Known Member

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    #16 GregP, Oct 22, 2015
    Last edited: Oct 22, 2015
    Sort of a meduim dog, huh? Not bad ... but also not all that good.

    The Zero wasn't all that fast, but was faster than that.

    I hope it could climb well ...
     
  17. Jabberwocky

    Jabberwocky Active Member

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    From the performance data, I don't think an XF5F is going to be doing much outclimbing of a Zero. By the time it would have been ready for combat - say mid 1942 - the Zero would have at better on RoC (and close in speed).

    Testing data shows the Skyrocket at 4.2 minutes to 10,000 ft and 9.3 to 20,000 ft.

    US TAIC tests show the A6M 32 at 3 min 10,000 and 7 min to 20,000 ft.

    Quite a deficit.
     
  18. GregP

    GregP Well-Known Member

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    I have the XF5F at 4,000 feet per minute initial climb ... but with a ceiling of only 33,000 feet. I don't think they would have stayed with 1,200 HP engines for very long, but I suppose you are right. I was actually thinking of the A6M2 as an early opponent, not the A6M3 Model 32.

    And the Grumman XP-50 was the follow-on and climbed better than 4,100 feet per minute with a service ceiling of 40,000 feet. They would have either fixed the XF5F's climb rate / /ceiling or maybe gone with the better-performing plane, had they elected to go that way. We know they didn't, but the potential was there had the choice been elected.
     
  19. tomo pauk

    tomo pauk Creator of Interesting Threads

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    Adding armament, ammo, protection for the pilot and fuel, plus more fuel will play havoc with RoC of serial produced examples. I'd rather see stepping up the production of P-38s, starting up in 1941, than wait until 1942 for a lesser fighter anyway.
     
  20. GregP

    GregP Well-Known Member

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    #20 GregP, Oct 23, 2015
    Last edited: Jan 7, 2016
    Agree, Tomo. I was playing with the idea that they might have adopted the big radial twin, not what they SHOULD have done. To me, they SHOULD have fixed the P-38's low critical Mach number issue, gone with Hydraulic ailerons much earlier, and probably added slats and area-increasing maneuvering flaps.


    But, that's all with 20-20 hindsight. I am also of the opinion they could have designed and deployed the Bearcat considerably earlier than they did.

    Alas, what happened has been recorded and no "alternate histories," fun though they may be to contemplate, are possible unless someone invents a practical time machine. Then they'd have to be able to convince people that they knew what they were talking about in a WWII-era world that was nothing if not consoderably different from today in what would be accepted by anyone in power at either manufacturing companies or the governments of ANY country.
     
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