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

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I'm not too sure the low critical Mach number couldn't have been fixed without a major redesign. It would certainly make for a change in tooling, but the wing profile might have been changed and the shock waves moveda bit ... I KNOW we could do it today and am wrestling with whether or not they could reasonably have done so with the knowledge available to them at the time.

That they DIDN'T fix it doesn't mean they couldn't have ... it means the change would have come during wartime production. That fact alone stopped some real improvements to the Hellcat and a few others as well, so maybe even if they COULD have done it, they wouldn't have. I'm leaning toward thinking they COULD have fixed it but elected not to, probably because the P-38 was an older fighter like the P-40 was.

When the XP-40Q showed what it could do, they elected not to produce it; and it would have outperformed all but a handful of what was flying in most theaters other than the ETO. At minimum, it would have been a serious upgrade in theaters where the P-40 was soldiering on ... but again, it was an older airframe and maybe the incentive just wasn't there.

More likely, the decision was made by non-pilots who were not aware of the seriousness of being outperformed on a regular basis by enemy aircraft. It was probably political as well.
 
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The halt of the production lines for the P-38 would've probably lasted for weeks had the major redesign took place, and that will kill the project had there been any; the example of what happened to XP-38 is just too clear, and there was a minor change of airframe involved there.


The XP-40 have had no legs for theaters other tham ETO, nor for ETO itself. Want a performer with legs made by Curtiss? They better sort out their production of P-47 then.

More likely, the decision was made by non-pilots who were not aware of the seriousness of being outperformed on a regular basis by enemy aircraft. It was probably political as well.
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The non-pilots were right in their decision to axe the (X)P-40Q - it is too late to matter, the ~300 miles of radius is pathetic, performance does not offer anything vs. current trio of fighters.
 
It offers a LOT above the current trio of fighters that weren't deployed to places where P-40s were. If you were ina P-40 theater, you got second-line stuff and the P-40Q was WAY better than a stock P-40 in those places. I thought I made that clear. They made the wrong desicsion in my book and should have not had Curtiss make the P-47G. They made only a handful.

We'll probably never think alike, Tomo, but the discussion is fun anyway.

One thing we can probably agree on is they should NOT have made the P-40-Twin! It is abysmal-looking. They shouldn't have even made the prototype ...
 
GregP said:
It offers a LOT above the current trio of fighters that weren't deployed to places where P-40s were. If you were ina P-40 theater, you got second-line stuff and the P-40Q was WAY better than a stock P-40 in those places. I thought I made that clear.
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By the time (late 1944) we can expect the serial produced P-40Q (with that F28R engine, of course), the USA produces more P-51/48/38 fighters than it can use. There were no 'P-40 theters' by late 1944. Historically, per 'America's hundred thousand': Sept 1944: The 23rd fighter group in China is swithching from P-40s to the P-51Cs.

Deploying a '300 mile' P-40Q instead '700 mile' P-51 or P-38 would be quite a task of it's own, and not worth it when acomplished.

 
tomo pauk said:
Yep, I love discussions.
It is too bad the powers to be (or whatever is the term) haven't stepped earlier at Curtiss, with the grim demand that either the prdouction of the P-47G is stepped up, or that accusations of sabotage will be issued.
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I wonder if the P-51 would have been a better fit for Curtiss to license-produce.
 
Question about XF5F climb rate: The XF5F had almost the same wingspan as an F6F, almost the same wing area as an F6F, loaded weight was 2,500 pounds less than an F6F and had 2,400 hp split between 2 3 blade props vs 2,000 hp applied to 1 prop. Why is it hard to believe the climb rate of the XF5F would be anything but stellar? The F6F could out climb a Zero, the XF5F should run circles around either of them.

Also, there is nothing special about the Skyrocket as far as technology. The engines are off the shelf from the time period (but they should use the P&W 1830, no the Wright Cyclones)the prototype flew April 1, 1940. I just don't see a reason why this plane couldn't be in production just before the start of the war instead of the F4F.
 
The F4F was first flown in 1937 and after three more years of trials and development, was introduced in 1940.

The XF5F first flew in 1940 and would be several more years of trials and development to make it to delivery, about 1943 if we use averages for other aircraft being developed at the time. However, several things to be considered here:

First, the XF5 was proving to have several difficulties, it's CoG effected it's handling, (which the Army's version, the XP-50 solved) it was also found to be time consuming to maintain and aquisition of materials for it's construction turned out to be a logistical problem.

Secondly, war clouds were gathering on the horizon. The Wildcat had just been accepted into Naval service about the time the Skyrocket was taking it's first flight. Also consider that the R-1820 was in high demand (used in mearly a dozen aircraft types at the time) as the U.S. hadn't started on it's war-time production yet.

And suppose that the Navy had put all it's eggs in one basket, turned back F4F production in favor of accelerated XF5 development/production and then War broke out nearly a year before the XF5 was to enter production. That would mean that the only aircraft the USN would have available in any quantities, would be the F2A and older F3F and would have been a disasterous decision.
 
Hi pinsog,

I was thinking very similarly. The XF5F could indeed have been in production. But the very meager data on it makes me think there is probably a reason it wasn't. The XP-50 could also have been adopted. I'm sure there was a reason why they didn't proceed, but the F7F Tigercat was a good one.

Hi Tomo,

I don't see anything in the XP-40Q that could not have been put there a couple of years earlier had the inclination to improve it been there. If we stick with the real-world timeline, then you are correct about the P-40Q. But, if we are playing with what might-have-been, then it's another story.

Actually I prefer to stick with the real world, but the XF5F discussion sort of runs into the what-if realm, making me want to have the P-40Q in 1942 (possible but didn't happen). Theaters other than the ETO got hand-me-down until the ETO was won, and the P-40Q would have been a giant step in performance. There is NO reaosn why it could not have had better range, If nothing else, they could have equipped it with drop tank like they did the P-51 ... one under each wing.

For every objection there is a what-if that can address it.

In the real world, the XP-40Q was too little, too late; I agree.
 
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I get the feeling the XF5F's famous 4000 fpm initial RoC was either at very low level or for a version without armament, self-sealing fuel tanks, armour and all the other military necessities that tended to weigh down combat aircraft.

The spec sheet I have gives a 7,990 empty weight and 10,021 lb loaded weight - no telling if that was with or without armament, as the guns/rnds ammunition cells are empty. Overload with 99 more gals of gas is 10891 lb. Wing area is given as 303 sq ft. Props used were three-bladed Curtis of 10 ft length .

In comparison, a F6F-3 with full internal fuel and armament/ammo is 11,365-11,550 lbs, or 12,200-12,600 lbs at overload with an extra 70-ish gallons of gas. Wing area is 334 sq ft, or 10% better than the XF5F-1

The F6F was never a great climber - F6F-3 performance testing at WW2 aircraft performance gives me max rates of climb between 2250 fpm and 3600 fpm, with an average at about 2750-2900 fpm. Certainly not a 109 or a Spitfire.

I get the impression that the XF5F-1 was cleared for power of 1200 hp for take-off and initial climb only. My suspicion is that the rest of the climb is performed at max output of 1000 hp/2300 rpm, or lower.
 
The XF5F was tested without ammo guns, per SAC I've provided the link earlier in the thread. An article at alternatewars.com ststes that no proection was provided, not for pilot nor for the fuel, and that it will be problematic to add protection.
The 1200 HP was for take off, max power was 900-1000 HP for actual flying, the engine was not military rated.
 
You don't seriously believe they'd have stayed with those engines ... had it been selected for production, do you? It's all a big guess since we didn't buy it but, if we HAD, I'm guessing some serious impriovements would have been in the wings.

In the actual event, there were no improvements made since we didn't buy it. I doubt any company would throw away their own money to improve something they weren't going to sell. They didn't even do that for the F-20 Tigershark.

I have to mostly agree with Tomo for the prototype XF5F ... it wasn't very good.

The follow-on F7F is a pretty good fighter with very hard-hitting armament. Most people aren't really aware of it's armament. Most of the people who see one at the museum have no idea that the little gun blisters on the bottom of the nose are for the lesser armament. They usually completely miss the four 20 mm cannons in the wing roots that didn't have to be synchronized since they miss the prop arc.
 

What armament was it supposed to have?

If you put on 4 M2 Browning .50 cals and 250 rounds per gun, plus gun accessories, gun camera, ammo boxes, mountings and chutes, it will add 545-565 lb to loaded weight.

Armoured glass, seat armour and fuel tank armour is going to add at least another 200 lb, most likely more. The P-39D added 245 lb just for pilot and cockpit armour. The P-40 added 175 lb for armour plate - front and rear - alone, not counting windscreens and fuel tanks. The RAF added more than 300 lb of equipment to their Kittyhawks before they were considered fit for combat.

All up, I can see the XF5F's loaded weight climbing by nearly 1000 lb before its combat capable.
 
The series produced aircraft will probably have the military-rated engines, that will add either ~2000-3000 ft to the rated height, or dome 100 HP per engine - should cover the increased drag, but not so well for increased weight, since the new engines would add some 200 lbs each. We also need to consider that going to the s-s tanks also add weight (200-300 lbs in this case?), while it reduces the fuel carried.

If the 4 MGs will do, then I'd suggest the 4 HMG P-40 or 5 (to cover for loss of RoF because of synchronysation) P-39.
 
The XF5F was to be armed with (2) .30 MGs and (2) .50 MGs

The XP-50 was to be armed with (2) .50 MGs and (2) 20mm cannon which were never installed however, it's been said that it did have pilot armor and self-sealing tanks installed in the prototype (unlike the XF5F).

It's difficult to verify if it did or did not, because hard data on the XP-50 is a little hard to find. In all honesty, I don't think it did, as the XP-50's empty weight is just a little heavier than the XF5F's empty weight, which would refelct the slight changes to the airframe as well as the extended nose.
 
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The engine, for one.
 
A P-40Q with the then-available engines would have been head and shoulders better than the stock P-40 for the theaters where the P-40 was deployed. I am having a very hard time understanding why that is so hard to see. It had a bubble canopy, turned better, climbed better, rolled better, and was and faster. All seem like pluses to me.

MOST of the P-40's faults were fixed in the XP-40Qs. It wouldn't perhaps match a P-51 in all respects ... probably better in some respects ... especially roll, but would have been better than, say, a P-40N.
 
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GregP said:
You don't seriously believe they'd have stayed with those engines ... had it been selected for production, do you? It's all a big guess since we didn't buy it but, if we HAD, I'm guessing some serious improvements would have been in the wings.
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I cant see a better engine being fitted until early to mid-1943.

The F4F-3 and -4 soldiered on in production with the 1200 hp R-1830 until early 1943. The FM-2 switched over to the more powerful R-1820-56 in about mid-1943.

As far as I can determine, the engine initially made 1300 hp at full military power. The engine was then cleared for 2700 rpm, producing 1350-1360 hp. Sometime later it was approved for water injection for take-off/initial climb. I have some sources that give the R-1820-56W and -56WA from 1425 to 1475 hp at 2700 rpm, but I'm not sure about the time period.

Interestingly, some of the Navy's own documentation shows that the regulator on the engine could be bypassed for more power at very low altitude. The regulated power seems to be limited to 50 inches of manifold pressure, giving 1400 hp. But the power and climb charts show the power curves from 2000 ft and below extending out to about 52.5 inches of pressure, giving 1475 hp. Same thing for the supercharger cut over point at about 12000 - 16000 ft, it looks like pilots could manually override the regulator at WEP for an extra 50-60 hp - good for about five or six mph extra.
 
The -56A and -56WA have had a revised crankshaft vs. the -56 and -56W, that allowed for 2700 rpm operation; take off rating was 1350 HP on those engines, per AHT. Water injection meant the power of 1360 HP at sea level, 2600 rpm and 52 in Hg, for -56W and -56WA engines. The pilots will probably seldom use the water injection for take off, with 10 minutes worth of mixture provided?
I'm afraid that versions of the Cyclone 9 with more than 1400 HP were available in 1945, not earlier.
 
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