A Wilder Wildcat

[Belisarius II]

It's said a fighter plane is no better than its engine. In the OTL the Grumman F4F Wildcat was powered by the 1,200 hp Pratt &Whitney R-1830 Twin Wasp radial engine. In the time frame of 1937-38 when the F4F was taking shape this compared favorable to the engines of other modern fighters coming online around the world. Unfortunately, the Wildcat was both heavier, and lacked the aerodynamic refinements of rival designs such as the Supermarine Spitfire, Bf-109, or Mitsubishi A6M Zero. Although the Wildcat was an amazingly tough aircraft, with a faster diving speed vs. her A6M Zero opponent she was inferior in level speed, rate of roll, and rate of climb.

Unless the Wildcat had the time to reach a superior altitude to perform diving attacks enabling them use what a later generation would call "Energy Maneuverability Theory" where energy is converted into speed, and speed back into energy they would find themselves at a great disadvantage. In other words, you dive to build up speed that can be converted back into altitude. Sound tactics such as the Thach Weave played into the Wildcats strengths and allowed them to compete with the Zero, but a more agile fighter could have done even better.

In February 1938 Grumman suggested to the USN that their new fighter could be equipped with a 1,600 hp Wright R-2600 twin cyclone engine. Grumman insisted no major modifications would be needed to adapt the more powerful engine to the existing airframe. The Bureau of Aeronautics however worried the R-2600 weighing 800 lbs. more than the 1830 would change the center of gravity of the aircraft, that the more powerful engine would need a longer propeller requiring a redesign of the landing gear, and significantly raise the landing speed of The F4F. So, the navy stayed with the P & W 1830, but what if they took Grumman up on its offer?

The Wildcat might have a longer fuselage, higher vertical stabilizer, lower mounted wing, with wing mounted landing gear to accommodate a longer propeller. In short, a fighter closer to Grumman's next model the F6F Hellcat. You may end up with a fighter 20-40 mph faster than the OTL F4F, with a much higher rate of climb, and far better acceleration. That would make it faster than the Zero in level speed, and much faster in diving speed. What effect might this kind of change have had on the desperate naval air battles of the first 18 months of the war in the Pacific, or for the British Fleet Air Arm in their struggles with the Axis?

 

[alspug]

power is everything to a fighter and the wildcat was already fairly good in every other aspect. an extra 400hp or %30 more power for %10 more weight. even if it was 15 to 20 percent it would be a positive.

 

[tomo pauk]

In February 1938 Grumman suggested to the USN that their new fighter could be equipped with a 1,600 hp Wright R-2600 twin cyclone engine. Grumman insisted no major modifications would be needed to adapt the more powerful engine to the existing airframe. The Bureau of Aeronautics however worried the R-2600 weighing 800 lbs. more than the 1830 would change the center of gravity of the aircraft, that the more powerful engine would need a longer propeller requiring a redesign of the landing gear, and significantly raise the landing speed of The F4F. So, the navy stayed with the P & W 1830, but what if they took Grumman up on its offer?

Navy was probably right.
The 800 lbs heavier R-2600 will also need the bigger and heavier prop to turn the extra power into thrust, will need heavier oil system, and will require more fuel to match the range of the less powerful engine that Wildcat had. All that weight increase will demand the bigger wing and heavier undercarriage, as well as stronger and (again) heavier fuselage). At the end, that produces...

The Wildcat might have a longer fuselage, higher vertical stabilizer, lower mounted wing, with wing mounted landing gear to accommodate a longer propeller. In short, a fighter closer to Grumman's next model the F6F Hellcat. You may end up with a fighter 20-40 mph faster than the OTL F4F, with a much higher rate of climb, and far better acceleration. That would make it faster than the Zero in level speed, and much faster in diving speed. What effect might this kind of change have had on the desperate naval air battles of the first 18 months of the war in the Pacific, or for the British Fleet Air Arm in their struggles with the Axis?

... a whole new aircraft: bigger, draggier and heavier than the F4F (and more stremlined, less draggy and lighter than the F6F).

Engine power of the R-2600 was good/very good at low altitudes, good at medium altitudes (talk 12-13 kft), and behind the curve at higher altitudes (say, 20 kft and above). For comparison sake, at 18000 ft, the R-1830-86 on the F4F-3 and -4 was good for ~1050 HP (to propel these at 330-320 mph), where the R-2600-23 (1600 HP version, as installed on later A-20s) was good for ~1000 HP.
Engine of the F4F-3 and -4 was outfitted with 2-stage S/C to help out at higher altitudes,however that S/C was only as good as the 1-stage S/Cs on the contemporary Merlins or DB 601s.

Good points of the 'big Wildcat' might've been that, at low and medium altitudes, the rate of climb and speed is better than it was the case with the OTL Wildcat. That in return might've saved the Lexington at Coral Sea, when the Wildcats were set too low to stop the inbound torpedo strike, and were unable to climb fast enough and catch the Japanese. Better show at Coral Sea would've also seen the earlier attrition of the well trained and experienced IJN crews manning the aicraft (these crews were one of major bottlenecks for the IJN).

Another good point of the 'big Wildcat' might've been that retrofit of the R-2800 is very easy (the R-2600 and R-2800 were very similar in weight and size), netting the useful increase in power, especially above 12000 ft. Still probably with 1-stage S/C, since these are easier to retrofit than the 2-stage versions, and are less draggy (no intercoolers).

 

[mack8]

I always thought that the twin F5F was a complete waste of time. So instead of that, working on this bigger R-2600 pre-Hellcat would have been a much better investment. Certainly any folding wing heavy and underpowered F4F-4s should have actually been built as this TTL R-2600 design. Maximum speed would have been what, 350-360 mph? I would think if USN demands it they could have put a 2 stage SC on the R-2600.
It's not like the Zero would have been totally outclassed, afterall the Zero went toe to toe vs F4U in the Solomons, but indeed would have made life harder for them in 1942.

 

[tomo pauk]

I always thought that the twin F5F was a complete waste of time.

Bingo.
Same for the XP-50.

 

[mack8]

Bingo.
Same for the XP-50.

Exactly, not to mention that both are absolutely butt ugly (in league with the XP-77). Many eons ago when i found out about the XF5F i though initially it's a cartoon plane or photoshop or something.

 

[Sekhmet_D]

What effect might this kind of change have had on the desperate naval air battles of the first 18 months of the war in the Pacific, or for the British Fleet Air Arm in their struggles with the Axis?

Focke Wulf Condors would be dropping like flies in the face of these Wilder-cats, thus preventing successful vectoring of U-boat wolfpacks. Also, you might be looking at a more successful defence of Wake Island, plus more evenly matched fights versus the A6M at Coral Sea and Midway. Given how the A6M was the deciding factor in (1) stopping US carrier aircraft from inflicting more severe damage on Shokaku/Zuikaku at Coral Sea, and (2) enabling Hiryu's successful second strike on Yorktown, the involvement of Wilder-cats in both these battles might very well result in Shokaku's demise at Coral Sea, and Yorktown's survival at Midway. Not to mention more severe losses of IJNAF personnel earlier on.

 

[mack8]

Focke Wulf Condors would be dropping like flies in the face of these Wilder-cats, thus preventing successful vectoring of U-boat wolfpacks. Also, you might be looking at a more successful defence of Wake Island, plus more evenly matched fights versus the A6M at Coral Sea and Midway. Given how the A6M was the deciding factor in (1) stopping US carrier aircraft from inflicting more severe damage on Shokaku/Zuikaku at Coral Sea, and (2) enabling Hiryu's successful second strike on Yorktown, the involvement of Wilder-cats in both these battles might very well result in Shokaku's demise at Coral Sea, and Yorktown's survival at Midway. Not to mention more severe losses of IJNAF personnel earlier on.

Re Coral Sea, my understanding is that Shokaku was attacked by largely intact USN squadrons of SBDs and TBDs (except the lost SBDs from VB or VS-2), the CAP Zeros having been mostly engaged by escorts thus not significantly attritting the SBDs and TBDs. So the problem was SBD precision and of course subpar TBDs and torpedos. A better F4F will not fix those issues on it's own.

Does the ALT-F4F has more range? If so it may affect things like VF-8 not getting lost and ditched at Midway (because i guess they could fly further and return with Ring), and i agree, it's possible fewer D3As and B5Ns might survive to attack Yorktown so maybe it's only hit by say 2 bombs and 1 torpedo, but unless the ALT-F4Fs are not actually close enough cover them, the massacre of the TBDs can't be avoided.

As an overall assessment, since according to Lundstrom the F4F vs A6M kill ratio was 1,1 to 1 for 1942, i guesstimate the ALT-F4F would have a ratio of about 1,4-1,5 to 1, though again, this is put into some doubt by the later 1 to 1 ratio of A6M vs F4U. The japanese will try to adapt to fight the faster, more powerful ALT-F4F.

 

[Sekhmet_D]

Re Coral Sea, my understanding is that Shokaku was attacked by largely intact USN squadrons of SBDs and TBDs (except the lost SBDs from VB or VS-2), the CAP Zeros having been mostly engaged by escorts thus not significantly attritting the SBDs and TBDs. So the problem was SBD precision and of course subpar TBDs and torpedos. A better F4F will not fix those issues on it's own.

The SBDs suffered heavily at the hands of the A6M CAP while attacking the Japanese carriers at Coral Sea. As per Lundstrom, Shokaku's Kenji Okabe alone likely accounted for three, including that flown by Jojo Powers, the Medal of Honor hero who suicidally maintained his course for a hit on Shokaku even after his mount was set aflame. Better F4Fs flying close escort will prevent these losses and ensure more hits are scored. You might even see Zuikaku not escape unscathed.

 

[Belisarius II]

Re Coral Sea, my understanding is that Shokaku was attacked by largely intact USN squadrons of SBDs and TBDs (except the lost SBDs from VB or VS-2), the CAP Zeros having been mostly engaged by escorts thus not significantly attritting the SBDs and TBDs. So the problem was SBD precision and of course subpar TBDs and torpedos. A better F4F will not fix those issues on it's own.

Does the ALT-F4F has more range? If so it may affect things like VF-8 not getting lost and ditched at Midway (because i guess they could fly further and return with Ring), and i agree, it's possible fewer D3As and B5Ns might survive to attack Yorktown so maybe it's only hit by say 2 bombs and 1 torpedo, but unless the ALT-F4Fs are not actually close enough cover them, the massacre of the TBDs can't be avoided.

As an overall assessment, since according to Lundstrom the F4F vs A6M kill ratio was 1,1 to 1 for 1942, i guesstimate the ALT-F4F would have a ratio of about 1,4-1,5 to 1, though again, this is put into some doubt by the later 1 to 1 ratio of A6M vs F4U. The japanese will try to adapt to fight the faster, more powerful ALT-F4F.

Thanks for your input. I need to re-read more about the tactical accounts of the battle of Coral Sea. Yes, the TBD was a death trap, and the Mk-13 Torpedo was disastrously unreliable. Even with the far superior Grumman Avenger USN Aviators would've been hard pressed in sinking IJN Battleships using Mk-13 Torpedoes before 1944 when most of its faults had been compensated for. I agree that this Wildcat would need a lot more fuel for its hungrier engine, and greater weight. Perhaps 50% more internal fuel plus drop tanks. And yes, this Wildcat would be a much better interceptor than in the OTL.

 

[fastmongrel]

Is there any extra power available from the twin wasp. It got to 1200hp fairly early then doesn't seem to have improved any more.

 

[tomo pauk]

Is there any extra power available from the twin wasp. It got to 1200hp fairly early then doesn't seem to have improved any more.

Water-alcohol injection would've helped. R-1830s was a small engine, and small air cooled engines do not grow in peak power like the small liquid cooled engines, even when one had the best fuel available. F4F was a too big a big fighter to be powered by the R-1830 and expect it to perform.
Issue with water-alc injection was that it became a thing by late 1943/early 1944 for P&W, ie. too late for this topic.

Another avenue of approach would've been that a more refined S/C is developed, since even the 2-stage S/C (that engines on the F4F-3 and -4 had) was meh. Another 100 HP perhaps with a more refined S/C?
Individual exhausts would've netted 10+ mph.

Very late R-1830s were making 1300 HP (1350?), but again these were too late to matter.

 

[mack8]

The only other early war engine option i can think of is the 1350HP R-2000, closely related to the R-1830, but it needs to be accelerated just to be ready to power the F4F-4 in time. All it would do is probably maintain the F4F-4 speed and climb at the same level as the F4F-3, but it's still a plus compared to OTL.

 

[tomo pauk]

The only other early war engine option i can think of is the 1350HP R-2000, closely related to the R-1830, but it needs to be accelerated just to be ready to power the F4F-4 in time. All it would do is probably maintain the F4F-4 speed and climb at the same level as the F4F-3, but it's still a plus compared to OTL.

Definitely the easiest retrofit on the Wildcat. Downside is that R-2000 is with a worse compressor than what the R-1830-86 had, meaning that increase of power will happne only at lower altitudes.

Perhaps not such a long shot for up-engining the Wildcat is that P&W keeps developing the R-2180A?

 

[mack8]

The SBDs suffered heavily at the hands of the A6M CAP while attacking the Japanese carriers at Coral Sea. As per Lundstrom, Shokaku's Kenji Okabe alone likely accounted for three, including that flown by Jojo Powers, the Medal of Honor hero who suicidally maintained his course for a hit on Shokaku even after his mount was set aflame. Better F4Fs flying close escort will prevent these losses and ensure more hits are scored. You might even see Zuikaku not escape unscathed.

You might have better/more exact information at hand, but overall the SBDs and TBDs at Coral Sea comparatively suffered much less at the hands of Zeros (i'm not counting ditchings or other losses not from Zeros), they weren't decimated/anihilated like the TBDs were at Midway or indeed like the japanese D3As and B5Ns usually suffered at the hands of F4Fs in pretty much all carrier battles of 1942.

 

[mack8]

Definitely the easiest retrofit on the Wildcat. Downside is that R-2000 is with a worse compressor than what the R-1830-86 had, meaning that increase of power will happne only at lower altitudes.

Perhaps not such a long shot for up-engining the Wildcat is that P&W keeps developing the R-2180A?

Well, i'm guessing it shouldn't be that difficult for PW to put the 2 stage supercharger from R-1830-86 on the R-2000.

I need to re-read on the R-2180 but iirc the diameter was significantly increased over R-1830 and presumably R-2000. On the other hand it could be a possibility too as the F4F does not have cowl guns that might be affected, they could get something like 1400 HP from it?

 

[Giant Man Eating Rabbits]

In February 1938 Grumman suggested to the USN that their new fighter could be equipped with a 1,600 hp Wright R-2600 twin cyclone engine. Grumman insisted no major modifications would be needed to adapt the more powerful engine to the existing airframe. The Bureau of Aeronautics however worried the R-2600 weighing 800 lbs. more than the 1830 would change the center of gravity of the aircraft, that the more powerful engine would need a longer propeller requiring a redesign of the landing gear, and significantly raise the landing speed of The F4F. So, the navy stayed with the P & W 1830, but what if they took Grumman up on its offer?

Outside the box!

How about a Merlin 24, 1,400 hp in 1941? or Merlin 32 Series in 1942 both built by Packard?

 

[tomo pauk]

Outside the box!

How about a Merlin 24, 1,400 hp in 1941? or Merlin 32 Series in 1942 both built by Packard?

Power is better - at all altitudes - than on the best R-1830 we can see installed on the F4F, drag is lower, exhaust thrust is better (since exhaust stacks are with a better layout). Weight increase is still manageable with the basic F4F airframe.

 

[ennobee]

In February 1938 Grumman suggested to the USN that their new fighter could be equipped with a 1,600 hp Wright R-2600 twin cyclone engine. Grumman insisted no major modifications would be needed to adapt the more powerful engine to the existing airframe. The Bureau of Aeronautics however worried the R-2600 weighing 800 lbs. more than the 1830 would change the center of gravity of the aircraft, that the more powerful engine would need a longer propeller requiring a redesign of the landing gear, and significantly raise the landing speed of The F4F. So, the navy stayed with the P & W 1830, but what if they took Grumman up on its offer

OTL, the F6F Hellcat started out as a design study for a next generation Wildcat using the 1600 HP Cyclone. However halfway the design process P&W pulled the plug on the next generation 1600 HP Cyclone the Grumman plane was suppose to use and offered a 2000 HP engine instead. The subsequent redesign of the plane around the new engine required so much work that Grumman decided to start with a blank slate and immediately incorporate ALL the changes they could to improve the Hellcat..... The final design of course looked not at all like a Hellcat any more.

 

[tomo pauk]

OTL, the F6F Hellcat started out as a design study for a next generation Wildcat using the 1600 HP Cyclone. However halfway the design process P&W pulled the plug on the next generation 1600 HP Cyclone the Grumman plane was suppose to use and offered a 2000 HP engine instead.

R-2600 was Wright's product, not P&W's.

The subsequent redesign of the plane around the new engine required so much work that Grumman decided to start with a blank slate and immediately incorporate ALL the changes they could to improve the Hellcat..... The final design of course looked not at all like a Hellcat any more.

Final design of the Hellcat looked pretty much as the Hellcat.