GRUMMAN F6F-3 HELLCAT ...

[Mark Allen M]

[lucky52]

What is that little area behind the pilots seat with the window? Did all the Hellcats have that?

[Mark Allen M]

[C VEICH]

First time I have seen a Hellcat in the tri-color scheme with the old style insignia sans bars. I bet there were not many with that combination. Great shots as always.

[Saville]

So can someone explain why the F6F - which uses the same engine as the P-47 (P&W R-2800 Double Wasp)
- does not have nearly the same top end performance as the P-47?

Is it a turbo/supercharging difference?

Max speed: P-47 433mph
F6F 391mph

Rate of Climb: P-47 3180 ft/min
F6F 2600 ft/min
Range of both ~ 800 miles

Gross T/O weight: P-47 17,500 lbs
F6F 15,415 lbs

thanks

[GarryW]

So can someone explain why the F6F - which uses the same engine as the P-47 (P&W R-2800 Double Wasp)
- does not have nearly the same top end performance as the P-47?

Is it a turbo/supercharging difference?

Max speed: P-47 433mph
F6F 391mph

Rate of Climb: P-47 3180 ft/min
F6F 2600 ft/min
Range of both ~ 800 miles

Gross T/O weight: P-47 17,500 lbs
F6F 15,415 lbs

thanks

Possibly a differently configured engine. The F6F looks to weigh a ton less (literally) and the P-47 is...well, it was called "The Jug". The Hellcat does look like a sleeker airframe...but that is subjective and I have no wind tunnel data to back that claim. Looks like the R-2800 came in a multitude of "flavors" from 1850HP to 2800HP.

Edit:
According to Wikipedia (take it for what its worth) the P-47D utilized a 2600HP variant where the F6F-5 utilized a 2200HP variant.

[Pat Carry]

Great photos Mark!!

[C VEICH]

The Hellcat is definitely not a sleeker airframe than the Jug and it has considerably more wing area which may account for the slower top speed. I do find it hard to believe that a Jug will outclimb a Hellcat though. More wing and less weight always results in a better climb.

[Saville]

The Hellcat is definitely not a sleeker airframe than the Jug and it has considerably more wing area which may account for the slower top speed. I do find it hard to believe that a Jug will outclimb a Hellcat though. More wing and less weight always results in a better climb.

Well unless the P-47's turbocharging has an effect at altitudes where the F6F's charging doesn't have an effect....or has less effect.

[Forgotten Field]

Very nice photos. In your archive, do you have a photo of a Hellcat tied down on a carrier deck, with a pair of officer's standing next to it? I'm interested in the tie-downs, but I remember distinctly it was a Hellcat. Thanks.

[Mark Allen M]

Very nice photos. In your archive, do you have a photo of a Hellcat tied down on a carrier deck, with a pair of officer's standing next to it? I'm interested in the tie-downs, but I remember distinctly it was a Hellcat. Thanks.

Hmm! that may take a bit of time. I have folders upon folders. I'll see what I can dig up.

M

[EstorilM]

The Hellcat is definitely not a sleeker airframe than the Jug and it has considerably more wing area which may account for the slower top speed. I do find it hard to believe that a Jug will outclimb a Hellcat though. More wing and less weight always results in a better climb.

Well unless the P-47's turbocharging has an effect at altitudes where the F6F's charging doesn't have an effect....or has less effect.

Basically this - the previous post of airspeeds for the two aircraft seem to reference Wikipedia, which had a stated altitude for the max Jug speed at 29,000'!!

At these altitudes the GE turbosupercharger absolutely has a huge advantage over the fixed two stage supercharger of the F6F. The Navy (and Grumman) had the technical knowledge and funds to incorporate a turbosupercharger, but neither wanted to do so due to reliability and maintenance concerns based around carrier operations. Indeed not a single naval fighter (no matter how complicated) ever featured this technology.

For example, some early numbers I found said the hellcat's top speed at 18,700 was 371mph, but climbing to 24,000 drops you down to 330mph. The P-47's were able to operate at extreme manifold pressures later in the war - I'm talking around and over 70". This is just not achievable with a conventional blower that the R-2800s employed. However they never really flew at those altitudes, but you'd need that height to achieve the type TAS seen here.

Actually in the P-47D you could achieve 1950bhp at 27,500ft - for a base unmodified D model this still got you 415mph TAS. With water injection, the D could achieve 435mph TAS at 31,000ft Considering you're up there with modern day jet airliners at that altitude, it's pretty incredible.

I believe power was rated at about 400hp more for the Jug, but of course it could achieve that power at any altitude, without pilot interaction or trying to remember manifold pressure and altitude curves for the blower settings.

The F6F reached peak performance at about 22,000ft and performance fell off a cliff after that (all variants, relatively speaking).

I'm not sure about climb rates - some of the best P-47s were later, including the D with the "paddle prop" and the up-rated 2,800hp engines - even then, it achieved around 3,500fpm which compares similarly to the F6F. In this case the wing area and HP plus the prop design are enough offset the weight differences of the two aircraft. This would likely be at low altitudes though, and here the Jug just benefited from getting hugely powerful R-2800 variants later in the war.

[Mark Sampson]

Perhaps it's a case of Grumman designing for the intended use. IIRC the F6F was meant to outperform the Zero, which it did. It may be that the designers went for 'good enough' rather than 'the ultimate'. The P-47 was built for a different mission- to take on the Luftwaffe.
And carrier aircraft need to be built stronger to handle the landings, no? And possibly have STOL characteristics for carrier takeoffs- or were there catapults by 1944?
In any case both aircraft excelled at their intended missions, for which I'm thankful.

[Kyleb]

Perhaps it's a case of Grumman designing for the intended use. IIRC the F6F was meant to outperform the Zero, which it did.

That's a common misconception. The F6F was ordered in the summer of 1941, with the first flight a year later. It was tweaked (like most designs) during the design process, including replacing the R-2600 with the R-2800.

The F6F was meant to be an improvement over the F4F, and it was, compliments of the R-2800.

[EstorilM]

Perhaps it's a case of Grumman designing for the intended use. IIRC the F6F was meant to outperform the Zero, which it did. It may be that the designers went for 'good enough' rather than 'the ultimate'. The P-47 was built for a different mission- to take on the Luftwaffe.
And carrier aircraft need to be built stronger to handle the landings, no? And possibly have STOL characteristics for carrier takeoffs- or were there catapults by 1944?
In any case both aircraft excelled at their intended missions, for which I'm thankful.

STOL wasn't a factor at all - figure the TBM had a wartime weight of over 18,000lbs with the same engine and got off carriers just fine. They were generally designed with large wings and high lift devices (enough to get back on a carrier) which aren't as much of a factor for the USAAF planes for example. Ironically the Jug actually took off from carriers a few times!

As far as catapults go, the Navy had hydraulic cats even on some pre-war ships such as the Enterprise (which had three independent cats). The entire Essex class (being designed during the war) had cats from the start. Interestingly they weren't always used, and even by the end of the war less than half of carrier takeoffs were performed using the cats - I'd assume this was the larger aircraft such as the TBM and SB2C.

It's absolutely a matter of being designed for a mission though, they wanted a relatively small and simple plane (as the Navy always does if possible) but for once, they could achieve similar climb and turn performance to the zero while still offering pilot protections that US aircraft were known for. Landing gear travel was probably also a factor, as I doubt a Jug could survive more than a few landings - but other elements like the airfoil (the P-47 had a low-drag, low-lift airfoil that really only Republic used) which was great for high speeds, but lacked climb-rate and low-speed lift performance.

EDIT: Just had the pleasure of meeting a 95-year-old WWII TBM pilot at an airshow this weekend and was able to get him up on the wing of our CAF TBM 'Doris Mae. I actually asked him about the cat launches and he said he was NEVER launched via a cat (and the TBM-3's were around 18,000lbs typically) - so kinda tells you all you need to know about that. He did say they typically had around 30kts over the deck.