Twin engine fighter for Ark Royal and Illustrious class?

look at the engine ratings at each altitude. Now notice that each speed is at that precise altitude. Notice speed at 4500 feet is 326 at 1000 hp per engine. Now notice that at 7300 feet it is only 324 mph, 2 mph slower because the engines are down to 900 hp each. If they only used the Wright 1820's from the F4F-3A the top speed at 14,000 would climb from 346 to 358. (2000/1800 =1.11 cube root is 1.0357 X 346 = 358mph) no turbo

top speed at 4500 feet with an F4F-3A engine would be 2400/2000 = 1.2 cube root is 1.0626 X 326 = 346 mph at 4500 feet. No turbo

pinsog said:

In the test the F5F did 346 mph at 14,000 on 1800 hp. With turbochargers you have 2400 hp. 2400/1800=1.3333333. Cube root of 1.3333 is 1.10 x 346 = 380 mph
346 mph to 380 mph at 14,000 would be just fine for carrier ops

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Can it do that with Bristol engines, pre-Hercules?

As an aside, after the Gladiator, I can't find any single-seat aircraft in either single or multi-engine format in British operational service powered by a Bristol until the Centaurus engine. The Dutch of course had their Bristol Mercury powered Fokker D.XXI, and the Poles the PZL P.11, but that's about it. So, if we can get a British F5F single-seat equivalent into service with Bristol engines it would be a first since the Gladiator.

pinsog said:

F4F-3A engine

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pinsog said:

If they only used the Wright 1820's from the F4F-3A

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The F4F-3A used a P&W R-1830 engine with a single stage 2 speed supercharger.
The British got Martlets with Wright R-1820s that had been ordered by the French.

AS far as timing goes.
Grumman built 32 F4F/G-36A's in Aug of 1940, another 29 in Sept. They totaled 103 built in 1940 according to one source, another says 106 in 1940.
They Built 324 in 1941, and 1470 in 1942.

Important dates are
Aug 8th 1939, USN orders 54 F4F-3 aircraft.
Oct 1939, France orders 100 export versions with Wright R-1820 engines.
Feb 1940, First production F4F-3 makes first flight, this is something of an illusion as Grumman is barely producing aircraft at even one per month.
March 1940, Flight tests begin on French first contract airplane.

In March and April Grumman is also working on a folding wing for the WIldcat to be installed on one of the already ordered aircraft,and installing Wright R-1820 Cyclones in two aircraft that will become XF4F-5s

By Oct 31st of 1940 the British have take delivery of 81 Martlet Is. A Martlet II with a single stage P&W R-1830 has flown. In Nov A USN XF4F-7 with single stage P&W R-1830 is flown to NAS Anacostia for tests. This is the "prototype" for the F4F-3A. IN Dec 1940 578 F4F3s and and F4F-3As are on order for the USN but only 22 have been accepted.

Dec 25th 1940. British Martlet I claims JU 88 over Scapa Flow.

Now at what point does Grumman, the USN, and the British (and Greece) throw all this out and start over again with the F5F?

The F4F may not have been what was wanted, however it was what was available.

Admiral Beez said:

Can it do that with Bristol engines, pre-Hercules?

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No.

Admiral Beez said:

So, if we can get a British F5F single-seat equivalent into service with Bristol engines it would be a first since the Gladiator.

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So what.
A crap airplane is a crap airplane.
Whatever the merits of the F5F powered by Wright Cyclones (turboed or not) the Bristol engines simply are not powerful enough to do the job.
The only one close is the Pegasus with two speed supercharger (all the rest of the available Bristol engines used single speed superchargers) and while it performs well at altitude is is about 200hp behind the Cyclone at low altitudes.

Shortround6 said:

The F4F-3A used a P&W R-1830 engine with a single stage 2 speed supercharger.
The British got Martlets with Wright R-1820s that had been ordered by the French.

AS far as timing goes.
Grumman built 32 F4F/G-36A's in Aug of 1940, another 29 in Sept. They totaled 103 built in 1940 according to one source, another says 106 in 1940.
They Built 324 in 1941, and 1470 in 1942.

Important dates are
Aug 8th 1939, USN orders 54 F4F-3 aircraft.
Oct 1939, France orders 100 export versions with Wright R-1820 engines.
Feb 1940, First production F4F-3 makes first flight, this is something of an illusion as Grumman is barely producing aircraft at even one per month.
March 1940, Flight tests begin on French first contract airplane.

In March and April Grumman is also working on a folding wing for the WIldcat to be installed on one of the already ordered aircraft,and installing Wright R-1820 Cyclones in two aircraft that will become XF4F-5s

By Oct 31st of 1940 the British have take delivery of 81 Martlet Is. A Martlet II with a single stage P&W R-1830 has flown. In Nov A USN XF4F-7 with single stage P&W R-1830 is flown to NAS Anacostia for tests. This is the "prototype" for the F4F-3A. IN Dec 1940 578 F4F3s and and F4F-3As are on order for the USN but only 22 have been accepted.

Dec 25th 1940. British Martlet I claims JU 88 over Scapa Flow.

Now at what point does Grumman, the USN, and the British (and Greece) throw all this out and start over again with the F5F?

The F4F may not have been what was wanted, however it was what was available.

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That's what I get for using memory. Your correct, the F4F-3A used the single stage P&W.

Shortround6 said:

The F4F-3A used a P&W R-1830 engine with a single stage 2 speed supercharger.
The British got Martlets with Wright R-1820s that had been ordered by the French.

AS far as timing goes.
Grumman built 32 F4F/G-36A's in Aug of 1940, another 29 in Sept. They totaled 103 built in 1940 according to one source, another says 106 in 1940.
They Built 324 in 1941, and 1470 in 1942.

Important dates are
Aug 8th 1939, USN orders 54 F4F-3 aircraft.
Oct 1939, France orders 100 export versions with Wright R-1820 engines.
Feb 1940, First production F4F-3 makes first flight, this is something of an illusion as Grumman is barely producing aircraft at even one per month.
March 1940, Flight tests begin on French first contract airplane.

In March and April Grumman is also working on a folding wing for the WIldcat to be installed on one of the already ordered aircraft,and installing Wright R-1820 Cyclones in two aircraft that will become XF4F-5s

By Oct 31st of 1940 the British have take delivery of 81 Martlet Is. A Martlet II with a single stage P&W R-1830 has flown. In Nov A USN XF4F-7 with single stage P&W R-1830 is flown to NAS Anacostia for tests. This is the "prototype" for the F4F-3A. IN Dec 1940 578 F4F3s and and F4F-3As are on order for the USN but only 22 have been accepted.

Dec 25th 1940. British Martlet I claims JU 88 over Scapa Flow.

Now at what point does Grumman, the USN, and the British (and Greece) throw all this out and start over again with the F5F?

The F4F may not have been what was wanted, however it was what was available.

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That's what I get for going with memory, it was the Martlet I engine, the 1820-G205 engine that was rated at 1200 hp from SL-4200 ft and 1000 hp up to 14,000. According to the test I posted the engines on the F5F were 1000 hp from SL to 4500 ft and 900 hp from 7300 up to 14,000 ft.
We do have the benefit of hindsight, but I believe they dragged their feet on the F5F. Why? It was too big a jump for the Navy to go from an F3F biplane to a heavy twin monoplane in one step, so Grumman went the safe route. I get it. But the 'crap' plane was 30 mph faster than an F4F-3 everywhere except 20,000 ft where it was only 22 mph faster and that was with the F4F-3 using a 2 stage P&W with 1200 hp while the F5F was using single stage Wrights and only using 1000 hp down low and 900 hp from 7300 on up. Adding self sealing material in the fuel tank would probably not add weight since it would carry less fuel and 100-150 pounds of armor won't make much difference in an 11,000 pound 2400 hp plane. Just changing to the 1820-G205 in the Martlet I would boost speed at SL to 331 and at 4200 ft to 346. We can agree to disagree on this, but if I were a kid fighting a Zero ace I'd like to have an airplane that has at least 1 performance advantage over the one the experienced ace is flying. Being told to fly straight until the Zero runs out of bullets would not boost my confidence at all

pinsog said:

Grumman submitted its bid for the F5F in April 1938 and had a full scale model built by October 1938. By October 22, 1938 it was at NACA for wind tunnel testing which was completed by March 1939. First flight was April 1, 1940. February 1, 1941, 11 months after first flight, it was dived vertically to 505 mph. 11 months after the first flight it is still the only prototype. The chase plane for the first flight was the XF4F-3 and I think there was only 1 or 2 Wildcats at that time, the production line wasn't running yet.

The Avenger was ordered in April 1940 and first flew in August 1941 and made its combat debut at Midway, 10 months after its first flight.

The turbocharged XP50, same wing and nacelles, was ordered November 25, 1939, first flight was 18, February 1941.

Based on all of this, especially the Avenger timeline, I think the F5F could have been and should have been in squadron service in the same timeline as the Wildcat. Squadron service by early 1941 at the latest. Personally, I would have had them testing turbocharged models as soon as production started instead of wasting time on the XP50.

Also, if you add 500 pounds of turbochargers and 150 pounds of armor and armored glass, weight goes from 10,900 to 11,550 with 2400 hp up to 25,000 feet. That means it has 100 more hp than a P38, weighs 3,000 pounds less, can be dived vertically to 505 mph and is carrier capable. does that sound good to you for a 1941 carrier fighter?

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Again, production F4Fs were coming off the line before the F5F flew.

The F5F concept was clearly a couple of years behind that of the F4F (original biplane and improved monoplane). I don't know why you could think that it would be available in the same timeline as the F4F.

The F5F may have had merit as built, the crap I referred to was trying to power it with available Bristol engines. The Mercury and Pegasus weren't crap engines but they were too small/low powered to get the job done. Replacing 1200hp take-off power engines with 800-1000hp take-off engines is not going to give the performance anyone is looking for.

Like Wuzak says, the F5F was at least year and more like 2 years behind the F4F. They had orders for hundreds of F4Fs when the XF5F made it's first flight and they had a production line set up and gathering speed. XF5F makes it first flight April 1st 1940 (any significance to that date?) and in August Grumman builds 32-33 F4Fs.
XF5F is nowhere near ready as production airplane, it has excessive drag, poor cooling of the engines (even without turbos) landing gear doors don't close properly and other issues.
Lots of other planes started with issues ( the XFU4 had hundreds of changes) but sorting out the issues on the Xf5F was going to take time. Perhaps it could have done faster, but it wasn't going to a matter of a few days or weeks. Waiting for the XF5F could mean several hundred fewer fighters as of Dec 1941 minimum.

AS to when the R-1820-40 was given a military power rating I don't know. It was not only used in the British Martlets, it was used in the US F2A-2 and F2A-3. The British Buffaloes got R-1820 G105 engines and the US planes got R-1820 G205 engines. Those are the commercial designations. It was also used in Lockheed Hudsons and some Lockheed Lodestar transports.
But like I said, some reference books from the beginning of 1941 list the military power for the G205 engine.

We don't know for sure what power ratings were being used.
The climb figures are none too good, 4.2 minutes to 10,000ft is about 2400fpm.
we also don't know which version/configuration the test figures are for.

If they are for the later, cleaned up/streamline configuration it puts the F5F time line back by months.

The French Potez 630/631 would just about fit the size requirements if the wing fold was just outboard of the engine nacelles. The only problem with the Potez is it's wimpy engines. 630 to 700 hp each, the French who were desperate for anything that could fly very quickly demoted the Potez 630 and 631 to training duties.

Potez 630 - Wikipedia

My 1/72 scale Potez painted and in the middle of applying decals.

Shortround6 said:

We don't know for sure what power ratings were being used.
The climb figures are none too good, 4.2 minutes to 10,000ft is about 2400fpm.
we also don't know which version/configuration the test figures are for.
View attachment 583376
If they are for the later, cleaned up/streamline configuration it puts the F5F time line back by months.

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Crap plane referred to Bristol engines, thank you for clarifying that.
Funny thing about the short nose vs long nose version, the original design had long nose and long nacelles, then they went to short nose (stalked at lower speed with no bad tendencies) and short nacelles (short nacelles make no sense). Then they went back to long nose long nacelles.
The over heating was the right hand engine only, it apparently ran hot the entire life of the aircraft. Grumman actually complained about faulty government equipment supplies to them over the engine when arguing about the cost, weight and performance of the F5F.
I don't understand how you can say we don't know what power they used during the test. They literally list the power rating as
1200 hp for takeoff, which the obviously use
1000 hp from SL to 4500 ft
900 hp from 7300-14000 ft
Then they fly it precisely at SL, 4500 ft, 7300 ft and 14000 ft.
It did 326 mph at 4500 on 1000 hp per engine, the it did 324 mph at 7300 on 900 hp per engine. It is 2 mph slower 2800 feet higher which matches the loss in hp perfectly.
As far as drag if turbochargers were installed, look at the pics of the XP50 and F5F. Notice how much cleaner the engine nacelles are on the XP50.
Anyway, they didn't build it, but I enjoy debating it anyway.

edit: poor climb rate. I think the poor climb rate is because they simply climbed it at normal power the whole time. I think the 4,000 ft per minute that is quoted is using takeoff power for the first 5 minutes.
If you look at British tests of the Hellcat and Corsair they list the climb rates as being pretty awful because they aren't using combat power settings. I'll post those climb rates when I get a chance.

Going back to the original question of what would the British Aviation industry have come back with if asked for twin-engined carrier fighters - If we are talking about the period 1939 -1941 then I'm sure Miles would have put forward a proposal based on their M22 design. This looked like a Grumman Skyrocket on steroids! - powered by two RR Griffon engines! This was a very poorly documented design, and a lot of the information out there on the internet about it seems to be just plain wrong. - The confusion was cleared up in the book "Miles Aircraft - The Wartime Years" by Peter Amos. But because it is such a huge, expensive book little of the information seems to have got out. - The pertinent facts for the purposes of this thread. Work on the M22 design seems to have started in 1938 (not 1941 as some descriptions indicate) even before the first prototype Griffon had run on a test-rig. In lay-out it was exactly like the Grumman Skyrocket but much more streamlined. In the later revisions of the design, it featured a "gun-pack" which enabled the four cannon and ammunition boxes to be swapped out together. Dimensions for the lift would be tight- length of 33 feet and span of 39feet - but looking at the layout, if the wings could be made to fold outside the propeller arc that could be reduced by about 15 -16 foot - bringing it just within the 24 foot limit of the lift. Performance with two Griffons would be (as expected) mind-blowing (estimate of 504 mph at 15,000 feet) But endurance would be very poor for a carrier fighter - only 2 hours. Which makes it look a non-starter from the very beginning. One major difference to the Skyrocket was a huge tailwheel, needed to give the pilot a better view forward when on the ground. - This could well have complicated the fitting of an arrestor hook. Now please don't reply saying it would never have been ready in time, etc etc. I KNOW it would not have been ready in the timeframe, I know it would not have had the endurance to be a navy fighter and a hundred other things. - I'm just flagging it up as Mile's likely tender if such a twin-engined design was called for. I won't post pictures of the design, it would be obvious I'd copied them from Peter Amos's book - Just do a google image search for "Miles M22" and you'll find lots.

As mentioned above, Winkle Brown pointed out that a 1 engine landing is problematic to say the least. And a Greyhound or tracker with their enormous wings and potential glide-in are not in the cards for this discussion.

So I see a real dead end. The odds of airframe loss due to engine failure now go UP, not down as is usual with twin engine aircraft. There is the benefit of pilot rescue. If one engine fails the pilot can still fly, just not land. So the pilot can choose where to ditch or bail.

But fundamentally, with two engines the odds of engine failure double. If you can't land on one engine that's twice as many planes in the drink due to breakdown (and double the target area for the enemy to hit an engine and cause an airframe loss).

RW Mk. III said:

As mentioned above, Winkle Brown pointed out that a 1 engine landing is problematic to say the least. And a Greyhound or tracker with their enormous wings and potential glide-in are not in the cards for this discussion.

So I see a real dead end. The odds of airframe loss due to engine failure now go UP, not down as is usual with twin engine aircraft. There is the benefit of pilot rescue. If one engine fails the pilot can still fly, just not land. So the pilot can choose where to ditch or bail.

But fundamentally, with two engines the odds of engine failure double. If you can't land on one engine that's twice as many planes in the drink due to breakdown (and double the target area for the enemy to hit an engine and cause an airframe loss).

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That is a very reasonable thought. The F5F had its engines as close together as possible, twin tales so they are directly in the prop wash to enhance their effectiveness and counter rotating engines to help with torque if one is dead. If the F5F couldn't land on one engine I don't think anything could. But without an actual test we don't know what it would or wouldn't do so it's all speculation.

One opposing thought is: if your single engine fighters don't have enough performance to defend your carrier and they sink it, it won't matter anymore.

fastmongrel said:

The French Potez 630/631 would just about fit the size requirements if the wing fold was just outboard of the engine nacelles.

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The wing fold needs to be outside the propeller circle, not the engine nacelles.

Admiral Beez said:

The wing fold needs to be outside the propeller circle, not the engine nacelles.

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The nacelles on the 630 are very wide don't know why it must have been very draggy, French design was a law unto itself.

Width outboard of the nacelles 18' 6" width outboard of the propeller circles 21' 8".

fastmongrel said:

The nacelles on the 630 are very wide don't know why it must have been very draggy, French design was a law unto itself.

Width outboard of the nacelles 18' 6" width outboard of the propeller circles 21' 8".

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That should work then, with the deck handlers being careful how they spot the aircraft on the lift.