Can we make a faster better performing Wildcat in 1942?

I think there are two more steps to that .50 cal progression. They improved the ammunition storage in the second or third quarter of 1942, greatly reducing the rate of jams / stoppages, and then they had the AN/M3 which had more like 1200 rpm, though I don't know if that was used during wartime. I know they used them in the Korean War.

Bottom line though, if you get a good number of hits, like more than half a dozen, on almost any WW2 aircraft, from any heavy machine gun, it's probably going to go down. The US M2 also had enough velocity and mass to punch through most of the aircraft armor being used, so there is a good chance the pilot died too. The same was true for 20mm of course.

Even to some extent, for .30 caliber / 7.62 / 7.7 / 7.92 / 8mm etc., a solid hit with multiple guns spelled doom. The latter just had a shorter effective range, partly because the rounds tended to scatter more. The HMGs traveled in a straighter line with a narrower cone for a good bit further.

FWIW

I read (a long time ago in the early-1990s) that the British request for 6x guns was actually originally intended to mean 6x .303 cal Brownings - as opposed to the 6x 7.5mm (DARNE?) MG of the French orders.

From my notes and IIRC:

When the British took over the French and Belgian orders it was decided to not fit the nose mounted guns (as the required synchronization would have been too limiting on the ROF of the .303 cal Browning) and only use the wing gun bays. Britain decided to order their own version of the Martlet at some point after this. As is common knowledge, the British had determined in the mid-1930s that 8x .303 cal was the minimum required for anti-bomber work, hence it was felt that the firepower of 4x .303 cal was too light. The British subsequently asked Grumman if they could increase the number of wing guns to at least 6, and preferably 8.

Grumman had originally designed the wing gun bays to accommodate either the .50 cal or .30 cal Browning. With the .303 cal Browning the ammunition load could have been upped to the minimum 750 rpg desired by the RN/FAA for CAP duties, in the same space as the 300-400 rpg of .50 cal.

After the British took over the French and Belgian orders and ordered their own Martlets, Grumman offered 4x .50 cal Browning in the wings in place of the 4x .303 cal MG to up the firepower, and as an alternate to the original (sort of) planned minimum 6x .303 cal requested by the British. The British adopted Grumman's 4x .50 cal arrangement.

Subsequently, the USN requested 6x .50 cal Browning in the wings, after Grumman had already done the basic engineering work to fit additional wing gun bays for the .303 cal Browning requested by the British.

This was from a fairly comprehensive write-up on the F4F/Martlet - but I do not know if it is accurate. As far as I know there have been no original source documents published in the last ~30 years that definitively answer the question of exactly how the 6x gun arrangement came about.

Just noticed the question upthread about the R-1830-75 or similar improved R-1830 availability for the F4F.

The R-1830-75 was the contemporary of the R-1820-65 used on the FM-2 (FM-2 first delivery Dec'43, service entry early'44 - I think). The R-1830-75 had a single-stage engine mounted supercharger, and was intended to be used with a turbocharger as the 2nd stage. Ratings without turbocharging were 1350 BHP at 3,000 ft and 1100 BHP at 7,500 ft. Notes say it had improved cylinder muffs and finning for better cooling - this is also contemporary to the improved muffs and finning on the 1350 BHP R-1820s.

First use(?) of the R-1830-75 was on the single XB-24K, the first flight of the aircraft being in Sep'43. It was intended to build the B-24N series with the -75 but there was only the single XB-24N (delivered in Nov'44) and as Geoffrey Sinclair mentioned upthread there were only the 7x YB-24N built in early-1945. These were delivered May/June 1945 before the order for over 5,000 production airframes was cancelled.

So the R-1830-75 was maybe not available in the time frame we are discussing?

ThomasP said:

First use(?) of the R-1830-75 was on the single XB-24K, the first flight of the aircraft being in Sep'43.

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ThomasP said:

So the R-1830-75 was maybe not available in the time frame we are discussing?

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I believe it was a contemporary of the R-1830-94 which used a 2 speed supercharger. Used in PB4Y-2 and a few other late WWII/post war B-24 derivatives.
I believe it used similar cylinder construction to the R-2800 "C" series engines.

It weighed as much as the two stage -86 engine and while it had more power at sea level or very low, it didn't make much more power at 14,000ft (or around there) as the -90 engines used in the F4F-3A. It seems to be around 1 1/2 to 2 years late?

Just a tiny digression. The F8F is almost long as F4F, has a wing span smaller by a good meter (and a smaller wing area). It certainly looks smaller. It has approximately 25% larger Wing loading but also a much heavier engine (and almost twice the Max takeoff weight). Bottom line - as if Wildcat is a bit too big. Maybe it's not about improving the F4F but reducing it to size e.g. P-36.

(http://imgur.com/nYqxwld)
View: https://imgur.com/nYqxwld

Zmauky said:

Just a tiny digression. The F8F is almost long as F4F, has a wing span smaller by a good meter (and a smaller wing area). It certainly looks smaller. It has approximately 25% larger Wing loading but also a much heavier engine (and almost twice the Max takeoff weight). Bottom line - as if Wildcat is a bit too big. Maybe it's not about improving the F4F but reducing it to size e.g. P-36.

(http://imgur.com/nYqxwld)
View: https://imgur.com/nYqxwld

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Wingspan of Bearcat is only ~0.75m less than Wildcat (10.82 vs 11.58m) with <1.5m^2 less area. And wing loading of Bearcat empty is higher than Wildcat at gross.

What it really demonstrates how much acceptable landing speed increased in the 4 years between the 2 Grumman fighters.

don4331 said:

I'm not sure a '40 USN pilot would be comfortable landing a fighter with wings of the size of a Me.109F (minus slats) on a carrier; I'm not sure if arresting gear of the period would stop it.

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Is there a math that proves that F8F was with wings of the size of Me 109F?

don4331 said:

The wider track of the Bearcat landing gear in nice, but it reduces the amount of the wing fold - 4 Bearcats with folded versus 5 Wildcats - how much is quantity alone worth? Obvious powers that be though 5 F4F-4s were worth more then 3 F4F-3 - which is number I've seen quoted for the advantage of the folding wings.

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A 100 mph difference between the two fighters, as well as far greater RoC, would've more than cancelled any shortcomings of having the lower number of fighters.

tomo pauk said:

Is there a math that proves that F8F was with wings of the size of Me 109F?

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Not the Bearcat with wings the size of the Me109F, but rather to get the wing loading of the Wildcat to equivalent.

Bearcat - 3,470 kg empty, wing area 22.67 m^2 = 153 kg/m^2
Wildcat - 2,225 kg empty same 153 kg/m^2 = 14.53 m^2

Me.109F wing area 16.05 m^2

So, my apologies to the Messerschmitt - it would be more like the clipped wing 109R.

My math OK for you?

A lot of the RoC increase is due to the near doubling of power.
The math for increase in speed/RoC are too complex for me to spitball (and I've seen how y'all rip people for making assumptions), so I'll leave it as significant for both. But is it worth the landing issues?

don4331 said:

My math OK for you?

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That math is good, but it is not what was claimed above wrt. wing size of the 109F being same as on the USN birds.

don4331 said:

There's a volume versus surface area relationship which means even though the Bearcat is larger, it doesn't have proportionately increased drag, so along with all that extra power, it will be proportionately faster.

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I'm not sure that we can read a lot into the "volume versus surface area relationship",since both aircraft were of similar shape and size.
By what token the Bearcat was larger, and if so, by how much?

don4331 said:

The math for increase in speed/RoC are too complex for me to spitball (and I've seen how y'all rip people for making assumptions), so I'll leave it as significant for both. But is it worth the landing issues?
Remember in '40 you are coming from F3F biplane - you don't have an F6F Hellcat/F4U Corsair as your 'advanced trainer before you hop into F8F.

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Yes, there was a learning curve for anything, including the landing of ever heavier aircraft on the carriers.
Companies making US naval aircraft were pretty slow to adopt Fowler flaps, these helped both for taking off and landing.

tomo pauk said:

I'm not sure that we can read a lot into the "volume versus surface area relationship",since both aircraft were of similar shape and size.
By what token the Bearcat was larger, and if so, by how much?

Yes, there was a learning curve for anything, including the landing of ever heavier aircraft on the carriers.
Companies making US naval aircraft were pretty slow to adopt Fowler flaps, these helped both for taking off and landing.

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I was comparing Z Zmauky proposal to decrease the wing area of Wildcat to that of Bearcat.
Simplify and add lightness - Fowler flaps, etc and both complexity and weight the opposite of what an aircraft designer should be attempting. Adding 'features' is more easily done when you have engines of 2k+ hp and you have several generations of examples.

don4331 said:

I was comparing Z Zmauky proposal to decrease the wing area of Wildcat to that of Bearcat.
Apologies, if in my 1st response I didn't spell out what I meant by it would involve decreasing wing area to that of the Luftwaffe fighter.

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Okay, thank you.

don4331 said:

Simplify and add lightness - Fowler flaps, etc and both complexity and weight the opposite of what an aircraft designer should be attempting. Adding 'features' is more easily done when you have engines of 2k+ hp and you have several generations of examples.

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Simplifying and adding lightness are great if not over-emphasized. Eg. the fixed U/C was very simple and light, people were still eager to implement the more complex and heavier retractable U/C.
Fowler flaps worked just fine on the Ki-43, a very light aircraft with 950-1100 HP engine.

In ww2, seems like the complex and heavy fighters were a better choice than light and simple types.

don4331 said:

Didn't Grumman test split vs plain flaps on a Wildcat and come to the conclusion that the extra weight/complexity cost more than the performance increase? (I'm reviewing my reference material; might update the post)

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I'm indifferent wrt. these two flap types, since there is a small difference in what was offered by both.
Contrary to that, Fowler flaps offered a lot more wrt. increased lift at low speeds.

don4331 said:

Wasn't the XP-38 written off in part because the Fowler flaps failed? Setting the whole program back.

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XP-38 was written off because of the crash? A thing that was visible was the engine section cracked from the wing, eg. here. See here for the wrecked wing, too.
Crash happened due to carb icing, I'd chalk that to the 'young guns' of the AAC trying to prove a point and score PR points. Lockheed taking a lot of time to came out with the 1st YP-38 is also nothing to congratulate about.

Isn't the Bearcat smaller than the Wildcat?

tomo pauk said:

Fowler flaps offered a lot more wrt. increased lift at low speeds.

XP-38 was written off because of the crash? A thing that was visible was the engine section cracked from the wing, eg. here. See here for the wrecked wing, too.
Crash happened due to carb icing, I'd chalk that to the 'young guns' of the AAC trying to prove a point and score PR points. Lockheed taking a lot of time to came out with the 1st YP-38 is also nothing to congratulate about.

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While Fowler flap do indeed offer increased lift at low speed - they effectively increase both wing area and camber. The effect of the Fowler is it reduces the controls effectiveness - aka makes the aircraft sluggish to controls input - the exact opposite to what you want in carrier aircraft. This is the issue Blackburn had with the Firebrand. And if you increase controls responsiveness at slow speed, you make the aircraft 'twitchy' at high speed. Which is bad for structural integrity.

XP-38 crash happened due a number of factors. Fowler flaps had broken in the previous landing, so they were wired shut. Kelsey was trying to bring the Lightning in as slow as possible clean when the carb icing issue reared its head. The result was he didn't make the airport and hit the ground...hot. Which wrote off the prototype. He never should have taken off for the last leg with a known damaged plane. As you say trying to score PR points.

Wild_Bill_Kelso said:

Isn't the Bearcat smaller than the Wildcat?

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The historic Bearcat is indeed marginally smaller than the Wildcat.

don4331 said:

The effect of the Fowler is it reduces the controls effectiveness - aka makes the aircraft sluggish to controls input - the exact opposite to what you want in carrier aircraft. This is the issue Blackburn had with the Firebrand.

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P-38 and F6F were both docile and maneuverable, and same goes for the last 3 Nakajima fighters's types designed - all of whom were outfitted with Fowler flaps.
Firebrand was an aircraft made bad. Perhaps pointing out to the Blackburn design bureau is in order, rather than to a device that worked well on other aircraft?

Zmauky said:

Just a tiny digression. The F8F is almost long as F4F, has a wing span smaller by a good meter (and a smaller wing area). It certainly looks smaller. It has approximately 25% larger Wing loading but also a much heavier engine (and almost twice the Max takeoff weight). Bottom line - as if Wildcat is a bit too big. Maybe it's not about improving the F4F but reducing it to size e.g. P-36.

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What is important is the actual take-off and landing speeds of the two aircraft. Wing loading is OK for first look. Once you start trying to figure out airfoils and types and flaps things go to crap pretty quick. Like actual flap area, how well the flaps actually work with the wing and airfoil and so on.

And lets be sure we are comparing apples to apples.
Like power off or on. Actual weights, like full fuel or empty and/or external loads.

The F8F-1 did stall at higher speed than than F4F-4. But under similar conditions it may have been only around 10% faster? Which is not what the comparison of wing loading suggests.

F7F with power on otherwise No power stalling speed at Gross Weight, plus take off distance in feet from a land base, no wind (FR-1 figures Piston / Piston & Jet, F4U-1D/FG-1D Normal / Emergency take off)

One thing I know about the US Navy flaps, at least on the Wildcat, is that they were not for maneuvering and would not deploy except at very low (i.e. landing) speeds. The Ki-43 and N1K2 flaps were definitely maneuvering flaps that could be deployed at a bit higher speeds. Same for the Bf 109, MC. 202, and many other aircraft, which had special maneuvering flap settings (which were like 5 degrees or something, much less than the landing deployment ratio). The Spitfire and Hurricane were either 'all up' or 'all down / landing' setting, as they didn't really need flaps for turning (at least not against German planes). The P-40 had a setting on the side of the cockpit which enabled a kind of dimmer switch on the control stick which could put in any amount of flaps, but of course if you deployed too much flaps at too high of a speed a variety of problems could ensue...

I think the P-38 maneuvering flaps deployed automatically, right? Or was it manual?

The problem is you don't get something for nothing.
If you use flaps for higher lift while maneuvering your drag goes way up.
The whole lift to drag thing.
If you are fine turning little circles (even vertical ones/loops) at 200mph fine, stick out those flaps. But if you want to maintain speed you can't stick out flaps.

Now this is a generality and there are exceptions.
The P-38 had well over 2000hp available and could trade drag for turning circle at times. P-38s usually had the best climb and the best level flight acceleration of any US fighters. It could recover from low speed/high drag period of flight quicker than any other US fighter.
A P-38F had roughly twice the acceleration ( ft/sec/sec) of a P-40E or F4F-4 using military power.
Using a P-38 as an example is not a good one.

Not sure if the Bf 109 had maneuver flap settings. The slats on the leading edge are different and are much misunderstood. By the time they pop out the wing is operating at around 12-14 degree angle of attack (entire wing is 12-14 degrees to the line of flight) and while that generates a lot of lift, it also generates a crap ton of drag. A lot of the German aces had learned to operate on the verge of the slats popping out (still high drag) and often went quickly in and out of the slats deploying. But they are at low speed and depending on engine power to keep from stalling or at least keeping decent to minimum. The slats were actually more important for maintaining aileron control when the wing stalled. A 109 in a tight turn could stall, the pilot could keep control, the plane could mush out of the turn (increase the radius) while keeping somewhat the original heading (and descending). Planes like the Fw190 stalled one wing before the other and rolled over (relative to the original angle of flight) and lost a lot more altitude before the pilot could recover. The 109 was not easy in that situation, but it was possible rather than impossible.
P-40s seem to show that flaps should not be lowered at speeds over 140mph (?).




This is why rate of climb is so important. It is not an ideal indicator of available power put it is the best we have that is quickly/easily available.
Planes that have a high climb rate (surplus power at low speed) can get back to altitude or speed faster than "fast" airplane that has low surplus power. Less time for an enemy to catch them in a low energy state.

tomo pauk said:

P-38 and F6F were both docile and maneuverable, and same goes for the last 3 Nakajima fighters's types designed - all of whom were outfitted with Fowler flaps.
Firebrand was an aircraft made bad. Perhaps pointing out to the Blackburn design bureau is in order, rather than to a device that worked well on other aircraft?

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Hellcat has slotted flaps, not Fowler flaps

Are any of the other fighters carrier planes?

Let's not confuse maneuverable at combat speeds with responsive at landing speeds.

Shortround6 said:

This is why rate of climb is so important. It is not an ideal indicator of available power put it is the best we have that is quickly/easily available.
Planes that have a high climb rate (surplus power at low speed) can get back to altitude or speed faster than "fast" airplane that has low surplus power. Less time for an enemy to catch them in a low energy state.

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But don't sailplanes (OK, for this discussion, let's limit to planes like Ta.152H have wonderful rates of climb? But that's kind of opposite of Bearcat concept, isn't it?

Geoffrey Sinclair said:

F7F with power on otherwise No power stalling speed at Gross Weight, plus take off distance in feet from a land base, no wind (FR-1 figures Piston / Piston & Jet, F4U-1D/FG-1D Normal / Emergency take off)

Model	Date	Pounds	MPH	Feet
F4F-3	14-Aug-42	7,556​	79.1​	550​
F8F-1/F3M-1	1-Jul-45	9,386​	92.1​	360​

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Thank you Geoffrey.

The numbers are very useful. As lift is a function of V^2, the increase from 79 mph to 92 mph represents a 35% increase in lift.

And it gets even more dramatic if you remove 20 knot (23 mph) wind over deck - speed delta becomes 56 versus 69 mph.
Stopping distance is whole different facet to this discussion.