Can we make a faster better performing Wildcat in 1942?

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Yes but you are thinking of 'full' flap deployment. Most WW2 fighters had 'takeoff', 'landing' and 'combat' flap settings. Combat is the least amount of deployment, usually somewhere between 5-15%, depending on the aircraft. That gives you a boost in lift without quite as much of a killing penalty in drag as you would have with full flap deployment (landing).

Skilled fighter pilots would drop partial flaps for a moment, and then retract them. Depending on the aircraft a partial flap setting can go up or down pretty quickly. So it could be used to tighten a turn for a few seconds, such as to pull lead, or escape from a pursuer pulling lead, before going 'clean' again.

Putting in partial flaps can be a way to control or burn off excess speed while turning, sometimes in combination with a vertical turn like an Immelmann or a Split-S, or a high yo yo. The speed can also be picked up again in a dive or a low turn like a low yo-yo.


That's interesting, though you are assuming level flight. Most WW2 fighters relied a lot on diving to pick up speed.

Shortround6 said:
A P-38F had roughly twice the acceleration ( ft/sec/sec) of a P-40E or F4F-4 using military power.
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What is that based on precisely?

Shortround6 said:
Using a P-38 as an example is not a good one.
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Compared to what? N1K2? I beg to differ...


Yes they had both combat flap settings and the slats. The slats deployed only in the tightest turns.


Yes, though again that is at very low speeds.


Agreed, riding a stall was not a good idea in a Fw 190

Shortround6 said:
P-40s seem to show that flaps should not be lowered at speeds over 140mph (?).
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That would mean full flap deployment (i.e. for landing). In a P-40, there are no pre-set flap settings. Instead, there is a hydraulic switch on the left side of the cockpit which can be set to landing gear, flaps etc. Once that is set to 'flaps', there is a switch on the control column which can activate it from 1-100%. For combat maneuvers you would set that to 5 or 10% at the most. And it's not something an inexperienced pilot would do in combat necessarily, but some of them clearly did.





Well, the other method is dive / zoom climb, which is for example how Fw 190s maintained altitude. Same for P-40s and many other fighter types.

Actually I'd say the P-38 is kind of unique because they had a disengagement maneuver, at least in the Pacific and China, which involved a high speed shallow climb to disengage. Not many other fighter types could do that, obviously depending on the opposition.
 
don4331 said:
Hellcat has slotted flaps, not Fowler flaps
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See here, Helcat's flaps were extendable away from the wing towards the tail and down (and not just tiltable down and up like the slotted and plain flaps), thus making the total lifting surface of bigger area and camber. IOW, same features as the Fowler flaps.
Also this, and this.

don4331 said:
Are any of the other fighters carrier planes?
P-38, Ki -44 and K-84 aren't. Smart @$$ in me, isn't Ki-115, Nakajima's last production fighter?
Let's not confuse maneuverable at combat speeds with responsive at landing speeds.
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Let's not. The aircraft with Fowler flaps were both maneuverable at combat speeds, as well as responsive at landing speeds and at taking off.
Carrier planes - Like the Hellcat, Firefly, D4Y - or not.

Shortround6 said:
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.
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Perhaps the wing thickness played the part, with the very thick wing profile of the F8F offering the better lift per unit of area than the thinner wing profile of the F4F?
 
Busy Sunday, so I didn't get to participate... actually, a short remark should have been about the design philosophy and sheer size. As the Bearcat is designed for the smallest airframe for the R-2800 and range, I think a wiff Wildcat with R-1820 and 4x12.7 and enough range (read fuel weight) could be at least 20-25% smaller aircraft than the RL F4F.
With a cigar silhouette, it expands even further after the engine.
Somewhere on the net there is a picture of the conversion where 4 passenger seats have been added behind the cabin - that's how big it is.
Smaller structure, lighter engine (not F8F r-2800 but R-1820), lower aerodynamic resistance ... somehow I believe that wing loading would remain the same or at least would not require complicated and heavy flaps or high lift devices. Now let's imagine the Me 109 enlarged to the size of the F4F (or A6M). How much his performance would drop. And our F4F-alt would probably lose weight (being smaller) and keep relatively low wing loading (required). And was significantly faster with all other performances rise.

 
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yeah I wonder how long it would take to redesign the fuselage though?

What you are saying is immediately clear if you look at a scale model of an F4F next to an A6M or Ki-43 (or look at real life warbirds side by side if you get that chance). The Japanese fighters look so slim and elegant compared to the Wildcat. They look like they are in a different scale. Same if you put a Wildcat next to a Spitfire or a Bf 109 or a Yak. It's a really beefy plane, the fuselage is like twice as thick and half again as high. I always assumed a lot of that internal space was being used for fuel, but if it isn't, definitely a slimming down would seem likely to help... a lot.
 
The Wright R-1820, required alternate engine, has diameter 1.38m vs Nakajima Sakae with diameter 1.12m means the Wildcat fuselage is almost 25% greater diameter by default. (It's Wildcats with P&W R-1830 - diameter 1.22m - that really looks "fat" in the mid section).

Also note, Wildcat fits an air to air intercooler under the cowl, which Zero doesn't. If you give up the intercooler, you're giving up altitude performance - can your '40 Wildcat afford that?

So, unless you commit hard to the P&W Twin Wasp, there isn't a lot of fuselage reduction possible.
 

Oh, I don't buy that for a second. Just because the engine is a certain diameter doesn't mean the whole fuselage has to be that wide



 
Wild_Bill_Kelso said:
Oh, I don't buy that for a second. Just because the engine is a certain diameter doesn't mean the whole fuselage has to be that wide
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That is true.
However.................
The speed difference between the F4F and the P-36/Hawk 75 is not that great.
Vultee Vanguard was supposed to be good for 340mph at 15,000ft?

199sq ft wing?

Granted there may have been some other features that were not good (exhaust thrust was on the sketchy side) And perhaps a longer fuselage/tail might have been traded for smaller vertical and horizontal stabilizers? They had been enlarged twice during development.

Not saying that things could not be improved at all. However improvements don't seem to easy or substantial.
 

I'm not arguing that a P-36 is necessarily a better airframe, it's just a good example of an airframe that is clearly thinner and more streamlined than an F4F. The P-36 itself looks a bit chunky compared to a Ki-43 or even an A6M, though it's much closer to them than the Wildcat. I'll pull some models down from the shelf to show what I mean.

Forgive the dust, these have been up on the shelf for a while:





As you can see clearly in that top photo, the Wildcat actually flares out considerably from the diameter of the engine, and gets a good bit thicker, being 'cigar shaped' as Zmauky put it.

As for top speed, did they ever put one of those two stage supercharger R-1830s like the Wildcats had on a P-36? Or even two speed? best speed is usually up around 20,000' or higher where the air is thinner, but I believe the critical altitude on the P&W or Wright engine used on those was around 12-15,000 ft
 
Shortround6 said:
That is true.
However.................
The speed difference between the F4F and the P-36/Hawk 75 is not that great.
Vultee Vanguard was supposed to be good for 340mph at 15,000ft?
Click to expand...

F4Fs that really mattered (-3, -4) have had the best R-1830s in the nose, yes speed was not what they did well.
On the same engine that powered the P-66, the Martlets were making 317 mph (300 mph if with folding wings and 6 HMGs). The P-36, with the engine tailored for same rated height but with 100 HP less was matching that turn of speed.
Conversely, the test mule that shared a lot of genes with the P-36, and was powered by the engine that the F4F-4 had, was 60 mph faster. Yes, some of the speed differential was due to no guns, light weight, no protection, and better exhausts (20 mph worth?).

F4F was many things. A fighter tailored for speed and RoC it was not.


Too bad Wildcat didn't gained the proper exhaust stacks until the FM2. Both speed and RoC would've benefited, and these exhaust stacks were not some too complicated, heavy or expensive item to add.
Trimming the wing will not be that easy, a lot of drag was due to it. The blown fuselage design was shared by only F2A IIRC, other radial-powered fighters were with the ever thinner fuselage past the engine cylinders. Windscreen does not say 'I'm streamlined' at all.
Size-wise, WIldcat was closer to the Centaurus-powered Tornado, than to the Zero or Ki-43, while the engine power was comparable with the Japanese fighters. Bigger size adds to the drag, and often to the weight.
 
Wild_Bill_Kelso said:
What do you mean by 'test mule'
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'Test mule' is another name for 'flying test bed'.
See here for a P-40 re-engined with the 2-speed 2-stage R-1830 (scroll a bit).

FWIW:
Nevertheless, this P-40/R-1830 could reach 388mph at 25 000ft (at this altitude its engine still maintained 1015hp in the "military" power mode). This is an excellent result, when you compare it to the 311mph of the P-36C. Pratt-Whitney calculated that for the fully-equipped aircraft weighting 8 300lbs it would decrease by 10mph, to about 378mph.

(that webapge's author is a member here)
 
wow... 388 mph at 25,000 ft, why didn't they follow up on this bad boy? I guess it just got put together too late.



I think Sr6 showed this once before and i was curious about it but never followed up. Quite an impressive performance.

I think this does indicate that a thinner body for the Wildcat might have paid dividends, if they could get it all ready for production quickly enough.
 
Wild_Bill_Kelso said:
wow... 388 mph at 25,000 ft, why didn't they follow up on this bad boy? I guess it just got put together too late.
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While they hit 380mph in the late fall of 1942 the 388mph figure was not achieved until sometime between July 1st and Oct 22 1943.
Wild_Bill_Kelso said:
I think this does indicate that a thinner body for the Wildcat might have paid dividends, if they could get it all ready for production quickly enough.
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Not saying that a thinner fuselage would not have helped.....................But....................................
The Plane used the same wing as a P-40B or Tomahawk II or 90.7% of the size of the F4F wing.
The plane was fitter for (but not given) four .30 cal guns. about 100lbs lighter than P-40E wing. And had smooth leading edge and no shell ejector slots. No cowl guns.
Used a rounded Windshield and not a flat on the front like later P-40s. The cowl appears to be very smooth and well finished going back to just about the cockpit.
The speed/power at 25,000ft is both notable and questionable.
Higher speed means higher RAM pressure inside the intake and means more power than a slower plane using the same engine at the same altitude.
Apparently P&W did very well with the RAM. However this does not translate as well into climb where the speed is much lower.
The other aspect is the ejector exhaust which P&W also apparently did very good work with.
However ejector exhaust also offers more benefit to a fast plane than a slow one. Power is not thrust. Thrust can be constant (under "certain conditions") but it is proportional the difference between the speed of the exhaust gases and the speed of the aircraft (or vehicle).

A piston plane using jet exhaust gets a much smaller benefit when climbing than it does at high speed.
Back to the "certain conditions". As the plane climbs higher into thinner air the back pressure (or atmospheric pressure) drops and the speed of the exhaust gases increases which helps compensate for the dropping mass (fuel and air weight) of the exhaust gasses. Some figures for a Merlin XX engine in a Hurricane II.
Altitude/speed..................Atmos pressure...........charge flow.......................Exhaust Velocity.................exhaust horse power.
15,000/325...............................16.68............................140.5lbs................................1395ft/sec.................................86.5
20,000/335...............................13.74............................144.0lbs................................1695ft/sec...............................113.0
25,000/330...............................11.10............................129.1lbs................................1840ft/sec...............................107.2
30,000/317..................................8.88............................107.2lbs................................1901ft/sec.................................89.0

80-120hp from the exhaust gas is certainly a nice boost at altitude for not a lot of weight/complication but it doesn't work as well at low altitudes and at low speeds. But it also doesn't cost much in weight or money so it doesn't hurt anything.
For the Radial P-40 it had both better speed than an F4F which means a bit more ram (more charge flow through the engine ) and a bit better match between the exhaust gas velocity and the aircraft speed.
 
So you are suggesting that most of the speed increase with this R-1830 powered P-40 / P-36 was due to lower weight (because no guns, armor etc.) and the jet effect from the properly ducted exhaust stacks?

It's an interesting point, certainly 80-120 hp is nothing to sneeze at. I hadn't realized the exhaust boost was that much.

One thing I notice though is that this prototype / testbed also had substantially improved speed at sea level ("the P-36C reached 272mph at sea level, while the P-40/R-1830 – 315mph."), where presumably the exhaust boost would be much less ? Or am I reading that wrong?

The F4F-4 also made about 275 mph at sea level, which isn't very good by the standards of the day.

For comparison, A6M2 is about 280 mph and Ki-43-II is 295 mph at sea level. A P-40E is 287 (military power) - 314 mph (WEP) at sea level (about the same as the experimental R-1830 one). A Hurricane IIC is 260 (9 lbs boost)-290 (at 16 lbs boost) at sea level. Spit V is 289 (9 lbs boost) to 316 (16 lbs boost) at sea level.

A bit more speed down low would also be quite helpful I think.

Isn't drag more significant in the thicker air at low altitude?
 
Wild_Bill_Kelso said:
So you are suggesting that most of the speed increase with this R-1830 powered P-40 / P-36 was due to lower weight (because no guns, armor etc.) and the jet effect from the properly ducted exhaust stacks?
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weight does not have a lot to do with speed if everything else stays the same.
Which it didn't.
Wild_Bill_Kelso said:
It's an interesting point, certainly 80-120 hp is nothing to sneeze at. I hadn't realized the exhaust boost was that much.
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Again the power is variable depending on the speed of the aircraft. This goes back to the true statement (technically) that a jet engine makes zero HP sitting on the runway with the brakes on. It is making a lot thrust but thrust is not horsepower. The same thrust makes more power the faster the plane/vehicle is moving.
At low altitude the exhaust is fighting the 29.92 in hg air pressure and is going to have several hundred fps less velocity.
We have to rather careful as to what the date is or what data we are using. The engines in P-36A/C had several different power ratings depending on the month/year and fuel used.

With 92 octane fuel they were allowed 1050hp take off at 2700rpm and 820hp at sea level at 2550rpm. There was no Military rating at this time.
With 100 octane fuel they were allowed 1200hp take off at 2700rpm and 1025hp at sea level at 2550rpm. There was no Military rating at this time.
Most of the early testing was done at 2550rpm for speed ratings but they did use 2700rpm for climb for 5 minutes.

So you may be rating a plane using 1200hp + exhaust thrust vs a plane with 1025-1050hp without exhaust thrust. The P-36 and F4F got very little or no exhaust thrust. What you see in pictures is a fairing over the actual exhaust pipes on the P-36 and the actual exhaust pipes directed the exhaust gases down, not rearward. And using more that 3 cylinders per exhaust pipe killed most of the thrust benefit.

The other thing to look at is that cooling flow through the cowling was changed..............a lot. You not only have the addition of exhaust thrust, you have less cooling drag. You also have less drag in general from the whole cowl area.

The Modern Air Show example. I don't believe the P&W test plane had the slot in side of the cowl aft of the adjustable cooling flaps. There is not a lot of good information on the P&W test plane but it appears they did an awful lot of work on the installation itself in regards to airflow inside the cowl and for cooling the engine. Fit and finish may have exceeded even air show standards.


The other thing is what are you willing to sacrifice

You can make the fuselage thinner in width, but can you make the fuselage shallower in depth (top to bottom)?
F4F pilot was sitting on a bigger fuel tank. P-36 had some of the fuel behind the pilot.
F4F had a very good view over the engine for carrier landing and for defection shooting.
The P-36?

If you don't change the diameter of the tube but only squash it a bit do you really gain that much drag reduction?
At least surface drag?
 
I'm no engineer, but to me, just eyeballing it, a thinner fuselage would still help. The Corsair actually looks a good bit slimmer than an F4F, and I think that helped with it's speed compared to the F6F.

In the comparison above, I would agree 'where to put the gas' is an issue - the P-40 ultimately had most of it's gas in the center / wing, with reserve fuel behind the cockpit (but this contributed to instability and was not used when there was an expectation of combat soon after takeoff) and with wings strengthened a bit more than those of the P-36, it turned out to be able to carry pretty heavy wartime loads, though as far as I know only the centerline was plumbed for fuel.

It was always a bit of a mystery to me why the Navy took so long to put external fuel tanks on the Wildcat, but maybe in part that had to do with the odd landing gear setup, which I suspected might also have something to do with it's girth.

If my numbers are correct, the Wildcat carried 144 gallons of fuel normally. The internal capacity of the (much slimmer) P-40 was actually a bit more, 157 gallons. The A6M also carried 156 gallons, and it's definitely slimmer in profile than the Wildcat, the very slim Ki-43 carried 147 gallons, which is a bit more than the Wildcat.

Placing the internal fuel tanks on a fighter plane (while leaving room for fuel, guns etc.) is a tricky science in and of itself, I think. I believe both the F4F and the P-36 had somewhat odd landing gear arrangements which took up a lot of space and contributed to drag.

But I'm increasingly convinced a slimmer Wildcat could have helped improve performance a bit. And while I understand the issue with the need for a high cockpit, I think that could be improved a bit too, the only real question is how long would all that have taken. Could you have had something into production in 1943, like maybe by GM or Goodyear or some other firm?
 
F4F-3 carried 160 gal. later reductions had to do with self sealing.
P-40s are all over the place. From 180 in the P-40__ down to 135 in some of the P-40Cs, some of the Ls and and Ns got down to 120 gal but that was without the forward tank.
The P-40F is supposed to have carried 157 gal. Different from the P-40D/E. This depends on source so????
The weight/balance really comes into play in the P-36/P-40 series. P-40F/L were supposed to empty the forward tanks and keep 35 US gal in the rear tank. Perhaps to balance the heavier Merlin engine? The Allison powered versions were supposed to empty the rear tank and keep the reserve fuel in the forward wing tank. Planes that had the forwrad tank take out/not fitted were suppose to empty the rear tank and keep some fuel in the rear wing tank.
The very slim Ki-43 carried all it's internal fuel in the wing. I don't know how much was under the fuselage.
P-36 used the same landing gear setup as the P-40. Perhaps the wing tank/s could not go out very far due to the landing gear wells. P-40 landing gear gets a lot of criticism. P-40 long nose was not much slower than a Spitfire I/II. Yes the P-40 was slower than Mustang, but then everything was using similar power.
On the F4F the landing gear may get some of the blame. Curtiss tried using similar landing gear on a slim fuselage radial engine biplane.

Now something to consider here for all of the carrier P-36 fans.
The F4F landing gear had 12.5in of oleo deflection.
The P-40 landing gear had 7.0 in of oleo deflection.
Wild_Bill_Kelso said:
It was always a bit of a mystery to me why the Navy took so long to put external fuel tanks on the Wildcat, but maybe in part that had to do with the odd landing gear setup, which I suspected might also have something to do with it's girth.
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They were planning on using drop tanks quite while before they actually showed up. Actual delay is??????
The tanks went where the 100lb bombs went, under the fixed part of the wing.

Supply of a lot things took a while in 1942.
 

This is a little garbled, allow me to untangle. First, P-40s and P-36s both lost fuel capacity due to self sealing tanks just like the Wildcat did.



Second, the "wing reserve fuel tank" of 35gal (F on the pic above) was normally used for any longer ranged missions. It was removed or left empty in some cases with P-40F and L as a weight saving measure, usually for interception or frontal aviation / fighter sweep type missions where they expected to be in combat shortly after takeoff. The wing main tank of 50.5 gallons (G on the pic) was always used in all versions. The 62 gallon rear fuselage tank (L on the pic above) was said to cause handling problems when full, so the goal was to burn that fuel first, during warmup, taxi, takeoff, even before the external tank if carrying one.

The fuel in all the Hawk 87 types was basically the same, with the exception that some of them the forward reserve tank (F) was stripped out.

Shortround6 said:
The very slim Ki-43 carried all it's internal fuel in the wing. I don't know how much was under the fuselage.
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Noteworthy that Ki-43s were fitted for, and were using external tanks pretty early on, as were P-40s and A6Ms.
Shortround6 said:
P-36 used the same landing gear setup as the P-40.
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Yep

Shortround6 said:
Perhaps the wing tank/s could not go out very far due to the landing gear wells. P-40 landing gear gets a lot of criticism.
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Yes... the landing gear does get in the way there as you can see in the diagram.

Shortround6 said:
P-40 long nose was not much slower than a Spitfire I/II. Yes the P-40 was slower than Mustang, but then everything was using similar power.
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Yes, Spitfire was faster at altitude though. P-40 was a little faster down low.

Shortround6 said:
On the F4F the landing gear may get some of the blame. Curtiss tried using similar landing gear on a slim fuselage radial engine biplane.
View attachment 771131
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Yeah, yikes! I forgot about the Goshawk. That definitely does illustrate the problem. Which in aggregate, does mean you needed not just a slimmer fuselage, but a redesigned wing with somewhere to put the main landing gear other than in the fuselage. Which means basically a whole new plane. A Hellcat, in other words.

Shortround6 said:
Now something to consider here for all of the carrier P-36 fans.
The F4F landing gear had 12.5in of oleo deflection.
The P-40 landing gear had 7.0 in of oleo deflection.
Click to expand...

For the record, I'm not suggesting putting a P-40 or a P-36 on a carrier, they were designed for that. I just showed the pic of the P-36 to make a point about the fuselage size.

The Corsair has a thinner fuselage (max width) than the Wildcat too I'm pretty sure, in spite of having a bigger engine with a wider diameter. So it's definitely doable.

Shortround6 said:
They were planning on using drop tanks quite while before they actually showed up. Actual delay is??????
The tanks went where the 100lb bombs went, under the fixed part of the wing.

Supply of a lot things took a while in 1942.
Click to expand...

They seemed to get external tanks to some types but not others, I suspect the Navy was lagging on this and it may have had a major impact to be honest.
 
It's interesting that the Wildcat had a bit better range than the P-40, on internal fuel, even though it carried a bit less and was obviously a good bit draggier. Is the R-1830 just that much more fuel efficient, or is it due to cruising at a higher altitude maybe?
 

Shortround6 said:
F4F-3 carried 160 gal. later reductions had to do with self sealing.
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Grumman probably considered that installing the fuel tanks in the wings was work of Dr. Evil, at least on it's 4 most known piston-engined fighters.

Shortround6 said:
They were planning on using drop tanks quite while before they actually showed up. Actual delay is??????
The tanks went where the 100lb bombs went, under the fixed part of the wing.
Click to expand...
The 1st Wildcats with drop tanks were with a single unit just under the fuselage. The -4 changed that, and gaind two under the wings.

The P-40Ns were supposed to carry 158 gals of fuel (bar the 'stripper' subtypes); the -M carried 10 less. Per the 1943 manual.
The P-40F carried the same as the -M, in all tanks.
The -L was without the front tank, so 158-35= 123 gals.
(all the figures are without the drop tanks taken in consideration)


Naval aircraft usually cruised on lower speeds and at lower altitudes (USN was cheerfully specifying 1500 ft as altitude on the return leg), a luxury the land-based aircraft cannot afford since the enemy is often much closer, the enemy AA guns are in vicinity. Surrendering the altitude and speed advantage to the enemy is still a bad advice to heed, let alone back in ww2.
 
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