Dive Bombing: USN vs USAAF/USAF

[KJ_Lesnick]

Wuzak

Engines for the F4U:

XF4U-1: XR-2800-1 - updraft carburettor
F4U-1: R-2800-8/8W - updraft carburettor
F4U-2: R-2800-8 - updraft carburettor

If these are updraft, wouldn't you be best off having the intake under the engine?

F4U-3A: R-2800-16 - single stage engine coupled to Turbo Engineering turbocharger, downdraft carburettor
F4U-3B: R-2800-14 - single stage engine coupled to Turbo Engineering turbocharger, downdraft carburettor

The F4U-3's were experimental designs to evaluate the turbocharger: Why did they switch from updraft to downdraft?  Was this due to the airflow through the turbo?

F4U-4: R-2800-18W - downdraft carburettor, fluid coupling for auxiliary supercharger

Firstly: Why the switch from updraft to downdraft?

Secondly: The F4U-4's supercharger was twin-speed with the first stage being twin-speed; the second having some variability?

It's called a "sidewinder".

The R-2800-32W had two auxiliary stage superchargers feeding the single main supercharger. These two superchargers were handed and mounted with their axes perpendicular to the engine's, and were driven by a cross shaft.

So the idea was like having two auxiliary superchargers to do what was normally done by one?

[wuzak]

Wuzak

Engines for the F4U:

XF4U-1: XR-2800-1 - updraft carburettor
F4U-1: R-2800-8/8W - updraft carburettor
F4U-2: R-2800-8 - updraft carburettor

If these are updraft, wouldn't you be best off having the intake under the engine?

The intakes fed the 1st stage or auxiliary supercharger. That discharged through one or more intercoolers (two for the F4U-1/2), and then was ducted to the carburettor. The carburettor fed the main stage supercharger, which fed the engine.

F4U-3A: R-2800-16 - single stage engine coupled to Turbo Engineering turbocharger, downdraft carburettor
F4U-3B: R-2800-14 - single stage engine coupled to Turbo Engineering turbocharger, downdraft carburettor

The F4U-3's were experimental designs to evaluate the turbocharger: Why did they switch from updraft to downdraft?  Was this due to the airflow through the turbo?

It may have had something to do with the arrangement of the turbo installation, or that the best available engine for the project had a downdraft carburettor. In any case, like the F4U-1 the carburettor was fed air from the intercoolers.

F4U-4: R-2800-18W - downdraft carburettor, fluid coupling for auxiliary supercharger

Firstly: Why the switch from updraft to downdraft?

Secondly: The F4U-4's supercharger was twin-speed with the first stage being twin-speed; the second having some variability?

May have been the best available engine, or Vought may have just refined the intercooling. Most likely because the intake was relocated from the wing leading edge to under the nose an updraft carburettor would have been in the way.

The R-2800-18W had an auxiliary stage supercharger with variable speed drive and the main stage supercharger with a single speed fixed ratio.

It's called a "sidewinder".

The R-2800-32W had two auxiliary stage superchargers feeding the single main supercharger. These two superchargers were handed and mounted with their axes perpendicular to the engine's, and were driven by a cross shaft.

So the idea was like having two auxiliary superchargers to do what was normally done by one?

Yes. In theory the two auxiliary stage superchargers could be smaller than one.

In the same way that the R-3350s in the B-29 and the R-4360 in the B-50 were fitted with two B-Series turbochargers rather than one larger turbo (the C-Series was big enough).

[KJ_Lesnick]

Wuzak

The intakes fed the 1st stage or auxiliary supercharger. That discharged through one or more intercoolers (two for the F4U-1/2), and then was ducted to the carburettor.

Firstly: So the airflow path was essentially altered by the supercharger and intercooling ducting?  Sounds like quite a complicated airflow path.

Secondly: The F4U-1 had two stages of cooling?

Most likely because the intake was relocated from the wing leading edge to under the nose an updraft carburettor would have been in the way.

Then what did those intakes in the wing-roots do?  I thought they were the primary intake?

The R-2800-18W had an auxiliary stage supercharger with variable speed drive and the main stage supercharger with a single speed fixed ratio.

Like the P-63?

Yes. In theory the two auxiliary stage superchargers could be smaller than one.

Okay

In the same way that the R-3350s in the B-29 and the R-4360 in the B-50 were fitted with two B-Series turbochargers rather than one larger turbo (the C-Series was big enough).

I thought one was for the pressurization system lol

[wuzak]

The intakes fed the 1st stage or auxiliary supercharger. That discharged through one or more intercoolers (two for the F4U-1/2), and then was ducted to the carburettor.

Firstly: So the airflow path was essentially altered by the supercharger and intercooling ducting?  Sounds like quite a complicated airflow path.

It is a complicated air flow path, but it is required to use intercoolers.

Compare with the P-38. The turbo's compressed air was fed into the leading edge intercoolers in the wings (on early versions) or fed forward to the chin mounted core-type intercooler (on later versions) before being sent back to the carburettor and the engine.

Secondly: The F4U-1 had two stages of cooling?

No, two intercoolers. One on each side.

Most likely because the intake was relocated from the wing leading edge to under the nose an updraft carburettor would have been in the way.

Then what did those intakes in the wing-roots do?  I thought they were the primary intake?

The leading edge intakes fed the intercoolers. On the F4U-1 they also fed induction air.

The R-2800-18W had an auxiliary stage supercharger with variable speed drive and the main stage supercharger with a single speed fixed ratio.

Like the P-63?

Yes.

In the same way that the R-3350s in the B-29 and the R-4360 in the B-50 were fitted with two B-Series turbochargers rather than one larger turbo (the C-Series was big enough).

I thought one was for the pressurization system lol

Later versions had a cabin pressurising supercharger, while earlier models may have bled air from the turbos or engine stage supercharger.

[KJ_Lesnick]

wuzak

It is a complicated air flow path, but it is required to use intercoolers.

Compare with the P-38. The turbo's compressed air was fed into the leading edge intercoolers in the wings (on early versions) or fed forward to the chin mounted core-type intercooler (on later versions) before being sent back to the carburettor and the engine.

Okay, so basically one could put the carburetor and oil-cooler on the bottom, then use an intercooler and exploit the torturous flow path to feed a downdraft carburetor?

Just to be clear (and yes this may or may not be repetitive but I want my facts straight): I'm curious if such an intake would be adequate for doing all the following: Feeding air to the engine and intercooler (being air-to-air cooled); cooling the oil and intercooler radiator in one?  Particularly if you had one scoop in another

• Inside Scoop: To carburetor and intercooler cooling
  
• Outside Scoop: Oil cooler and intercooler radiator
  

While I'm at it: Could oil be used as a liquid coolant for an intercooler as well as the engine (It would be more compact, and you could use one radiator for both)?  Also, had that ever been thought of or proposed?

No, two intercoolers. One on each side.

Wait... the airflow path after going through the first stage divided into two paths?  The term "intercooler" implies it's between the first and second stage...

The leading edge intakes fed the intercoolers. On the F4U-1 they also fed induction air.

So on the F4U-1 they fed air to both the engine and intercooler; on the F4U-4, the ventral intake fed the engine, and the sides fed the intercooler alone?

Yes.

Gotcha

Later versions had a cabin pressurising supercharger, while earlier models may have bled air from the turbos or engine stage supercharger.

Okay

[wuzak]

Okay, so basically one could put the carburetor and oil-cooler on the bottom, then use an intercooler and exploit the torturous flow path to feed a downdraft carburetor?

You contradicted yourself there.

The intercoolers were required to give the engines their best performance. The air flow path was determined by where the intercoolers were located, which in turn was dictated by how much air was required to cool them and how that could all be controlled.

Just to be clear (and yes this may or may not be repetitive but I want my facts straight): I'm curious if such an intake would be adequate for doing all the following: Feeding air to the engine and intercooler (being air-to-air cooled); cooling the oil and intercooler radiator in one?  Particularly if you had one scoop in another

• Inside Scoop: To carburetor and intercooler cooling
  
• Outside Scoop: Oil cooler and intercooler radiator
  

There are several cases where the one duct has fed air to multiple coolers. The P-40's duct, for example, feeds air through the radiators and oil coolers.

The P-51B's belly scoop fed the radiator, the intercooler radiator and the oil cooler. The latter was a duct within the duct, as it were, and had its own exit for controlling cooling. The intercooler radiator and radiator were, of course, in one unit, but using separate coolant flow paths. In teh P-51A the oil cooler was mounted inside teh radiator.

The problem with trying to do too much in one intake is that the whole system could become big, and necessarily locates all of the components in the same place.

While I'm at it: Could oil be used as a liquid coolant for an intercooler as well as the engine (It would be more compact, and you could use one radiator for both)?  Also, had that ever been thought of or proposed?

Oil could be used as a coolant for the intercooler, but I believe that using the same cooling solution as the engine was the best way.

No, two intercoolers. One on each side.

Wait... the airflow path after going through the first stage divided into two paths?  The term "intercooler" implies it's between the first and second stage...

Yes, the auxiliary supercharger had and two discharges. So it wasn't divided in a duct taken off the supercharger, but as a function of the supercharger itself.

The engine stage supercharger for an R-2800 had 9 discharge pipes.

Yes, intercooler means cooling between first and second stage compressors, and that is exactly what the two intercoolers of the F4U did.

The leading edge intakes fed the intercoolers. On the F4U-1 they also fed induction air.

So on the F4U-1 they fed air to both the engine and intercooler; on the F4U-4, the ventral intake fed the engine, and the sides fed the intercooler alone?

The oil coolers were located in the outer portion of the leading edge ducts. The inner portion fed induction and intercooler cooling air on the F4U-1, but only the intercoolers in the F4U-4, F4U-7 and F4U-5

[KJ_Lesnick]

Wuzak

The intercoolers were required to give the engines their best performance.

To densify the air and keep the temperature in control

The air flow path was determined by where the intercoolers were located, which in turn was dictated by how much air was required to cool them and how that could all be controlled.

True, but you said that the torturous flow path on the F4U and P-38 was due to the need for intercoolers.  So I figured if the airflow path would naturally under convolutions -- it would be possible to put an intake on the bottom to feed a downdraft carburetor.  I'm sorry if I misinterpreted...

There are several cases where the one duct has fed air to multiple coolers. . . The problem with trying to do too much in one intake is that the whole system could become big

And possibly draggy if done improperly: I assume one would have to configure the duct in such a way as to get the minimum drag out of it.

necessarily locates all of the components in the same place.

And that would pose a single point of failure for the engine I would suspect: Probably not desirable for a ground-attack aircraft.  Admittedly the oil-cooler was already on the bottom, so it couldn't have been that big a deal.

Oil could be used as a coolant for the intercooler, but I believe that using the same cooling solution as the engine was the best way.

True enough

Yes, the auxiliary supercharger had and two discharges. So it wasn't divided in a duct taken off the supercharger, but as a function of the supercharger itself.

Okay

The oil coolers were located in the outer portion of the leading edge ducts. The inner portion fed induction and intercooler cooling air on the F4U-1, but only the intercoolers in the F4U-4, F4U-7 and F4U-5

Until just now, I didn't even know there was an F4U-7...

Regardless, getting back down to things

1. Could the BT2D/AD/A-1 Skyraider turn with any WW2 Era Fighter?
2. What factors would effectively step up the range of the XA-41 to that of the AD-1 Skyraider?

[wuzak]

The intercoolers were required to give the engines their best performance.

To densify the air and keep the temperature in control

Yes.

The air flow path was determined by where the intercoolers were located, which in turn was dictated by how much air was required to cool them and how that could all be controlled.

True, but you said that the torturous flow path on the F4U and P-38 was due to the need for intercoolers.  So I figured if the airflow path would naturally under convolutions -- it would be possible to put an intake on the bottom to feed a downdraft carburetor.  I'm sorry if I misinterpreted...

With the set-up used in the F4U the position of the carburettor doesn't dictate the location of the inlet. It does for Griffon and Merlin powered aircraft, however.

The F4U4 does what you ask. The intake is below, and teh carburettor is a downdraft and is fitted on top of the accessories section.

Until just now, I didn't even know there was an F4U-7...

Engines for the F4U:

XF4U-1: XR-2800-1 - updraft carburettor
F4U-1: R-2800-8/8W - updraft carburettor
F4U-2: R-2800-8 - updraft carburettor
F4U-3A: R-2800-16 - single stage engine coupled to Turbo Engineering turbocharger, downdraft carburettor
F4U-3B: R-2800-14 - single stage engine coupled to Turbo Engineering turbocharger, downdraft carburettor
F4U-4: R-2800-18W - downdraft carburettor, fluid coupling for auxiliary supercharger
F4U-5: R-2800-32W - updraft carburettor, the one with the side mounted auxiliary superchargers
F4U-6: R-2800-83W - single stage engine for ground attack variant, downdraft carburettor
F4U-7: R-2800-18W - F4U-4 for French Navy.

Regardless, getting back down to things

1. Could the BT2D/AD/A-1 Skyraider turn with any WW2 Era Fighter?
2. What factors would effectively step up the range of the XA-41 to that of the AD-1 Skyraider?

1. Some say they could, but I would think only in a limited way (like at low speeds).

2. More internal fuel.

[KJ_Lesnick]

Wuzak

With the set-up used in the F4U the position of the carburettor doesn't dictate the location of the inlet. It does for Griffon and Merlin powered aircraft, however.

Due to the elbow?  As for the Wasp Major what effect does it have?

1. Some say they could, but I would think only in a limited way (like at low speeds).

So the A-41 was more agile?

2. More internal fuel.

A. I just came across something interesting: According to this the XA-41 (pgs 190-91), could carry 6,500 pounds of bombs and haul 3,200 a distance of 800 miles.  I'm curious if you believe this figure to be correct: It would be convenient, but the fact is that I'm not sure if all the data mentioned is accurate (I was under the impression the AD-1 had 2 x 20mm with 400 rpg, not 2 x 20 mm with 400 rounds among both which is cited here), and most sources cite a max-load of 3,200 lbs, but a maximum range of 800 miles with 1,000 lbs.

B. Provided A. is not true, would additional supercharging and cooling help for improving range in any way?
C. How much fuel was the XA-41 to carry?  I know the XBT2D-1 and AD-1 had 365 gallons and the AD-2 had 380 gallons.
D. What kind of supercharger did the Skyraider have?

[wuzak]

With the set-up used in the F4U the position of the carburettor doesn't dictate the location of the inlet. It does for Griffon and Merlin powered aircraft, however.

Due to the elbow?  As for the Wasp Major what effect does it have?

Due to the fact that the inlet directly feeds the carburettor - unlike in the F4U where the auxiliary supercharger and intercoolers feed the carburettor.

The R-4360 in the XA-41 is similar to the Griffon and Merlin powered aircraft, the intake directly feeding the carburettor.

1. Some say they could, but I would think only in a limited way (like at low speeds).

So the A-41 was more agile?

Wouldn't have a clue.

2. More internal fuel.

A. I just came across something interesting: According to this the XA-41 (pgs 190-91), could carry 6,500 pounds of bombs and haul 3,200 a distance of 800 miles.  I'm curious if you believe this figure to be correct: It would be convenient, but the fact is that I'm not sure if all the data mentioned is accurate (I was under the impression the AD-1 had 2 x 20mm with 400 rpg, not 2 x 20 mm with 400 rounds among both which is cited here), and most sources cite a max-load of 3,200 lbs, but a maximum range of 800 miles with 1,000 lbs.

I have no opinion on this. I don't have any information on the AD-1 or XA-41 other than what I can get from Wiki.

B. Provided A. is not true, would additional supercharging and cooling help for improving range in any way?

No. Well, it depends on whether running at increased power will improve the speed enough to increase the range to offset the loss of endurance.

C. How much fuel was the XA-41 to carry?  I know the XBT2D-1 and AD-1 had 365 gallons and the AD-2 had 380 gallons.

What does Wiki say?

D. What kind of supercharger did the Skyraider have?

An aluminium one.

[jcf]

The R4360-9 used in the A-41 was single-stage, variable speed.

http://www.enginehistory.org/P&W/R-4360/Wasp%20Major%20Index.pdf

[KJ_Lesnick]

joncarrfarrelly

The R4360-9 used in the A-41 was single-stage, variable speed.

http://www.enginehistory.org/P&W/R-4360/Wasp%20Major%20Index.pdf

Thanks!

[KJ_Lesnick]

wuzak

Due to the fact that the inlet directly feeds the carburettor

Okay so the carburetor comes before the superchargers on the Merlin and R-4360?  The air goes in, fuel gets mixed in; then it goes through the superchargers, then the engine?  I assume this reduces convoluted airflow pathways...

Wouldn't have a clue.

The XA-41 could turn inside a P-51B.  Could the AD-1 do this?

I have no opinion on this. I don't have any information on the AD-1 or XA-41 other than what I can get from Wiki.

You read the link I mentioned right: URL Here, it's on pages 190-191.

No. Well, it depends on whether running at increased power will improve the speed enough to increase the range to offset the loss of endurance.

I'm not 100% sure about this, but as I understand it

• For a given fuel/air ratio: A given amount of horsepower can be produced for a given engine
  
• For a given amount of horsepower: A given RPM can be produced
  
• For a given RPM at a given airspeed/mach-number and altitude: A certain amount of thrust is produced by the propeller based on blade-geometry, pitch, number of blades, and diameter
  
• As air-pressure lowers: Fuel-burn is lowered, however horsepower lowers, which in turn reduces RPM and engine thrust
  
• Airframe drag is lower in the thinner air, and the thrust of the propeller doesn't seem to fall off linearly with the airframe drag for a given engine RPM it would appear.
  
• If horsepower can be kept up into the higher altitudes: Thrust/Drag seems to be higher, allowing one to cruise with greater speed
  
• For a given amount of horsepower, a given amount of fuel is burned: If you can go faster for the amount of fuel burned, you cover more distance on the same tank
  

.
Am I correct?

Regardless: Initial climb-rate is listed at 2,730 fpm which seems kind of low compared to the AD-1 (3,590 fpm), as well as the P-47N (3,580 fpm) and the P-51D (3,410 to 4,350+ depending on load, manifold pressures, and fuel), though it's substantially faster than the B-29 which profited actually from flying lower due to slow climb-rate (900 fpm).

What does Wiki say?

I can't find anything on wikipedia, however I have looked at some figures and 350 gallons internal seems a common figure, though I've also seen a figure of 445 gallons (I'm not sure if this is an auxiliary tank, or just filling up the bomb-bay); ferry load is 1140 gallons (350 internal, 790 external)

BTW: Supercharger type for the AD-1 was 1-stage, 2-speed; the XA-41 according to JCF above was 1-stage, variable-speed.

[wuzak]

Due to the fact that the inlet directly feeds the carburettor

Okay so the carburetor comes before the superchargers on the Merlin and R-4360?  The air goes in, fuel gets mixed in; then it goes through the superchargers, then the engine?  I assume this reduces convoluted airflow pathways...

2 stage Merlins and Griffons had the two supercharger impellers mounted on the same shaft. The air is directly fed from one to the other, the volute cooled by a water passage, the output air cooled by the large aftercooler.



The XA-41 R-4360 was a single stage engine, so didn't need intercooling systems like the F4U.

Wouldn't have a clue.

The XA-41 could turn inside a P-51B.  Could the AD-1 do this?

Possibly. At what speed?

I have no opinion on this. I don't have any information on the AD-1 or XA-41 other than what I can get from Wiki.

You read the link I mentioned right: URL Here, it's on pages 190-191.

No, I did not.

No. Well, it depends on whether running at increased power will improve the speed enough to increase the range to offset the loss of endurance.

I'm not 100% sure about this, but as I understand it

• For a given fuel/air ratio: A given amount of horsepower can be produced for a given engine
  
• For a given amount of horsepower: A given RPM can be produced
  
• For a given RPM at a given airspeed/mach-number and altitude: A certain amount of thrust is produced by the propeller based on blade-geometry, pitch, number of blades, and diameter
  
• As air-pressure lowers: Fuel-burn is lowered, however horsepower lowers, which in turn reduces RPM and engine thrust
  
• Airframe drag is lower in the thinner air, and the thrust of the propeller doesn't seem to fall off linearly with the airframe drag for a given engine RPM it would appear.
  
• If horsepower can be kept up into the higher altitudes: Thrust/Drag seems to be higher, allowing one to cruise with greater speed
  
• For a given amount of horsepower, a given amount of fuel is burned: If you can go faster for the amount of fuel burned, you cover more distance on the same tank
  

.
Am I correct?

The engine power is defined by boost, rpm and mixture.

To have an engine which maintains power at a higher altitude (assuming still the same number of supercharger stages) you need to run the impeller(s) at higher speeds. This requires more power to drive the compressor, which means you have to burn more fuel to achieve the same power.

If you don't change the engine at all, the maximum power for a given set of engine settings (rpm, boost, mixture) will be at what is known as the critical altitude (US) or Full Throttle Height (UK). Up to this height the boost can be maintained as constant by controlling the throttle plate. This is less efficient than a fully open throttle.

Above that critical altitude the boost cannot be maintained, and power falls away. Fuel consumption follows boost, so you do get reduced consumption.

However, as power is falling, the speed may not increase and may decrease.

The engine cannot give more boost, so unless you increase rpm you will not get more power above critical altitude. But that, of course, uses more fuel.

The aircraft will have a sweet spot for cruising, which may be above the critical altitude, but not well above it.

Also, you would be aware that there are more than one type of cruising - high speed cruise can be held for shorter periods (30 minutes, 60 minutes) while lower speed cruises can be held indefinitely (until the fuel runs out). Engine cooling is another factor in this.

Regardless: Initial climb-rate is listed at 2,730 fpm which seems kind of low compared to the AD-1 (3,590 fpm), as well as the P-47N (3,580 fpm) and the P-51D (3,410 to 4,350+ depending on load, manifold pressures, and fuel), though it's substantially faster than the B-29 which profited actually from flying lower due to slow climb-rate (900 fpm).

I would check the loading and the engine settings used - was it climb at WEP, military power or normal climb power?

What does Wiki say?

I can't find anything on wikipedia, however I have looked at some figures and 350 gallons internal seems a common figure, though I've also seen a figure of 445 gallons (I'm not sure if this is an auxiliary tank, or just filling up the bomb-bay); ferry load is 1140 gallons (350 internal, 790 external)

OK

BTW: Supercharger type for the AD-1 was 1-stage, 2-speed; the XA-41 according to JCF above was 1-stage, variable-speed.

I'm sure I told you that before (about the AD-1).

[KJ_Lesnick]

Wuzak

2 stage Merlins and Griffons had the two supercharger impellers mounted on the same shaft. The air is directly fed from one to the other, the volute cooled by a water passage, the output air cooled by the large aftercooler.

So the cooled volute acts as an intercooler so to speak?

The XA-41 R-4360 was a single stage engine, so didn't need intercooling systems like the F4U.

The reason I asked the question was based around the possibility of adding a twin-stage supercharger of some sort with cooling to boost performance.

Possibly. At what speed?

I don't know, but the maneuverability of the A-41 lead it to be proposed as a long-range fighter so it couldn't have been too slow -- top speed was poor though.

No, I did not.

Okay, I hope you found it useful

The engine power is defined by boost, rpm and mixture.

Boost is either manifold pressure, or the increase from the supercharger?

To have an engine which maintains power at a higher altitude (assuming still the same number of supercharger stages) you need to run the impeller(s) at higher speeds. This requires more power to drive the compressor, which means you have to burn more fuel to achieve the same power.

I would assume the additional fuel-burn would be due to more horsepower taken off the shaft to do it?  The question would then revolve around

• How much airframe drag is reduced by flying higher
  
• How much propeller-based thrust falls off by flying higher (and/or faster) in comparison to airframe drag reduction
  
• How much speed is gained versus how much fuel required to achieve it (it's kind of like miles per gallon)
  

Unless I'm missing a basic detail

Above that critical altitude the boost cannot be maintained, and power falls away. Fuel consumption follows boost, so you do get reduced consumption.

However, as power is falling, the speed may not increase and may decrease.

Which depending on circumstances could ultimately increase range, but also might decrease speed.  It still may provide an increase in range because of the lower fuel-burn, correct?  

The aircraft will have a sweet spot for cruising, which may be above the critical altitude, but not well above it.

So if the critical altitude was like 25,000 - 28,500 feet, you'd have a sweet spot around 28,000 to 32,000 feet?

Also, you would be aware that there are more than one type of cruising - high speed cruise can be held for shorter periods (30 minutes, 60 minutes) while lower speed cruises can be held indefinitely (until the fuel runs out).

Which gets you the maximum range for practical use in the following type of aircraft mission

I'm curious what kind of profiles were typically flown by the the A-36, P-47D/N, and P-51D for the following missions

• Close-Air Support
  
• Interdiction attacks on bridges and point-targets
  
• Interdiction attacks on trains and roads
  
• Strafing planes on airfields
  

in terms of altitudes used for the cruise portion of the flight (heading to target area); the altitude ranges for approaching the target; heights at which dive-bombing/glide-bombing entry is initiated.

As well as attack profiles used by the Navy such as

• Bombing ships
  
• Bombing docks
  
• Close Air support
  

I would check the loading and the engine settings used - was it climb at WEP, military power or normal climb power?

Well the P-47 and P-51's implied manifold pressures maximized for new fuel so I'd assume either military or WEP.  I'm not sure about the others.

While I'm curious: How far could the P-47D-25 and P-47N fly with 1,000 and 2,000 pounds of bombs?