P-47D Model Fuel Consumption

[Stoney74]

Did some testing today and compared this with this P-47D chart:



All 3 D models, D11, D25, and D40 exhibited the same consumption ratings, except in WEP

The chart shows specific fuel consumption at the following settings:

Military Power of     52" MP, 2700 RPM:  275 GPH
Max Continuous of  42" MP, 2550 RPM:  210 GPH
Max Cruise of          32" MP, 2250 RPM:  105 GPH

Minimum Specific Fuel Consumption at:

 5,000 feet MSL of    32"MP, 1700 RPM:  60 GPH
15,000 feet MSL of   31"MP, 1850 RPM:  70 GPH
25,000 feet MSL of   31"MP, 2150 RPM:  95 GPH

My testing shows the following:

Mil Power consumption equals the chart at 275 GPH
Max Continuous equals the chart at            210 GPH

Max Cruise does not equal the chart at       138 GPH--33 GPH difference
5,000 feet MSL does not equal the chart at   81 GPH--21 GPH difference
15,000 feet does not equal the chart at        90 GPH--20 GPH difference
25,000 feet does not equal the chart at      123 GPH--28 GPH difference

My testing took into account the 50 RPM error on the P-47 Tachometer (it displays 2650 when it should read 2700).  This testing was conducted with a 1.0 fuel burn, which means that in the MA, these higher burn rates are even more drastic with the following differences:

At Max Cruise, difference is 66 GPH higher than what it should be in the MA

For min specific fuel consumption at 5,000 feet, difference is 42 GPH higher in the MA.  At 15,000 feet, difference is 40 GPH higher, and at 25,000 feet, difference is 56 GPH higher.

I fly the Jug a lot, and fuel consumption is always a factor.  If the chart I posted is accurate, then a corrected fuel burn curve for the Jug could add as much as 10 minutes to flight time if max cruise and super-cruise type Lyndberg settings are used during what is a normal mission profile for me.

Comments???  I know the chart shows a R-2800-21 but was the fuel consumption so different for the -59 and -63 models?  What block numbers of D's were equipped with the -21?

[nuchpatrick]

This chart is for the C model P-47C-1RE & P-47C5-RE. The -21 did not have water-injection.

[Sketch]

Originally posted by nuchpatrick
This chart is for the C model P-47C-1RE & P-47C5-RE. The -21 did not have water-injection.

Doesn't the N-model have water injection in the game?  Just a question is all....

[Rebel]

Originally posted by nuchpatrick
This chart is for the C model P-47C-1RE & P-47C5-RE. The -21 did not have water-injection.

Later models of the -21 came with a water injection kit.

I believe these were the very early D models- the last model to be outfitted with a -21 was the D-10.  it had water injection.

[Bruno]

Late Cs and early Ds were were both upgrade with ADI kits and other 'fixes'.

[Stoney74]

Originally posted by nuchpatrick
This chart is for the C model P-47C-1RE & P-47C5-RE. The -21 did not have water-injection.

Well, given that typically, the use of water injection increase fuel efficiency, I wouldn't see that as being a factor, not to mention that the power settings listed initially are no where near the water injection range.  It was still a 2800 cubic inch displacement engine.  Bore and stroke stayed the same during the war, and, at least on the P-47D models, higher horsepower values were developed through increasing the approved manifold pressure ratings, rather than different supercharger gearing or other changes that could affect fuel consumption.  However, I don't know for sure, so that's why I was asking the question.  Seems to me that with same bore and stroke, and the same supercharging gearing, at the power settings I listed, the fuel consumption would be the same, for all the models.

[Stoney74]

Originally posted by nuchpatrick
This chart is for the C model P-47C-1RE & P-47C5-RE. The -21 did not have water-injection.

Come to think of it, all the Jugs, rather than just the N model, should burn less fuel on WEP than at WOT.  According to a couple of books, most C model Jugs were converted to a water injection standard once the factory started puting them on the new planes.  Conversion kits were sent to the field.

[Ghastly]

WEP as modeled on the R2800-based engines is currently incorrect anyway ( it operates for a period of time but then once used up, appears to "refresh"  as some ratio of the time spent operating with WEP off).

If you'd like I'll check the manuals for the F4U's which I have at home, and see how it compares to the chart posted for your engine.

However, before someone states the obvious, I'm infinitely happier with the fuel consumption modeling in AH than I was used to "elsewhere", since it ( at least approximately, if not perhaps exactly) models the appropriate difference between lower power and higher power settings, rather than simply being a linear factoring of "throttle percent".

It introduces engine management to the gameplay, since power settings cah make a tremendous difference in the time you can remain airborne.

Ideally, though, I'd like to see the fuel modifier in the range of 1.33 to 1.66 rather than 2 in the MA's, since the more drastic the modifier, the more of an advantage it grants to the faster climbing aircraft.  As it is now, and F4U just climbing to 20K burns around 1/4 of the fuel internal.   This artificially limits your ability to adjust your altitude in order to engage, since lost altitude "costs" tremendously in mission duration.

[F4UDOA]

Beware of the F4U and F6F fuel consumption. They both had carburator fixes that allowed them to run at auto lean in mil power. This significantly lowered fuel consumption.

I have no charts showing this for the P-47 R-2800 but this does not mean that the change did not take place.

[Stoney74]

Originally posted by Ghastly
However, before someone states the obvious, I'm infinitely happier with the fuel consumption modeling in AH than I was used to "elsewhere", since it ( at least approximately, if not perhaps exactly) models the appropriate difference between lower power and higher power settings, rather than simply being a linear factoring of "throttle percent".

Ideally, though, I'd like to see the fuel modifier in the range of 1.33 to 1.66 rather than 2 in the MA's, since the more drastic the modifier...

1st paragraph, agree totally, just trying to see if there is an opportunity to tweak a little more range out of the Jug, especially the D11 model.

2nd paragraph, agree again.

[Stoney74]

Just to answer the question of what models used what engines, link here

Basically, the -21 was the R-2800 installed in the P-47C and D1-D5.  The -63 was the R-2800 with water injection and all -21's when retrofitted, were redesignated -63's.  The -63's were installed on D's 10-16 series.  The D-20-26 were equipped with the -59, which were water injected and had a different wiring harness.