# P-51 internal fuel capacity (how?)



## gjs238 (Aug 21, 2009)

How come the P-51 had such a large internal fuel capacity relative to other fighters interceptors?
Was it a larger aircraft?
Was construction lighter, freeing up internal space?
Did the designers figure out a more space-efficient way to arrange internal components?


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## drgondog (Aug 21, 2009)

gjs238 said:


> How come the P-51 had such a large internal fuel capacity relative to other fighters interceptors?
> Was it a larger aircraft?
> Was construction lighter, freeing up internal space?
> Did the designers figure out a more space-efficient way to arrange internal components?



It was rare in that the original design placed large fuel tanks (internal) in wing (92 gallons each) and wing racks capable of 750 pounds in P-51A. Most contemporary fighters put all fuel tanks in fuselage (P-47, F4U, Bf 109, Spitfire, etc).. P-38 of course had internal wing tanks also

The P-47 didn't get to that design until 1944 in the late D models - which is why the 8th converted to all Mustangs except 56th FG. There is no teeling how large the run up of scores would have been if the 56th had not been cut out of the big air battles deep in Germany during 1944.

It (51BC) evolved to include an 85 Gallon fuel tank in the fuselage and get 1000 pound capacity wing racks (P-51D/K) - the latter capable of 160 gallon Ferry tanks or 108/75 for standard ops.


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## davparlr (Aug 21, 2009)

gjs238 said:


> How come the P-51 had such a large internal fuel capacity relative to other fighters interceptors?
> Was it a larger aircraft?
> Was construction lighter, freeing up internal space?
> Did the designers figure out a more space-efficient way to arrange internal components?



Compared to other American aircarft, the P-51 had a relative light internal fuel load. 

*P-38J* 410 gal

*P-47D-20* 305 gal

*F4U-1* 351 gal

*P-51D* 269 gal

The P-51 was a very aerodynamically clean aircraft which allowed it to get great performance out of each gallon.


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## Airframes (Aug 21, 2009)

All of the above is, of course, spot on. The biggest single advantage of the P51, regarding range, was the efficiency of the laminar flow wing. Also, due to the design of the fuselage, the placement of the cooling system etc, there was room to fit the fusealge tank, behind the pilot, which increased the range still further, although not without some handling problems, until at least half (?) the fuel in that tank had been used. Earlier designs, the Spitfire and Bf109 being prime examples, had been designed to meet the requieremnts of the time (pre war), that is, a short-range interceptor, and had never been envisged as having to fly great distances on, for example, escort missions. Wheras the P51, from the outset, was designed with range and endurance in mind, which even then, was improved as the needs dictated.


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## MikeGazdik (Aug 22, 2009)

While the laminar wing design did in fact give the Mustange great performance, it was the decision of the North American engineers that placed the main tanks between the forward and aft spars of the wing. This enabled a much greater fuel load vs other Liquid cooled aircraft. (Spitfire, Messerschmitt} The other aircraft carried thier main fuel load in the fuselage. Which was the secondary area the later Mustangs used to add to thier fuel capacity.

I think that the decidsion to carry the fuel in the wings, may be one of the biggest acheivements of the Mustang. If it did not have the great range, it would have been just another fighter. The range gave it the ability to be used over enemy territory, which was not possible ( except for the P-38 ) in any other front line fighter.


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## gjs238 (Aug 22, 2009)

MikeGazdik said:


> While the laminar wing design did in fact give the Mustange great performance, it was the decision of the North American engineers that placed the main tanks between the forward and aft spars of the wing. This enabled a much greater fuel load vs other Liquid cooled aircraft. (Spitfire, Messerschmitt} The other aircraft carried thier main fuel load in the fuselage. Which was the secondary area the later Mustangs used to add to thier fuel capacity.
> 
> I think that the decidsion to carry the fuel in the wings, may be one of the biggest acheivements of the Mustang. If it did not have the great range, it would have been just another fighter. The range gave it the ability to be used over enemy territory, which was not possible ( except for the P-38 ) in any other front line fighter.



Didn't one version of the F4U place fuel in the wings, with mixed results?


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## davparlr (Aug 22, 2009)

gjs238 said:


> Didn't one version of the F4U place fuel in the wings, with mixed results?



The F4U-1 had two 57 gallon wing tanks. The F4U-1D, and on, did not have these tanks. I have no information on issues with these tanks other than their removal.


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## drgondog (Aug 22, 2009)

davparlr said:


> Compared to other American aircarft, the P-51 had a relative light internal fuel load.
> 
> *P-38J* 410 gal
> 
> ...



Note: P-38 had two inline engines so in comparison the 51 had quite a bit more fuel.

The 47 and F4U had gas guzzling Piston engines, so by comparison the 51 had an advantage ther also.

But of course Drag was the key.


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## GrauGeist (Aug 22, 2009)

In regards to drag, I've heard the expression that the P-51D "sliced through the air, like a knife" and if this is the case, then the P-47D simply "tore a hole in the sky, and shoved it's way through"


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## Shortround6 (Aug 22, 2009)

drgondog said:


> Note: P-38 had two inline engines so in comparison the 51 had quite a bit more fuel.
> 
> The 47 and F4U had gas guzzling Piston engines, so by comparison the 51 had an advantage ther also.
> 
> But of course Drag was the key.



Actually in cruise settings the the P-47 and Corsair engines may have burned a trife less fuel per horsepower hour and thus been , in one way, more efficient.
They were just making a lot more horse power in cruise settings to begin with

P-51 was designed to be better than a P-40. 

Even early P-40s had tankage for 160 US gallons of fuel internal. 
Late model Brewster Buffalos had tankage for 240 US gallons which might have been part of their problem.


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## MikeGazdik (Aug 22, 2009)

The point of what I was trying to imply, is that because of the fuel in the wings design of the Mustang, it lent itself to more easily be modified and given additional fuel in the fuselage. The internal space of the wings on most of the single engine fighters were used in a way that once into production, only small changes could be made to make them adapt. Maybe change out a machine gun for a cannon, or in some cases add leading edge tanks to the wings. 

But a wholesale change to making the wing the primary fuel storage area was not possible without a complete change in at least the wing design. ( such as the P-47N) So with that fact the Mustang, though it had good range out the outset, was able to expand even more with the addition of the fuselage tanks.

The wing was really THE greatest part of the Mustang, both in airfoil and in the internal structure, which was stong yet light and enabled the aircraft to carry a large amount of fuel. ( yes, I know there may be an argument about the Merlin engine being the greatest aspect)


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## Elvis (Aug 23, 2009)

On top of aerodynamics, I've heard a few times in the past, that the P-M engine was actually quite thrifty with the fuel, in cruise mode.
It was a combination of both of those factors that allowed the plane to have the long range that it did have.

Also, I understand that the little internal tank, located behind the piilot, came into being because technology had progressed enough that the radio in that plane could be shrunk down with no detriment to performance.
This opened up a cavity and it was decided to put fuel in there.
This idea could've coincided with the P-51 being picked for bomber escort duty into Germany, but on that point, I'm mearly speculating.


Elvis


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## Milosh (Aug 23, 2009)

A 'little internal tank' Elvis?

It is half again as big as this 55gal drum.


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## davparlr (Aug 23, 2009)

Elvis said:


> On top of aerodynamics, I've heard a few times in the past, that the P-M engine was actually quite thrifty with the fuel, in cruise mode.
> It was a combination of both of those factors that allowed the plane to have the long range that it did have.
> 
> Elvis



The P-51 was much cleaner than the P-47 or F4U and thus required less HP to cruise. So, even at equal efficiency, the P-51 would use less fuel. I think this advantage would reduce as altitude increased, however, engine efficiency at altitude also becomes a factor so a blanket statement like this is risky.


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## drgondog (Aug 23, 2009)

davparlr said:


> The P-51 was much cleaner than the P-47 or F4U and thus required less HP to cruise. So, even at equal efficiency, the P-51 would use less fuel. I think this advantage would reduce as altitude increased, however, engine efficiency at altitude also becomes a factor so a blanket statement like this is risky.



Very true. Period. I believe the 51 had it way over both of those ships up to critical altitude respectively, both for reasons of drag and also the fuel consumption for each ship in optimal range cruise speed.

IIRC the optimal cruise (range vs loiter) for the 51D (and B-10 and -15) with the 1650-7 was around 16-17K at 27" and 2000 rpm. As you well know the optimum is influenced by payload but that fuel consumption was around 48gpm. I'm goind to have to dig but I believe the fuel consumption for cruise speed for optimal range for both the F4U and P-47 were about 35-40% higher.


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## drgondog (Aug 23, 2009)

Elvis said:


> On top of aerodynamics, I've heard a few times in the past, that the P-M engine was actually quite thrifty with the fuel, in cruise mode.
> It was a combination of both of those factors that allowed the plane to have the long range that it did have.
> 
> Also, I understand that the little internal tank, located behind the piilot, came into being because technology had progressed enough that the radio in that plane could be shrunk down with no detriment to performance.
> ...



Elvis - The command radio for the P-51, A-36, P-51A and P-51B/C and P-51D/K were the SCR-274 with variations including the SCR 522 from P-51A through P-51D/K. In other words the radio behind the pilot didn't change - the fuse tank wasn't placed there in the P-51A and prototype B only because of the cg issue.


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## Elvis (Aug 23, 2009)

Hey, guys, it's what I've heard.
Please, don't shoot the messenger.
If that's incorrect, fine. I was only trying to help shine some light on the initial question.
---------------------------------------------------------------

Daveprlr,

If I had started my post with "_In addition to..._", instead of "_On top of..._", then in your mind, would that have changed the meaninig of what I posted?
I ask this, because to me, it seems you misinterpreted my post.


Elvis


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## drgondog (Aug 23, 2009)

Elvis said:


> Hey, guys, it's what I've heard.
> Please, don't shoot the messenger.
> If that's incorrect, fine. I was only trying to help shine some light on the initial question.
> ---------------------------------------------------------------
> ...



we all hear and repeat 'stuff' myself included. Didn't intend to thump your nose


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## davparlr (Aug 23, 2009)

Elvis said:


> Hey, guys, it's what I've heard.
> Please, don't shoot the messenger.
> If that's incorrect, fine. I was only trying to help shine some light on the initial question.
> ---------------------------------------------------------------
> ...



I am not sure of what you mean by this comment. In you initial comment, you seem to imply that the aerodynamics and engine of the P-47 allowed very good cruise, which I would agree, however it could mislead someone to assume this cruise perfomance was equavlent to the P-51, which it was not. The P-51 cruise performance was not only very good but excellent. The extended range of the later P-47s were due to the massive amount of fuel carried.


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## davparlr (Aug 23, 2009)

drgondog said:


> Very true. Period. I believe the 51 had it way over both of those ships up to critical altitude respectively, both for reasons of drag and also the fuel consumption for each ship in optimal range cruise speed.
> 
> IIRC the optimal cruise (range vs loiter) for the 51D (and B-10 and -15) with the 1650-7 was around 16-17K at 27" and 2000 rpm. As you well know the optimum is influenced by payload but that fuel consumption was around 48gpm. I'm goind to have to dig but I believe the fuel consumption for cruise speed for optimal range for both the F4U and P-47 were about 35-40% higher.



In an earlier post where I was comparing escort performance of American aircraft, and using AF pilot performance charts, I had calculated that the fuel used at cruise for the P-47D-22 was about 260 gallons for 600 miles. For the P-51, the fuel used was 108 gallons for 600 miles. This seems much higher than the 35-40% higher. If I have time, I will go back and reevaluate my calculations to see if i committed some error.


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## davebender (Aug 23, 2009)

For what it's worth, The History Channel stated the P-51 used only half as much fuel as the P-47 when covering the same distance. 

Perhaps the P-47 really was that much of a fuel hog.


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## MikeGazdik (Aug 23, 2009)

To make horsepower, you have to provide fuel, the more fuel, (along with air) the more power. Cubic inches also make power, and the more cubes, the more fuel. Simple really. It should not be a surprise that a 2,800 cubic inch engine that develops 2,000 horsepower would use much more fuel than a 1,650 cubic inch engine that developes 1,500 horsepower.

Even if they were in the exact same airframe, the P&W will in comparison gulp the fuel.

Which has lead me to another off subject thought of seeing some effieciency comparisons of the P-47 vs F4U vs F6F.

To better understand the genius of the P-51 wing, imagine the Messerschmitt 109 of having a wing of the same design. Just the layout and structure, not the Laminar flow. Obviously the wing would be smaller than that of the P-51 wing, but just imagine a wing capable of carrying fuel AND ammo on the Bf109 in 1940!!! Or during the duration of the war!


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## drgondog (Aug 23, 2009)

MikeGazdik said:


> To make horsepower, you have to provide fuel, the more fuel, (along with air) the more power. Cubic inches also make power, and the more cubes, the more fuel. Simple really. It should not be a surprise that a 2,800 cubic inch engine that develops 2,000 horsepower would use much more fuel than a 1,650 cubic inch engine that developes 1,500 horsepower.
> 
> Even if they were in the exact same airframe, the P&W will in comparison gulp the fuel.
> 
> ...



Imagine a winspan of 20% increase, heavier structure in the wing and a lot less climb performance for the 109


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## MikeGazdik (Aug 24, 2009)

drgondog said:


> Imagine a winspan of 20% increase, heavier structure in the wing and a lot less climb performance for the 109



Very true, but if a wing of similar area was used,( as to the original Bf109 wing) but with the internal layout of the P-51.


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## Elvis (Aug 24, 2009)

davparlr said:


> I am not sure of what you mean by this comment. In you initial comment, you seem to imply that the aerodynamics and engine of the P-47 allowed very good cruise, which I would agree, however it could mislead someone to assume this cruise perfomance was equavlent to the P-51, which it was not. The P-51 cruise performance was not only very good but excellent. The extended range of the later P-47s were due to the massive amount of fuel carried.


Dave,

Not sure where you got that idea from, but I was referring to the P-51 in that post, not the P-47.



Elvis


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## Elvis (Aug 24, 2009)

drgondog said:


> Elvis - The command radio for the P-51, A-36, P-51A and P-51B/C and P-51D/K were the SCR-274 with variations including the SCR 522 from P-51A through P-51D/K. In other words the radio behind the pilot didn't change - the fuse tank wasn't placed there in the P-51A and prototype B only because of the cg issue.


Do you know if that radio, while basically remaining the same unit, ever shrank (physically) at any point in time?
This is what I was getting at in my post.
I wasn't saying the radio got changed out, only that I've heard that it shrank in size, due to advances in electronics around that time.
It's been my understanding that the radio, originally, was quite large and that it shrank down a good deal, thus opening up the cavity that was later used to house the little 5th fuel tank ("5th", if you're using wing tanks).



Elvis
P.S. Re: "Don't shoot the messenger". I actually wasn't referring to you so much, but its cool. I was just sort of taken aback by the responses to my post. I probably shouldn't have posted that, to begin with.


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## Milosh (Aug 24, 2009)

In Gruenhagen's Mustang book, he has the command radio as SCR-522, or SCR-274, or ARC-3.


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## davparlr (Aug 24, 2009)

Elvis said:


> Dave,
> 
> Not sure where you got that idea from, but I was referring to the P-51 in that post, not the P-47.
> 
> ...



Okay, I see. Sorry for the misunderstanding. What did you mean by P-M engine?


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## Colin1 (Aug 24, 2009)

davparlr said:


> What did you mean by P-M engine?


I was wondering too
in context, I think it's Packard Merlin


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## davparlr (Aug 24, 2009)

davebender said:


> For what it's worth, The History Channel stated the P-51 used only half as much fuel as the P-47 when covering the same distance.
> 
> Perhaps the P-47 really was that much of a fuel hog.



This would tend to verify my analysis.


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## renrich (Aug 24, 2009)

From USAAF table of combat radius at 25000 feet..... P47D with 670 gallons of fuel-600 miles
P51B,C,D with 419 gallons of fuel-700 miles.
This would include start up, warmup, takeoff, climb, cruise, combat, cruise back and reserve. That little 85 gallon tank behind the pilot would add 510 pounds to the P51, not including the weight of the tank. Was the tank self sealing? 
The wing tanks in the F4U1 were not self sealing but had a CO2 purge system. A lot of F4U1s had the wing tanks which substantially increased the range of the Corsair over the Wildcat and was a big help in escort missions in the Solomons.


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## drgondog (Aug 24, 2009)

Elvis said:


> Do you know if that radio, while basically remaining the same unit, ever shrank (physically) at any point in time?
> This is what I was getting at in my post.
> I wasn't saying the radio got changed out, only that I've heard that it shrank in size, due to advances in electronics around that time.
> It's been my understanding that the radio, originally, was quite large and that it shrank down a good deal, thus opening up the cavity that was later used to house the little 5th fuel tank ("5th", if you're using wing tanks).
> ...



A change in electronics resulting in a change of 'frame' would be the same as a new model Command Radio. They were all the same or pretty much the same size


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## davparlr (Aug 24, 2009)

Colin1 said:


> I was wondering too
> in context, I think it's Packard Merlin



I thought he had mistyped P-W.


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## davparlr (Aug 24, 2009)

MikeGazdik said:


> Which has lead me to another off subject thought of seeing some effieciency comparisons of the P-47 vs F4U vs F6F.



Based on drag analysis of max airspeed at SL, I would say the F4U had somewhat better cruise efficiency than the P-47, which, in-turn, was somewhat better than the F6F. All of these were considerably less efficient than the P-51. Comparisons were between the F4U-1, P-47B, and F6F-3, all which used similar engines with equal HP.


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## drgondog (Aug 24, 2009)

davparlr said:


> In an earlier post where I was comparing escort performance of American aircraft, and using AF pilot performance charts, I had calculated that the fuel used at cruise for the P-47D-22 was about 260 gallons for 600 miles. For the P-51, the fuel used was 108 gallons for 600 miles. This seems much higher than the 35-40% higher. If I have time, I will go back and reevaluate my calculations to see if i committed some error.



Dave - I think you are pretty close for the 51 results. SOP was ~ 35" 2700 RPM for the loaded birds on the way to RV and also essing in escort to keep TAS at 260. That would have been ~ 52 gph average, including MP at take off, assembly and climb out at 55", then down to 35"/2700 in steady formation cruise. Higher figures than for single ship Ferry.


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## Elvis (Aug 24, 2009)

davparlr said:


> I thought he had mistyped P-W.


Dave,

Yes, "P-M" = "Packard-Merlin".
I can see where someone might see "P-M" and think "P&W", but its cool.
...its also cool to use your reading glasses when reading these posts (I know, the printing at some of these web pages are absolutely miniscule).
If anyone laughs at you, just hold them down with your walker and beat 'em with your cane.  
-------------------------------------------------------------------------------

DragonDog,

Thanks for the further confirmation.
Apparently, I've been misinformed all these years.


Elvis


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## Elvis (Aug 24, 2009)

Re: Range.

According to the MustangsMustangs website, The P-51D/K had an internal fuel capacity of 269 gallons.
This increased to 489 gallons with drop tanks.
This gave the plane a range of 1155 miles on internal fuel (cruising @ 294mph and 20K feet) and 2055 miles if you include drop tanks (cruising @ 280mph and 20K feet).

How that compares to the P-47, as it existed at that time, I don't know.



Elvis


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## drgondog (Aug 24, 2009)

Elvis said:


> Re: Range.
> 
> According to the MustangsMustangs website, The P-51D/K had an internal fuel capacity of 269 gallons.
> This increased to 489 gallons with drop tanks.
> ...



Elvis the late B/C and all D/K had the 1000 pound racks so the options were 75 gallon, 110 gallon (actually 108) gallon and 150 gallon Ferry tanks (165 for P-51H). So the basic internal load is 269 as you said, then the 'pairs' are +150 gallons, + 216 gallons and +300 gallons for the 75, 108 and 160 respectively. 

A really good pilot could get a lot more than 2100 miles (Ferry) if he managed his throttle/rpm and altitude as he shed weight. No winds aloft of course but the extra 80 gallons in the ferry tank would easily extend the range another 450-500 miles.


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## Elvis (Aug 25, 2009)

Dr. Gondog,

Good info, thanks for posting that.
You should email that information to the guy at the MustangsMustangs website. I'm sure he'd want to know.


Elvis


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## drgondog (Aug 25, 2009)

Elvis said:


> Dr. Gondog,
> 
> Good info, thanks for posting that.
> You should email that information to the guy at the MustangsMustangs website. I'm sure he'd want to know.
> ...



Which 'guy'. Charlie Neely for example is an absolute expert on the 51 in all its forms.


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## Elvis (Aug 26, 2009)

drgondog said:


> Which 'guy'. Charlie Neely for example is an absolute expert on the 51 in all its forms.


Oh now, don't be coy. Its alright. Email him.
...and who's "him"?
Whoever posted all that info at that site, some of which I've just quoted.
I assume its the site's owner, who may or may not be Curtis Fowles, but to be honest, I don't really know.



Elvis


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## drgondog (Aug 26, 2009)

Elvis said:


> Oh now, don't be coy. Its alright. Email him.
> ...and who's "him"?
> Whoever posted all that info at that site, some of which I've just quoted.
> I assume its the site's owner, who may or may not be Curtis Fowles, but to be honest, I don't really know.
> ...



Curtis knows his stuff. What uou quoted is correct info regarding the 'rule of thumb' to incorporate take off, landing and 30 minutes of buffer for the combat tanks (75/110). all I did was add the 150 gallon ferry tanks to your numbers (or Curtis) to show the greater range.

I also expanded a little on fuel management - which is far easier to do solo than on a leader's wing in formation


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## Elvis (Aug 26, 2009)

drgondog said:


> Curtis knows his stuff. What uou quoted is correct info regarding the 'rule of thumb' to incorporate take off, landing and 30 minutes of buffer for the combat tanks (75/110). all I did was add the 150 gallon ferry tanks to your numbers (or Curtis) to show the greater range.
> 
> I also expanded a little on fuel management - which is far easier to do solo than on a leader's wing in formation


Oh, I never meant to imply your info was incorrect, only that some of your info was different from what I posted and that maybe the owner of the website might be interested in getting that info (on the chance that he didn't know that).
Whether you actually want to go through with that or not, is completely up to you.


Elvis


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## drgondog (Aug 26, 2009)

Elvis said:


> Oh, I never meant to imply your info was incorrect, only that some of your info was different from what I posted and that maybe the owner of the website might be interested in getting that info (on the chance that he didn't know that).
> Whether you actually want to go through with that or not, is completely up to you.
> 
> 
> Elvis



If you have the link to the specific data link that Curtis posted I will go check it out.


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## Elvis (Aug 26, 2009)

drgondog said:


> If you have the link to the specific data link that Curtis posted I will go check it out.


Actually, it was included in my initial post, but no need for all that scrolling.
Here ya' go - The P-51 Mustang Specifications -MustangsMustangs.com:


Elvis


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## drgondog (Aug 26, 2009)

Elvis said:


> Actually, it was included in my initial post, but no need for all that scrolling.
> Here ya' go - The P-51 Mustang Specifications -MustangsMustangs.com:
> 
> 
> Elvis



It is correct - just doesn't tell you he is using the 110 (108 ) gallon long range tanks for his 269+220 (216) gallon fuel load and doesn't talk about ferry range.

I did note his top speed of "387 at 25K" for the P-51H is a misprint and just sent him an email.


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## Elvis (Aug 27, 2009)

True, but he did mention that the total, w/tanks, was 489 gallons, so you could do the math.
Just another way of stating it. No wrong or right "procedure" here.

What's wrong with the top speed you mentioned?



Elvis


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## drgondog (Aug 27, 2009)

Elvis said:


> True, but he did mention that the total, w/tanks, was 489 gallons, so you could do the math.
> Just another way of stating it. No wrong or right "procedure" here.
> 
> What's wrong with the top speed you mentioned?
> ...


it is about 100mph short at 387MPH from actual NAA tests at 25K w/o wing racks in Interceptor config.

Curtis says he is fixing it.


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## Elvis (Aug 27, 2009)

Oh yeah, it does say *3*87 @ 25K ft.

I see its been changed to [email protected] ft.

Good eye ballers!



Elvis


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## drgondog (Aug 27, 2009)

Elvis said:


> Oh yeah, it does say *3*87 @ 25K ft.
> 
> I see its been changed to [email protected] ft.
> 
> ...



Thank you E. If I could proofread as well I would be happier.


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## davparlr (Aug 27, 2009)

drgondog said:


> It is correct - just doesn't tell you he is using the 110 (108 ) gallon long range tanks for his 269+220 (216) gallon fuel load and doesn't talk about ferry range.
> 
> I did note his top speed of "387 at 25K" for the P-51H is a misprint and just sent him an email.



I believe that the data shown on mustangmustang reflects typical data on the mustang, I do not believe it reflects fairly the performance of the P-51 in fighter configuration, nor does it reflect the impact of 150 grade fuel, which was authorized in May, 1944, about the same time the D was in service, with a max boost of 75”.

My estimate of the performance of the P-51B/C and the P-51D/K in June, 1944 is as follows (mustangmustang values are in italics):

Gross weight – full internal tanks, not including extended range tank (while this than in fact may have had some fuel, it typically was burned down first due to stability issues, also fighters stationed in France would probably not have this tank filled). Weight is based on data from “America’s Hundred Thousand”.

P-51B 9024 lbs _9800_
P-51D 9611 lbs _10100_

War Emergency HP – This is based on 75” of boost, which was authorized. While policy was to limit boost to 72”, combat reports show 75” was used. This is based on AF test of 100/150 grade fuel (spitfireperformance site)

P-51B 1860 _1720_
P-51D 1860 _1720_

Maximum speed (without racks) – This is based on AF test of 100/150 grade fuel (spitfireperformance site). P-51D estimated from 67” boost.

P-51B 447 at 21K _439 at 25k_
P-51D 441 at 26K _437 at 25k_

Time to Climb to 20k (tested P-51B weight is 600 lbs heavier than combat weight. This is the correct weight for the P-51D). This is based on AF test of 100/150 grade fuel (spitfireperformance site)

P-51B 5.3 minutes (600 lbs heavy) _6.9_
P-51D 5.3 minutes (correct weight) _7.3_

Not covered by mustangmustang, but interesting still, is rate of climb at SL. This is based on AF test of 100/150 grade fuel (spitfireperformance site)

P-51B 4350 ft/min	(600lbs heavy)
P-51D 4000 ft/min

I think this better defines the combat performance of the P-51 over Germany.


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## davparlr (Aug 27, 2009)

Elvis said:


> Oh yeah, it does say *3*87 @ 25K ft.
> 
> I see its been changed to [email protected] ft.
> 
> ...



I believe the 487 mph number, which is well reported, is incorrect. It appears this is from a NAA document that is a engineering analysis, not flight test (no a/c number or test points). Flight test data shows less performance. I would guess it is more in the 475 mph range.


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## drgondog (Aug 28, 2009)

davparlr said:


> I believe the 487 mph number, which is well reported, is incorrect. It appears this is from a NAA document that is a engineering analysis, not flight test (no a/c number or test points). Flight test data shows less performance. I would guess it is more in the 475 mph range.



Dave - I once had my hands on the NAA Test Report written ~ March 1945, via Al White who was chief Test Pilot for the B-70 program. It did indeed state 487mph w/o racks, at 300 rpm and 90" hg. The flight test plot had ~ 10 values for 90"hg/3000 rpm (don't recall weight) and several were below 487 but only a couple of mph.

I am aware of the calc report as it is in Mike William' site.. I have recently contacted Boeing to see what I can obtain from the NAA files.

I don't know why the USAAF tests in 1946 achieved a lower test result but suspect some issues with the 1650-9
WI.

To your analysis above, are you basing your P-51B predictions on the 1650-3 (implied) or the 1650-7? If 1650-3 the top speed should be at 29K+ at 3000rpm/67" hg. Are you sure the -3 could take 72-75" boost? 

The -9 in the P-51H was a beefed up -3 designed for 75-90".


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## NeilStirling (Aug 28, 2009)

F-51H SAC figures http://www.alternatewars.com/SAC/F-51H_Mustang_SAC_-_22_March_1949.pdf 

http://www.alternatewars.com/SAC/F-51H_Mustang_CS_-_22_March_1949.pdf

From here Standard Aircraft Characteristics Arcive

Neil.


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## Mike Williams (Aug 28, 2009)

drgondog said:


> If 1650-3 the top speed should be at 29K+ at 3000rpm/67" hg. Are you sure the -3 could take 72-75" boost?



Hi Bill:

Please see: Project P.P.F. - Installation and Operating Instructions, 20 June 1944.

_“Final release on Project P.P.F. has been made approving 70” manifold pressure for the P-38, 65” manifold pressure (with and without water injection) for the P-47, and 75” manifold pressure for the P-51 (both the 1650-3 and 1650-7 engines).”_​Hiya Neil: Nice!


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## drgondog (Aug 28, 2009)

NeilStirling said:


> F-51H SAC figures http://www.alternatewars.com/SAC/F-51H_Mustang_SAC_-_22_March_1949.pdf
> 
> http://www.alternatewars.com/SAC/F-51H_Mustang_CS_-_22_March_1949.pdf
> 
> ...



Thanks neil - the 412kts works out to 472mph TAS and has racks - which takes another 10kts off the top end. That would place the SAC pilot handbook right with the NAA report for March 1945 for the p-51H without racks.


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## drgondog (Aug 28, 2009)

Mike that answers the question about the -3 at 75". It is interesting to me that Packard allegedly beefed up the -3 to make the -9 but the -9 was designed for 90" so not so strange after all.


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## davparlr (Aug 28, 2009)

drgondog said:


> > Dave - I once had my hands on the NAA Test Report written ~ March 1945, via Al White who was chief Test Pilot for the B-70 program. It did indeed state 487mph w/o racks, at 300 rpm and 90" hg. The flight test plot had ~ 10 values for 90"hg/3000 rpm (don't recall weight) and several were below 487 but only a couple of mph.
> >
> > I am aware of the calc report as it is in Mike William' site.. I have recently contacted Boeing to see what I can obtain from the NAA files.
> >
> ...


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## drgondog (Aug 29, 2009)

davparlr said:


> drgondog said:
> 
> 
> > This issue has been overcome by later post, but the data I used from wwiiaircraftperfomance was from a P51B with a -7 engine. I do not know how many -3 engined P-51s were made or how long they were in use. I would indeed, like to know.
> ...


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## Mike Williams (Aug 29, 2009)

davparlr said:


> My point was that after May, 1944, the P-51B/D, at fighter weight, pulling 72-75” inches of boost, typically had better performance than is usually shown.



Hi Dave: 

I agree with that assessment! I'd put the widespread conversion to 150 grade fuel and increase of boost at mid June 1944 though.


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## drgondog (Aug 29, 2009)

Mike Williams said:


> Hi Dave:
> 
> I agree with that assessment! I'd put the widespread conversion to 150 grade fuel and increase of boost at mid June 1944 though.



I believe intro to 8th AF for test was June-july.. I do know that 355th didn't recieve any until early September - and two engine failures on take off almost immediately - under MP @3000 and 67" - both D-5 Mustangs.


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## Mike Williams (Aug 29, 2009)

Sorry Bill, the evidence for June 44 is overwhelming and incontrovertible. Please refer to: 100/150 Grade Fuel. Don’t read more into those two engine failures than is there.


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## drgondog (Aug 29, 2009)

Mike Williams said:


> Sorry Bill, the evidence for June 44 is overwhelming and incontrovertible. Please refer to: 100/150 Grade Fuel. Don’t read more into those two engine failures than is there.



Mike - I don't disagree with report but I know what the squadron histories said in the Engineering sections


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## Civettone (Aug 30, 2009)

Which fighters used internal wing tanks? The P-51 and P-38 have already been mentioned. I also know of the Reggiane Re.2000-2005 ... but anything else?


Kris


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## Shortround6 (Aug 30, 2009)

Civettone said:


> Which fighters used internal wing tanks? The P-51 and P-38 have already been mentioned. I also know of the Reggiane Re.2000-2005 ... but anything else?
> 
> 
> Kris


Hawker Hurricane and Typhoon.
Brewster Buffalo?
Westland Whirlwind?
Some Zeros.
Spitfire MK VIIIs and few others.


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## davparlr (Aug 30, 2009)

F4U-1


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## paradoxguy (Sep 11, 2009)

Civettone said:


> Which fighters used internal wing tanks? The P-51 and P-38 have already been mentioned. I also know of the Reggiane Re.2000-2005 ... but anything else?
> 
> 
> Kris



Focke-Wulf Ta 152H

I forget if the Ta 152C also had internal wing tanks, but since it was never operational, this point is probably moot.


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## Coors9 (Sep 11, 2009)

here's a few...

Seafury
P-40 (slightly inside the wing)
D 520
Ki-43 /84
Beaufighter
Typhoon
Mig-3
Mosquito
Me-163
La's Yak's


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## drgondog (Sep 13, 2009)

Mike Williams said:


> Sorry Bill, the evidence for June 44 is overwhelming and incontrovertible. Please refer to: 100/150 Grade Fuel. Don’t read more into those two engine failures than is there.



Mike - i'm at the 2009 reunion at Tcson. Two crew chiefs validated delivery to 355th in late June/July 1944


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## Mike Williams (Sep 13, 2009)

drgondog said:


> Mike - i'm at the 2009 reunion at Tcson. Two crew chiefs validated delivery to 355th in late June/July 1944




Hi Bill:

Thanks for checking with those fellows. I salute them. Their recollection fits with the established time line. You’re familiar with this material but the other members may find it of interest. It puts things into perspective fairly well.










Headquarters Eighth Air Force, Use of 100/150 Grade Fuel by Eighth Air Force


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