Lightweight Mustang (XP-51F/G/J vs H) in flight G loadings question/in general, what's a good G loading for a World War II fighter?

[BarnOwlLover]

Since the XP-51F carried more fuel in the wing tanks than the P-51B/D, is there a way to figure out what the range on internal fuel would be for those aircraft? I haven't had much luck finding range for the P-51D for example on the wing tanks only. And because the XP-51F (and other lightweight Mustangs such as the P-51H) had more fuel in those wing tanks and even better aero, it should have better range on those tanks.

Also, not directly related to this, the P-82B/XP-82 had a range on internal fuel of 1390 miles. Is that point to point, or radius?

 

[ddwhitney]

Attached are the pages from the P-51J NAA Specification detailing design loads.
Please heed:
Dan

 

[drgondog]

Since the XP-51F carried more fuel in the wing tanks than the P-51B/D, is there a way to figure out what the range on internal fuel would be for those aircraft? I haven't had much luck finding range for the P-51D for example on the wing tanks only. And because the XP-51F (and other lightweight Mustangs such as the P-51H) had more fuel in those wing tanks and even better aero, it should have better range on those tanks.

Also, not directly related to this, the P-82B/XP-82 had a range on internal fuel of 1390 miles. Is that point to point, or radius?

Simple answer for calculated, pre-test, yes. Same engine as the P-51B/C pre March 1944......

What is tricky about this question, specifically, is that THP Available vs THP Required to maintain cruise velocity at a specific altitude requires a.) Thrust HP based on propeller efficiency and RPM for a range of low MP, as well as b.) jet Thrust Hp - are factors influencing specific fuel consumption at different speeds and altitudes.

It is an iteritive, table based set of Integral equation calculations that integrate function of velocity, fuel consumption rate (-->decreasing gross weight) and THPreqd, over Beginning Gross Weight to Final Gross Weight range.

With computers, you are able to vary angle of attack as weight decreases to maintain same V with less drag and less THPreqd as fuel is consumed.

Usually, the factors of warm up at say 1200 rpm, taxi, single ship takeoff at METO MP, climb at Max Continuous HP to cruise altitude, cruise, descend, loiter for 30 minutes - all have defined estimates for the fuel consumption as function of MP/RPM for each stage for P-51B clean.

At a guess, I would offer that the max cruise range point to point for the XP-51F is in range of 1100 mi on usable fuel of about 180gal. at 10,000 feet

 

[BarnOwlLover]

I was able to find the P-51H's range on internal fuel of 755 miles at 339mph. I know that speed and alt. do make a difference in terms of max range figures. So it does seem that the XP-51F on max internal fuel with drop tanks can do missions to Berlin and such, but probably not the longer ranged missions in the ETO or the Pacific.

 

[BarnOwlLover]

Mod notice: feel free to split this and relocate as needed.

I'm wondering if anyone might have any updates on the XP-51G that's supposed to be under restoration? Or any other lightweight P-51s (including H's)?

 

[BarnOwlLover]

I apologize for necroposting, but, one, I did read that the F-82 was designed to an 11G absolute loading, like the P-51H and the lightweight Mustangs. Source was the book Twin Mustang: North American's P-82, F-82 and XP-82 Fighters.

Also, one thing that I read was that the P-51D tested by the US Navy as far as carrier landings did show damage on the fuselage after a certain numbers of landings, while a P-51H that they tested in simulated arrested landings didn't show the same type of wear and tear. I suspect (provided that a similar number of simulated landings were carried out) was due to the P-51H being designed for a 7.33G/11G absolute load at 9500 lbs vs the P-51D which was still built to the old 8G/12G absolute at 8000 lbs loading.

 

[drgondog]

I was able to find the P-51H's range on internal fuel of 755 miles at 339mph. I know that speed and alt. do make a difference in terms of max range figures. So it does seem that the XP-51F on max internal fuel with drop tanks can do missions to Berlin and such, but probably not the longer ranged missions in the ETO or the Pacific.

XP-51F had max 180gal internal fuel - no internal fuselage tank. It had equivalent combat radius of ~ 150 mi similar to P-51B before 85 gal kits.

 

[Peter Gunn]

They (XP-51F/G/J and P-51H were all designed to Limit loading of 7.33G and ultimate = 1.5xLimit (11G) - but for different comat gross weights.

I devote time in the book covering the Gensis and development of the XP-51F because the first flight was in February 1944 and the end of my book was D-Day. I present the performance testing against light P-51B with each having 1650-3 engine at 67". According to Chilton, the 'hot rod' at 75" was his favorite Mustang to fly... that comment is anecdota as I don't have published source.

I know I've asked this question before but how fast was the "hot rod" at 75" MP?

 

[drgondog]

I know I've asked this question before but how fast was the "hot rod" at 75" MP?

I'll have to check but near 470mph at 24K and >6000 fpm climb. Chilton recalled 7K but I believe that is only remotely possible with only 80+ gallons of fuel

 

[BarnOwlLover]

I thought that the F/G had provision for a 105 (or so) gallon tank in each wing, or was the 180 total capacity how it was flown in testing? Other than the fuselage tank, did the H get a fuel capacity increase?

 

[drgondog]

I thought that the F/G had provision for a 105 (or so) gallon tank in each wing, or was the 180 total capacity how it was flown in testing? Other than the fuselage tank, did the H get a fuel capacity increase?

The 105gal right wing was the Main tank. The 75gal Left Wing was axilliary tank and could be removed.

The H did increase Left wing to 102gal along with 50 gal fuse tank for a total of 257 gal.

 

[BarnOwlLover]

Why did they stagger the tanks like that? I did read that it was to counter engine torque but wouldn't that much of a difference cause a weight balance issue in flight? Of course I also read that a dedicated interceptor version of the P-51 would either fly with only one of the wing tanks, or at least with only one wing tank filled.