Fuel Fraction & Range of WWII Aircraft

[Zipper730]

I'm curious if anybody has compiled data regarding fuel-fraction data on aircraft in WWII? I know there are a number of variables that affect an aircraft's range and performance

 

[pbehn]

I'm curious if anybody has compiled data regarding fuel-fraction data on aircraft in WWII? I know there are a number of variables that affect an aircraft's range and performance

Fuel fraction?

 

[tomo pauk]

Fuel fraction?

Weight of fuel carried vs. total weight of aircraft before take off.

 

[PFVA63]

Weight of fuel carried vs. total weight of aircraft before take off.

Hi,
I thought I had some for US Fighters from the book "America's 100,000" but it turns out what I have is Empty Weight/All Up Weight

 

[Zipper730]

To start off, I've found the following data: I could use some help with refinements.

1. Hawker Hurricane
   • Prototype (F.36/34)
     • Notes: Fixed Propeller
     • Weight: 5672 pounds
     • Fuel: 827.75 pounds (107.5 Imperial Gallons)
     • Oil: 63 pounds (7 Imperial Gallons)
     • Fuel/Oil Ratio: 6.51%
     • Fuel Fraction: 14.59%
   • Mk.I
     1. Early
        • Notes: Twin-Pitch Propeller
        • Weight: 6363 pounds
        • Fuel: 589 pounds (78.5 Imperial Gallons)
        • Oil: 68 pounds (7.5 Imperial Gallons)
        • Fuel/Oil Ratio: 9.62%
        • Fuel Fraction: 9.26%
     2. Later
        • Normal
          • Weight: 6316 pounds
          • Fuel: 589 pounds (78.5 Imperial Gallons)
          • Oil: 68 pounds (7.5 Imperial Gallons)
          • Fuel/Oil Ratio: 9.55%
          • Fuel Fraction: 9.33%
        • Overload
          • Weight: 6750 pounds
          • Fuel: 589 pounds (78.5 Imperial Gallons)
          • Oil: 68 pounds (7.5 Imperial Gallons)
          • Fuel/Oil Ratio: 9.55%
          • Fuel Fraction: 8.73%
        • Notes: Constant Speed Propeller
   • Mk.IIB
     • Weight: 7397 pounds
     • Fuel: 699 pounds (97 Imperial Gallons)
     • Oil: 81 pounds (9 Imperial Gallons)
     • Fuel/Oil Ratio: 9.28%
     • Fuel Fraction: 9.45%
2. Supermarine Spitfire
   • Mk.I
     1. Early
        • Notes: Fixed-Pitch Propeller
        • Weight: 5819 pounds
        • Fuel: 630 pounds (84 Imperial Gallons)
        • Oil: 49 pounds (5.5 Imperial Gallons)
        • Fuel/Oil Ratio: 6.55%
        • Fuel Fraction: 10.83%
     2. Middle
        • Notes: Twin-Pitch Propeller
        • Weight: 5935 pounds
        • Fuel: 630 pounds (84 Imperial Gallons)
        • Oil: 49 pounds (5.5 Imperial Gallons)
        • Fuel/Oil Ratio: 6.55%
        • Fuel Fraction: 10.61%
     3. Later
        • Notes: Constant-Speed Propeller
        • Weight: 6050 pounds
        • Fuel: 630 pounds (84 Imperial Gallons)
        • Oil: 49 pounds (5.5 Imperial Gallons)
        • Fuel/Oil Ratio: 6.55%
        • Fuel Fraction: 10.41%
   • Mk.VII
     • Weight: 7900 pounds
       • 8125 pounds with 30 imperial gallon tank
       • 8233 pounds with 45 imperial gallon tank
       • 8557 pounds with 90 imperial gallon tank
     • Fuel: 874.8 pounds (121.5 Imperial Gallons)
       • 1090.8 pounds with 30 imperial gallon tank
       • 1198.8 pounds with 45 imperial gallon tank
       • 1522.8 pounds with 90 imperial gallon tank
     • Oil: 67.5-76.5 pounds (7.5-8.5 Imperial Gallon)
       • Can carry up to 14.5 when hauling the 170 gallon slipper tank.
     • Fuel/Oil Ratio: 6.17%
       • 5.62% with 30 imperial gallon tank
       • 5.11% with 45 imperial gallon tank
       • 4.02% with 90 imperial gallon tank
     • Fuel Fraction: 11.07%
       • 13.43% with 30 imperial gallon tank
       • 14.56% with 45 imperial gallon tank
       • 17.8% with 90 imperial gallon tank
3. F4F Wildcat
   • F4F-3
     1. Normal
        • Weight: 6895 pounds
        • Fuel: 660 pounds (110 gallons)
        • Oil: 68 pounds (9 gallons)
        • Fuel/Oil Ratio: 8.18%
        • Fuel Fraction: 9.57%
     2. Overload
        • Weight: 7432 pounds
        • Fuel: 882 pounds (147 gallons)
        • Fuel Fraction: 11.87%
   • F4F-4
     1. Normal
        • Weight: 7426 pounds
        • Fuel: 660 pounds (110 gallons)
        • Oil: 68 pounds (9 gallons)
        • Fuel/Oil Ratio: 8.18%
        • Fuel Fraction: 8.89%
     2. Overload
        • Weight: 7972 pounds
        • Fuel: 864 pounds (144 gallons)
        • Fuel Fraction: 10.84%

That's a small starting point. It seems that they rarely broke into the twin-digits for fighters.

 

[PFVA63]

Hi,
That makes sense. After doing a little more digging I did find a spreadsheet where I had the data for some Hawk 75 (P-36) variants and some Brewster Buffalo variants. They all appear to be around 10-13%.

Pat

 

[pbehn]

The fuel fraction on strike aircraft was a trade off. With bombers there is a fuel load and cruising speed that gives a range where no bombs can be carried. With the Halifax and Lancaster on long range missions at the same cruising speed, being in the same bomber stream the extra drag of the Halifax meant it carried a much lighter bomb load and so was much less effective.

 

[Zipper730]

After doing a little more digging I did find a spreadsheet where I had the data for some Hawk 75 (P-36) variants and some Brewster Buffalo variants. They all appear to be around 10-13%.

Agreed. I'm compiling data on the F4U & F6F series, I'm curious if you got anything on the early P-51B's (they lacked the 85 gallon center tank), the later P-51B/C/D's and the P-51H.

With bombers there is a fuel load and cruising speed that gives a range where no bombs can be carried.

Actually, from what it would appear, bombers usually had a higher fuel-fraction. That said, it kind of makes sense because volume favors large objects.

With the Halifax and Lancaster on long range missions at the same cruising speed, being in the same bomber stream the extra drag of the Halifax meant it carried a much lighter bomb load and so was much less effective.

You mean the Halifax had a lower L/D or it's presence in the stream actually affected the Lancs?

 

[Zipper730]

drgondog , since your father flew the P-51's, do you have any figures for fuel fractions for the P-51B/C/D/H?

 

[pbehn]

Actually, from what it would appear, bombers usually had a higher fuel-fraction. That said, it kind of makes sense because volume favors large objects.
You mean the Halifax had a higher L/D or it's presence in the stream actually affected the Lancs?

To cruise at the same speed the Halifax needed more fuel so carried less bombs. Planes aren't designed around this ratio it is what results, bombers had to carry a load and defensive armament a long way, so had more fuel.

 

[DarrenW]

F6F-3 Hellcat:

Fighter Condition
Gross Weight: 11,506 lbs
Fuel (182 US gallons): 1092 lbs
Oil (13 US gallons): 97.5 lbs
Oil/Fuel Ratio: 8.93%
Fuel Fraction: 9.49%

Fighter-Overload Condition
Gross Weight: 12,415 lbs
Fuel (250 US gallons): 1500 lbs
Oil (16 US gallons): 120 lbs
Oil/Fuel Ratio: 8.00%
Fuel Fraction: 12.08%

Note: In most cases the F6F-5 variant varied little if any in gross weight compared to late production F6F-3s, and having the same fuel/oil loads the fuel fraction figures above will suffice for it as well. Oil capacity for both variants was increased to 19 gallons when in the 'fighter-bomber' condition, which made oil weigh out to 142.5 lbs (oil/fuel ratio 9.50%).

Source: http://www.wwiiaircraftperformance.org/f6f/f6f-3-detail-specification.pdf

 

[drgondog]

To cruise at the same speed the Halifax needed more fuel so carried less bombs. Planes aren't designed around this ratio it is what results, bombers had to carry a load and defensive armament a long way, so had more fuel.

The fuel fraction for P-51D with269 gal internal fuel at full internal combat load out Gross Weight of 10200 pounds = 1614/10200 = 15.8%, the P-51B was slightly higher at 1614/9600 = 16.8%.

Pbehn is correct re: WWII and long into the 60's. Then airframe designers used historical fuel (and payload) fractions as the start of design assumptions. Mission profiles defined the ranges examined.

 

[pbehn]

For the Mosquito the range of fighter bombers was increased by putting a fuel tank where the bombs had been. If you replace the cannons with fuel you get a prodigious range but the weapons are reduced to cameras. Since P/R Mosquitos had the highest take off weight they had the highest ratio. As commented earlier (somewhere by someone) carrier borne dive bombers had a lower bomb (higher fuel fraction) load if they were at the front on the deck because they had a shorter take off run than those further back, that is a slightly higher fuel fraction simply based on take off run for the same mission from the same ship.

 

[XBe02Drvr]

You mean the Halifax had a higher L/D or it's presence in the stream actually affected the Lancs?

Didn't you mean a lower L/D? A higher L/D implies higher performance. A plane with a drag problem is stuck with a lower L/D.

 

[Zipper730]

To cruise at the same speed the Halifax needed more fuel so carried less bombs.

Oh, okay

Planes aren't designed around this ratio it is what results, bombers had to carry a load and defensive armament a long way, so had more fuel.

I assume that, for a long-ranged fighter, there would be the natural presumption that you'd want as much internal fuel, while having enough structural strength to pull the target g-load, even if they didn't think of a specific percentage.

Source: http://www.wwiiaircraftperformance.org/f6f/f6f-3-detail-specification.pdf

Good source, I was actually planning on using that exact one. I didn't know the F6F-3 and F6F-5 were almost the same in weight (usually, designs have a tendency to creep up as time goes on). That said, I do remember the USN wanting to increase the oil-capacity (to 19 gallons evidently), the RAF also had started increasing oil capacity on fighters as well. I figured it had to do with longer-ranged flying.

The fuel fraction for P-51D with 269 gal internal fuel at full internal combat load out Gross Weight of 10200 pounds = 1614/10200 = 15.8%, the P-51B was slightly higher at 1614/9600 = 16.8%.

The P-51D had longer range right? As for the drop-tanks the P-51B/C/D carried, what sizes were typical when they started using them for escorts?

Didn't you mean a lower L/D?

Yeah, I mistyped. I corrected it.

 

[drgondog]

Oh

The P-51D had longer range right? As for the drop-tanks the P-51B/C/D carried, what sizes were typical when they started using them for escorts?

.

For same internal fuel the P-51B had slightly longer range - with and without tanks, due to less induced drag at cruise speeds (all speeds).

75 gallon externals until May 1944, 110 and 165gal (Pacific only).

 

[pbehn]

Oh, okay
I assume that, for a long-ranged fighter, there would be the natural presumption that you'd want as much internal fuel, while having enough structural strength to pull the target g-load, even if they didn't think of a specific percentage.

Things progressed as horsepower increased. To design a long range fighter in the early to mid 1930s you needed 2 engines. Things also progressed much more quickly when it was obvious war was coming and when it was actually declared. Range is one issue, the plane has to be competitive with the opposition when it gets to where it is going though.

 

[Zipper730]

For same internal fuel the P-51B had slightly longer range - with and without tanks, due to less induced drag at cruise speeds (all speeds).

That's interesting, I thought the P-51D was cleaner.

75 gallon externals until May 1944, 110 and 165gal (Pacific only).

the 110 and 165's were how they were able to escort the B-29?

 

[Zipper730]

Things progressed as horsepower increased. To design a long range fighter in the early to mid 1930s you needed 2 engines. Things also progressed much more quickly when it was obvious war was coming and when it was actually declared. Range is one issue, the plane has to be competitive with the opposition when it gets to where it is going though.

Plus, a lot of proponents of long-range fighters had some bizarre ideas of what they wanted in an escort.

1. Multi-crew
   • At least two, which included a gunner: The idea was a gunship that could rove over the bomber formation and add to the defensive firepower
   • There also seemed a strong predilection among some for multi-role aircraft (such as the Zerstorers) that were both fighters and bombers
2. Internal Fuel: This was the US only, we were adamantly opposed to external fuel tanks for some time, so the range had to be totally internally.

If we rid these specifications from things, it would have been way easier to achieve. The point, was simply a fighter that could do all the stuff a fighter could, and fly very far, and that probably would require two engines if we didn't want to go the way of the A6M.

 

[pbehn]

Plus, a lot of proponents of long-range fighters had some bizarre ideas of what they wanted in an escort.

1. Multi-crew
   • At least two, which included a gunner: The idea was a gunship that could rove over the bomber formation and add to the defensive firepower
   • There also seemed a strong predilection among some for multi-role aircraft (such as the Zerstorers) that were both fighters and bombers
2. Internal Fuel: This was the US only, we were adamantly opposed to external fuel tanks for some time, so the range had to be totally internally.

If we rid these specifications from things, it would have been way easier to achieve. The point, was simply a fighter that could do all the stuff a fighter could, and fly very far, and that probably would require two engines if we didn't want to go the way of the A6M.

Who proposed an escort and when?