# Fuel Fraction & Range of WWII Aircraft



## Zipper730 (Feb 17, 2020)

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

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## pbehn (Feb 17, 2020)

Zipper730 said:


> 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?


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## tomo pauk (Feb 17, 2020)

pbehn said:


> Fuel fraction?



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

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## PFVA63 (Feb 17, 2020)

tomo pauk said:


> 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


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## Zipper730 (Feb 18, 2020)

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


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
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%*

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%*


Supermarine Spitfire
Mk.I
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%*

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%*

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* 



F4F Wildcat
F4F-3
Normal
Weight: 6895 pounds
Fuel: 660 pounds (110 gallons)
Oil: 68 pounds (9 gallons)
Fuel/Oil Ratio: 8.18%
Fuel Fraction: 9.57%

Overload
Weight: 7432 pounds
Fuel: 882 pounds (147 gallons)
Fuel Fraction: 11.87%


F4F-4
Normal
Weight: 7426 pounds
Fuel: 660 pounds (110 gallons)
Oil: 68 pounds (9 gallons)
Fuel/Oil Ratio: 8.18%
Fuel Fraction: 8.89%

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.


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## PFVA63 (Feb 18, 2020)

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

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## pbehn (Feb 18, 2020)

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.


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## Zipper730 (Feb 18, 2020)

PFVA63 said:


> 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.



pbehn said:


> 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?


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## Zipper730 (Feb 18, 2020)

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


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## pbehn (Feb 19, 2020)

Zipper730 said:


> 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.

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## DarrenW (Feb 19, 2020)

*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

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## drgondog (Feb 19, 2020)

pbehn said:


> 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.


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## pbehn (Feb 19, 2020)

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.


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## XBe02Drvr (Feb 19, 2020)

Zipper730 said:


> 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.

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## Zipper730 (Feb 19, 2020)

pbehn said:


> 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.



DarrenW said:


> 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.



drgondog said:


> 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?



XBe02Drvr said:


> Didn't you mean a *lower* L/D?


Yeah, I mistyped. I corrected it.


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## drgondog (Feb 19, 2020)

Zipper730 said:


> 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).


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## pbehn (Feb 19, 2020)

Zipper730 said:


> 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.

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## Zipper730 (Feb 19, 2020)

drgondog said:


> 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?


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## Zipper730 (Feb 19, 2020)

pbehn said:


> 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.

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

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.

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## pbehn (Feb 19, 2020)

Zipper730 said:


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


Who proposed an escort and when?


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## Zipper730 (Feb 19, 2020)

pbehn said:


> Who proposed an escort and when?


From what I remember the USAAC had looked into the idea at several different periods: First, they started with a single-engined design (with a rear gunner); then they went to a modified variant of the Martin B-10 in 1935; then they went to the YFM-1


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## DarrenW (Feb 19, 2020)

Zipper730 said:


> I didn't know the F6F-3 and F6F-5 were almost the same in weight



It depends on the level of maturity of the F6F-3. There was an gradual increase over time of about 200 lbs as slight changes were made to the air-frame and engine, with the addition of a water injection system being the primarily culprit. Introduced in May 1944, the F6F-5 just incorporated all the piece-meal changes made to -3 variant up to that point. There's very little physical difference between the last -3s and first -5s. Easiest way to tell if it's a -5 variant is by the overall Gloss Dark Sea Blue paint scheme and the modified windscreen (which mimicked the -3N). F6F-5s had strengthened tails and slightly more armor plating which increased weight accordingly, but still not by any appreciable amount (about 60 lbs). A further increase was experienced by cannon armed versions which weighed approximately 280 lbs more than those with standard machine guns but those were in the minority.


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## Shortround6 (Feb 19, 2020)

Zipper730 said:


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



If you are referring to the Bf 110 this idea is incorrect. The Bf 110 carried the same radio as the He 111 bomber (and some other German bombers). The radios used by single seat fighters in the late 30s and into the beginning of WW II were rather short ranged. On the Bf 110 the rear seater was also part of the loading mechanism for the 20mm cannon. This was also part of the duties of the 2nd crewman on the Beaufighter (and that 2 seater didn't get a gun for the 2nd crew member until late it's career).
Since the Bf 110 needed a 2nd crewman for several functions anyway, why not give him a gun a 1/2 dozen magazines of ammo? 

Don't judge prewar or very early war designs by late war capabilities. 

Bolton Paul Defiant.





Please note the antenna mount near the firewall and the 2nd mount a few feet forward of the tail wheel, this mount (or both?) had to be retracted for landing, ground handling and take-off. The Defiant used a different radio than the Hurricane and Spitfire and could not talk to them. 

Building long range fighters than cannot talk to (or morse code key) their bases or bomber formations in order to set up a rendezvous puts some severe limitations on their usefulness. 

Full fraction is an interesting number from a design point of view but only if you are comparing aircraft of similar timing (year/s of design) and requirements. 

For somethings it is near worthless. A P-47D-25 could have 305 gallons on fuel on board for a fuel fraction of 13%, filling the internal tanks to 370 gallons gives a fuel fraction of 15.4% and adding a pair of 150 gallon drop tanks gives a fuel fraction of 25.6% but what does that tell you?


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## drgondog (Feb 20, 2020)

Zipper730 said:


> That's interesting, I thought the P-51D was cleaner.
> the 110 and 165's were how they were able to escort the B-29?



The P-51B and D have essentially the same Parasite drag except the wing racks on the D are cleaner. That said, at Cruise where Induced drag as the same as Parasite drag, the P-51B has lower Gross weight ---> lower Induced drag and optimal cruise speed is slightly higher with same cruise setting for same RPM/MP and fuel consumption. Over 700 miles it will net to 25+ miles of combat radius.

The P-51Ds in Pacific used the 165s

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## Zipper730 (Feb 20, 2020)

Shortround6 said:


> On the Bf 110 the rear seater was also part of the loading mechanism for the 20mm cannon.


And I guess this was because a really long belt of ammo would jam too easily?


> Building long range fighters than cannot talk to (or morse code key) their bases or bomber formations in order to set up a rendezvous puts some severe limitations on their usefulness.


I guess later on with the P-38J, P-51, and P-47N's that this had been worked out with technological changes?


> Full fraction is an interesting number from a design point of view but only if you are comparing aircraft of similar timing (year/s of design) and requirements.


Seems like a valid point.


> For somethings it is near worthless. A P-47D-25 could have 305 gallons on fuel on board for a fuel fraction of 13%, filling the internal tanks to 370 gallons gives a fuel fraction of 15.4% and adding a pair of 150 gallon drop tanks gives a fuel fraction of 25.6% but what does that tell you?


It can fly further with 2 x 150 gallon tanks 



drgondog said:


> at Cruise where Induced drag as the same as Parasite drag


That's how cruise speed is determined on aircraft? Regardless, the P-51 typically, on long-ranged missions, flew around 300 mph. Probably above the optimum cruise speed.


> The P-51Ds in Pacific used the 165s


I remember being told that the B-29's cruised at around 310-320 mph, and the P-51's cruised around 300-305 mph. My guess was part of the range increase was that the P-51's didn't have to S-weave. I figured either the bombers flew slower, or they somehow increased range.


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## pbehn (Feb 20, 2020)

Zipper730 said:


> 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.


 This post seems to want to get a P-51B/C or D into service earlier. Most planes are designed around an engine and then they go into an airforce structure. When the P-51 was designed the Merlin two stage engine didnt exist and neither did the fuel it used, neither did the bomber force, or the concrete airfields or indeed the few thousand extra pilots needed to take part in a bomber offensive from Europe.

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## Zipper730 (Feb 20, 2020)

pbehn said:


> This post seems to want to get a P-51B/C or D into service earlier. Most planes are designed around an engine and then they go into an airforce structure. When the P-51 was designed the Merlin two stage engine didn't exist and neither did the fuel it used


That's all entirely correct. That said, a twin-engined aircraft with turbochargers could potentially muster adequate range. The Beaufighter could do around 1750 miles, correct?


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## Shortround6 (Feb 20, 2020)

Zipper730 said:


> And I guess this was because a really long belt of ammo would jam too easily?


It is because, when the design work started on many of these airplanes the 20mm guns didn't have belt feeds. They were drum feed guns and the drums were simply large magazines. 
Many of the 20mm guns could trace their parentage back to the Becker gun




Becker is the one on the left. The mechanism is basically a scaled up automatic pistol. 
Let's remember that the Browning .50 cal had some real problems in 1939-41 with feeding it's belt. There are several types of jam and some of the most basic are not belt twists but simply having enough power in the mechanism to move the belt or lift the weight of the belt the desired distance against gravity (this is on the ground, not in a hard turning airplane which just makes things worse. The .50 was modified to more than double the belt pull which solved a number of it's problems (but not all).

Somehow you have to translate the power of the burning powder into a ratcheting mechanism that will pull the belt into the gun (usually done by a cam track on the feed and a stud on the bolt ) And then you have to get the ammo out of the belt. This gets a bit tricky as most smaller machine guns in this period pulled the cartridge backwards out of the belt and then shoved it forward into the breech, this required a longer receiver and bolt travel than a magazine fed gun which only needed to get the bolt to travel to behind the magazine (length of the cartridge) and not the amount needed to get the cartridge out of the bolt. A few guns did use push through belts. 
The Hispano was in the same difficulty and resorted to a belt feed device on the outside of the gun that pulled the ammo from the belt, discarded the links and presented the ammo to the original drum magazine feed way. It was powered by a spring that was continual rewound by the action of a stud on a recoiling (reciprocating) part. 

Adding a belt could be and was done but usually needed a redesigned receiver or some sort of Rube Goldberg contraption on the outside of the gun,


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## pbehn (Feb 21, 2020)

Zipper730 said:


> That's all entirely correct. That said, a twin-engined aircraft with turbochargers could potentially muster adequate range. The Beaufighter could do around 1750 miles, correct?


I think, for a twin engine design with turbos, a single seat twin boom design would be best, something like the P-38 for example.


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## Zipper730 (Feb 21, 2020)

Shortround6 said:


> It is because, when the design work started on many of these airplanes the 20mm guns didn't have belt feeds.


When did they start featuring them?


> Let's remember that the Browning .50 cal had some real problems in 1939-41 with feeding it's belt.


I did not know that...



pbehn said:


> I think, for a twin engine design with turbos, a single seat twin boom design would be best, something like the P-38 for example.


That's to make it easy to mount the turbo and everything?


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## pbehn (Feb 21, 2020)

Zipper730 said:


> That's to make it easy to mount the turbo and everything?


In part but you need the minimum frontal and surface area, you could advocate for a whirlwind type configuration with the turbos and landing gear in the nacelles. What you cant do is advocate a sort of Beaufighter as a long range escort, it is just a plane that would be shot down from UK to Berlin. When in a close escort role the Bf 110 was easier to shoot down than a bomber. As I said in a previous post a long range fighter has to be competitive with the opposition where it can reach, simply covering the miles was not enough.


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## Zipper730 (Feb 21, 2020)

What speed do you think a design like this could do?






2 x V-1710, 1-2 crew.

Also, what would you think of a design that had a redesigned tail, a contra-propeller, and engines mounted in the mid-fuselage, with a ventral fin to keep the prop from hitting the ground?


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## pbehn (Feb 21, 2020)

Zipper730 said:


> What speed do you think a design like this could do?
> 
> View attachment 570822
> 
> ...


Less than a P-38 but better dive performance.

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## XBe02Drvr (Feb 21, 2020)

pbehn said:


> Less than a P-38 but better dive performance.


Still wouldn't turn and burn with an ME or FW, and if built in USA wouldn't have the climb performance to get on top for a vertical fight, at least not with the engines available.

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## Zipper730 (Feb 22, 2020)

pbehn said:


> Less than a P-38 but better dive performance.


So with the tractor arrangement (as drawn), you'd probably guess somewhere from 330 to 350 mph? As for dive performance, would that be in terms of acceleration rate in the dive or actual mach limit as well? 



XBe02Drvr said:


> Still wouldn't turn and burn with an ME or FW, and if built in USA wouldn't have the climb performance to get on top for a vertical fight, at least not with the engines available.


Makes sense, even if its stall speed was lower, it'd have more control forces to make them happen?


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## pbehn (Feb 22, 2020)

Zipper730 said:


> So with the tractor arrangement (as drawn), you'd probably guess somewhere from 330 to 350 mph? As for dive performance, would that be in terms of acceleration rate in the dive or actual mach limit as well?
> 
> ?


It is a drawing!

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## Zipper730 (Feb 22, 2020)

pbehn said:


> It is a drawing!


Generally a shape would give some insight


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## pbehn (Feb 22, 2020)

Zipper730 said:


> Generally a shape would give some insight


Compare to a Mosquito or Hornet.

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## Zipper730 (Feb 22, 2020)

pbehn said:


> Compare to a Mosquito or Hornet.


The mosquito and Hornet are less plump, so...


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## pbehn (Feb 22, 2020)

Zipper730 said:


> The mosquito and Hornet are less plump, so...


They aren't, you need to find someone with experience of compressibility and plastic flow on sketches.

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## PFVA63 (Feb 25, 2020)

Zipper730, sorry for not getting back to you sooner. I've been out of town for a family funeral. I will try and look up the P-51B and some other USAAC fighters from Dr. Dean's book tonight or tomorrow to see what it says.
Pat

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## drgondog (Feb 26, 2020)

Zipper730 said:


> Generally a shape would give some insight


Zipper - the Wing design is number 1 Parasite Drag fraction, as well as Induced drag based on span, Aspect Ratio, Lift Coefficient, Tip design.

Not much of those details are visible in your drawing.

FWIIW - the best cruise speed for a full internal combat loaded 51 - now wing tanks - was about 300mph TAS at 25,000 feet. Yielded about 5 mpg. The P-47D, F4F, F6F were in the range of 3mpg at optimal cruise altitude. I can't remember the P-38 figures but optimal cruise was near 225mph. I have no idea what the Mosquito cruise data is.


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## pbehn (Feb 26, 2020)

drgondog said:


> Zipper - the Wing design is number 1 Parasite Drag fraction, as well as Induced drag based on span, Aspect Ratio, Lift Coefficient, Tip design.
> 
> Not much of those details are visible in your drawing.
> 
> FWIIW - the best cruise speed for a full internal combat loaded 51 - now wing tanks - was about 300mph TAS at 25,000 feet. Yielded about 5 mpg. The P-47D, F4F, F6F were in the range of 3mpg at optimal cruise altitude. I can't remember the P-38 figures but optimal cruise was near 225mph. I have no idea what the Mosquito cruise data is.


No actual speeds involved but from this account a P/R Mosquito had a higher economical cruise speed than a P-51 with external tanks, I presume the situation reversed when the tanks were dropped. From here www.mossie.org/stories/Norman_Malayney_2.htm

Quote "The Mosquito met the fighter escort as planned; but now heavily loaded with l,000 gallons of fuel, flew at a severe speed disadvantage. Geary attempted to maintain economical cruising speed but outpaced the P-51s and was forced to throttle-back to continue flying formation with them. The Mustangs had long-range drop tanks and were also fully loaded. Once involved with enemy action, they would jettison their tanks, and therefore, were attempting to conserve and obtain maximum range from their fuel supply. This exacerbated the problem. It was a very-long flight to the Polish border, and on three occasions Geary throttled-back and did not receive the mileage planned.


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## XBe02Drvr (Feb 26, 2020)

pbehn said:


> No actual speeds involved but from this account a P/R Mosquito had a higher economical cruise speed than a P-51 with external tanks,


A preview of history repeating itself; think photo Banshees with Panther escorts in Korea, recon Voodoos with Super Sabres in cold war days, and Vigilantes with Phantoms in Vietnam.

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## drgondog (Feb 26, 2020)

pbehn said:


> No actual speeds involved but from this account a P/R Mosquito had a higher economical cruise speed than a P-51 with external tanks, I presume the situation reversed when the tanks were dropped. From here www.mossie.org/stories/Norman_Malayney_2.htm
> 
> Quote "The Mosquito met the fighter escort as planned; but now heavily loaded with l,000 gallons of fuel, flew at a severe speed disadvantage. Geary attempted to maintain economical cruising speed but outpaced the P-51s and was forced to throttle-back to continue flying formation with them. The Mustangs had long-range drop tanks and were also fully loaded. Once involved with enemy action, they would jettison their tanks, and therefore, were attempting to conserve and obtain maximum range from their fuel supply. This exacerbated the problem. It was a very-long flight to the Polish border, and on three occasions Geary throttled-back and did not receive the mileage planned.



Interesting but not definitive... the mission range was the framework for operations planning. A clean Mustang at 46"MP and 2700 RPM cruised at 380-395 at max Continuous Power for 2/3 the combat radius of much lower RPM/MP for max cruise.

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## pbehn (Feb 26, 2020)

drgondog said:


> Interesting but not definitive... the mission range was the framework for operations planning. A clean Mustang at 46"MP and 2700 RPM cruised at 380-395 at max Continuous Power for 2/3 the combat radius of much lower RPM/MP for max cruise.


I read similar about one of the Mosquito raids which were escorted by Mustang IIIs. I would imagine its a planning nightmare. The range is the same and the engines are the same, the Mosquito has slightly more fuel per engine. The Mustang uses more fuel on any engine setting while carrying tanks and less fuel when it has dropped them. As fuel is burned off the cruising speed increases slightly for both planes but differently. Then there is the unknown, how much the Mustangs must spend on combat power if intercepted, that is when the Mosquito crew want the Mustang crew to have as much as possible.


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## Zipper730 (Feb 26, 2020)

drgondog said:


> Zipper - the Wing design is number 1


That's a good point. For the most part, I had largely operated around the assumption that the aspect ratio would be around 6.5 to 7.5. That probably reveals little.


> FWIIW - the best cruise speed for a full internal combat loaded 51 - now wing tanks - was about 300mph TAS at 25,000 feet. Yielded about 5 mpg.


That would have been on variable that would have helped the P-51 out: It could cruise at a speed that was also tactically useful for combat, despite fuel burn being a little high.

The P-38's cruise speed down at 225 mph would have made it harder to pull off longer legged flights, especially at altitude. That said, they did seem to do okay as photo-reconnaissance aircraft.


> A clean Mustang at 46"MP and 2700 RPM cruised at 380-395 at max Continuous Power for 2/3 the combat radius of much lower RPM/MP for max cruise.


Wait, the airplane could do 380-395 mph while only losing a third the range over the 300 mph cruise figures? If I do those numbers right that means you could fly 400-500 miles (I guess it was the supercruise of it's day).



pbehn said:


> No actual speeds involved but from this account a P/R Mosquito had a higher economical cruise speed than a P-51 with external tanks


Yeah, I've heard the same thing.


> Quote "The Mosquito met the fighter escort as planned; but now heavily loaded with l,000 gallons of fuel, flew at a severe speed disadvantage. Geary attempted to maintain economical cruising speed but outpaced the P-51s and was forced to throttle-back to continue flying formation with them.


I'm not sure I grasp using the escorts as the Mosquito could outmaneuver the Me.109 and Fw.190 at altitude.


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## pbehn (Feb 27, 2020)

Zipper730 said:


> Yeah, I've heard the same thing.
> I assume they were flying these missions at altitude? If so, I'm not sure I grasp the point of using the escorts at all: From what I remember the Mosquito could outmaneuver a Fw.190 at higher altitudes (from what I recall, and I could be wrong, the Fw.190 and Me.109 have similar turn rates).


No need to read the link I provided, you just keep firing questions and I will keep doing the reading to serve the answers to you.

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## Zipper730 (Feb 27, 2020)

pbehn said:


> No need to read the link I provided, you just keep firing questions and I will keep doing the reading to serve the answers to you.


Actually, I did read the link. I kind of read it after I asked the questions though.


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## pbehn (Feb 27, 2020)

Zipper730 said:


> Actually, I did read the link. I kind of read it after I asked the questions though.


 Well it was about encounters with 262s. I presume escorts were called for when aircraft were lost flying alone or were going to heavily defended areas.


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## Zipper730 (Feb 28, 2020)

pbehn said:


> Well it was about encounters with 262s.


That I'm aware of. The reason I used the Fw190 and Me109 as estimates for a reference was that it was the previously biggest threat to the Mosquitos.

When it came to heavily defended areas, I guess extra fighters can add more aircraft to the equation when the bombers would just be overwhelmed.


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## Zipper730 (Feb 28, 2020)

PFVA63 said:


> Zipper730, sorry for not getting back to you sooner. I've been out of town for a family funeral.


No problem., family events are of greater importance.


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## pbehn (Feb 28, 2020)

Zipper730 said:


> That I'm aware of. The reason I used the Fw190 and Me109 as estimates for a reference was that it was the previously biggest threat to the Mosquitos.
> 
> When it came to heavily defended areas, I guess extra fighters can add more aircraft to the equation when the bombers would just be overwhelmed.


It was a photo recon aircraft.


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## Zipper730 (Feb 28, 2020)

pbehn said:


> It was a photo recon aircraft.


True enough, both the bomber and recon variants of the Mosquitos are equally unequipped with defensive armament.


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## Zipper730 (Apr 13, 2020)

drgondog said:


> Interesting but not definitive... the mission range was the framework for operations planning. A clean Mustang at 46"MP and 2700 RPM cruised at 380-395 at max Continuous Power for 2/3 the combat radius of much lower RPM/MP for max cruise.


Wait, it could fly 400+ miles at 380-395 mph?


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## Shortround6 (Apr 13, 2020)

It might do better than that,

See: 






from Zeno's Warbirds. 
Zeno's had a number of these charts and the manuals section of this site has a bunch more.

Other Mechanical Systems Tech. 
The flight manuals are organized by country.


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