Wikipedia and the B-25: Is this true?

[Krusty]

"An interesting characteristic of the B-25 was that its range could be extended by using one-quarter wing flap settings. Since the aircraft normally cruised in a slightly nose-high attitude, about 40 US gallons (150 l) of fuel was below the fuel pickup point and thus unavailable for use. The flaps-down setting gave the aircraft a more level flight attitude, which resulted in this fuel becoming available, thus slightly extending the plane's range."

I wonder if that's true. And if that's modeled in AH!

[BlauK]

So, how would it behave when climbing or diving with the last drops of fuel? If it pulled the nose up in final approach, the engine would not get anymore fuel?

[Krusty]

I don't know.

I find it comical. I doubt they'd leave such a problem in a plane that had many upgrades. If it was such a problem they'd move the fuel pipes to the rear (lower) end of the fuel tanks.

I think Wiki's done it again, is all. Just another reason why I'm skeptical of their info!

[scottydawg]

The only reference on the internet I can find to this "fact" is that page on wiki.

HOWEVER, it does cite a reference, complete with ISBN. Anyone care to check it out?

Higham, Roy and Williams, Carol, eds. Flying Combat Aircraft of USAAF-USAF (Vol.1). Andrews AFB, Maryland: Air Force Historical Foundation, 1975. ISBN 0-8138-0325-X.

Looks like you can pick a copy of that book up from Amazon for the low low price of $0.38.  Search the ISBN on Amazon.

[moneyguy]

all airplanes have "un-usable fuel".  it helps prevent crap from getting sucked into the fuel system. so the stuff just rests on the bottom.

[PanzerIV]

Originally posted by Krusty
"An interesting characteristic of the B-25 was that its range could be extended by using one-quarter wing flap settings. Since the aircraft normally cruised in a slightly nose-high attitude, about 40 US gallons (150 l) of fuel was below the fuel pickup point and thus unavailable for use. The flaps-down setting gave the aircraft a more level flight attitude, which resulted in this fuel becoming available, thus slightly extending the plane's range."

I wonder if that's true. And if that's modeled in AH!

Did Ben affleck know that on Pearl Harbor(love triangle extravadganza).

[Oleg]

Originally posted by moneyguy
all airplanes have "un-usable fuel".  it helps prevent crap from getting sucked into the fuel system. so the stuff just rests on the bottom.

I doubt its true, at least for fighters.

[Angus]

This looks dubious.
If the fuel pickup was above a nose-up attitude, that is an alterable thing.
And for flying straight, - more speed will bring the nose down.....

[scottydawg]

Originally posted by PanzerIV
Did Ben affleck know that on Pearl Harbor(love triangle extravadganza).

Consider yourself punched in the face.

[Golfer]

Tis true, Oleg.  Total fuel capacity and usable fuel are different numbers even for fighters.  This number can be very small as little as 1-2 gallons but it does exist.

[Widewing]

Originally posted by Oleg
I doubt its true, at least for fighters.

Every aircraft carries fuel it cannot use, even fighters. Many manufacturers publish the volume of trapped fuel, or its weight as part of the basic weight. Others list total trapped fluids (fuel and oil). For example, for American fighters:

P-38J: 3.5 gallons
P-39Q: 1.2 gallons
P-40E: 2.1 gallons
P-47D-25: 9.0 gallons
P-51D: 3.2 gallons
P-63A: 1.3 gallons
F4F-4: Not listed, but thought to be about 1.5 gallons
F4U-1: Listed as 88 lb of trapped fuel and oil.
F6F-5: Listed as 89.5 lb of trapped fuel and oil.

My regards,

Widewing

[Oleg]

Is that trapped fuel actually served for keep soiling away from engine? Or there was other purpose?

[Stoney74]

Originally posted by Oleg
Is that trapped fuel actually served for keep soiling away from engine? Or there was other purpose?

No, its usually a figure derived to account for fuel that can't be reliably transferred from the tanks to the engine.  I doesn't have anything to do with keeping trash out of the fuel supply.  That's what gascolators are for.

[LancerVT]

Originally posted by scottydawg
Consider yourself punched in the face.

[68Hawk]

Wikipedia sucks, find a real source.

Theoretically the flaps would cause more drag in the long run and would only reduce range.  If the 40 gallons is true you might be able to use them up with the flaps technique, but how much burn time is that anyway?  What's the standard GPM on a B25?  Probably wouldn't be worth a loss of airspeed unless you're really bone dry.

I'm sure if there was something like this involved in flying the B25, Doolittle and his men new about it.  Affleck wouldn't even have been allowed on the Hornet.  Its sad how Hollywood butchers history.