Peter Stickney wrote:

In article ,
(The Revolution Will Not Be Televised) writes:

snip


Whatever happened, the tanks were going to be jettisoned before
initiating combat, so I don't think the 90 gallon tanks - which should
be substantially emptied and consequently lighter before the aircraft
got to the prospective combat area anyway - would in those
circumstances impose as much of a performance restriction as we might
suppose.

True - I was thinking in terms of a way to add 90 gallons to a Mk V's
fuel capacity (Which would be about 50% of total fuel anyway) withoug
the stability and drag penalties that the 90 gallon tanks imposed.
(It's not much good being an escort fighter if you cruise slower than
the bombers that you're escorting.) To my ming, 29-30 gallons
internal, with another 60 or so external would about do it, especially
if the 60 gallon tank has no restrictions.

Pete, the drag penalty of the 90 gallon tank wasn't all that much. It knocked about 20
mph off the Spit XIV's top and max. cruise speeds, and less than 18 mph (337.5 vice 354)
off the top speed of a Mk. VC Trop, AB 320, that A&AEE tested; go here for the full report
on level and climb performance with and without the tank:

http://www.fourthfightergroup.com/eagles/ab320.html

A Mk. VIII/IX would presumably take a speed hit in between the two, given that it's faster
than the Mk. V and slower than the Mk. XIV. In short, not significant, and there's
absolutely no danger of cruising "slower than the bombers that you're escorting." WITH
the tank, the Spit XIV was still faster than the Me-109 or FW-190A. The Mk. IX wouldn't
be, but would still be able to cruise at 300TAS or higher at the heights of interest with
no problem.

Remember, I'm not asserting that any of this was an optimal solution
for long-range escorting, or could have competed with aircraft that
were better suited to expanding their internal fuel capacity. I'm
trying to work along the lines that would be dictated by operational
neccessity and addressed with existing equipment and experience in
certain circumstances.

Well, in htat case, gin up a 60 gallon tank, and add teh 2 13-gallon
leadig edge tanks. The 80 gallon tank would give you about 40% of teh
total fuel, allowing it to be empty before the target area is reached,
and the 13 gallon tanks can be swapped in as a Deport-level job. They
fit in the leading edge outboard of the 20mm gun bays. but inboard of
the .303s, and slotted in between a pair of ribs. That sort of
sheet-metal work would be well within what they could do withoug a
need fr a factory-level rebuild.

Again, I'll raise a practical objection to installing tanks outboard of the guns (any
guns): where are you going to route the tank piping? You can't route it through a gun bay
(well, you could, if you didn't mind the constant danger of broken fuel pipes owing to
vibration loads when shooting, not to mention the danger of fires -- I can't see even the
most clueless RAF type signing off on this), and there's really not a whole lot of room in
the wing aft of the cannon bay (but forward of the flaps/ailerons and their actuators) to
pass them, even assuming that you're willing to make a couple of 90 degree or so bends in
the piping to do so. This is an interim mod until the RAF's Mustangs become available, so
it needs to be something that's already been done, and that's the Mk. VIII tank
installation, with maybe an aft tank added if the Cg is okay for combat (and the max.
gross weight isn't exceeded when also carrying a 90 gal. or larger drop tank).

Guy