Long range, high speed Spitfire fighter: the best approach?

[OldSkeptic]

Look again and look at the rib sections in the lower right hand corner. By the time you get to the 4th gun the wing is about 1/2 the thickness it is at the beginning of the wheel well and start of the "normal" leading edge tank.
Even rib 14 (just inboard of the of the 2nd gun) shows a sizable reduction cross section of the leading edge compared to Rib 5.

And here is a link to a photo of the inside of the leading edge.

http://www.vintagewings.ca/Portals/0/Vintage_Stories/News Stories E/Just Wingin' It/Wings10.jpg

Trying to fit large tanks in the leading edge WITH protection is going to be a nightmare.

Perfectly correct, concentrating on outer leading edge tanks is more practical.

Been doing some checking and Boscomb Down cleared the FR XIV for combat with about 15 gals in the rear tank.
Given that Berlin in a XIV is possible, even with just the standard inner leading edge tanks.

One thing I need to find out is that the VIII had 96 gals in the 2 front tanks (the IX had the usual 85 gals) but the XIV reverted to the 85 gals.

Not sure why that was, since the XIV is a VIII with a Griffon, unless there was some sort of issue with space. Any ideas would be useful.

 

[wuzak]

Griffon was actually shorter than the Merlin. So there shoudl have been more space.

Maybe it needed a bigger oil tank?

 

[tomo pauk]

...

One thing I need to find out is that the VIII had 96 gals in the 2 front tanks (the IX had the usual 85 gals) but the XIV reverted to the 85 gals.

Not sure why that was, since the XIV is a VIII with a Griffon, unless there was some sort of issue with space. Any ideas would be useful.

Contrary to Merlin Spitfires, the Mk.XIV carried engine oil between top fuel tank and engine. Per 'Spitfire - History', pg. 419 cutaway.

added: the drop tank from the P-38, 126 IG (150 USG), would not looked bad on the Spitfire either.

 

[drgondog]

Perfectly correct, concentrating on outer leading edge tanks is more practical.

Been doing some checking and Boscomb Down cleared the FR XIV for combat with about 15 gals in the rear tank.
Given that Berlin in a XIV is possible, even with just the standard inner leading edge tanks.

One thing I need to find out is that the VIII had 96 gals in the 2 front tanks (the IX had the usual 85 gals) but the XIV reverted to the 85 gals.

Not sure why that was, since the XIV is a VIII with a Griffon, unless there was some sort of issue with space. Any ideas would be useful.

I don't have access to the weight/balance charts that were used to calculate the CG for fixed and disposable loads. My speculation is that a.) the Griffon is longer, thereby reducing space, b.) probably heavier.

Possibly the combination of more engine mass forward, combined with more fuel forward could have had an adverse effect on Take off relative to 'forward' cg issues.

 

[wuzak]

I don't have access to the weight/balance charts that were used to calculate the CG for fixed and disposable loads. My speculation is that a.) the Griffon is longer, thereby reducing space, b.) probably heavier.

According to Lumsden, the 2 stage Merlin is 88" long, and the 2 stage Griffon is 81" long. So the Griffon is shorter.

But it is definitely heavier -1640-1670lb for the Merlin (depending on accesories) vs 1980lb for the 2 stage Griffon (100 series Griffons were slightly heavier, because they had 3 speed supercharger drives and many had CR prop shafts).

Possibly the combination of more engine mass forward, combined with more fuel forward could have had an adverse effect on Take off relative to 'forward' cg issues.

I do believe the XIV is longer, so the engine is more forward.

But to counteract that they put balance weights in the tail.

I don't have access to the weight/balance charts that were used to calculate the CG for fixed and disposable loads.

Spitfire Mk XIV Testing

Does that help?

 

[tomo pauk]

Look again and look at the rib sections in the lower right hand corner. By the time you get to the 4th gun the wing is about 1/2 the thickness it is at the beginning of the wheel well and start of the "normal" leading edge tank.
Even rib 14 (just inboard of the of the 2nd gun) shows a sizable reduction cross section of the leading edge compared to Rib 5.

And here is a link to a photo of the inside of the leading edge.

http://www.vintagewings.ca/Portals/0/Vintage_Stories/News Stories E/Just Wingin' It/Wings10.jpg

Trying to fit large tanks in the leading edge WITH protection is going to be a nightmare.

Great photo.
In order to accommodate the LE fuel tanks, the Spitfire VII/VIII/XIV have had leading-edge ribs 6 and 7 removed (together with 'W' shaped supports), while the top and bottom skin were doubled in order the wing retains rigidity. I would not bet my house on this, but it does not seem too much a stretch: do the similar thing with the remainder of the leading edge, while installing the self sealing tanks between ribs 10-16 (start of the outboard .303 gun bay).

 

[parsifal]

thinking outside the box for a second, what about trade offs to achive weight savings so as to increase the fuel load? What might be considered expendable or reducable?

Armament
Armour
Radio
Ammunition supply

Any others?

 

[wuzak]

thinking outside the box for a second, what about trade offs to achive weight savings so as to increase the fuel load? What might be considered expendable or reducable?

Armament
Armour
Radio
Ammunition supply

Any others?

I thought the issue would be finding the volume to place the fuel, not the weight.

 

[parsifal]

maybe, but one would think that the elliptical wing with all that volume, would make an odeal integral fuel tank, along the lines of the zero and its internal fuel tankage arrangements. has some nasty side effect ("flying ronson"), but I would not think volume or space was such an issue.

 

[wuzak]

maybe, but one would think that the elliptical wing with all that volume, would make an odeal integral fuel tank, along the lines of the zero and its internal fuel tankage arrangements. has some nasty side effect ("flying ronson"), but I would not think volume or space was such an issue.

That lovely elliptical wing is thinner than most in its era.

It had a 13% thickness to chord ratio at the root (~16% for the P-51). But it also was an older, non-laminar flow, section - that means the thickest point is closer to the leading edge than for the P-51. The Leading edge, and just behind the main spar would make for reasonable spaces for fuel storage, but after that, not so much. Also have to have structure in the wing, guns, coolers and landing gear. I guess if teh coolers were moved to teh fuselage, some space could have been made there.

 

[Neil Stirling]

Planned long range Spitfire XXI

Neil.

 

[tomo pauk]

Great stuff

Neil, would it be possible top post the aircraft data sheets for the other Spitfires with one or two rear fuselage tanks? Maybe also for the PR/FR versions?

 

[fastmongrel]

Why the effort to get to Berlin. Leave the big city to BC at night and concentrate on turning the Ruhr into a wasteland by day. For this the LR MkVIII Spit with 90 gall slipper tank and rear fuselage tank would have been fine without cramming fuel into every available space.

 

[Neil Stirling]

Neil

Last three images got through some how and are not what was asked for.

 

[Neil Stirling]

Neil.

 

[tomo pauk]

Last three images got through some how and are not what was asked for.

No problems about that
If we would post only what was asked for, the forum would've been a dull place.

 

[Camden]

I've sometimes wondered why the Hispano V wasn't produced earlier. The measures used to increase the rate of fire (shorter barrel; lighter bolt) were all well-understood pre-war and could easily have been introduced in 1940. You could fit 2 of these to a Spitfire and remove the Hispano II's and machine-guns without any significant change in firepower, then fit extra tanks where the mg's had been. Once the wing tanks were empty, the aircraft would also be about 150-200 pounds lighter than the actual aircraft, and would probably have a somewhat better roll-rate.

 

[Aozora]

Planned long range Spitfire XXI

View attachment 233329

Neil.

Shown below are the fuel systems and capacities of the Seafire 45 and 46, which are the same as, or very similar to, the Spitfire 21/22:

The main problem I can see was the numbers of tanks and the handling required; lots of things to go wrong:

One of those images slipped through totally accidentally.

 

[parsifal]

youve done it again Aozora......what were we discussing????

 

[OldSkeptic]

Me too, I've completely lost track of the thread