Allied AFs in 1943: realistic options for long range fighters?

[bobbysocks]

IIRC the P-51 pilots were to take off on fuselage tank (85 USG), expand a half of it, then switch to external fuel? That would leave some 40-45 USG (or 32-35 imp gals) prior using the drop tanks.
I agree that it would be very hard* to make a P-51 from a Spit (range-wise), but a Spit VIII with 30 imp gals in the rear fus. tank would be very close. And feasible/available in early 1943, the best quality of the modification had it been done.

*but not impossible, see Yak-9D/DD

taxi and take off on internal wing tanks....shortly after switch to fuse tank and take it down to 35 - 30 gallons ( approx 50 min flight time ) then switch to drop tanks alternating every 30 minutes

 

[tomo pauk]

Thanks, bobbysocks.

...
Typhoon ... We need to find the way to install another, say, 40 IG into the plane. In wing leading edge, perhaps - all the way from fuselage to cannons.

Doh - they are already there, 2 x 40 gals
Well than - maybe an L-shaped tank, a-la the one Bf-109 had, some 40-50 gals?

 

[wuzak]

Re the F4U, were there enough for the task in 1943, given that they were also being supplied to the USN, USMC, RN and RNZAF?

 

[bobbysocks]

Every 5 min on combat power subtracts 75 or 60 miles. So 3 x 5 min on combat power makes the 'return range' of 385 or 310 miles.

that i think is going to be the determining "straw for the camel"...you can load up a lot of planes with external tanks and get them long distances you want....but once they drop their tanks they have to be able to engage in combat and still make it all the way home on their inboard fuel...so you are back to your original configurations and possible in frame mods.

 

[Shortround6]

Was there a way to 'sneak in' the F4U-1 in the ETO as a long range fighter? Maybe under RAF's guise?
At 21500 ft and with 360 gals of internal fuel, the endurance was 5 hrs 20 mins at 75% of the high speed - 1600 miles?

The plane carried 237 gallons in a protected fuselage tank. Each wing had a 57 gallon tank, unprotected, but with a CO2 system to keep fuel vapors from reaching a flammable range. Very early planes carried NO drop tanks. Later planes deleted the wing tanks and adopted two drop tanks instead of one.

 

[tomo pauk]

that i think is going to be the determining "straw for the camel"...you can load up a lot of planes with external tanks and get them long distances you want....but once they drop their tanks they have to be able to engage in combat and still make it all the way home on their inboard fuel...so you are back to your original configurations and possible in frame mods.

Fair points. However, in the same post I've said the following:

We need to find the way to install another, say, 40 IG into the plane.

The wing leading edges are already taken, so this might have worked:

Well than - maybe an L-shaped tank, a-la the one Bf-109 had, some 40-50 gals?

Hi, wuzak:

Re the F4U, were there enough for the task in 1943, given that they were also being supplied to the USN, USMC, RN and RNZAF?

The major shortcoming of the type

 

[tomo pauk]

When one sees the wing LE tanks of the Mk.VIII and XIV, it seems to be a shame that the tanks were not any greater (instead of 25 IG, maybe 45 IG total; the '?' marked area). Also, substituting the LMGs with HMG clears the good part of the leading edge and inter-spar part, new areas for additional fuel tanks (almost the 'E' wing). Not quite as big a fuel quantity as at the PR versions, but still useful.

 

[bobbysocks]

can the existing wing design handle the added stress of those tanks being there during combat maneuvers or is it going to have to be "beefed" up?

 

[tomo pauk]

There is no such thing as a free lunch. The beefing up must take into account how much the weight is being added. If extra 30 imp gals per wing is added, that makes 2 x 30 x 7,2 = 432 lbs of extra fuel. Total weight gain, with fuel tanks and reinforcements maybe 650 lbs?

 

[bobbysocks]

the more i think about it the more i cant help but ask if a mod like that was feasible why they didnt do it...even on a limited basis? gaining extra range would have been adventageous to some degree. my guess is the "Beefing " up that would be necessary to accomidate the mods and effect they would have on the aircraft's CG would have changed the flight characteristics to something less than desireable. so you are back at square 1... instead of using an existing ac and trying to make it fit the role you will have to find a new airframe.

 

[wuzak]

The leading edge tanks shouldn't be too far from teh CoG?

 

[tomo pauk]

As wuzak said.
The wing tanks were installed in many an aircraft, either from get go or as a modification. P-39, P-47N, F4U, P-51, Spitfire, Hurricane, TYphoon, LaGG-3, La-5 etc. Being close to the CoG (when looking from the side) made them more desirable than the rear fuselage tanks; only P-51 and Spitfire having those, and used them with many restrictions.

 

[tomo pauk]

The P-47 have had all the potential to become an long range fighter, even without going after the P-47N.
It was not until mid 1944 that planes were flying with 370 gals of internal fuel (305 prior that date). In the AHT book the combat radius jumps from 125 miles (with 305 USG) up to 225 (with 370 gals). The another thing was the unfortunate drop tank installation. The ferry tanks (200/205 gals, shaped as 'slipper' tanks from Spitfires) were ill suited to be pressurized - a major issue for a fighter that is at it's best at 25000-35000 ft. So we have accounts (from the same book) of filling the ferry tank half full and then dropping it, in order to extend the combat range. Another quick fix was to adopt the 75 or 108/110 USG fuel tank to be carried under belly.
The fat belly was the obstacle to adoption of Lockheed's 150/165 gal tank (from P-38). However, in the ATH there is some interesting info about local modifications, like the custom made 200 gal belly tank, or an attempt to modify the P-38's tanks for the P-47. Even the rear fuselage tank of unknown volume was tried, but it was found being 'not really satisfactory'. The agile Gen. Kenney was a force behind that, the depots at Port Moresby and Brisbane adopting 75 and 110 gal tanks for the P-47.
In ETO, apart from the 'abuse' of the ferry tanks, the 75 and 108/110 gals tanks were put to a good use.

Now, how was the P-47 suited to carry wing tanks? Again, from the same book:
-Aug 1943: Ten P-47D-5 aircraft with two 165 gallon P-38 type external fuel tanks adapted are air-ferried to the UK.

It's not stated whether these P-47 had any ammo and/or armament. Since that was an adaptation for ferry purposes, the tanks were likely unperssurised. It was not until the advent of the P-47D-15 that wings were fully suited/reinforced to carry that amount of fuel (2000 lbs) and full armament. Once reinforced, there were instances that planes were going on combat missions with 300 gal tanks under wings.

 

[Edgar Brooks]

The Spitfire's wing derived its strength from the spar/leading edge "D" box combination, which had 21 wingribs inside (it was never a hollow shell); you are planning to remove 11 of those ribs, each of which has four angled braces built-in, and hope that the wing could retain its strength.
It couldn't happen; the D box had already required internal strengthening in November 1939, since there had been a few incidences of Spitfires shedding wings around that time. Supermarine also undertook to increase the strength, to enable the airframe to cope with 12G, in 1941, which also couldn't happen if the wing's structure was weakened to any extent. The wing tanks (that were inserted in the VII/VIII/XIV) were fitted in the area of the wheel wells (already considerably strengthened,) also meaning that the fuel did not have to pass the gun barrels, which your modification certainly would entail.

 

[tomo pauk]

The fuel tubes can pass either above gun barrels or behind the guns (red circles in the pic attached).
In the area were I've depicted additional LE tanks Supermarine can seal the area and make integral tanks. Or come out with ribs of a different design, leaving the space for tanks.
With both of those proposals failed during testing, they still can try adding the tank to the area once occupied by external two pairs of LMGs their ammo, that's also depicted at post #47 here.

BTW, what was the position of wing fuel tanks of the PR.XIX?

 

[Shortround6]

You have several issues here. One is that what was done to a small number of special Spitfires (225 built over 2 years?) may not be applicable to a mass produced version. Changes in the tooling for the mass produced version may interrupt production for several weeks. Another is that just because there is empty space in a drawing or photograph does not mean you can fill it with something. Running fuel lines through the guns bays (which are heated) may or may not interfere with servicing the guns which includes the removal and installation of the guns for servicing.

 

[tomo pauk]

The red circles are for illustration purposes - I could have paint them right by the rear spar so the guns have all the space they need. The lines flowing above barrels (within the 'D' box) do not interfere with the guns anyway.
As for what it would be good to produce from late 1942/early 1943 on - hopefully not the Mk.Vs?

I'd appreciate any info re. PR.XIX

 

[cimmex]

I'm sure the aircraft designers at this time were not dumb and considered all possibilities to fulfil the requirements of the military planers and there must be a reason when their decision differs to some ideas which are done by some crazy guys seventy years later.
Cimmex

 

[tomo pauk]

Who said the designers were dumb? Were the requirements of military planers always sound? Were the military planers really addressing every possibility right? Was there an instance or two where the newly appointed person at high command immediately made a decision or two that were far better than the previous decisions?
And now whose decisions differ to the ideas of the crazy guys seventy years later?

Your comment sounds like anything done in military history is above any comment, or, god forbid, critique.


Now into a more constructive tone - here is what I've googled up re. the wings of the PR Spitfires:

D type

This designation applied to the unarmed long-range wing for reconnaissance versions. Space for substantial amount of additional fuel was provided in the space ahead of the wing spar, which together with the reinforced skin of the wing's leading edge formed a rigid torsion box. Its otherwise empty interior was converted into an integral fuel tank capable of carrying 66 imp gallons. On hot summer days, so large amount of fuel inside the wing would produce a substantial volume of vapour, so relief valves were fitted to the tanks in the outboard rib position.

article drawing:
http://spitfiresite.com/2010/04/concise-guide-to-spitfire-wing-types.html/2

 

[cimmex]

Where are the guns?

When the military planers requires more range for a plane, this is a technical challenge to the engineers and when the engineers tell them that this is not possible for that reason I believe the engineer of this time.
Cimmex