P-51 fuselage fuel tank

[Reluctant Poster]

Actually it was a high priority.

The acceleration into standard combat tanks, 52/60/75/100 &150gal was bogged down with perception that self sealing and low priority materials (wood, plastic, paper) drove Mat.Cmd into a bureaucratic design, build protortype, test and re-design cy cle.

Further complicating the challenge was a real logistics issue of transporting high volume/low weight tanks via shipboard when tanks, aircraft, vehicles, POL were critical.

I agree your point about British not solving the problem. That said the RAF had no high-altitude daylight strategic aims and were content, to a degree with what we provided to augment those few instances.

My experience on large infrastructure structure projects is that unless one individual is given the mandate to do what ever it takes things don't happen quickly. If you truly want to give high priority a Leslie Groves type must be assigned.

 

[MiTasol]

I am not suggesting that it was done with malice I am merely stating that it wasn't a high priority. They simply weren't paying much attention to it. Each party was assuming someone else was taking care of the problem. The issue I have is that posters on this forum are blaming the British for not solving the problem by extending the range of the Spitfire when they had other more pressing needs just like the US.

and the most pressing of those needs was to keep the Spitfires coming off the line without all the lost production that comes with a major design change.

Ideally they should have filled the wing leading edge with a large fuel tank but that would have been a massive redesign. Given how light the fuselage structure is on the Mk V (the only version I have worked on) just fitting the tank(s) behind the pilots seat would have involved some substantial structural changes. The wing design aft of the main spar means fitting bag tanks between each rib like used on some US aircraft was not practical so where else were they going to add fuel without going outside the CofG range?

 

[pbehn]

and the most pressing of those needs was to keep the Spitfires coming off the line without all the lost production that comes with a major design change.

Ideally they should have filled the wing leading edge with a large fuel tank but that would have been a massive redesign. Given how light the fuselage structure is on the Mk V (the only version I have worked on) just fitting the tank(s) behind the pilots seat would have involved some substantial structural changes. The wing design aft of the main spar means fitting bag tanks between each rib like used on some US aircraft was not practical so where else were they going to add fuel without going outside the CofG range?

Ther is a logical nonsense in the history of the Spitfire. The Mk V was a stop gap using new engines in old Mk I/II airframes. The Mk IX was a stop gap using new engines in Mk V airframes and the Mk XIV was a stop gap using new Griffon engines in Mk IX airframes. So a MK XIV used the same airframe as a MKI/II? No it didnt because when the already manufactured airframes were completed design changes were introduced to improve the marque. As far as I can see there wasnt a huge amount of work done on making long range Spitfires because "more" was always more important. The Mustangs range and use changes the debate, the RAF didnt need massive range in its fighters except for crtain missions and it specifically developed the Mustang and later P-51 for that type of mission.

 

[MiTasol]

My experience on large infrastructure structure projects is that unless one individual is given the mandate to do what ever it takes things don't happen quickly. If you truly want to give high priority a Leslie Groves type must be assigned.

As a friend of mine puts it - A committee of one gets things done.

 

[PAT303]

"Following the order to "Scramble', Spitfires needed 13 minutes to climb to 20,000feet; Hurricanes needed 16 minutes. Then a screen of Bf 109s almost invariably flew above the bombers, which on Dowding's and Park's insistence, were the prime targets, so, as RAF fighters attacked, they were assaulted from above. Soon some squadron leaders, when ordered to fly at a given height, used their initiative and added two or three thousand feet in an attempt to meet the enemy on equal terms."

There were no limitations on Spitfire operations during the Battle of Britain due to fuel capacity.

You are validating my argument, with an extra 20G of fuel the Spitfires wouldn't need 13 minutes climbing as hard as possible to meet the threat, they would already be at 20,000ft when the 109's cross the coast.

 

[PAT303]

Ideally they should have filled the wing leading edge with a large fuel tank but that would have been a massive redesign. Given how light the fuselage structure is on the Mk V (the only version I have worked on) just fitting the tank(s) behind the pilots seat would have involved some substantial structural changes.

There was no need for a redesign of anything, the space for fuel was already there, in fact no changes were made to fit the 13G or 17G bag tanks in MkVIII's and XI's because the space they filled was empty. The MkV had a 29G aux tank fitted that required no structural changes, nor did the 170G ferry tank which was a huge tank.

 

[PStickney]

The G-suit was in continuous operation, and the output of the Vacuum pump nominally delivered 5-6psi through 30,000 feet. So, I might be wrong (gasp) but the G-suit was always in competition so long as the external tank was connected.

Only if the inflation valve opened - which only happened when you were pulling G, and the weight it used as a G reference overpowered the spring that held it up.
There has been some mention of fighters intended for Very Long Range Missions having a "Massage Mode" built into the G-Suit valves, that would pulse the suits to prevent the Pilot's legs from cramping and such.

 

[Geoffrey Sinclair]

You are validating my argument, with an extra 20G of fuel the Spitfires wouldn't need 13 minutes climbing as hard as possible to meet the threat, they would already be at 20,000ft when the 109's cross the coast.

Actually it is being refuted, the last thing Fighter Command needed was more airtime. They were already flying more sorties on average than the Luftwaffe offensive fighter sorties. August 8 to 30 September 1940 Fighter Command reports 24,019 interception sorties and 11,045 other sorties, things like convoy protection and "sector", total 35,064 sorties by day. ER Hooton reports 20,900 Luftwaffe offensive fighter sorties, 5 August to 29 September.

The earlier the interceptors launch the more accurate the information on enemy intentions needs to be.

There was no need for a redesign of anything, the space for fuel was already there, in fact no changes were made to fit the 13G or 17G bag tanks in MkVIII's and XI's because the space they filled was empty. The MkV had a 29G aux tank fitted that required no structural changes, nor did the 170G ferry tank which was a huge tank.

The 29 gallon tank for the mark V was for ferry operations., adding more than the weight of the pilot plus parachute. You need to check things like the pilot notes to see what the limitations were. The 170 gallon tank required removal of all armament and ammunition, with only gentle turns allowed.

Digital Reel Archive

Reel A2074
page 607 of PDF for start of US version of Spitfire range extension program.
page 689 for P-38, P-47, P-51 and modified Spitfire ranges
page 735 for P-38, P-47, P-51 and modified Spitfire load limits

 

[MiTasol]

There was no need for a redesign of anything, the space for fuel was already there, in fact no changes were made to fit the 13G or 17G bag tanks in MkVIII's and XI's because the space they filled was empty. The MkV had a 29G aux tank fitted that required no structural changes, nor did the 170G ferry tank which was a huge tank.

Regarding the ferry tank and 29 gallon fuselage tank you are partially correct - the Mk V had all the provisions for the ferry tanks and small rear fuselage tank fitted at the factory but as Geoffrey Sinclair pointed out that tank and its associated drop tank were NEVER used in combat operations.

Regarding the wing tanks you are very wrong. The tanks are not just floating around in space with nothing attaching them to the structure and nothing protecting them from having holes rubbed through the bag by the structure. There was attaching sub-structure required that was not fitted at the factory on the Mk V and the plumbing for the tanks likewise was not hanging around in space but affixed to the aircraft structure. Even if this only involved drilling holes for the attaching P clips in the fuselage or wing that is a structural modification. Then there are the other affiliated changes like adding the fuel selector valve(s) (Fuel Cock(s)) because the standard Mk V does not have provision for selecting the wing tanks, etc, etc, etc. I only worked on Mk V Spits so do not have first hand knowledge of how the wing tanks were fitted or how they were filled on later marks. My guess is they have there own filler caps in the wing leading edge and that is another modification as it the vent system that is needed to prevent them developing a vacuum and become unable to supply fuel. I am glad that I never worked on such a version as threading the tank through this structure without getting wrinkles and all the other defects that prevent bag tanks feeding properly would be a nightmare. Most bag tanks are held on to the top of the containment area so that they do not collapse. Access is usually through holes in the top of the structure.

You say there were no mods to fit these tanks so how did the Spitfire prevent its bags from collapsing and from chaffing on structure and how were they vented? I would love to know how this was achieved without any modifications to the wing.

Note all the diagonal structural members on EVERY rib.

Again note all the diagonal structural members and rivet and bolt heads which will chafe holes in the bags unless there is some protection fitted.

 

[Reluctant Poster]

You are validating my argument, with an extra 20G of fuel the Spitfires wouldn't need 13 minutes climbing as hard as possible to meet the threat, they would already be at 20,000ft when the 109's cross the coast.

You're suggesting they leave early with limited information on the possible raid so that they can have a nice leisurely climb? I suppose they could do an aerial tour of the Kent hop fields while waiting for something to happen.
In any event you're missing the point. There is plenty of fuel to leave early. The 29 gallon tank is not necessary. Standing patrols were flown over Dunkirk and over the costal convoys without running out of fuel. The standing patrols left the ground before the Luftwaffe did.

 

[MiTasol]

You are validating my argument, with an extra 20G of fuel the Spitfires wouldn't need 13 minutes climbing as hard as possible to meet the threat, they would already be at 20,000ft when the 109's cross the coast.

And you are ignoring the fact that the 29g tank could only be used when the 170g drop tank was fitted and all the guns and ammunition were removed.

Please tell me how the Spitfire was going to destroy German aircraft in that configuration, especially with only gentle turns allowed.

 

[pbehn]

And you are ignoring the fact that the 29g tank could only be used when the 170g drop tank was fitted and all the guns and ammunition were removed.

Please tell me how the Spitfire was going to destroy German aircraft in that configuration, especially with only gentle turns allowed.

Dowding created the Dowding system, at huge expense with the development of all sorts of technologies. Much knowledge of the minute details of that era are now lost. From the few documents I have seen posted that were created by Dowding and Park, they went into the far end of a fart about improving overall performance of the RAF as a unit. If either of them thought an additional tank would have improved things and it could be done, it would have been done.

 

[MiTasol]

And as well as those two gentlemen there was Lord Beaverbrook kicking butts to get the necessary materials and manpower to required to get urgent items into production.

 

[pbehn]

And as well as those two gentlemen there was Lord Beaverbrook kicking butts to get the necessary materials and manpower to required to get urgent items into production.

It is impossible to unlearn what we now know. Most RAF planning and training was based on WW1 experience, no one predicted the rapid fall of France and the losses in planes and pilots there.

 

[tomo pauk]

If I may.

And you are ignoring the fact that the 29g tank could only be used when the 170g drop tank was fitted and all the guns and ammunition were removed.

The 170 gal drop tank was used only if the 29 gal tank was used, not the other way around.
Bending the "rules" to test the idea - too bad that configurations of light armament (ie. all-MG set-up) + the 29 gal tank + the ever increased fuel tankgae in the 170 gal tank (say, start with 120 gals) was never tested. But. as always: no doctrine = no resulting hardware.
170 gals on the drop tank will get us much further than the return is possible, with how much of fuel ( 65+- gals ?) is left after a combat or two.

Please tell me how the Spitfire was going to destroy German aircraft in that configuration, especially with only gentle turns allowed.

We can safely assume that the 29 gals from the rear tank is perhaps 10-15 gals before the German (or other Axis) A/C; or empty, since the manual prescribes that the rear tank is to be used up 1st. Once the drop tank is jettisoned, the influence at the CoG coming from the rear tank is negligible. Some re-shuffling of the counterweights might've helped, too.
Th early (talk 1941/42) and regular use of 29 gal tank on the Spitfires also puts the Spitfire IX and VIII in a better position, range- and usability-wise.

Spitfires with more fuel onboard can cruise on faster speed where the danger is suspected, so the German fighters have the harder time to dictate terms of combat.

 

[MiTasol]

If I may.

The 170 gal drop tank was used only if the 29 gal tank was used, not the other way around.

Sorry to disagree but the wording in the manual is Rear fuselage tank (used only with 170 gal, tank) and I read that as the 29 gal tank was only used when the 170 gal drop tank was used and could never be used otherwise.

 

[PAT303]

Actually it is being refuted, the last thing Fighter Command needed was more airtime. They were already flying more sorties on average than the Luftwaffe offensive fighter sorties

You don't seem to understand what I'm saying, I don't want fighter command to fly more sorties or have more airtime, I simply want the extra fuel to gain a tactical advantage over raids they did intercept.

And you are ignoring the fact that the 29g tank could only be used when the 170g drop tank was fitted and all the guns and ammunition were removed.

Please tell me how the Spitfire was going to destroy German aircraft in that configuration, especially with only gentle turns allowed.

Why would you fit the 170G ferry tank and remove all the guns in the BoB????, I have no idea what you are talking about.

 

[PAT303]

Regarding the ferry tank and 29 gallon fuselage tank you are partially correct - the Mk V had all the provisions for the ferry tanks and small rear fuselage tank fitted at the factory but as Geoffrey Sinclair pointed out that tank and its associated drop tank were NEVER used in combat operations.

View attachment 787183

Regarding the wing tanks you are very wrong. The tanks are not just floating around in space with nothing attaching them to the structure and nothing protecting them from having holes rubbed through the bag by the structure. There was attaching sub-structure required that was not fitted at the factory on the Mk V and the plumbing for the tanks likewise was not hanging around in space but affixed to the aircraft structure. Even if this only involved drilling holes for the attaching P clips in the fuselage or wing that is a structural modification. Then there are the other affiliated changes like adding the fuel selector valve(s) (Fuel Cock(s)) because the standard Mk V does not have provision for selecting the wing tanks, etc, etc, etc. I only worked on Mk V Spits so do not have first hand knowledge of how the wing tanks were fitted or how they were filled on later marks. My guess is they have there own filler caps in the wing leading edge and that is another modification as it the vent system that is needed to prevent them developing a vacuum and become unable to supply fuel. I am glad that I never worked on such a version as threading the tank through this structure without getting wrinkles and all the other defects that prevent bag tanks feeding properly would be a nightmare. Most bag tanks are held on to the top of the containment area so that they do not collapse. Access is usually through holes in the top of the structure.

You say there were no mods to fit these tanks so how did the Spitfire prevent its bags from collapsing and from chaffing on structure and how were they vented? I would love to know how this was achieved without any modifications to the wing.

View attachment 787182
View attachment 787184 Note all the diagonal structural members on EVERY rib.
View attachment 787186Again note all the diagonal structural members and rivet and bolt heads which will chafe holes in the bags unless there is some protection fitted.

I said the room for the leading edge tanks is already there, instead of fitting the 13G tank fit a 26G one, the space is empty, use it for fuel.

 

[PAT303]

Sorry to disagree but the wording in the manual is Rear fuselage tank (used only with 170 gal, tank) and I read that as the 29 gal tank was only used when the 170 gal drop tank was used and could never be used otherwise.

The 29g tank gravity fed directly into the 170G tank, the reason it could not be used without it. It was set up that way because they were removed after the flight to Malta, having gravity feed made the whole installation as cheap and easy as possible.

 

[PAT303]

If either of them thought an additional tank would have improved things and it could be done, it would have been done.

Yet they went to great lengths to develop all kinds of aux and drop tanks for this pointless issue?, makes you wonder why the MkV's over Darwin were all fitted with slipper tanks and the Seafire MkIII had the MkVIII leading edge tanks?, the FAA were so desperate for range they used surplus P40 droppers in the Med, but there wasn't a problem with range?.