Drop Tanks…Spitfire/P-51….Range…….?

Just checked in the Robert Goebel autobio ‘Mustang Ace’,he confirmed that they did indeed completely fill the 85usg rear tank,He says that he would take off with main (wing) tanks selected,after take off he selected the rear tank and burned that down to approx 30usg at which point he emptied the drop tanks before reselecting the rear tank to empty that !
He also said that if too much fuel was left in the rear tank (C of G too far aft) the a/c would ‘tighten up’ in the turn and loss of control could follow.

rgds baz

ISTR with the Meteor NF there was a speed restriction with drop tanks because they had the nasty habit of the noses collapsing if made to go above about Mach 0.73, especially when empty.

Yes I’d heard that too in fact the NF Meatbox was just one of the ships that restriction was placed on as I recall. IIRC even the humble litttle Vampire was capable of speeds which would do it too.

Nothing new there Mike,they didnt normally jettison drop tanks during WW2,only if they were forced to by enemy action or perhaps to lessen drag if running short of fuel.
As a small aside,the americans were originally a little sceptical about the british designed Paper Mache drop tanks but did eventually adopt them (much cheaper to throw away than ‘real’ tanks :D)

Yep I reckon the cost of alloy tanks has to have been atleast 10 times that of the compressed cardboard things we introduced them to. I’d have thought the alloy ones would also be heavier.

Although the P51 Pilot’s notes don’t forbid combat manouvers with a full rear tank, they DO forbid taking off with one!! 65 gallons was the max.

Also, it was noted that more than 25 galls in that tank would result in “negative control response” when pulling more than 6.75G (not sure what that means, but it sounds unpleasant). I think whereas the authors of the Spit pilot’s notes thought prohibition was best, the P51 authors just told you what would happen and let you make your own mind up.

I agree that it definitely sounds like a warning that the scope for the results to be unpleasant was relatively high.

I don’t know about then but when the jets arrived RAF pilots were asked to please bring the drop tanks back except in dire emergencies owing to their expense and being in short supply. Makes you want to laugh doesn’t it?

Nothing new there Mike,they didnt normally jettison drop tanks during WW2,only if they were forced to by enemy action or perhaps to lessen drag if running short of fuel.
As a small aside,the americans were originally a little sceptical about the british designed Paper Mache drop tanks but did eventually adopt them (much cheaper to throw away than ‘real’ tanks :D)

Thats because it had more fuel on board. I believe that the P-51’s fuselage fuel was used first, and the drop tanks were jettisoned as soon as required in a combat situation..With a full fuselage tank, the Centre of Gravity was at best very close to, if not beyond, the rearward CofG limit. With the Spitfire, all the fuel was on or near the CofG.

Just like I said in post No 8 then 😉

Was thinking about this down the pub last night,away from home and sources !!

I dont know how standard the different groups operating procedures were but at least one P51 unit (from memory again) …
Take off with main (wing) tanks selected,then first switch to aft tank – use approx half aft tank contents to bring the c of g forward a little and make the a/c handle nicer – then select drop tanks until empty if poss (in case they had to jettison for combat !) – then go back to aft fuselage tank and empty that.
As I said in post 8…the a/c was unstable in pitch until at least some of the fuel was used from the aft tank.

rgds baz

I don’t know about then but when the jets arrived RAF pilots were asked to please bring the drop tanks back except in dire emergencies owing to their expense and being in short supply. Makes you want to laugh doesn’t it?

ISTR with the Meteor NF there was a speed restriction with drop tanks because they had the nasty habit of the noses collapsing if made to go above about Mach 0.73, especially when empty.

But aerobatic monouvers i.e. combat manouvering were forbidden in Mk IX’s with fuel in the rear tank from my recollection of the pilot’s notes.

Although the P51 Pilot’s notes don’t forbid combat manouvers with a full rear tank, they DO forbid taking off with one!! 65 gallons was the max.

Also, it was noted that more than 25 galls in that tank would result in “negative control response” when pulling more than 6.75G (not sure what that means, but it sounds unpleasant). I think whereas the authors of the Spit pilot’s notes thought prohibition was best, the P51 authors just told you what would happen and let you make your own mind up.

If the drop tanks are full can the fuel be sucked out and fill the other tanks before dropping or do you just have to use it first then drop?

Can’t have been much fun in a city if you dropped the tanks from 12 thousand feet but then again neither would a bomb!

I don’t know about then but when the jets arrived RAF pilots were asked to please bring the drop tanks back except in dire emergencies owing to their expense and being in short supply. Makes you want to laugh doesn’t it?

Thats because it had more fuel on board. I believe that the P-51’s fuselage fuel was used first, and the drop tanks were jettisoned as soon as required in a combat situation..With a full fuselage tank, the Centre of Gravity was at best very close to, if not beyond, the rearward CofG limit. With the Spitfire, all the fuel was on or near the CofG.

I’d rather go to Berlin and back in a P-51, even if I did have to mix it with the Hun..:D

But aerobatic monouvers i.e. combat manouvering were forbidden in Mk IX’s with fuel in the rear tank from my recollection of the pilot’s notes.

Thats because it had more fuel on board. I believe that the P-51’s fuselage fuel was used first, and the drop tanks were jettisoned as soon as required in a combat situation..With a full fuselage tank, the Centre of Gravity was at best very close to, if not beyond, the rearward CofG limit. With the Spitfire, all the fuel was on or near the CofG.

I’d rather go to Berlin and back in a P-51, even if I did have to mix it with the Hun..:D

The Mustang’s rear tank was an adaption, just like the rear tanks etc on the Spit, and was introduced on the P51B (as per Moggy’s comment, the Mustang was never designed specifically to be a long-range aircraft). That’s why it affected the C of G so drastically when full. But it DID prove useful, as it turned out!

The Mustang simply had more room for internal fuel, both as originally designed and with the extra tankage. There was an apparent difference in design philosophies.

I’d rather go to Berlin in a P51 too – if I felt DVT coming on, I could get up and go for a walk.

If I remember correctly (in a Spit, at least) on take-off it was the main tank, before switching over to the drop-tanks. In the event of meeting enemy aircraft, it was back over to the main tanks and ditch the drag.

Pretty sure that’s how it worked for other fighters, too.

If the drop tanks are full can the fuel be sucked out and fill the other tanks before dropping or do you just have to use it first then drop?

Can’t have been much fun in a city if you dropped the tanks from 12 thousand feet but then again neither would a bomb!

It’s mostly about fuel capacity with the Mustang. The dogfighting ability of the Mustang with full fuel load in the rear fuselage and wing/drop tanks was poor. A fully fuelled Spitfire on the other hand was still better balanced.

Thats because it had more fuel on board. I believe that the P-51’s fuselage fuel was used first, and the drop tanks were jettisoned as soon as required in a combat situation..With a full fuselage tank, the Centre of Gravity was at best very close to, if not beyond, the rearward CofG limit. With the Spitfire, all the fuel was on or near the CofG.

I’d rather go to Berlin and back in a P-51, even if I did have to mix it with the Hun..:D

Now i need to check with Mr MK 12 but im sure the Mk VIII had a novel feature , the main tank was semi rigid.

Mark?

Ah! Mk VIII main fuel tanks – a source of some embarrassment to me in years past.

The main fuel for all Spitfires lies in upper and lower tanks situated between the pilot and the engine.

The lower tank for marks up to Mk IX was a single curvature riveted construction item of some 37 gallons and with a similarly constructed upper tank of 48 gallons.

Striving for more internal fuel without detriment to the C of G, for more powerful Spitfires emerging, a new lower tank was designed of double curvature welded construction fitting in all the nooks and crannies. Despite being fitted with a self sealing coating it still raised the capacity to 49 gallons. This in conjunction with a pair of 13 gallon leading edge tanks were introduced on Mks VIII and XIV. The Mk XIV Griffon Spitfire top tank had to be reduced from 48 gallons to 36 gallons to accommodate an adjacent oil tank.

I had thought that that all top fuel tanks from Mks 1-47 were similar in construction and fitted using four quick release pip pins. When former Indian Air Force Mk VIII MT719 arrived in Italy and was found to have a MK XIV small top tank fitted from a Griffon Spitfire I saw an immediate opportunity to trade a spare Mk IX top tank for this small tank for my then current Griffon project.

Disaster…and much muttering form Italy come the time to trial the new tank. It would not fit the Mk VIII. I was puzzled and immediately made arrangements to inspect Rob Lamplough’s Mk VIII under restoration to try and see what the problem was.

The Mk VIII has a unique top fuel tank arrangement. It is 47 gallons, covered in self sealing coating and just sits on top of the bottom tank with no pip pin retainers. It is retained by the closeness of its fit to adjacent metalwork and the clamping down of the external armoured cover. Semi rigid if you like.

The Italians forgave me for a genuine error, and adapted the local area so that it would fit. 🙂

Mark

Now i need to check with Mr MK 12 but im sure the Mk VIII had a novel feature , the main tank was semi rigid.

Mark?

MT818 was first MKVIII to be fitted with 75 gall fuel tank behind pilot.

Steve

Now i need to check with Mr MK 12 but im sure the Mk VIII had a novel feature , the main tank was semi rigid.

Mark?

Hi, not sure what you mean semi rigid main tank ! All main tanks were of a rigid construction. A 45 gallon torpedo shaped tank was developed & tested against a MK IX in 1943 with a slipper tank. MK IX was 10mph faster than MKVIII with streamline tank

Steve

Now i need to check with Mr MK 12 but im sure the Mk VIII had a novel feature , the main tank was semi rigid.

Mark?

Didn’t the VIII’s have them too?

The later IX’s and XVI’s had the fuselage fuel tanks too, although the aircraft was a dog with ’em filled as it put the cg well back.

I thought so.