1. #11
    Originally posted by Blutarski2004:
    The enlarged internal forward tank, the wing tanks, and the rear internal tanks were all introduced into the production line over the course of the war.
    Onto selected Marks, yes. Most had 85 gallons internal capacity through the war as the documents show.

    Mk VII (140 built), VIII (1658), XII (100 built) and XIV (957) had wing tanks AND enlarged for. Due to the increased consumption of the Griffon, only the VII and VIII (~1800 aircraft) could actually take advantage of it in range and endurance.

    "Some aircraft, generally those with rear-view fuselage" ie. very late 1944/45 production XVIs had enlarged forward tank by 10 gallon for 95 gallon capacity instead of the usual 85 gallon capacity.

    "Later IX and all XVI aircraft" had 75/66 gallon rear tank. Flight limitations were excessive though, and those tanks "were only filled for special operations at the discretion of the appropiate Area commander"

    The vast majority, ie. the main Marks Mk V and IX) had only 85 gallons internal and 434 miles range (IXLF) on it on economic cruise, or 240 miles range at maximum weak mixture cruise.

    http://www.spitfireperformance.com/s...e-lfix-ads.jpg

    If 5 minutes are spent at combat rating, this being reduced to 352 miles at economic cruise, or to 195 miles on maximum weak mixture cruise. This latter represented the furthest distance most Spitfires could realistically venture from it's base and return on internal fuel capacity, after jettisoning the droptank before combat, unless it wanted to fly over German held territory for 1+ hours at a mere 220 mph (ie. economic cruise), and risking being caught by an over-ambitious pursuing Stuka.

    The 195 miles, which would include 5 minutes at Combat, and withdrawal at 328 mph apprx. equals the distance from London to Paris or Normandy.

    The Mk VII/VIII of course was much longer range, hence it's primarly deployment to the Med and the Pacific, where operational distances absolutely demanded it.
    Share this post

  2. #12
    Blutarski2004's Avatar Banned
    Join Date
    Jan 2004
    Posts
    3,020
    Originally posted by Kurfurst__:
    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blutarski2004:
    The enlarged internal forward tank, the wing tanks, and the rear internal tanks were all introduced into the production line over the course of the war.
    Onto selected Marks, yes. Most had 85 gallons internal capacity through the war as the documents show.

    Mk VII (140 built), VIII (1658), XII (100 built) and XIV (957) had wing tanks AND enlarged for. Due to the increased consumption of the Griffon, only the VII and VIII (~1800 aircraft) could actually take advantage of it in range and endurance.

    "Some aircraft, generally those with rear-view fuselage" ie. very late 1944/45 production XVIs had enlarged forward tank by 10 gallon for 95 gallon capacity instead of the usual 85 gallon capacity.

    "Later IX and all XVI aircraft" had 75/66 gallon rear tank. Flight limitations were excessive though, and those tanks "were only filled for special operations at the discretion of the appropiate Area commander"

    The vast majority, ie. the main Marks Mk V and IX) had only 85 gallons internal and 434 miles range (IXLF) on it on economic cruise, or 240 miles range at maximum weak mixture cruise.

    http://www.spitfireperformance.com/s...e-lfix-ads.jpg

    If 5 minutes are spent at combat rating, this being reduced to 352 miles at economic cruise, or to 195 miles on maximum weak mixture cruise. This latter represented the furthest distance most Spitfires could realistically venture from it's base and return on internal fuel capacity, after jettisoning the droptank before combat, unless it wanted to fly over German held territory for 1+ hours at a mere 220 mph (ie. economic cruise), and risking being caught by an over-ambitious pursuing Stuka.

    The 195 miles, which would include 5 minutes at Combat, and withdrawal at 328 mph apprx. equals the distance from London to Paris or Normandy.

    The Mk VII/VIII of course was much longer range, hence it's primarly deployment to the Med and the Pacific, where operational distances absolutely demanded it. </div></BLOCKQUOTE>


    ..... Nice, reasonable, well supported post. I'm cool with everyrhing you say. A few comments -


    (1) The references which you posted have changed my position from uncertain to agreement with your statement that the majority of Spits still had 85gal internal tank stowage even into the later war years.


    (2) I ran the numbers on your Spit IX document attachment to get ranges under both cruise speed, allowing for 15 minute at combat power -

    -----------------87 gal---+45gal/dt---+90gal/dt
    220mph cruise----188 m------439 m-------654 m
    328mph cruise----105 m------252 m-------385 m

    A Spitfire on 85 gal internal tank only is, without question, a point interceptor.

    Adding a 45gal drop tank permit the lpane to fight over coastal France.

    Fitted with a 90gal drop tank, the Spitfire now has legitimate legs to reach and fight over western Germany and the Swiss frontier. The logic here is that the plane will not being flying at 328mph from the moment it lifts off. some portion(s) of the flight will be over friendly or undefended territory, or perhaps over water. This implies that the true operational range likely lies somewhere between that obtained at fast cruise and that economical cruise. Assuming use of a 90gal drop tank, this suggests to me a real-world operational range of 400-450 m .... a little more than fast cruise range, but less than economical cruise range.

    - - -

    All that having been said, it's worth remembering that the above ranges are based upon still air, standard atmosphere, and the assumption that no enemy attack will cause a premature jettison of the external tank.

    - - -

    (3) You wrote - "...unless it wanted to fly over German held territory for 1+ hours at a mere 220 mph (ie. economic cruise), and risking being caught by an over-ambitious pursuing Stuka."

    ..... Now THAT's legitimately funny.
    Share this post

  3. #13
    An imperial gallon is equal to 1.2 US gallons.

    So:

    85 imp gal = 102 US gal (Mk I,II,V,IX)
    95 imp gal = 114 US gal (Mk IX, XVI)
    120 imp gal = 144 Imp gal (Mk VIII, XIV, XXI)
    128 imp gal = 153.5 imp gal (Mk VII)


    The most curious thing is why the Air Ministry ignored the recommendations of the A&AEE and Geoffry Quill and never introduced the 29 gallon rear tank and the enlarged lower foward tank as standard from the Mk V, which would of increased total tankage from 85 to 122 gallons. The majority of the rear tank would of been used on warm-up, taxi and climb, and wouldn't of affected combat performance, unless they are fighting as soon as they took off.

    The problem is that the 'interim' designs - Mk V, Mk IX and Mk XIV - always seemed to get produced over the intended mainline designs - Mk III, Mk VIII and Mk XXI - for a variety of reasons.

    The foward tank mod could be done on the production line, while the additional rear tank seems to be (at least on the Mk Vs used for the Malta ferry flights) and 'after market' addition.

    This would of given the "standard" Spitfire an 800 mile combat radius with a 90 gal external tank.

    The largest mistake the British made with Spitfire was not introducing Mk III production in late 1940 as originally intended (1,000 Mk IIIs ordered in October 1940). They then spent the next 3 years incrementally introducing some of the design features of the Mk III (strengthened fuselage, revised alierons, clipped wings, Hispano mounting, retractable tailwheel, larger foward tanks) into the production line.
    Share this post

  4. #14
    Blutarski2004's Avatar Banned
    Join Date
    Jan 2004
    Posts
    3,020
    Originally posted by hop2002:

    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">well over 2,000 miles and a consumption ... of nine miles per gallon"
    Do you have an exact quote? That fits very nicely with the Australian test of the Spitfire VIII with Merlin 66, which achieved 10 mpg at 20,000 ft.

    The reason I ask for the quote is that a certain person maintains the Spitfire couldn't do better than about 6.5 mpg... </div></BLOCKQUOTE>



    ..... Hop, the exact wording is as follows -

    "The result was an unarmed aircraft capable of Spitfire speed with a range of well over 2,000 miles and a consumption in propelling 3-1/2 tons through the air of nine miles per gallon."
    Share this post

  5. #15
    Blutarski2004's Avatar Banned
    Join Date
    Jan 2004
    Posts
    3,020
    Originally posted by hop2002:
    Yes, those are imperial gallons.

    Only the early rear fuselage tanks were 33 gallons. The later ones, fitted to all Spitfire XVIs and many late mark IXs and XIVs, were of up to 75 gallons (less for those aircraft with cut down rear fuselage)

    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">well over 2,000 miles and a consumption ... of nine miles per gallon"
    Do you have an exact quote? That fits very nicely with the Australian test of the Spitfire VIII with Merlin 66, which achieved 10 mpg at 20,000 ft.

    The reason I ask for the quote is that a certain person maintains the Spitfire couldn't do better than about 6.5 mpg... </div></BLOCKQUOTE>
    Share this post

  6. #16
    Originally posted by Xiolablu3:
    SOme good info here, thanks!

    Some serious range in those Spit IX's with drop tanks, 1350 miles!

    Basically it would be quite obvious that the plane would be unstable when heavily loaded with fuel and drop tanks. You should always burn off the fuel in the drop tanks and rear tank first. Using them for take off and flight to target. P51 was the same when rear tank was full I believe?

    SPitfire VIII , 740 miles on internal tankge only....
    The Spitfire Mk.VIII had 2x 48 Imp. Gal. fuel tanks as main fuel tanks. In addition, it had 2x 14 IG fuel tanks in the wings. Max. int. fuel range was about 660 - 680 incliding warmup and other factors. May seem short, but not bad for a Spitfire. Gotta love those rear fuel tanks (1x 41 IG tank; 1x 34 IG tank) lol. With this mod, (MOD. 1335) those Mustang pilots couldnt laugh at the spitfire anymore. too bad it was in 1945 when it was implemented.
    Share this post

  7. #17
    hop2002's Avatar Senior Member
    Join Date
    Jun 2002
    Posts
    1,210
    .... Hop, the exact wording is as follows -

    "The result was an unarmed aircraft capable of Spitfire speed with a range of well over 2,000 miles and a consumption in propelling 3-1/2 tons through the air of nine miles per gallon."
    Thanks. That fits very well with this:


    The references which you posted have changed my position from uncertain to agreement with your statement that the majority of Spits still had 85gal internal tank stowage even into the later war years.
    Every Spitfire VII had extra fuel, usually 121 gallons. 140 built

    Every Spitfire VIII had extra fuel, usually a minimum of 123 or so gallons. 1,658 built

    Every Spitfire XIV built had extra fuel, usually 110 gallons 957 built

    Every Spitfire XVI had extra fuel. All carried at least the rear fuselage tank of up to 75 gallons, many had the enlarged forward tank as well. 1054 built

    The rear fuselage tanks were also fitted to late mark IXs, as was the enlarged forward tank.

    Note that Isegrim's highlighting of the prohibition of the use of rear tanks comes from the post war Spitfire manual. Post war the RAF also removed rear tanks from its Mustangs.

    During the war, the Spitfires had slightly less restrictions on their rear tanks than RAF Mustangs. The Spitfire IX manual notes:

    "When the rear fuselage tanks are full there is a very marked reduction in longitudinal stability, the aircraft tightens in turns at all altitudes and, in this condition, is restricted to straight flying, and only gentle manoeuvres; accurate trimming is not possible and instrument flying should be avoided whenever possible."

    The RAF Mustang III manual:
    "Stability."”Except when earning full fuselage tank, the aircraft is stable longitudinally, laterally, and dircc-tionally. When the fuselage tank is full, the aircraft is longitudinally unstable in all conditions of flight, and tends to tighten up in turns; until at least 40 Imp. gallons (48 U.S. gallons} have been consumed from the fuselage tank, no manoeuvres other than very gentle turns should be attempted."

    Regarding aerobatics the manuals note:

    Spitfire
    "Acrobatics are not permitted when carrying any external stores (except the 30-gallon " blister " drop tank) nor when the rear fuselage tanks contain more than 30 gallons of fuel, and are not recommended when the rear fuselage tanks contain any fuel."

    Mustang
    "Flick manoeuvres arc not permitted. When carrying bombs or drop tanks, or with fuel in fuselage tank, aerobatics are prohibited."

    So the RAF prohibited aerobatics in the Mustang with any fuel in the rear tank, but allowed them in the Spitfire with up to 30 gallons in the rear tank.

    SPitfire VIII , 740 miles on internal tankge only.
    That appears to be for the Merlin 61 engined version. The Merlin 61 was the last of the major marks to have the old SU carb, the later ones like the Merlin 66 had the Bendix Stromberg carb, and as the Australian test shows, and Blutarski's quote confirms, the later engines were capable of much better consumption.

    The most curious thing is why the Air Ministry ignored the recommendations of the A&AEE and Geoffry Quill and never introduced the 29 gallon rear tank and the enlarged lower foward tank as standard from the Mk V, which would of increased total tankage from 85 to 122 gallons.
    I think it was simply they felt they didn't need it for normal use. There were no technical problems, and the cost of the slightly larger forward tank would have been little different.

    When they did have a requirement for it, like in the Spitfire VIII for overseas, or the recce Spits, it got fitted.

    The easy otpions for increasing the range were:

    enlarged forward tank. Increase capacity by 10 gallons in Merlin versions

    Wing tanks. Adds up to 36 gallons, although 26 - 28 was more common

    Rear fuselage tank. Adds 75 gallons in aircraft with normal fuselage.

    Each of these options was common, fitted to more than 1,000 Spitfires. Taken together they would increase the internal fuel load to a minimum of 196 gallons.
    Share this post

  8. #18
    The usual old stuff.

    Basically Hop doesn't like the RAF's data, so he relies the RAAF data, which is higher. I wouldn't say it's better, since the the RAAF is giving it's figures for entirely different conditions.

    As for the arguement, Hop claims that the Merlin 61 engined 'with the old SU fuel carb' had much worser comsumption than the 'new Bendix Stormberg carb. Needless to say, Hop is the only one who'd claim (rather, make up) the story about the 'much improved' Bendix Stormberg, which is not supported by any engine or aircraft literature, so I must wonder where it originates from (answer, Hop made it up).
    Most likely the new carburattor maker had negligable relevance in performance or consumption.Similiarly the 'post war manual' excuse is just smokescreen, as the only manual publicly available is the latest, post war ones. In any case I can post war time testing with rear tanks and they say the same about the effect on handling.

    If anybody wants to cross check if there was any improvement in fuel consumption between the Merlin 61 and Merlin 66 which at least according to Hop had allegadly, not 5, not 10%, but 50% better fuel consumption (MEGAROFLOL), please check the range figures given by the RAF for Merlin 61 and 66 Spitfires.

    If the latter engine would have better consumption, that would certainly show up in the range figures, ie. the Merlin 66 engined fighter would have listed with far greater range. It isn't the case.

    The RAF range figures are consistent, however :

    Mk IXF (Merlin 61) : 450 miles / 85 gallons = 5,29 mpg on avarage
    Mk IXLF (Merlin 66) : 434 miles / 85 gallons = 5,10 mpg on avarage
    Mk XVI (Merlin 266) : 434 miles / 85 gallons = 5,10 mpg on avarage
    Mk VIII (Merlin 66) : 740 miles / 120 gals. = 6.16 mpg on avarage

    In fact the RAF lists the IXLF at 434 miles vs. 450 miles. The Merlin 61 'old SU carburattor' has actually better range.

    The mileage figures are consistent between the same engines, in fact the higher-powered Merlin 66 seems to be a bit worse, the aerodynamically cleaner Mk VIII is better, which is probably down to it's better drag, and even more so that range figures would include fuel spent on climbing (poor mileage) and economic level cruise (good milage); the Mk VIII's avarage mileage is obivously a result of a higher proportion of economic cruise, since the same amount of fuel is spent on climb in both cases, but the VIII has more fuel overall.

    <BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">SPitfire VIII, 740 miles on internal tankge only.
    That appears to be for the Merlin 61 engined version. The Merlin 61 was the last of the major marks to have the old SU carb, the later ones like the Merlin 66 had the Bendix Stromberg carb, and as the Australian test shows, and Blutarski's quote confirms, the later engines were capable of much better consumption. </div></BLOCKQUOTE>

    Range with the Merlin 66 had the Bendix Stromberg carb, from the same Australian archives - 740 miles it seems :





    Basically one can choose between the opinion of a lone Spitfire partisan who never respected the facts and simply strives for the highest figures or simply take what the RAF's documentation says. I wouldn't even say the RAAF's tested figures are wrong, they just probably refer to some different condition or to something different. Simple thing is that if the Spitfire VIII would realistically capable of 10 mpg it would be listed at some 1100-1200 miles range instead of 740, and the Allies would have never needed the Mustang. Comparison of the milage achieved on armed fighter versions with the unarmed, cleaned up (cannon-less, polished, streamlined canopy and shallower radiators) 20-30 mph faster PR versions is really reaching. It's perfectly reasonable that those cleaned up planes using high altitude engines and operating in thin air would reach up to 9 mpg vs. the ca 6.76 measured on fighters. Anyway, I am sure this is not the last time Hop will sell this story again, as said, for the 6 years I know him, he argues exactly the same over and over again.

    I think we shouldn't bother.
    Share this post

  9. #19
    HellToupee's Avatar Senior Member
    Join Date
    Feb 2002
    Posts
    1,255
    dont they factor climb/combat/reserve in their ranges.


    Basically Hop doesn't like the RAF's data, so he relies the RAAF data, which is higher.
    dont you do that with the g2 and finnish tests?

    I wouldn't say it's better, since the the RAAF is giving it's figures for entirely different conditions.
    what conditions are differnt to invalidate it?

    Got any similar charts that display mpg and have the engine and altitude settings to achive it.
    Share this post

  10. #20
    Xiolablu3's Avatar Senior Member
    Join Date
    Jan 2003
    Posts
    8,755
    Good call on the Finnish 109/Aussie Spit tests, Wolf. Totally true of course. If someone is going to use the high figures from the FInns for the 109, then they should also use the high figures for the SPitfire and other planes from whereever they come from.

    We must remember to cherry pick these Aussie tests when Kurfie comes out with his top end tests of the Bf109.


    Whether its 'the usual' stuff or not, its very interesting to those who have not seen it before.

    Anyway..

    The RAF didnt seem to see the SPitfires range as a problem during WW2, looking back now and comparing it with the P51 and such the range looks short, but when you are doing fighter sweeps, you are usually over the front lines, or just behind, not reaching deep into Germany. During 1940-43 when Germany was still strong it would have been extremly dangerous to go very deep behind the German lines, it only really became necesary with the US daylight bombing campaign.

    The US used the Mustang for bomber escort work, but it wasnt planned for this, its just how it happened. It was actually ordered by the RAF and used by the USAAF afterwards. The P51 was capable of extreme range and it was lucky it came along when it did as it slid right into that role. SO saying that 'if the Spitfire was capable of long range then the Allies would never have NEEDED the P51 is a moot point. A fully armed SPitfire could never have escorted bombers from London to berlin and back even with the ranges listed above. It could however do certain legs of the journey and escort bombers a far way behind the lines. As the Germans were pushed back through France and RAF bases opened up there, then Spits would have ranged far into Germany.

    Most of the hard fighting on the West front between 1939-44 would have taken place either over England, the channel and France as the Brits went slowly onto the offensive as the Luftwaffe got pushed back and became weaker. Gotta remember that the channel is only 20 miles wide so planes ranging deep into France and the border of Germany was very sufficient for most of the War. Even a Spit with no extra tanks reaching 250 miles from a Southern airfield is going to reach far into France and into the German lines, easily reaching the main German airfields in France when it was occupied 1940-44.

    Had range been such a major issue to the RAF in Britain, then more effort would have been put in to making more long range SPits like the MkVIII and the others mentioned above.

    RAnge was seen as very important in the Med and the desert, not in Britain/France/Germany (except of course for the US daylight heavy bomber escort), which is why all the Spitfire VIIIs were sent abroad to the Aussies, Italy, MAlta, the Med and the Desert.
    Share this post