Spitfire range cruise engine settings?

[Jabberwock]

Does anyone have typical long-range cruise engine settings for the Spitfire Mk V and Mk IX F (Merlin 61) and IX LF (Merlin 66) for the ETO?

I've got their respective manuals, but they don't list what actual boost and rpm settings range cruise was performed at.

The Darwin Spitfires site gives 1600 rpm and +0 lbs boost, giving 32 gal p/h and a 200 mph TAS for a Mk Vc with Volkes filter. This seem a little low for the ETO though. I understand that the Mk V more typically cruised at 220-240 mph with correspondingly higer engine settings.

The reason I'm asking is that I've finally gotten some spare time and I'm trying to work out realistic (if theoretical) combat radii for a long-range Spitfire with 150 imperial gallons internal and a 50 gal external drop tank.

My back of the envelope calculations suggest that even with all the RAF's usual caveats - 10 minutes for warm up/taxi, 5 minutes at full climb power, 15 minutes fast cruise, 5 minutes full combat power and a 20% reserve - a properly modified Spitfire Mk V could have a combat radius of 400 miles. Enough to escort BC to Hamburg and back.

[Zimme83]

I have read somewere that problem was that in case of enemy contact it took too long to accelerate to top speed so it was not recommended to fly at max cruise setting over enemy territory.

[Karnak]

The USAAF and RAF both modified a Spitfire Mk IX to increase its fuel load to allow to Berlin and back escorting, but then the P-51B happened and long range Spitfires weren't needed.

[PR3D4TOR]

PR Spits regularly flew over Germany.

[Zimme83]

PR spits also had their guns replaced with leading edge fuel tanks and had an extra fuel tank in the fuselage. (+drop tanks)

But the question was how long the spits could fly and fight w 150+50 gallons of fuel...

For combat purposes u have to expect that a lot of the flight has to be done at nearly full trottle, flying around over enemy territory on max cruise is unwise. So what u have to do is estimate how much of the flight that can be done at max cruise setting and how long time u need to fly at a more "combat ready" power setting.

[Chalenge]

For the Spit IX (both versions) the Economical Flying settings are given on pages 33, 34, and 35 of the manual.

I believe Zeno has the manuals online.

[MiloMorai]

One can't fly any further than the range for internal fuel to get home.

Jabber, iirc, there is a graphic at Spit Performance for the MkVIII that might be of help to you.

[Jabberwock]

The USAAF and RAF both modified a Spitfire Mk IX to increase its fuel load to allow to Berlin and back escorting, but then the P-51B happened and long range Spitfires weren't needed.

This is a theoretical exercise. I'm proposing a small bit of alternative history.

The basic premise is something along the lines of some bright spark in the Air Ministry recognising in very early 1941 that the PR Type G - an armed Mk IA with a 29 gal rear fuselage tank - meant that a long-range Spitfire was a realistic proposition, and then shouting down the opposition from Portal and Douglas in April/May/June 1941 and actually developing the bloody thing.

This leads the RAF to develop the Spitfire as a long range fighter. The alternative proposal I've got in mind is roughly this:

LR Type 1: 85 gal front tanks + 29 gal rear tanks for 114 gal - in service by June/July 1941 - radius of ~220-230 miles
LR Type 2: 96 gal front tanks + 29 gal rear tanks for 125 gal - in service by September/October 1941 - radius of ~230-250 miles
LR Type 3: 96 gal front tanks + 29 gal rear tanks + 20 gal in wing tanks, for 145 gal - in service by April/May 1942 - radius of ~ 280-300 miles
LR Type 4: 96 gal front tanks + 29 gal rear tanks + 26 gal in wing tanks, for 151 gal  in service by June/July 1942 - radius of  ~ 290-310 miles

Add various drop tanks - 30, 45, 90 gal slipper tanks, or torpedo/blimb style 44/45/50/54 gal drop tanks - to add more range as these become available.

[bozon]

The spit XIII had increased internal fuel load. Wasn't that sufficient for the ETO?

[Jabberwock]

The spit XIII had increased internal fuel load. Wasn't that sufficient for the ETO?

Mk VII had around 120 gallons and was used in the ETO, but only produced in limited numbers and wasn't available until early to mid 1943.
Mk VIII had around 120-124 gallons, but was mostly sent to the MTO, CBI and Pacific and didn't get into combat until June 1943

Maximum combat radius with a 90 gallon tank was about 400 miles - but using the 90 gal slipper tank was rare. As I understand it, Spitfires tended to cruise faster in the crowded airspace of the ETO, cutting range.

What I'm proposing is that some of the fuel mods that made it into the Mk VII/VIII - the larger nose tanks and the wing tanks - as well as the 29 gal rear tank make it into a Merlin 45 powered Spitfire, with fuel capacity progressively increased from mid 1941 to late 1942.

[PR3D4TOR]

[Zimme83]

Edit: Mk XIV combat radius was 400 miles so i would not be unrealistic to have earlier models modified to have that range but question is how it would have affected performance.