Escort Fighter Performance Comparison

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PAT303 said:
We are not trying to make the Spit a Mustang, we are trying to extend the range of the Spit before the Mustang comes into service.
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I understand that, but I'm a little confused as to why? In 1943, the P-47 and P-38 were already in use. The big missing piece is the Mustang which has the range necessary to provide coverage at the full range of the bomber force. The failures of the USAAC bombing campaign in 1943 are due to more than just the lack of escort fighters beyond the 400 mile range arc. The small size of the force itself contributed to the high loss rates. If you take a look at the graphic I added to my earlier post and the ones below, escort fighter coverage occurred in a series of zones. The Spitfire and P-47 were well used in the 200 and 400 mile arcs (ok, slightly shorter). Beyond that required a plane with really long range and that was the P-38 and Mustang. It seems to me that trying to give a Spitfire that kind of range is, in essence, trying to make it a Mustang.
 
You are adding almost 200lbs of fuel plus the weight of the tanks. over the weight of MK VIII with the existing tanks.

Why didn't they do themselves?

Some of the early MK VIIIs had a fuel cooler added in the port wing root. It may have depended on which engine and when the plane was built.
Some planes had a gun camera in the wing root/leading edge. That seems to have bounced back and forth Between sides?

When the MK VIII was being designed (not when they were built) what was the promised power out put of the Merlin engine?
The Merlin 61 had been cleared for 60.5in, they were testing for 66.5in for emergency use.
The Merlin 45 was cleared for 60.5 but when they went for 66.5in they had to reinforce the supercharger drive.

What was the Performance they were going after?

The point of the PR Spits is that they would load them down with more fuel because they didn't expect them to perform violent maneuvers. They expected them to run at high speed and gentle maneuvers.

You can reinforce the wings to handle more weight (if you have the time to do the calculations and the change the production drawings).
 
And again I will say NO plane including the much vaunted P51 can do combat maneuvers when loaded with fuel, I have already posted evidence of this, why is it okay for the P51 to have to drop it's tanks and have no more than 35G in the rear tank before combat but it's a major issue with the Spit?. I will repeat myself again, by the time the Spit gets into combat the rear upper 41G tank will be empty because it's burnt off in warm up, taxing and climb to altitude, the bottom 33G is it's reserve, the IDENTICAL procedure used by the P51.
 
PAT303 said:
Look at the diagram you posted, there's your answer.
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Correct, that the P-47 and P-38 were already providing coverage for all but the longest missions.

To your point that you aren't trying to make the Spitfire into the Mustang, that is exactly what you are arguing for, a plane that can provide coverage for the longest missions. In other words a P-51.
 
Actually no, go back and read through the thread, what I'm asking for is a Spit with increased fuel capacity that could have been flying 300+ mile missions late 1942 early '43 before the P47-P38 were available.
 
You are adding almost 200lbs of fuel plus the weight of the tanks.

Why didn't they do themselbes?
The much vaunted P-51 was used with 55 US gallons (45 Imp) in the rear tank, plus the 180 US (150 imp) gallons in the wing tanks.

the Mustang rear tank was worth 240 miles of radius. 460 miles with the wing tanks and a pair of 75 gallon drop tanks, 700 miles with the wing tanks, the rear fuselage tank and the pair of 75 gallon drop tanks. 55 gallons was getting them 4.36 gallons (US) per mile which is perfectly reasonable for a Mustang.

The Manual for the Spit says to have no more than 30 Imp gallons in the rear tanks (post war manual does not say 33 IMP, it says 30.) the handling trial from Jan 1945 used the metal covered elevator. I would very hesitant to use that recommendation on a normal MK IX and we do know that not all MK IXs used the same elevators.

If they had wanted to they might have changed things (they sure changed the horizontal stabilizers/elevators on the Typhoon to carry 1000lb bombs.)

The Spitfire needs more fuel per mile, It will only old about 2/3rds the fuel in the rear tank for combat. It won't hold as much as the Mustang without jumping through some more hoops in the forward/wing tankage.

Now as a sort of Benchmark the Mustang without drop tanks had a radius of 150miles without the rear tank and 375 miles without drop tanks and with the rear tank filled.
269 gallons vs 334 gallons for the wing tanks (184) and drop tanks (150) for the 460 mile radius.

Warm up, take-off, and climb to 25,000ft can take a fair amount of fuel and combat allowance of 5 minutes WEP and 15 minutes military can also suck up fuel.

A Mustang with wing tanks and 75 US gallon drop tanks and no rear fuselage was carrying close to 2000lbs of fuel for take off.

A Spitfire needs to lift over 270 Imp gallons of fuel for that weight.
That is part of the problem for a long range Spitfire, you have to get the weight off the ground not on a special one off mission but for every mission for weeks on end, without breaking the planes or having a high accident rate.
 
What part of I'm not trying to make the Spitfire a P51 don't you understand?. MkXIV's did 300 mile missions with just a 90G drop tank so lets stop pretending it can't be done.
 
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PAT303 said:
What part of I'm not trying to make the Spitfire a P51 don't you understand?,
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You need a MK VIII.
It should make it back at the desired speed over 300miles after burning the 20 minutes of combat time fuel and with 30 minutes of reserve.

You just need about 116 gallons of fuel when you drop the external tank.
Play games with your tank size and a bit of juggling with the internal fuel (use 30 gallons in the rear, it will work)

The problem comes with the 300 plus.

Like trying to make it much past Cologne.

You are going to need about 1 imp gallon for every 5 miles you go in and 1 imp gallon for every 5 miles you come out.
350 mile radius is going to need and extra 20 gallons.

And with even a 90imp gallon drop tank you are over the normal max gross weight and may be restricted as to what runways you can use.
 
And again they got 1,000 mile ranges out of them as per posts a page or so back, your determined to find reasons why it couldn't be done when it clearly was.
 
The ranges depicted for the P-47s are approximately 108gal C/L ranges in the January-February timeframe. The lack of 357FG Mustang assignment (mid Feb) and inclusion of 20th FG P-38 implies very late 1943 though January. The inclusion of 358FG specifically ties from early Jan to very late January, 1944.

It was traded for 357FG to 9th AF and its last Op for 8th was end of January. That said all 9th AF P-47 FGs (and P-51/P-38) flew escort per 8th AF operational control well into May 1944.

The P-47 assignments for Penertration, Withdrawal escort legs are interchangable. The only Only) Target escort denoted by 354FG Mustangs are joined after bombing with R/V to pick up the trailing two BD.

Loger range Penetration and Withdrawal escort from Spit IX would have duplicated only the legs depicted by 355th, 359th, 78th (B) - would augment but not replace the P-47D intermediate legs.

The key to this document is that just providing ONE LR escort FG per BD (354 P-51, 20&55 P-38s) to Brunswick was possible at the time depicted.
 
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PAT303 said:
And again they got 1,000 mile ranges out of them as per posts a page or so back, your determined to find reasons why it couldn't be done when it clearly was.
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A Range is Not a Combat Radius. The Internal fuel remaining after droping external tanks, fighting for 20 minutes - then cruising at optimum (clean) from that Radius point back to base with ~ 30gal for loiter - controls your planning 'maximum'.

For comparison, the CR of a Mustang I with 170gal internal fuel - with same combat burn off and loiter asumptions, no external tanks possible, was about 120 mi. But the Range (max) for Ferry conditions was ~ 1000 miles.

Your loiter assumptions are crucial for bad weather and adverse headwinds.

Rough rule of calc for Merlin 60 series is 5mi/gal (as good as cleaner - less drag- Mustang) = 60 gallons for 300 miles at 300mph, plus 30 gal for loiter = 90 gallons internal required to make it back to base. You can complicate all you wish to account for decent leg, but trivial differences in total internal fuel required.
 
Thank you, drgondog.

The mission profile is from January 11, 1944. I was using the image to illustrate escort practices for longer range bomber operations. I recognize that as US squadrons shifted to the P-51 we would see fewer P-47/38, but I believe that we would still see multiple squadron/groups handling different outbound and return legs.

I'll see if I can find a graphic illustrating this.
 
Actually, in context of 8th AF assets for escorts, including P-47 and P-38, the number of P-38FG increased to 5 or six and the P-47D asset base expanded slightly even as they were converting from P-47D to P-51B through May, 1944. The 9th AF P-47D and P-38J forces expanded as P-51B equipped FG shed their P-47s and P-38s. That said the P-38 FG 20/55/364 didn't convert until Summer with the 470th last at end of September, 1944.

The effect was to enable 8th AF planners to plan more complex missions in which individual BD and Task Forces branched to distant targets, but because there were more P-51s and P-38s, the actual Target escort force grew from 'one' LR FG per Target group, to two+ per target group while maintaining P-47D forces for Penetration and Withdrawal of the main stream before 'branches'
 

Again I say there is nothing wrong with the Spitfire as it existed.

You keep trying to improve on something that doesn't need improvement except for development of more engine power and performance. Performance, it had in abundance, as it was designed to have. I'll have to give you good marks for persistence, but the SPitfire was just fine the way it was.
 
Thank you drgondog,

I always appreciate the quality and clarity of your responses.
 
PAT303 said:
Actually no, go back and read through the thread, what I'm asking for is a Spit with increased fuel capacity that could have been flying 300+ mile missions late 1942 early '43 before the P47-P38 were available.
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Greetings PAT303,

I appreciate your argument about extending the range of the Spitfire in 1942, but I think there are a number of factors working against you. First, I think the engineering to make a LR Spitfire is greater and more involved than adding gas tanks where possible. I'm not an aviation engineer, but from what I was able to read my guess is that you are looking at a fairly substantial redesign of parts of the aircraft to make it sounder that role. Second, in 1942 the majority of USAAC/RAF leadership didn't believe in long range escort and there was a general lack of interest in seeing it developed. The conversion of the Mustang to a Merlin engine wasn't about range, but flying higher. Range was a bonus. Also, it was the US that was committed to daylight bombing not the British and the US was bringing its own fighter aircraft, the P-47 and P-38. We can debate the relative merits of each of these, but in the P-47 the US had the preeminent high altitude fighter of the war and the P-38 had the longest legs until the P-51. It's unlikely that the US would have been advocating for a long range Spitfire. Lastly, the RAF needed every fighter it could get and it would have been a drain on the RAF to redirect fighter production to an aircraft designed around long range escort. That production capacity would have to come from the US and that production capacity was dedicated to the P-47, P-38, and later P-51.
 
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GregP said:
You keep trying to improve on something that doesn't need improvement
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So you would have it fight the entire war with nothing more than an 85G tank?, you may as well not bother building them if that's the case.
 
Well, they did go to 120-123 gallons when they had the chance, but that was one factory while an other factory stayed with 85 and 96 gallon set up.

When they went to the Griffon engine even on the Mk 21 and MK 22 they stayed with 120 gal of internal fuel despite increasing gross weight by 1300-1400lbs.
They went for more performance (a bigger engine) and more firepower (four 20mm guns) rather than range.

Had they had more production facilities they might have have gone for a long range version with extra fuel instead of the bigger engine.

One reason the Spitfire has trouble being turned into a long range fighter (IMHO) is that a Merlin 60 series airplane was a just under 8000lb airplane and that includes a belly tank of some sort. The P-51D went 9600lbs without drop tanks and without the rear tank. The rear tank brought it to 1020lbs and a pair of 75 SU G drop tanks brought it over 11200lbs.

The P-51D was about 1 ton heavier when clean. You can do better than a MK IX, they did it with the MK VIII.
The question we have been arguing over for over 12 pages is, while you can't equal the Mustang, how close can you get with a plane that was around 77% as heavy when clean (neither using rear tanks)?
Both are using the same engine for all practical purposes.

The Mustang started larger/heavier and was easier to add weight to especially considering that the American fighter was built to different standards.

As you increase the "overload" the Mustang can absorb more overload simply because it was larger/heavier to begin with.

The MK VIIIs went to NA/Italy and the Far east because that is where they needed the extra range.
Had they needed the extra range over Europe more in early/mid 1943 they might have changed their priorities or changed production.
 
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