A Critical Analysis of the RAF Air Superiority Campaign in India, Burma and Malaya in 1941-45

[RCAFson]

Lets see a mission plan instead of theoretical.

I've ready presented a rough outlinebut here it is again:
At start.
200IG internal fuel, 45IG ST, 2 x 50IG DTs,

50IG of internal fuel for TO, cruise climb to reach the coast at 30K ft.
Cruise for ~1.5 hrs at 300mpg at Max weak mixture = 100IG in DT's to reach rendezvous point.
Rejoin bombers with 150IG internal fuel and 45IG ST.
Expend 70-95IG covering bombers
Return to UK when fuel reached 130-100IG remaining.

Here's map of the Schweinfurt raid:

And these fuel numbers match up with Spitfire Data cards and seem tp present no problems with flying the mission.

 

[BiffF15]

Dan,

Do you have any sources used to get to your opinion?

Cheers,
Biff

Dan,

Do you have more than one guys opinion that the Merlin was not a good/great engine? That is the first negative comments I've seen regarding the Merlin. I have heard that the parts count was higher, but there was another stage to the supercharger which means the associated parts count will increase as well. Also one data point does not a trend make.

Would you want to be in an Allison powered BCD Mustang deep over Germany? With only a single stage of SC. I would not due to the large power disadvantage I would have against my adversaries. Maybe the Merlin isn't as reliable as the Allison, however it was good enough. And that's a big maybe. Also realize that the more power an engine makes the greater stress it's under and the potential for less reliability goes hand in hand with that. Don't get me wrong, I think the Allison was a good/great engine too. Modular, easy to overhaul and work on, able to reverse rotation easily and in mass production. It just didn't offer the power needed to make the Mustang competitive / more than competitive with expected threats.

Also realize there is a difference between a pilots point of view vice the MX officer / logistics guy.

The pilot wants more power and longevity. He is the guy whose life is on the line over bad guy land and who has the most to lose.

The MX officer wants easy to work on and reliable. He is the guy who spends all night turning / preparing the plane for tomorrows sortie/sorties.

The logistician wants lots of spares and a reliable shipping method. All US F15s have Pratt engines. They consist of three major sections, front middle and back for the purpose of this discussion. Should one portion get damaged you can pull the motor, swap the appropriate section out, and put it back in the jet. A logisticians dream. The equivalent GE engine is one big motor. Should any internal part be damaged, out the motor comes and back to the nearest overhaul/ repair base (not usually located in theater). You need more engines to support this set up, more lift to move engines, more people to support this endeavor.

Big picture the GE engine is lighter and makes more thrust. Which one would you want?

Cheers,
Biff

 

[XBe02Drvr]

Should one portion get damaged you can pull the motor, swap the appropriate section out, and put it back in the jet. A logisticians dream. The equivalent GE engine is one big motor. Should any internal part be damaged, out the motor comes and back to the nearest overhaul/ repair base

The eternal dichotomy of aviation: robustitude, versatility, and maintainability vs power to weight ratio and fuel efficiency. In WW1 it was liquid cooled V8s vs air cooled rotaries, then next war, it was Allison vs Merlin then in early jet days, centrifugal vs axial flow. In general aviation, Lycoming vs Continental, and in the commuters, Pratt vs Garrett. And then when jet airliners got big, all of a sudden customers could get a smorgasbord of engine options on their Boeing, Lockheed, or McD. Having been a maintainer and a pilot, but never a bean counter, it's pretty obvious where my prejudices lie.
Cheers,
Wes

 

[Shortround6]

The Allison could go to 1500 hours before rebuild.
Few Merlin got past 500 hrs...

would love to know where those numbers came from.
The Allison did reach around 1000 hours in some P-40s used as trainers in the US, Good runways, good maintenance, no flying in crappy conditions like sand storms. Little or no operation at WEP power settings, in fact in some cases little or no operation at military power.

Merlins were rated at 500 hours in 1945 when used in transports compared to 360 hours in 1945 when used in fighters.

I wish people would not confuse the time expired life with some sort of guarantee that the engine was supposed to last that long.
Engine life figures are the number of hours an engine was allowed to run before it was pulled for overhaul regardless of the condition it was in when reached that time limit.
The US training command was violating the Allison time limit.

Widen the flight performance as they were still using and shipping the P40 to combat theaters to end of war.
Would have even been a better ground attack fighter than the P47.

The last P-40 built ( A P-40N-40) was completed on Nov 30th 1944. It was part of a contract issued on June 30th of 1944 for 1000 aircraft which was cut to 220 aircraft well before Nov 1944.

There were 13788 P-40s built according to one source, of those 11,995 went to the US Army for it's use or for lend lease. 5482 went ot lend lease which leaves the US Army with 6,503 P-40s of all types. Yes the P-40 was used up until the end of the war but in rapidly decreasing numbers. Units were converting to newer airplanes as fast as the supply of new aircraft would allow.

The idea that the P-40Q would have been better at ground attack than a P-47 is pretty far out there, some people condemn the P-47 as a ground attack plane because it was lugging around a turbo-charger and intercooler that it didn't need for ground attack.
The P-40Q was lugging around a hydraulically driven auxiliary supercharger anda water injection system that was not needed for ground attack.

(sarcasm) I KNOW, lets take out the aux supercharger and water injection, that will lighten up the plane so we can stick in two more .50 cal guns for ground strafing bring the total to six, then we can extend the wings for more wing area to handle high weight-high temperature take offs and help with pull outs from dives, then we can.............................wait a minute this is beginning to sound like a late model P-40N (end sarcasm)

 

[michael rauls]

BULLCRAP!! Clearly you've never flown a plane loaded out of limits aft. It wallows like a wounded pig, over reacts to every control input, won't trim up for level flight, and has to be "herded" by hand every inch of the way. And that was in a normally highly stable commuter airliner with 400 pounds of illegal undocumented cargo in the aft baggage compartment, for which the captain and I almost lost our licenses. Now try that in an at best neutrally stable overloaded fighter plane climbing in formation through the soupy skies over the UK, and you've got a recipe for disaster. There's a reason they didn't do it back then.
DON'T LET PAT303 ANYWHERE NEAR A REAL AIRPLANE!!

As an aside, I've never flown a plane and I'm sure that is much more difficult but aside from the trim that is exactly how an overloaded 18 wheeler handles.

 

[PAT303]

No, only used on Vc Trop in late 42.

The argument is the Spit could not fly escort missions, my argument is just because it did doesn't mean it couldn't. Sydney Cotton had no issues fitting extra fuel in his PR spits like the under seat 20G tank, if the Spit was given to men like him, men that found solutions to problems instead of excuses the Spit could have had modifications to greatly improve it's range, the Mk111 was a good example of what improvements could have been done to the basic design, but there was a war to be won.

 

[PAT303]

BULLCRAP!! Clearly you've never flown a plane loaded out of limits aft. It wallows like a wounded pig, over reacts to every control input, won't trim up for level flight, and has to be "herded" by hand every inch of the way. And that was in a normally highly stable commuter airliner with 400 pounds of illegal undocumented cargo in the aft baggage compartment, for which the captain and I almost lost our licenses. Now try that in an at best neutrally stable overloaded fighter plane climbing in formation through the soupy skies over the UK, and you've got a recipe for disaster. There's a reason they didn't do it back then.
DON'T LET PAT303 ANYWHERE NEAR A REAL AIRPLANE!!

So the Mustang with full wing tanks, rear aux and a pair of droppers handled beautifully did it?, spare us the dramatics because it was done, I've posted the link twice.

 

[PAT303]

As an aside, I've never flown a plane and I'm sure that is much more difficult but aside from the trim that is exactly how an overloaded 18 wheeler handles.

As a former HV fitter and driver I agree, not the best idea but at least in a plane by the time you get settled at 25,000ft the rear upper tank is gone and as per this report http://www.spitfireperformance.com/Spitfire_IX_ML-186_Handling.pdf the handling is back to normal. I'm not arguing about whether the Spit could be an escort plane, it could never be a P51 but it's range could be easily tripled with the technology Supermarine had at the time.

 

[PAT303]

I'm aware of that; so, I presume, is p303. That's why I took his statement to advocate another tank even further aft. It was the comment: "Who cares where the extra fuel is, there's plenty of room in the rear fuselage" that set me off. Fallout from many a battle with UPS drivers when I had to refuse additional packages in my freighter, even though there was visible empty space in the way-back fuselage compartment. Non-pilots seem to have a hard time comprehending CG as an item of worship.
Cheers,
Wes

You jumped to conclusions, when I said it doesn't matter where it is I didn't mean way back aft or the tail.

 

[XBe02Drvr]

You jumped to conclusions, when I said it doesn't matter where it is I didn't mean way back aft or the tail.

Explanation accepted. My apologies for the sharp retort. Your frivolous sounding comment hit a sore spot, given the experiences I've had and the funerals I've been to. Are we good now?
Cheers,
Wes

 

[DerAdlerIstGelandet]

Widen the flight performance as they were still using and shipping the P40 to combat theaters to end of war.
Would have even been a better ground attack fighter than the P47.

 

[PAT303]

Explanation accepted. My apologies for the sharp retort. Your frivolous sounding comment hit a sore spot, given the experiences I've had and the funerals I've been to. Are we good now?
Cheers,
Wes

No worries mate, if we were having this discussion standing around a BBQ drinking beer there'd be no need for explanations or apologies.

 

[XBe02Drvr]

standing around a BBQ drinking beer

Your on, man! You find your way to Vermont, and I'll find the beef and brew. Vermont has more breweries per capita than any other state in the US. Something for every taste you can imagine.
Cheers,
Wes

 

[Kevin J]

The argument is the Spit could not fly escort missions, my argument is just because it did doesn't mean it couldn't. Sydney Cotton had no issues fitting extra fuel in his PR spits like the under seat 20G tank, if the Spit was given to men like him, men that found solutions to problems instead of excuses the Spit could have had modifications to greatly improve it's range, the Mk111 was a good example of what improvements could have been done to the basic design, but there was a war to be won.

The overseas Spitfire VIII version did fly long missions, over the seas. The Spitfire VII was a limited production run, 141 only, it too flew an over the seas mission. The debate here is about how far into Europe you can safely go. You being the optimist.
What we have to play with in 1943/44 is the Spitfire IX. So 85 IG main, 29 rear ferry tank, 90 IG ST total 204 IG so almost the same as the Mustang with rear fuselage tank total 210 IG. So it should be good for 300-325 mile radius over NW Europe. We know that the Spitfire Vc could carry 284 IG with the cannons removed. We know that it can carry 2 X 250 lb bombs under the wings if you clip them. We know that the Spitfire XVIII could carry 266 safely with full armament. So maybe 2 X 30 IG drop tanks under clipped wing LF IX adding another 85 miles to the combat radius, making max effective radius of 385/410 miles. Total fuel 264 IG.

Between Nov 43 and Jan 44, 9 squadrons equipped with the Halifax B.III, which cruised at 20k ft powered by Hercules radials,. So this would be your bomber to escort all the way to the Ruhr in daylight.

 

[DerAdlerIstGelandet]

lol

Just saw what the picture in my post said. Not what I was trying to post in response to Dan's P-40 vs. P-47 ground attack post.

 

[Shortround6]

As a former HV fitter and driver I agree, not the best idea but at least in a plane by the time you get settled at 25,000ft the rear upper tank is gone and as per this report http://www.spitfireperformance.com/Spitfire_IX_ML-186_Handling.pdf the handling is back to normal. I'm not arguing about whether the Spit could be an escort plane, it could never be a P51 but it's range could be easily tripled with the technology Supermarine had at the time.

Part of the argument is that range and operational radius are not the same thing for a fighter. Obviously radius is, in theory, 1/2 the range but operational radius is NOT figured using max range of the aircraft using auxiliary tanks.
It is figured using the fuel capacity of the plane in combat condition.
Any none combat rated external fuel tanks are gone with whatever fuel was still in them.
The fighter must be in condition to at least make some sort of credible fight, A Spit MK XIV might haul a 90 gallon slipper tank around in a fight, a Spit MK V would be in serious trouble trying to do that. From power to weight, thrust to drag and structural strength standpoints. A MK VIII or IX falls where?

As the pilots may tell us at these aft center of gravity situations it is not like flipping a switch. At some point it might be but I believe that there is a more gradual shift/change in flying characteristics. The Mustang is a real puzzle, somehow at 25 US gallons in the rear tank the plane is not only safe to fly, they want you to keep that 25 gallons in the rear tank as the reserve and use every other drop of fuel in the plane because the plane lands better (handles better) with 25 gallons in the rear tank, but at 26 gallons the plane is dangerous???

The RAF allowed the Mustang III to use 40imp gallons in the rear tank as the change over point from aceptable (my word, I am going from memory here) to not acceptable?

A wartime manual for the P-51 says things rather different than the post war manual.
For one thing they figured the stick reversal at 4 Gs rather than 6.75 and the manual is somewhat contradictory.

"When you are carrying more than 40 gallons of fuel in your rear tank do not any acrobatics. The weight of this fuel shifts the center of gravity back so that the airplane is unstable for any but straight and level flight."
which is followed by
"Be sure you are accustomed to the changed flying characterics of the airplane before engaging in any maneuvers with full fuselage tank. You need at least one or two hours of flying with the airplane in this condition to accustom yourself to it."

Apparently acrobatics and maneuvers are not the same thing. Not sure where straight and level falls

The manual is for planes fitted with tail warning radar and many of them had a 20lb bob weight fitted to the elevator controls. I have no idea if that really fixed things or if they only thought it did at time.

The manual also states (under fuel tank usage) that fuel return line from the carb went to the left wing tank on early planes and the rear fuselage tank on later planes, the return line could send up to 10 gallons an hour depending on flight conditions back to the tank. If space was not available in the tank the fuel was vented overboard.

There is no need to try to warm up and tank off on auxiliary tanks as the main tank used for those purposes will be partially (or fully) refilled in flight.
apparently there was little problem in partially filling the Mustang rear tank in flight????

getting to another post

The argument is the Spit could not fly escort missions, my argument is just because it did doesn't mean it couldn't. Sydney Cotton had no issues fitting extra fuel in his PR spits like the under seat 20G tank, if the Spit was given to men like him, men that found solutions to problems instead of excuses the Spit could have had modifications to greatly improve it's range,

Photo recon planes were not expected to maneuver like a fighter, they were expected to use speed and altitude to evade interception so CG location was much less critical (or if you prefer lousy cg location was considered more acceptable for them).

Some of the "solutions" only became possible with the fitting of more powerful engines that used better fuel. And lets not forget better runways/flying fields. AN extra 500-1000ft of take-off distance to the proverbial 50 ft obstacle is a big help in getting a heavily loaded plane off the ground regardless of how much extra power the plane had.
A plane that has 250imp of fuel on board that crashed into the trees at the end of the runway isn't escorting anything anywhere.
We also have to see what the different Merlins were rated at for take-off power vs combat power and when (or if) the take-off power ratings were changed.
The Merlin 61 was rated at 1280hp for take-off at 12lbs, the V-1650-3 was rated at 1380hp at 15 1/4 lbs and the V-1650-7 was rated at 1490hp at 15 1/4 lbs, some of the later British Merlin's had increased take-off power settings. Using WEP power for take-off might have been possible but would have been frowned upon. A Manual for the P-51 says that each use and duration of WEP power had to logged and when the engine reached 5 hours of WEP use the engine ws to be pulled for a complete knock down inspection (this assumes the engine made it that far without particles in the oil or some other sign of distress).

Please note that I am not trying to Criticize the British Merlins or degrade the Spitfire here, simply noting that there were other considerations that somewhat depended on time that might have prevented or counted against a much earlier development of the escort fighter.

 

[XBe02Drvr]

Apparently acrobatics and maneuvers are not the same thing. Not sure where straight and level falls

Not sure where WWII falls, but in my days attached to the jet fighter community, maneuvers were anything other than S&L that was more or less right side up and less than 2-3 Gs, such as joining up, tanking, flying the landing pattern break, etc. Acrobatics was anything more strenuous or spectacular than that.
Not exactly "flipping a switch", but in most planes the aft CG limit is where annoying behaviour starts to deteriorate exponentially into dangerous. A Cessna 150 with two big guys in it stalls like your proverbial pussycat, but add 100 pounds in the aft baggage, and it turns into an infuriated bronco that will rear up at the slightest back pressure, stall sharply with little warning, and spin if you sneeze or blink. Spin recovery has to be with kid gloves or it will go flat on you, or you'll overstress it pulling out of the dive. This the result of a (not quite legal) demonstration by my acro instructor in a 150 Acrobat.
I suspect the bob weights in the P51 were there to add a little stick force gradient in aft CG ops. Stick forces get really light in aft CG conditions, and an adrenalated pilot can easily overstress the airframe. The T34 with a large back seat passenger and the small allowable bit (30lb? I've forgotten) in baggage was scarily light on the stick and you could easily put an uncomfortable level of G on it without intending to.
Cheers,
Wes

 

[michael rauls]

Widen the flight performance as they were still using and shipping the P40 to combat theaters to end of war.
Would have even been a better ground attack fighter than the P47.[/QUOTEh
Have to disagree just a bit. As much as I think the p40 was a good plane and under rated in general I can't think of anything the p47 cant do better in relation to ground attack. It's tougher, it can lift more, has more fire power, it's faster( more difficult to intercept), and I believe the later models had a greater range as well.

 

[BiffF15]

SR6,

Did not the Griffon engine burn fuel at a higher rate than the Merlin (Spitfires)? That would no doubt cut into range / time on station/ actual combat time.

Cheers,
Biff

 

[michael rauls]

Widen the flight performance as they were still using and shipping the P40 to combat theaters to end of war.
Would have even been a better ground attack fighter than the P47.

To be fair I did think of one area where the p40 has it on the p47 and alot of other planes for that matter in ground attack or in general. That is the p40s ability to operate well from shorter unimprooved airstrips.
The p47, so I have read, needed quite the long runway.