F4U in Europe

NTGray said:

Whatever the specific suggestion was, everybody thought it would wreck the engines, and therefore were reluctant even to try it. Lindbergh assured them it would NOT wreck the engines, but they were still hesitant. I don't remember how he persuaded them to try, but they finally did, and then it was all good.

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They were reluctant to try it because they were never taught what "Lean of Peak" was, as a matter of fact IIRC when the AAC did preliminary testing on P-38 power settings they kept some of that data classified which was a great disservice to the men flying the machines.

I believe Lindberg took a flight out on a long training mission, all aircraft had full tanks. Upon their return Lindberg had a substantial amount of fuel left in his aircraft when compared with the other pilots, that's how he proved his point. He flew with Tom McGuire (475th FS) and later with 4 or 5 different Marine squadrons

There was a lot of incredibly bad information floating around during WWII.

The P-38s in both Europe and the Pacific got a lot of bad information.

The thing here was the planes were NOT being "flown by the book" or at least not the book Lockheed was telling them use AND not the book that Allison was telling them to use.
The Army (or mid level officers) were using their own books and it took quite a while to get the squadron pilots to fly the planes that both Allison and Lockheed wanted to be flown.

The British had gone through the whole low RPM and high boost cruise thing in 1941 and/or early 1942.

Tony LeVier had done a number of demonstration flights In Europe in 1944 showing the same things.
Most any commercial pilot that had flown before WW II could have done the same thing. Airline pilots that flew rich mixture the entire route weren't going to be around long.

Shortround6 said:

Tony LeVier had done a number of demonstration flights In Europe in 1944 showing the same things.

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You beat me to the punch, I was about to mention LeVier.

Clayton Magnet said:

That was the joke

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Yeah, I figured, Clayton, but there are some who forget the British role in the Mustang story, so I like to remind people every now and then

FLYBOYJ said:

I believe Lindberg took a flight out on a long training mission, all aircraft had full tanks. Upon their return Lindberg had a substantial amount of fuel left in his aircraft when compared with the other pilots, that's how he proved his point. He flew with Tom McGuire (475th FS) and later with 4 or 5 different Marine squadrons

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And, again, IIRC, they took apart and inspected Lindbergh's engines to see whether they had been damaged. They hadn't.

NTGray said:

And, again, IIRC, they took apart and inspected Lindbergh's engines to see whether they had been damaged. They hadn't.

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Yes, because what he was doing was known in the civilian community and if done properly (which is easy) wouldn't have any bad effects on the engine(s), if anything flying "Lean of Peak" is good for an engine as you're getting close to the perfect air/ fuel mixture AKA "stoichiometric mixture."

For some ungodly reason this wasn't taught during flight training and as ShortRound6 stated, it seems the AAC/AAF had their own agenda

You have to keep pretty close track of the temp running lean of peak. So, if you change altitude (or if the ambient pressure changes), the mixture should change a bit to stay at target temp. Maybe they did this when they were alone (recon or ?), but weren't doing this when they were in formations that changed altitude frequently. In any case, lean of peak has also gotten better as we improved the metallurgy and digital sensors definitely make this something that CAN be automated (at some cost) whereas it was all manual in WWII.

I'd bet if we were still flying military piston in fighters, the engines would be single-lever power systems with digital control, digital fuel injection, and completely automatic turbo and superchargers, and the TBO would be longer because the mixtures would be WAY better than with a carburetor.

Well, you pays your money and your take your chances.

American civil engines (R-1820s and R-1830) did NOT have automatic boost control prewar because the pilots (or co-pilots?) were expected to adjust the boost and mixture to get the best performance from the engine. Now you are in the middle of a dog fight and you don't have a 3rd hand (or 4th) while climbing and diving several thousands feet per minute you can very quickly wind up with blown engine as you try to keep all the levers where they are supposed to be.
Perhaps the instructors over simplified things somewhat?

"Cadet Not-too -bright, when in combat keep your fat fingers away from the mixture control. People smarter than you have can set it up so you can fly with at least one eye outside the cockpit so you have 1/2 a chance at not being shot down the first few time an enemy plane is within 20 miles of you. I Still have my doubts Cadet, so repeat after me, Keep your fat fingers away from the mixture control and let the pressure limiter do it's job. You have enough on your plate trying to steer the airplane and getting the throttle to go in the right direction.!"

GregP said:

You have to keep pretty close track of the temp running lean of peak. So, if you change altitude (or if the ambient pressure changes), the mixture should change a bit to stay a target temp. Maybe they did this when they were alone (recon or ?), but weren't doing this when they were in formations that changed altitude frequently. In any case, lean of peak has also gotten better as we improved the metallurgy and digital sensors definitely make this something that CAN be automated (at some cost) whereas it was all manual in WWII.

I'd bet if we were still flying military piston in fighters, the engines would be single-lever power systems with digital control, digital fuel injection, and completely automatic turbo and superchargers, and the TBO would be longer because the mixtures would be WAY better than with a carburetor.

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During WW2 I can see running the settings Lindberg suggested (lean of peak) during cruise or at a time when you're not in a combat zone, maybe that was part of the AAC's position on not adopting this as SOP. Between a CHT gauge, watching manifold pressure and knowing when you get that engine shudder when you're starting to run too lean, this is not too difficult of a task.

When I bop around in my club's 172 prior to take off I do my normal engine run and Mag check at 1800 RPM, lean until I see a rise in CHT and then back off when I start feeling the engine running a little rough. I'll go full power and do the same and see how close I can lean without getting the engine starting to run a little rough (keeps the spark plugs nice an clean). In the air I'll continue to check CHT and lean as required as I climb, but then again I'm flying at an airport at 5673 MSL!

FLYBOYJ said:

During WW2 I can see running the settings Lindberg suggested (lean of peak) during cruise or at a time when you're not in a combat zone, maybe that was part of the AAC's position on not adopting this as SOP. Between a CHT gauge, watching manifold pressure and knowing when you get that engine shudder when you're starting to run too lean, this is not too difficult of a task.

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In the Pacific most of the cruising time was over empty ocean with little chance of being jumped by enemy fighters, so maximizing cruise efficiency is easier in practice as compared to
Europe, where the chance of running into enemy fighters would pretty much be present the moment of crossing the coast.

When the P-38 was prevalent in the PTO, it was still dominated by the Japanese.
The distances covered in that theater were often further than the radius between England and France, too.

Two different situations with different requirements.

Don't think the P-38 was dominated by the Japanese ... but opinions vary.

In my opinion you are using the incorrect column

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wuzak said:

So I had a look for myself in the

View attachment 653632

To try and calculate range.

Full internal fuel (87 USG) and external tank (75 USG) is 162 USG (which the manual rounds up to 165 USG?). This gives a t/o weight of ~8,100lb.

In the Take-off, Climb and Landing Chart the following numbers are given for climb to 25,000ft.

View attachment 653633

That is, allow 39 USG for the P-39Q to climb to 25,000ft*. The note at the bottom says "fuel includes warm-up and take-off allowance".

That leaves 126 USG for cruising, fighting and reserve. The manual does not specify a reserve, either in USG or time.

The Flight Operation Instruction Chart says that at maximum continuous the speed is 287mph TAS, fuel consumption is 62 USGPH.

• In my opinion you are using the incorrect column
  [*]

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• First, do not use the Take-Off, Climb and Landing chart to figure range or combat radius. Those figures don't apply to range. For (ferry) range just use the Flight Operation Instruction Chart. For combat range or radius the only additional figures needed are for the reserve for combat and the reserve for landing. Reserve for landing uses the far right column V (max range) for low altitude search for the airfield. 33gph for 20min = 11gal reserve. I usually use 10. Reserve for combat requires estimating the GPH at combat power (3000rpm) for 25000'.
  

  wuzak said:

  [*]
  [*]
  View attachment 653636
  
  That would give a cruising time of 2.03 hours, or 583 miles. But that does not give allowance for combat or reserve. I can't find an actual fuel consumption for combat power either.

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  Combat fuel consumption isn't listed in the manual, it must be calculated (estimated). Converting max continuous power (aka normal power) 2600rpm to combat power 3000rpm can be done a couple of ways. Simply converting 62gph from 2600rpm to 3000rpm would increase it to 72gph or 24gph for 20min. Or refer to the Specific Engine Flight Chart in the manual and see that military power (3000rpm) burns 138gph at 15000' (while max continuous (2600rpm) burns 109gph at 14000' so military power burns 1.27 times the fuel that max continuous burns at 14000' Convert this to 25000' by multiplying 62gph X 1.27 = 79gph or 26gph for 20min. Take your pick, 24gph or 26gph, I normally use the 26gph.
  

  wuzak said:

  Maximum speed for the P-39Q at 25,000ft is 361mph from 772hp. If we use the ratio of speeds to calculate combat consumption at 25,000ft we get approximately 83 USGPH.
  
  But the Note in the instructions for using the chart says that maximum continuous power is for Emergency Use Only.
  
  That means that the bulk of the cruising will have to be performed at 20,000ft or lower.
  
  View attachment 653641

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  All the flight manuals have the Emergency Use Only disclaimer for normal power at 2600rpm. However normal (max CONTINUOUS) power was used universally with no time limit as noted in the Specific Engine Flight Chart. Column I (max continuous/normal power) at 25000' can certainly be used continuously as it was for all the other AAF fighters.
  

  wuzak said:

  179mph IAS ~ 250mph TAS.
  
  Assume 30 minutes @ maximum continuous at 25,000ft, that gives 133.5 miles, used 31 USG.
  Assume 5 minutes at Combat power at 25,000ft ~4 USG (don't count distance traveled as it could be further away).
  
  That leaves 126 - 4 - 31 = 91 USG for cruise.
  
  If we use the fastest cruise that we can for a sustained period, that is 250mph @ 20,000ft using 76 USG per hour, we get a total cruise time of 1.19 hours.
  
  We may want a 20 minute reserve, which is 0.33 hours, gives remaining time of 0.86 hours. At 250mph that is 216 miles.
  
  Total range is 216 miles + 133.5 miles ~ 350 miles.
  
  Seems wrong. I must have messed up somewhere.
  
  * The Flight Operation Instruction Chart gives 20 USG allowance for warm-up and take-off and climb to 5,000ft, but the Take-off, Climb and Landing Chart shows 25 USG for 8,100lb take-off weight

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  Use column I (max continuous/normal power) at 25000' just as the manual says. Deduct the 20gal takeoff allowance, the 26gal for 20min combat and the 10gal landing reserve for net fuel of 106gal (87 internal + 75 drop tank = 162gal less 56gal reserves = 106gal net). 106gal divided by 62gph = 1.7hrs. X 267mph TAS (per chart) = 453mi. Divide by 2 for combat radius = 226mi.
  
  In my opinion you are using the incorrect column (column II instead of I), incorrect duration of combat power (5min vs 20min ) and incorrect speed (250mph vs 267mph per manual). I'll stick with my calculations.
  
  Again, don't use the Takeoff, Climb and Landing chart to calculate range. Hope this helps.

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Shortround6 said:

There was a lot of incredibly bad information floating around during WWII.

The P-38s in both Europe and the Pacific got a lot of bad information.

The thing here was the planes were NOT being "flown by the book" or at least not the book Lockheed was telling them use AND not the book that Allison was telling them to use.
The Army (or mid level officers) were using their own books and it took quite a while to get the squadron pilots to fly the planes that both Allison and Lockheed wanted to be flown.

The British had gone through the whole low RPM and high boost cruise thing in 1941 and/or early 1942.

Tony LeVier had done a number of demonstration flights In Europe in 1944 showing the same things.
Most any commercial pilot that had flown before WW II could have done the same thing. Airline pilots that flew rich mixture the entire route weren't going to be around long.

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Dead on. The root causes were primarily at Wright Field which never stablished any semblance of operational testing before unleashing untested production aircraft into combat ops to learn the hard way. That is a major reason, such testing was mandated to occur at Eglin Field, but a little late to catch the nyriad of a.) bugs in wiring harnesses, radio comms, etc in P-47C to ETO. Air Technical Services as part of Materiel Command, ignored both Lockheed and Allison when the high altitude issues really brought the stupid recommended cruise settings to the forefront.

Lockheed and Allison pioneered optimized cruise settings on the long range runs in early 1942, testing the 30 gal Ferry tanks and new pylon/fuel feed systems.

P-39 Expert said:

First, do not use the Take-Off, Climb and Landing chart to figure range or combat radius. Those figures don't apply to range.

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Why not?

The take-off, climb and landing chart shows how much fuel is required to reach the specified altitude, including warm-up and take-off. How much fuel you use in that phase determines how much fuel is available for the rest of the flight plan.

P-39 Expert said:

For (ferry) range just use the Flight Operation Instruction Chart. For combat range or radius the only additional figures needed are for the reserve for combat and the reserve for landing. Reserve for landing uses the far right column V (max range) for low altitude search for the airfield. 33gph for 20min = 11gal reserve. I usually use 10. Reserve for combat requires estimating the GPH at combat power (3000rpm) for 25000'.

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We're not talking about ferry range. We're talking about flying in the world's most contested air space from 1942/1943-1945.

There is no "landing reserve" described or listed in the manual. Only a "reserve", the time for which does not seem to be specified.

Why would you use the max range speed for the reserve calculation? Looking at the chart and changing from IAS to TAS it is actually faster (280mph, without drop tank) at 20,000ft than max continuous at 25,000ft (with drop tank)! That seem odd to me.

P-39 Expert said:

Combat fuel consumption isn't listed in the manual, it must be calculated (estimated). Converting max continuous power (aka normal power) 2600rpm to combat power 3000rpm can be done a couple of ways. Simply converting 62gph from 2600rpm to 3000rpm would increase it to 72gph or 24gph for 20min. Or refer to the Specific Engine Flight Chart in the manual and see that military power (3000rpm) burns 138gph at 15000' (while max continuous (2600rpm) burns 109gph at 14000' so military power burns 1.27 times the fuel that max continuous burns at 14000' Convert this to 25000' by multiplying 62gph X 1.27 = 79gph or 26gph for 20min. Take your pick, 24gph or 26gph, I normally use the 26gph.

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You can't use the fuel consumption at 3,000rpm and 15,000ft compared to 2,600rpm and 14,000ft to calculate a consumption for 3,000rpm and 25,000ft.

Though I used speeds at 25,000ft to get a similar number to you.

You obviously meant 26 USG for 20 minutes or 24 USG for 20 minutes, not gph.

P-39 Expert said:

All the flight manuals have the Emergency Use Only disclaimer for normal power at 2600rpm. However normal (max CONTINUOUS) power was used universally with no time limit as noted in the Specific Engine Flight Chart. Column I (max continuous/normal power) at 25000' can certainly be used continuously as it was for all the other AAF fighters.

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If use of max continuous power was allowed, why put a note saying that it should only be used in emergency situations?

P-39 Expert said:

Use column I (max continuous/normal power) at 25000' just as the manual says. Deduct the 20gal takeoff allowance, the 26gal for 20min combat and the 10gal landing reserve for net fuel of 106gal (87 internal + 75 drop tank = 162gal less 56gal reserves = 106gal net). 106gal divided by 62gph = 1.7hrs. X 267mph TAS (per chart) = 453mi. Divide by 2 for combat radius = 226mi.

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226 miles isn't very useful in the ETO.

Nor, really, is a cruise of 267mph TAS in highly contested airspace conducive to remaining alive.

Your reserve should be calculated at higher fuel consumption, as it may be needed in the combat area. It may even need to be used when the drop tank is affixed (the pilot goes a bit off track trying to make the rendezvous with the bombers). It is NOT a "landing" reserve.

And your take-off allowance only gets you to 5,000ft.

That's why you use the take-off, climb and landing chart. It specifically says how much fuel is required for warming up, take-off and climb to altitude. FWIW there is a discrepancy between the take-off climb and landing chart and the Flight Operation Instruction Chart, in that the latter says 20 USG to warm-up, take-off and climb to 5,000ft, and the former says 25 USG.

To warm-up, take-off and climb to 25,000ft uses 39USG in a combat climb with drop tank (8,100lb t/o weight). In a ferry climb it uses 42 USG.

So we can apply that to your figures, we have -> 162 - 39 - 26 - 10 = 87 USG. 87 USG/62gph = 1.4 hours. 1.4 hours * 267mph = 374 miles. Combat Radius = 187 miles.

But we can go further than that.

Warm-up, Take-off and initial climb is undertaken using internal fuel. As is combat. And the reserve.

If we use the 20 USG to climb to 5,000ft as the basis of internal fuel usage, we have:
Full internal tank: 87 USG
Less warm-up, take-off and climb to 5,000ft: 87 - 20 = 67 USG
Less combat fuel allowance: 67 - 26 = 41 USG
Less reserve allowance: 41 - 10 = 31 USG

Chart for P-39Q without drop tank says maximum cruise is 330mph @ 25,000ft, 62 USG per hour.

31/62 * 330 = 165 miles. And that would be your combat radius.

P-39 Expert said:

Again, don't use the Takeoff, Climb and Landing chart to calculate range. Hope this helps.

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Why the F not?

The take-off, climb and landing chart shows how much fuel is required to reach the specified altitude, including warm-up and take-off. How much fuel you use in that phase determines how much fuel is available for the rest of the flight plan.

And why do you think you are helping anyone?

P-39 Expert said:

First, do not use the Take-Off, Climb and Landing chart to figure range or combat radius. Those figures don't apply to range. For (ferry) range just use the Flight Operation Instruction Chart. For combat range or radius the only additional figures needed are for the reserve for combat and the reserve for landing. Reserve for landing uses the far right column V (max range) for low altitude search for the airfield. 33gph for 20min = 11gal reserve. I usually use 10. Reserve for combat requires estimating the GPH at combat power (3000rpm) for 25000'.

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No, DO use Take-Off, Climb and Landing Chart to begin your 'range OR 'combat radius. Every pilot of the mystical P-39 a,) aspired to the exhiliration of flight, b.) the even greater joy of landing.The Ferry range discussion is irrelevant to your aspirations to transform the Iron Dog into an Axix Slaying Beast...

P-39 Expert said:

Combat fuel consumption isn't listed in the manual, it must be calculated (estimated). Converting max continuous power (aka normal power) 2600rpm to combat power 3000rpm can be done a couple of ways. Simply converting 62gph from 2600rpm to 3000rpm would increase it to 72gph or 24gph for 20min. Or refer to the Specific Engine Flight Chart in the manual and see that military power (3000rpm) burns 138gph at 15000' (while max continuous (2600rpm) burns 109gph at 14000' so military power burns 1.27 times the fuel that max continuous burns at 14000' Convert this to 25000' by multiplying 62gph X 1.27 = 79gph or 26gph for 20min. Take your pick, 24gph or 26gph, I normally use the 26gph.

All the flight manuals have the Emergency Use Only disclaimer for normal power at 2600rpm. However normal (max CONTINUOUS) power was used universally with no time limit as noted in the Specific Engine Flight Chart. Column I (max continuous/normal power) at 25000' can certainly be used continuously as it was for all the other AAF fighters.

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But NOT in Combat estimates - which are REQUIRED to provide fuel consumption for the engine. The Military Power and Combat Power fuel consumption rates are provided by the Engine manufacturer but are tested by Static Bench Tests for Sea Level at Wright Field. Those values over-ride the mfr and are contained in the range tables.

P-39 Expert said:

Use column I (max continuous/normal power) at 25000' just as the manual says. Deduct the 20gal takeoff allowance, the 26gal for 20min combat and the 10gal landing reserve for net fuel of 106gal (87 internal + 75 drop tank = 162gal less 56gal reserves = 106gal net). 106gal divided by 62gph = 1.7hrs. X 267mph TAS (per chart) = 453mi. Divide by 2 for combat radius = 226mi.

In my opinion you are using the incorrect column (column II instead of I), incorrect duration of combat power (5min vs 20min ) and incorrect speed (250mph vs 267mph per manual). I'll stick with my calculations.

Again, don't use the Takeoff, Climb and Landing chart to calculate range. Hope this helps.

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Bovine Fecal Matter - again, repeatedly. Your opinions are unfounded on multiple planes and dimensions - overridden by eternal optimism and unwarrented belief in the Tooth Fairy. You have neither historical record nor understanding of flight mechanics nor the laws of physics to achieve the triumph of an uncluttered mind and bring a fantasy to life. Help yourself on the path to healing - Give It Up.

Regarding mixture, once when my aviation nut buddy and I were returning to New Orleans from Lafayette, La, in his Grumman American, he had me take the controls enroute (about one hour) back I asked if I could adjust mixture from autorich and lean to a cruise setting. Pulling mixture out till just a quiver and back in appx 1/4 inch, we then watched the cylinder head temp which did not change during the flight. Immediately upon entering MSY control the first thing he did was push in to auto rich. The only aircraft I was in with him that he did not use autorich was in a glider. Although he was checked out in very many different birds, had single land and sea, twin, instrument, glider and instructor tickets he always used autorich. I know he was well informed, because in an effort to get me back into full scale aviation, he gave me all of his study material, articles, study guides, all with copious notes and high lighting. He also used only auto rich later in his L-19 although I showed him articles on reduced engine maintenance with proper mixture control, he kept it in autorich.

P-39 Expert said:

Again, don't use the Takeoff, Climb and Landing chart to calculate range. Hope this helps.

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Say what?



I think I need to call my old flight instructor up and demand my money back.

But…

I have to put my moderator hat on for a second.

:_putsmoderatorhaton:

I know this is frustrating, god knows I am frustrated, but everyone please remain civil (me included).

:takesoffmoderatorhat:

Carry on…

drgondog said:

Dead on. The root causes were primarily at Wright Field which never established any semblance of operational testing before unleashing untested production aircraft into combat ops to learn the hard way.

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And here I thought that the problem that submariners had with their torpedoes was unique.
Although, to be sure, the admins at the torpedo factory were busy rejecting the reports of the submarine captains in actual combat. telling them that there was nothing wrong with the torpedoes, they were just being used incorrectly. Did the pilots in the war zone have that same problem, or did the army brass listen to reason when they heard it?