Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)

P-39 Expert said:

Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.

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In ETO, multiply that by three as Group level operations of 50+ (incl spares) were Norm. Warm up was 5+ minutes, take off in pairs every 30seconds, (24 minutes) for all in the air, 5+ minutes for all of the last squadron to hook up to the preceding two squadrons... so 34 minutes in great weather.

BTW - that is optimistic for fuel consumption as the last squadrons are warming up and taxiing longer, while the early take offs are at Max Continuous after take off while forming up for longer period. Switch to drop tanks and continue Max Continuous for climb to altitude for cruise.

Do more research on topic of escort operations.

drgondog said:

In ETO, multiply that by three as Group level operations of 50+ (incl spares) were Norm. Warm up was 5+ minutes, take off in pairs every 30seconds, (24 minutes) for all in the air, 5+ minutes for all of the last squadron to hook up to the preceding two squadrons... so 34 minutes in great weather.

BTW - that is optimistic for fuel consumption as the last squadrons are warming up and taxiing longer, while the early take offs are at Max Continuous after take off while forming up for longer period. Switch to drop tanks and continue Max Continuous for climb to altitude for cruise.

Do more research on topic of escort operations.

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Ascent said:

I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.

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Cool!

Map here

P-39 Expert said:

Thanks for posting. Hmmm, nowhere in these instructions from the flight manual is there mention of using the Takeoff, Climb and Landing chart to compute range. Nowhere. These instructions say to use the Flight Operations Instruction chart and refer to "Operating Data" which is a part of the Flight Operation Instruction Chart. Operating Data is a little more than halfway down the chart in each column. No mention of the Takeoff, Climb and Landing chart at all.

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ThomasP tried to help you but UN-Like ALL others on this forum, you fart and fall down struggling with the concept maximum range versus Combat Radius. For the two links you reposted, you failed to note Range discussion in the Op manual, or instructions to look at the tables for a flight plan different from takeoff, cruise at a specific altitude/engine setting, and land - with fudge for 'reserve' to accommodate warm up, taxi, take off at MP, climb to altitude or return to what you thought might b your airfield -but reserve 20 gals 'just in case'.

I'm curious - what make your mental processes so unique?

Maybe you should understand that CONTRACTOR developed operating tables, But AAF developed Combat Radius tables for Planning 'first cut' visibility to Potential Combat radius given the allocated circumstances - FOR SINGLE AIRPLANE, Perfect weather, No winds aloft, no changes in cruise altitude, engine operating settings or airspeed.

As Greg pointed out - neither the Allison with Aux supercharger, nor any Merlin (front or back) could be installed in a P-39 without exceeding CG limits - or maintaining aerodynamic shape or cooling system. Te closest to feasible change was the P-63 which had to be lengthened 2 1/2 feet. and total redesign of the aft fuselage/empennage and wing.

What is sooooooo darned hard for you to find examples of ETO operations on Utube or internet, in which a mission is selected and planned - all the way down to fighter groups and their planning after receiving briefing for their assigned role. Look at Mission maps and see if you can find a straight line to a target longer than 200 miles. Look at films showing engine warm up at each assembly area (different depending on squadron take off assignment), taxi to active runway, form up in pairs, takeoff and circle for formation assembly - element by element, flight by flight in composed squadron - and repeat two more times, before setting course for climb destination. Add time for assembly/climb in the ever present crappy cloud cover/weather over England East Anglia - while dodging un-briefed RAF returns, recon flights, late forming 9th AF medium bomb groups forming around Bunchers.

You on the other hand, exercising extreme analytical abilities, see through all that BS and declare "Take off and seek der Foe, flee at first sight and return in tranquility" to stretch the P-39 to design parameter it could Never meet.

Find another audience for the Gospel - everyone else here is a Sinner.

Personally, I prefer to feed troops into combat two at a time, so they can be defeated in detail. What the problem is?

pbehn said:

https://mediafiles.thedms.co.uk/publication/ee-eet/cms/pdf/information-sheets/USAAF%20Airfields%20Guide%20and%20Map.pdf#:~:text=Introduction%20During%20the%20Second%20World%20War%2C%20the%20East,were%20over%20100%2C000%20US%20airmen%20based%20in%20Britain.

Map here

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Great link! I'd love to visit Attlebridge. I'd love to watch those turkeys forming up on the runway for take-off.

SaparotRob said:

Cool!

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Unfortunately there is very little to see on most of them, either returned to farmland or built on now but I do get to cycle down what was one of the runways at what was RAF Glatton, a B-17 base.

Still cool.

Ascent said:

I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.

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Hi

There are not many places in the UK that are vaguely 'flat' that were not used for airfields, the book 'Military Airfields in the British Isles 1939-1945 (Omnibus Edition)' by Willis and Holliss has brief details and small plans of 654, as at 1 December 1944. There cannot have been many places without an airfield circuit over them.

Mike

I still go back to the question, if a number of countries using the P-39 were fighting for their existence why would the engineers and designers of the day not put the resources into "fixing" the aircraft into a formidable fighter instead of pouring even more resources and time into building and designing brand new fighters?

When you're drowning, most people try to fix the leaking life jacket they have instead of trying to design and build a new one.

I think this is just an example of "the simplest explanation is usually the best one", the life and abilities of the combat design was at its end.

The P-39 was a pretty good airplane relative to the design parameters specified. It was reasonably fast and was OK at the altitudes where it was specified.

Unfortunately, the design spec was short-sighted and didn't address the realities of WWII, even though the WWII realities were apparent to most observers. The ETO was a high-altitude, longer-range theater of war, and the basic P-39 could not be modified to meet the new requirements. There was no place to add fuel and the engine was never developed into a 2-stage supercharged engine with two integral superchargers. Ironically, if the Allison HAD been developed into an integral 2-stage unit, it MIGHT have fit into a P-39 because it would have been considerably shorter than the aux-stage unit that was later developed. But it still had no place for added fuel and still had a CG problem.

I think you are correct above. It was recognized that the P-39 was useful in a niche mission, but it was not an airframe rich with development potential. So, they used it for what it could be used for, moved on, and got rid of it when better aircraft came along. That meant most any other fighter with some range and altitude capability along with a decent turn of speed. We'd likely have been better off with the same number of P-43 Lancers. At least there were no CG issues when the ammunition was used up.

In the end, the only way to upgrade the P-39, was to build an entirely new type as the P-63...

GrauGeist said:

In the end, the only way to upgrade the P-39, was to build an entirely new type as the P-63...

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And as you, and so many others have pointed out, might as well go with P-51's and P-47's and P-38's and....

Ascent said:

I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.

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Yep...lived for 15 years in Cambridgeshire, at Great Paxton and then Keyson, so I know the county well.

GregP said:

No it wouldn't have, because there is not room in the P-39 airframe for a two-stage Allison.

There MIGHT be room for a 2-stage Merlin (a bit shorter), but the Merlin was never considered for the P-39, nor would it have been. The P-39 was an American airplane. The Merlin got into the P-51 simply because the British specified the P-51 and it WASN'T strictly an American airplane. You didn't see an Allison in a British airplane, other than the one (P-51) spawned in the U.S.A., did you?

Also, the Merlin was never built in a remote drive configuration like the E-series Allison was.

You have been told this repeatedly, by someone with access to actual P-39s. In fact, there are TWO P-39s at Chino airport, and neither of them have room for a 2-stage Allison engine. My thoughts are that since the P-39 were mass-produced, there wasn't room for a 2-stage Allison in ANY of them. When they needed a 2-stage Allison, they built the P-63, so it would fit. Maybe that's another 150-page thread, though.

Just saying.

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Same amount of room in the P-39 as the P-63. Items would need to be rearranged, but it would fit. You have not proven a thing. I have continuously proven that both engine compartments were exactly the same size.

P-39 Expert said:

Same amount of room in the P-39 as the P-63. Items would need to be rearranged, but it would fit. You have not proven a thing. I have continuously proven that both engine compartments were exactly the same size.

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Well, someone has to ask the obvious question, why bother with the P-63?

drgondog said:

ThomasP tried to help you but UN-Like ALL others on this forum, you fart and fall down struggling with the concept maximum range versus Combat Radius. For the two links you reposted, you failed to note Range discussion in the Op manual, or instructions to look at the tables for a flight plan different from takeoff, cruise at a specific altitude/engine setting, and land - with fudge for 'reserve' to accommodate warm up, taxi, take off at MP, climb to altitude or return to what you thought might b your airfield -but reserve 20 gals 'just in case'.

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The pilot's manual was very clear, no mention was made of using the Takeoff, Climb and Landing chart. Everything needed to plan a mission was on the Flight Operations Instruction Chart.

drgondog said:

I'm curious - what make your mental processes so unique?

Maybe you should understand that CONTRACTOR developed operating tables, But AAF developed Combat Radius tables for Planning 'first cut' visibility to Potential Combat radius given the allocated circumstances - FOR SINGLE AIRPLANE, Perfect weather, No winds aloft, no changes in cruise altitude, engine operating settings or airspeed.

As Greg pointed out - neither the Allison with Aux supercharger, nor any Merlin (front or back) could be installed in a P-39 without exceeding CG limits - or maintaining aerodynamic shape or cooling system. Te closest to feasible change was the P-63 which had to be lengthened 2 1/2 feet. and total redesign of the aft fuselage/empennage and wing.

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The two stage Allison would require a four blade propeller which would have offset the extra weight of the auxiliary stage. Ballast could have been used also if needed. I have said this numerous times in the auxiliary stage discussions.

drgondog said:

What is sooooooo darned hard for you to find examples of ETO operations on Utube or internet, in which a mission is selected and planned - all the way down to fighter groups and their planning after receiving briefing for their assigned role. Look at Mission maps and see if you can find a straight line to a target longer than 200 miles. Look at films showing engine warm up at each assembly area (different depending on squadron take off assignment), taxi to active runway, form up in pairs, takeoff and circle for formation assembly - element by element, flight by flight in composed squadron - and repeat two more times, before setting course for climb destination. Add time for assembly/climb in the ever present crappy cloud cover/weather over England East Anglia - while dodging un-briefed RAF returns, recon flights, late forming 9th AF medium bomb groups forming around Bunchers.

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I simply quoted an actual P-39 pilot in NG on how his squadron formed up for an actual mission. NG had lousy weather too. I have had discussions on this board comparing P-39 range with P-47 range (both with drop tanks) and these same calculations matched up very close to what combat radius maps indicated was the P-47's combat radius. P-39 radius was calculated the same way. In neither case was the Takeoff, Climb and Landing chart used.

drgondog said:

You on the other hand, exercising extreme analytical abilities, see through all that BS and declare "Take off and seek der Foe, flee at first sight and return in tranquility" to stretch the P-39 to design parameter it could Never meet.

Find another audience for the Gospel - everyone else here is a Sinner.

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Thanks for your condescending and derogatory comments.

GregP, with no dog in the fight and access to "2" actual aircraft actually measures the aircraft and is told he wrong.

"But I read the manual"

P-39 Expert said:

Thanks for your condescending and derogatory comments.

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You're lucky that's all you got.

You're arguing with historians, pilots and someone who actually has access to the actual aircraft and YET, you insist that your fatally flawed ideas are correct.

You state that you "read the manual" but clearly show that you have no idea how to use it...