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

[pbehn]

Someone's had too many Big Macs, haven't they? Or is it just the nose armour and gas heater that make him look fat?

Hes eaten such a big supercharger hes fallen on his tail, as predicted.

 

[FLYBOYJ]

Rolf Gunther Hermichen was in the LW at the start of the war, served in the French campaign, The Battle of Britain, on the eastern front before returning to France in 1942. He claimed a Hurricane at the end of July which was a Hurricane, a Spitfire on the 18 August, another Spitfire on the 19 August plus another he claimed as an Airacobra. This was his 18th claim 5 previous claims for Spitfires. He must have had reasons to think it was a P-39.

Focke-Wulf 190s Over Dieppe

From a quick internet scan it seems the P-39s that were operated in the UK carried similar camouflage and colors as the Spitfire Mk Vs flown over Dieppe. Am I wrong?

 

[pbehn]

From a quick internet scan it seems the P-39s that were operated in the UK carried similar camouflage and colors as the Spitfire Mk Vs flown over Dieppe. Am I wrong?

As far as I know yes, but so did all RAF planes including the Mustang I. The Spitfire Vs operated by US forces at the time simply had a US star painted over the RAF roundel. These subjects have been modelled frequently on the forum, to me they look a little curious just because they are Spitfires with US markings, they dont look like P-39s. Spitfires and Hurricanes with a Russian red star also dont look like P-39s.

 

[fubar57]

Here is an American Southern P-39

View attachment 634547

David. I wish I could give Bacon, Winner and Funny

 

[pbehn]

In the movie Heartbreak Ridge, Clint Eastwoods character Gunny Highway said it best, when asked by the CO what the hell was going on, to which he replied, "It's a clusterf—k sir!".

Arriving at a fight in single file allows the enemy to bring a mass formation to bear against your line. Not a winning move.

This was thought about, by making a cunning 90 degree turn after take off your formation is line abreast, looking for a 25 mile wide gap in the coastal defences to take on the enemy in twos. Some would say it is not a formation at all, just a lot of pairs of aircraft in the air at the same time who's only option when meeting any opposition is to turn back.

 

[FLYBOYJ]

As far as I know yes, but so did all RAF planes including the Mustang I. The Spitfire Vs operated by US forces at the time simply had a US star painted over the RAF roundel. These subjects have been modelled frequently on the forum, to me they look a little curious just because they are Spitfires with US markings, they dont look like P-39s. Spitfires and Hurricanes with a Russian red star also dont look like P-39s.



View attachment 634555

Just thinking that LW intelligence might have briefed that P-39s were in England and in the heat of battle a Spitfire looked like a P-39

 

[BiffF15]

Just thinking that LW intelligence might have briefed that P-39s were in England and in the heat of battle a Spitfire looked like a P-39

It's easy to get a Visual Identification (VID) incorrect. I have seen guys of all experience levels get it wrong, and that is in training with nothing real being shot at you.

In F-15 school the intel officer was teaching us aircraft recognition, and he got it wrong and they were his slides. He didn't take having his error pointed out very well either.

Cheers,
Biff

 

[P-39 Expert]

By the way, the P-39 is not all that much smaller in the engine bay area than the P-63. But it IS a slight bit smaller and the Aux-stage Allison does not fit. The Aux supercharger would be up against a lateral brace and bulkhead (sort of a bulkhead, anyway). The fuselage is simply not big enough for the Aux S/C to fit inside, but it COULD be knocked out for a fit and the bulkhead COULD be moved. That would mess up the airflow around the area and the CG would be aft of the gear, but it COULD be done.

As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.

To fix these somewhat minor inconveniences, they made the P-63. If has very little in common with the P-39 except the general layout.

P-39:
http://www.aviastar.org/pictures/usa/bell_p-39.gif


P-63:
http://www.aviastar.org/pictures/usa/bell_p-63.gif

If you go look carefully at a 3-view of the P-39 and P-63, notice the placement of the wing.

In a P-39, the tip airfoil maximum thickness runs through the bulkhead line that is just behind the rear of the door. In the P-63, the tip airfoil maximum thickness runs through the middle of the exhaust manifolds. From the top view, the P-39 looks like the wing is almost exactly halfway along the fuselage, but it actually is located forward of halfway. From the top view of a P-63, the wing is definitely placed more rearward than on a P-39.

What happened is what Drgondog said, the CG moved aft with an aux-stage Allison installed, so the landing gear had to be moved aft. That's very hard to do without moving the wing, too. While it was somewhat POSSIBLE to move a few things around inside a P-39 and shoehorn in an aux-stage Allison, it was not really possible to move the wing attach point without major reconstruction. Hence, the P-63 design to accomplish all the changes required.

P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.

It may not seem obvious, but the Aux-stage supercharger, with shaft, comes in at between 220 and 250 pounds. Let's call it 200 pounds, just for the sake of discussion.

Proof? AHT lists the weights as 1435lb for the P-39D-2 and 1620lbs for the P-63A, a difference of 185lb. These were both production airplanes. The coolant expansion tank would be moved forward to about the CG and the carb should have been on the engine stage like the other Allison production models, providing an extra 3000' critical altitude. Neither of those items weighed much but moving both forward would have helped the CG situation. But mainly CG would have been restored by using a larger (heavier) four blade propeller to handle the extra HP at high altitude.

In the P-39, there is no structure where the Aux-stage would go if it could be fitted inside. The airplane was designed for 8 gs and an overload of 12 gs at some design weight. The Aux-stage sits behind the V-1710 power section a distance of some 2 feet or so. At 12 gs, we have about 2,400 pounds (200 x 12) cantlevered aft of the power section. To support that, you need a structure that also can withstand the stress of landing many times over with no maintenance (how many engine mount systems require regular maintenance?). A load-bearing structure doesn't come without some weight penalty. The middle structure is one of the primary differences between the P-39 and P-63 structure.

It certainly would fit inside, it was exactly the same size on both planes. And the structure to withstand the stress was already there. The twin longitudinal beams that made up the fuselage structure provided a very robust mount for the propeller reduction gear, nose landing gear, nose armament, cockpit, and engine compartment which would include the aux stage SC, as it did on the P-63. This structure also provided for attachment of the wing to the fuselage. The tail empennage was of conventional construction.

Why am I wasting my time doing this?

I don't know. I make one post and get 10 replies and then everyone blames me for the length of the thread.

 

[BiffF15]

As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.

P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.

Proof? AHT lists the weights as 1435lb for the P-39D-2 and 1620lbs for the P-63A, a difference of 185lb. These were both production airplanes. The coolant expansion tank would be moved forward to about the CG and the carb should have been on the engine stage like the other Allison production models, providing an extra 3000' critical altitude. Neither of those items weighed much but moving both forward would have helped the CG situation. But mainly CG would have been restored by using a larger (heavier) four blade propeller to handle the extra HP at high altitude.

It certainly would fit inside, it was exactly the same size on both planes. And the structure to withstand the stress was already there. The twin longitudinal beams that made up the fuselage structure provided a very robust mount for the propeller reduction gear, nose landing gear, nose armament, cockpit, and engine compartment which would include the aux stage SC, as it did on the P-63. This structure also provided for attachment of the wing to the fuselage. The tail empennage was of conventional construction.

I don't know. I make one post and get 10 replies and then everyone blames me for the length of the thread.

P-39Expert,

You get ten replies per posting because the guys are deconstructing your comments and repeatedly proving some of what you post as wrong. I remember the engine bay discussion from before, yet here we are again.

You are under the belief that you have discovered something that no one in WW2 who actually built, flew or maintained the plane knew. In reality you haven't, and guys go to exaggerated lengths, and very nicely for the most part, to explain where you got off the correct path. Alas, to no avail.

Good luck,
Biff

 

[Glider]

As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.

P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.

Proof? AHT lists the weights as 1435lb for the P-39D-2 and 1620lbs for the P-63A, a difference of 185lb. These were both production airplanes. The coolant expansion tank would be moved forward to about the CG and the carb should have been on the engine stage like the other Allison production models, providing an extra 3000' critical altitude. Neither of those items weighed much but moving both forward would have helped the CG situation. But mainly CG would have been restored by using a larger (heavier) four blade propeller to handle the extra HP at high altitude.

It certainly would fit inside, it was exactly the same size on both planes. And the structure to withstand the stress was already there. The twin longitudinal beams that made up the fuselage structure provided a very robust mount for the propeller reduction gear, nose landing gear, nose armament, cockpit, and engine compartment which would include the aux stage SC, as it did on the P-63. This structure also provided for attachment of the wing to the fuselage. The tail empennage was of conventional construction.

I don't know. I make one post and get 10 replies and then everyone blames me for the length of the thread.

Stuff this lot as the facts as you state them are anything but. Personally I would like your reasons for so deliberately being very selective about quotes from books which you claimed were providing slam dunk evidence proving you belief about how P39 units formed up.

When the unaltered document shows that the
1) P39 was to slow in a straight line,
2) Too slow in a climb,
3) Couldn't manoeuvre,
4) Tended to overspeed in a dive
5) Everyone had to circle until the unit formed up

I don't really expect a reply let alone an explanation, but it highlights the lengths you will go to support your misguided belief.

 

[P-39 Expert]

I read Nanette, Edwards Park's first book about 20 years ago, so I knew the local library had a copy, so I checked it out a reread it last night, and today.
Not a big book, just 186 pages.

It describes their take off and joining up procedures.

P39 expert left out one important detail. A circle.

They did take off 2 by 2, then joined another 2 to form a flight.
Then the first 4 began a climbing circle, the other flights joined during the circling climb.
When everything was done right, they'd usually have all 4 flights joined by the time they'd completed one circle, and take a heading for their assigned mission.

Nanette was fiction, Angels Twenty was fact based on the same location and time period. From the book: "We (two planes) started our takeoff run before the first element (two planes) was off the ground. They began their turn, a wide gentle swing. Wingman and I were able to turn easily inside them and so put the flight in proper formation. By the time we were on course for the coordinate Blue Flight was with us, all in position." That was only two flights (eight planes, half a squadron), but the process was very quick and simple.

A lot of the missions were done with just one flight, but joined other flights from another of the many fields around Port Moresby, P40s or P38s..

I'll quote Park from Nanette pg 18-19.
" But that wasn't the thing that was really wrong about the P-39 ( he's referring to it's tumbling habit ) The plane was simply underpowered for the kind of work it was supposed to do. It could not climb high enough or quickly enough, it could not go fast enough except in a dive, ( when it had a tendency to go too fast), it could not maneuver handily enough. It's controls were extremely delicate. The slightest hint of abruptness on the pilots part would be rewarded with a high speed stall .

Park was no friend of the P-39, but in the other book he made it clear that the biggest fault was too much weight, coming mainly from the wing guns and too much armor plate. In neither book did he say that the plane was difficult or dangerous to fly and was particularly easy to take off and land.

Just the words of one man who flew the P-39

I thoroughly enjoyed both books, finding them at times laugh out loud funny at the situations he and his squadron mates found themselves in both in combat and on leave. I thought it was an accurate portrayal of day to day life on a forward base in NG during a time early on when the AAF was on the defensive. I recommend both books as very entertaining for someone interested in WW2 aviation.

 

[SaparotRob]

As far as I know yes, but so did all RAF planes including the Mustang I. The Spitfire Vs operated by US forces at the time simply had a US star painted over the RAF roundel. These subjects have been modelled frequently on the forum, to me they look a little curious just because they are Spitfires with US markings, they dont look like P-39s. Spitfires and Hurricanes with a Russian red star also dont look like P-39s.



View attachment 634555

Maybe just a quick glance during combat when things are happening fast? Star or roundel catches the eye and brain lables it a different plane.

 

[Glider]

Park was no friend of the P-39, but in the other book he made it clear that the biggest fault was too much weight, coming mainly from the wing guns and too much armor plate. In neither book did he say that the plane was difficult or dangerous to fly and was particularly easy to take off and land.

I would be interested to know where in the book it states that the additional weight came from having wing guns and too much armour. Its a long time since I read the book but nowhere do I remember it being specific about guns and armour. Just that the P39 weighed too much

 

[pbehn]

Maybe just a quick glance during combat when things are happening fast? Star or roundel catches the eye and brain lables it a different plane.

Just thinking that LW intelligence might have briefed that P-39s were in England and in the heat of battle a Spitfire looked like a P-39

It's easy to get a Visual Identification (VID) incorrect. I have seen guys of all experience levels get it wrong, and that is in training with nothing real being shot at you.

In F-15 school the intel officer was teaching us aircraft recognition, and he got it wrong and they were his slides. He didn't take having his error pointed out very well either.

Cheers,
Biff

Ive put all three posts together because they cover the same basic subject

From other posts, it is perfectly possible that P-39s were available in UK and were due to lease lend and other contractual wrangles the property of the USA by the time 601 squadron stopped using them in March 1942. Also from other posts there is some anecdotal evidence that P-39s were used for CAS at Dieppe.

I agree that misidentification is quite easy, from the link I posted Hermichen did mis identify some aircraft, like Typhoons for P-47s, and I know it isnt easy, the Typhoon was confused with an Fw190 so often they put stripes on it. However advising the LW pilots that P-39s were in the area may have planted an idea in a pilots head, but only one reported shooting down a P-39, and it would only be done if P-39s were there, Hermichen would certainly know what a P-39 looked like in August 1942. I dont have a side in the argument, I just thought it was an interesting contradiction Joe Baugher and Bill dont write things on a whim. And in any case it is a distraction from the normal groundhoggery. The various ins and outs of it would make a great Agatha Christie plot.

 

[pbehn]

P-39Expert,

You get ten replies per posting

And he is the lucky one, because I get one reply from ten posts from our expert, like most others on the forum, my posts are completely ignored and the same crap dragged up after a suitable period of internet mourning, it seems that if you put BS on one side for a period of time it starts smelling all fresh and new again, like mown grass.

 

[BiffF15]

And he is the lucky one, because I get one reply from ten posts from our expert, like most others on the forum, my posts are completely ignored and the same crap dragged up after a suitable period of internet mourning, it seems that if you put BS on one side for a period of time it starts smelling all fresh and new again, like mown grass.

He doesn't answer my posts either.

 

[Milosh]

The Brits did say they encountered He100s.

 

[FLYBOYJ]

The Brits did say they encountered He100s.

I think Robert Johnson claimed an Me209

 

[pbehn]

He doesn't answer my posts either.

Dont take it personally, you are among a several hundred "Joe Pilots" whose written reports are discounted, as an interested poster I am miles behind you, but you are in great company, ahead of you are Dowding and Park who also didnt have a clue, I am reliably informed.

 

[buffnut453]

As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length.

Please explain the term "construction drawings". I'm familiar with: Detail Drawings, which depict an individual part; Assembly Drawings, which describe an object made up of two or more parts; Installation Drawings, which shows a part or assembly in its installed location, and; Sectional View Drawings, which cut away part of an object to show the shape and construction along the cutting plane. There are also schematics which describe, at some degree of abstraction, systems within an aircraft. So what are "construction drawings"?

I presume you're referring to the "drawings" you cited in this post: XP-39 II - The Groundhog Day Thread. Those are Installation Drawings showing the station positions in the airframe. They ONLY show the distance between stations. They DO NOT show the height or width dimensions.

Just because compartments are "exactly the same length" does not mean that a 3-dimensional object will fit in that space. You need distances across length, width and height...and you also need to reflect any changes to those measurements to see if the physical space is sufficient...and, even then, there may be issues fitting an assembly into the available space because other parts or assemblies might get in the way.