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P-38 Lightning Speculation Thread

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2 hours ago, =475FG=DAWGER said:

That is a calculated chart at 50 lbs of stick force. It is not a chart of the maximum possible roll rates.

 

At high speed, the unboosted aircraft would have the pilot straining to achieve the 50 lbs force and there would be a resultant delay in achieving the roll rate while the boosted aircraft can easily go to maximum deflection.

 

The difference between P-38J and P-38L rollcharts indicates that this was factored in.

I highly doubt the boosted ailerons were "touch of the pinky finger"-light. If they had been, you'd have run into serious wing-twist problems - especially with a high aspect-ratio wing as in the 38*.

 

What seems reasonable to me is a normal gear-ratio, that will increse the full deflection to a higher airspeed and will see an eventual blow-down. The value of that blow-down airspeeds would depend on the pilot's input-strength. 50lbs is nothing to sneeze at in a relatively confined cockpit.

 

Unfortunately, the provided boost-ratio seems hard to come up with. I haven't been able to find it in Dean's "America's 100k" or in Bodie's book.

 

*The engines do provide for increased torsional stiffness across the span, but they can only do so much if your aileron goes "full deflection" at 500mph...

Edited by Bremspropeller

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23 minutes ago, Bremspropeller said:

I highly doubt the boosted ailerons were "touch of the pinky finger"-light.

I quote Eric Brown, who flew the F-5 photo recon variant for purposes of assessing the boosted aileron as well as the "dive flaps".

 

"[...] It soon became apparent that the Lighning system was very unsophisticated, because it's ailerons lacked feel in that they had a constant force for any amount of stick displacement, increase in speed or rate of application. Such lack of feel is disconcerting to the combat pilot, and disturbing in instrument flight, particularly if the control column does not self-centre after displacement as indeed it did not in case of the Lighning. [...]"

 

It seems you could bend the wings like that. But it is an arrangement I would not like in my aircraft. Elevator force however increased strongly at high speeds. But overall he liked the aircraft, especially due to its otherwhise extremely benign handling and landing qualities.

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8 hours ago, Bremspropeller said:

 

The difference between P-38J and P-38L rollcharts indicates that this was factored in.

I highly doubt the boosted ailerons were "touch of the pinky finger"-light. If they had been, you'd have run into serious wing-twist problems - especially with a high aspect-ratio wing as in the 38*.

 

What seems reasonable to me is a normal gear-ratio, that will increse the full deflection to a higher airspeed and will see an eventual blow-down. The value of that blow-down airspeeds would depend on the pilot's input-strength. 50lbs is nothing to sneeze at in a relatively confined cockpit.

 

Unfortunately, the provided boost-ratio seems hard to come up with. I haven't been able to find it in Dean's "America's 100k" or in Bodie's book.

 

*The engines do provide for increased torsional stiffness across the span, but they can only do so much if your aileron goes "full deflection" at 500mph...

There is no evidence anywhere that the P-38 suffered from any wing twist at any speed. Wing twist is not present in every aircraft. 

 

There is a long way from pinkie light to 50 lbs of force.

 

I have flown aircraft with and without boosted ailerons at 300+ mph. Unboosted controls feel like they are set in concrete. Boosted, they "feel" like whatever artificial feel is built into the system. In the P-38 there was none. The yoke is a valve actuator, nothing more.

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2 hours ago, =475FG=DAWGER said:

 

I have flown aircraft with and without boosted ailerons at 300+ mph. Unboosted controls feel like they are set in concrete. Boosted, they "feel" like whatever artificial feel is built into the system. In the P-38 there was none. The yoke is a valve actuator, nothing more.

 

I am imagining that, in any case, gaining enough familiarity with practice will eventually compensate for the lack of feel, right?

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10 hours ago, danielprates said:

 

I am imagining that, in any case, gaining enough familiarity with practice will eventually compensate for the lack of feel, right?

Yes. F-16 pilots would tend to agree with that.

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17 hours ago, =475FG=DAWGER said:

There is no evidence anywhere that the P-38 suffered from any wing twist at any speed. Wing twist is not present in every aircraft

 

That is incorrect.

Wing twist always exists - it's just a matter of how severe it is.

Either structurally or aerodynamically/ flight-mechanically.

 

17 hours ago, =475FG=DAWGER said:

There is a long way from pinkie light to 50 lbs of force.

 

You implied that P-38s could roll way quicker than the roll helix angle-derived chart would suggest, by mentioning the 50lbs force-limit of the chart.

The roll-chart provided by CUJO showed that actual roll-rate is reasonably close to the calculated 50lbs values.

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1 hour ago, Bremspropeller said:

 

That is incorrect.

Wing twist always exists - it's just a matter of how severe it is.

Either structurally or aerodynamically/ flight-mechanically.

 

 

You implied that P-38s could roll way quicker than the roll helix angle-derived chart would suggest, by mentioning the 50lbs force-limit of the chart.

The roll-chart provided by CUJO showed that actual roll-rate is reasonably close to the calculated 50lbs values.

Wing twist caused by aileron deflection is ONLY structural twisting of the wing caused by the force of the aileron. The physical twisting of the wing causes the aircraft to roll in the opposite direction from the intended.

 

There is another use of the term, wing twist, also known as washout which is a airfoil design feature. Its main function is to provide the outer portion of the wing with a lower angle of attack so that the tips, where the ailerons are, stall after the roots. It makes the stall much more manageable.

 

I suspect you are confusing the two.

 

Edited by =475FG=DAWGER
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4 minutes ago, =475FG=DAWGER said:

Wing twist caused by aileron deflection is ONLY structural twisting of the wing caused by the force of the aileron. The physical twisting of the wing causes the aircraft to roll in the opposite direction from the intended.

 

There is another use of the term, wing twist, also known as washout which is a airfoil design feature. Its main function is to provide the outer portion of the wing with a lower angle of attack so that the tips, where the ailerons are, stall after the roots. It makes the stall much more manageable.

 

I suspect you are confusing the two

 

I'm not confusing anything.

 

There are wing-twist limitations that are imposed by structural or aeroelastic considerations (static overload, dynamic issues/ flutter) and there are considerations concerning pure controllability issus (aileron reversal).

 

Both might also appear together in a rather nasty combination.

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14 minutes ago, Bremspropeller said:

 

I'm not confusing anything.

 

There are wing-twist limitations that are imposed by structural or aeroelastic considerations (static overload, dynamic issues/ flutter) and there are considerations concerning pure controllability issus (aileron reversal).

 

Both might also appear together in a rather nasty combination.

 

 

There is ample documentation that p-47 suffered from this at 550mph++ dives, but does anyone have any sources that this was an issue in P-38? 

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21 minutes ago, CptSiddy said:

but does anyone have any sources that this was an issue in P-38? 

EVERY wing is aeroelastic. Ironically, if it wasn‘t it couldn‘t bear the loads and it would break up.

 

But with the P-38 this seemed to be less of a problem, as you had to address other problems before that. 

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7 minutes ago, ZachariasX said:

EVERY wing is aeroelastic.

 

 Even space shuttles?

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8 minutes ago, CptSiddy said:

with all the tiles?

 

Any solid object, regardless of what it is made of, deflects when you put a load on it. Doesn't matter whether it is made of chewing gum, aircraft-grade aluminium, or ceramic tiles. It has to, because basic physics requires it.

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5 minutes ago, CptSiddy said:

with all the tiles? 

Not the ones that come off. It's an aluminum wing structure. Not ceramic. Ceramic is the outer skin layer. And if a tile is missing, there melts your aluminum on your way home.

 

But you should get used to the fact that every wing flex *is* a wing flex, even though your particular wing might flex much less than other wings, it stil is elastic to some degree. If was absoulutely brittle, you would have to make the wing much stronger, as flexing absorbs load. The more brittle you make your construction the more load it has to bear. This comes into play even with rigid structures. Flex is also good for you as an aircraft designer. The question is just how you handle it.

 

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53 minutes ago, CptSiddy said:

with all the tiles?

 

The tiles on the Shuttle are more of a silicate foam (basicly quartz sand pressed into a block) - very abrasive and physically closer to styrofoam than to your plain vanilla bathroom-tile.

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Sooo, now that we have the 262 show us what basically no engine torque feels like, can I expect the same for the P-38´s counter rotating engines or is it still a bit different due to being a piston engine and not a jet?

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13 hours ago, Psyrion said:

Sooo, now that we have the 262 show us what basically no engine torque feels like, can I expect the same for the P-38´s counter rotating engines or is it still a bit different due to being a piston engine and not a jet?

The Hs 129 has counter-rotating propellers too.

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10 hours ago, ROTER_BART said:

The Hs 129 has counter-rotating propellers too.

 

It just lacks engines to go with them!

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On 6/11/2019 at 12:59 PM, Bremspropeller said:

 

I'm not confusing anything.

 

There are wing-twist limitations that are imposed by structural or aeroelastic considerations (static overload, dynamic issues/ flutter) and there are considerations concerning pure controllability issus (aileron reversal).

 

Both might also appear together in a rather nasty combination.

So, absent aileron deflection, what is twisting the wing and causing your mysterious structural or aeroelastic wing twist? Is the air going faster on the wing closer to the moon or something?

 

Structural twisting of the wing requires a twisting force be applied. What is the twisting force if not aileron deflection?

 

You appear to be referring to asymmetrical G limitations which aren't wing twist limitations. Of course, wing twist is certainly a possible failure mode if asymmetric G limits are exceeded but it is more likely to produce a vertical stabilizer failure first and, of course, its very hard to get into high asymmetric G without deflecting the ailerons. We keep circling back to wing twist being caused by aileron deflection.

 

I am no longer sure what you are even arguing about.

 

 

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Like wind, turbulance..? Have you ever flown an airliner in bad wheater?

 

All wings flex. All wings are designed to be flexible to a high degree. All wings are subject to aileron induced twists when the ailerons are applied, albeit to a different degree, depending on design and resistance to torsional flexing - multi spar designs, box spars are usually (but not neccesarily) offer more torsion resistance.

 

I fear it is you who has confused aileron reversal and wing twist; but it is wing twist that can - at least in theory, since the reversal speeds are usually waaay above Vne - eventually leads that the counter force becoming so severe that rolling stops and with higher speed, even reverses.

 

But this effect is not bineary, the counter force and thus the increasing loss of aileron roll is present at all airspeeds, and in practice leads to a loss of some % of the maximum theoretical roll rate at all times.

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So hey about that P-38, being a fan of it led me to get Martin Caidin's book about it some years ago and like other authors mentioned above he also got pretty preachy/pitchy about the plane at the end, a fair amount of hyperbole in the closing paragraphs that made me picture him wearing a plaid sportcoat and polyester pants in a used car lot. But an overall good read before that point nonetheless. Making a long-winded  story short, I got the impression that the lack of relative success in the ETO compared to the Pacific was due to some early teething problems, primarily related to cold-weather operations and difficulty with the superchargers at cold, high altitude that affected oil viscosity, leading to supercharger surging and failures, generally neutering the planes at altitude and making them pretty unpopular with pilots (in addition to the lack of creature comforts needed to keep the pilot warm and comfy).

 

By contrast, operations in the Pacific took place at lower altitudes where the superchargers were not quite as critical, or at least sensitive, but also the thicker air allowed pilots to take advantage of the plane’s additional maneuverability down low.  And of course, freezing your buns off wasn’t a big risk there either.

 

In addition, I also have "Hub" Zemke's book about his adventures flying P-47's in the ETO, and he discusses the P-38 a little bit, and certainly not in very glowing terms, referring to similar engine and supercharger difficulties at altitude and in the cold, describing "many" P-38 pilots "leaving formation to limp home trailing blue smoke while cursing the plane under their breath" (or words to that effect), and how he barely was able to avoid being reassigned to a P-38 squadron when transitioning away from the P-47, pulling strings to get into a P-51 group  (ironically his Mustang later breaking apart while diving in pursuit of a ‘109, leading to his capture and internment).

 

I love the airplane and am very excited to see it coming out (twins is where it’s at, man!!), but I'm curious to see how much of these environmentally-related powerplant difficulties may be modeled in the sim for us to deal with.

 

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On 6/14/2019 at 12:11 AM, =475FG=DAWGER said:

So, absent aileron deflection, what is twisting the wing and causing your mysterious structural or aeroelastic wing twist? Is the air going faster on the wing closer to the moon or something?

 

Structural twisting of the wing requires a twisting force be applied. What is the twisting force if not aileron deflection?

 

You appear to be referring to asymmetrical G limitations which aren't wing twist limitations. Of course, wing twist is certainly a possible failure mode if asymmetric G limits are exceeded but it is more likely to produce a vertical stabilizer failure first and, of course, its very hard to get into high asymmetric G without deflecting the ailerons. We keep circling back to wing twist being caused by aileron deflection.

 

I am no longer sure what you are even arguing about.

 

 

 

And it shows...

I'm talking about aileron-load imposed wing-twist. I have never talked about anything else.

 

Kurfy is correct, any gust or disturbance will trigger a structural response (bending + twist) of the wing.

Edited by Bremspropeller

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On 6/14/2019 at 1:29 AM, VO101Kurfurst said:

Like wind, turbulance..? Have you ever flown an airliner in bad wheater?

 

All wings flex. All wings are designed to be flexible to a high degree. All wings are subject to aileron induced twists when the ailerons are applied, albeit to a different degree, depending on design and resistance to torsional flexing - multi spar designs, box spars are usually (but not neccesarily) offer more torsion resistance.

 

I fear it is you who has confused aileron reversal and wing twist; but it is wing twist that can - at least in theory, since the reversal speeds are usually waaay above Vne - eventually leads that the counter force becoming so severe that rolling stops and with higher speed, even reverses.

 

But this effect is not bineary, the counter force and thus the increasing loss of aileron roll is present at all airspeeds, and in practice leads to a loss of some % of the maximum theoretical roll rate at all times.

There is no doubt all wings flex.

 

I have personally  seen many a wing flexing outside my window. I even flew one airplane that made creaking noises in turbulence. Nothing more comforting than penetrating a line of heavy weather and listening to the wing creaking like the main mast of a tall ship in a gale.

 

Wing twist is NOT going to happen except by aileron deflection.

 

You aren't going to twist a wing by going fast or in turbulence.

 

Flexing them up and down has plenty of causes. 

 

You can flex them by pulling or pushing on the stick. You can flex them by landing. Turbulence will flex them. Lift flexes them.

 

Wings flex up and down all the time but there are very limited options when it comes to twisting them.

 

Aileron reversal comes from wing twist. The deflected aileron twists the wing. I cannot think of another way to twist  a wing.

 

23 hours ago, Bremspropeller said:

Come on let's twist again...

 

attachment.php?attachmentid=210577&stc=1

Notice the ailerons are deflected?

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Poor choice of words on my part indeed, however as you say changes in lift may induce twist (aileron deflection does in fact nothing else then decreasing the lift on one wing and increasing it on another), and that includes effects of turbalance and local, momentary lift separation. 

 

The effect is not great and to induce significant enough twist effect you have to increase the pressure difference, meaning you either travel in high speed or in some kind of superstorm.

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Probably some will like her less. For my part, I think it is an absolutely beautiful and unique plane.  I also think that if you have got used to her and her flying style, you can get a lot out of it.  
Here in the game, as you said before, she will probably suffer from the performance levels that the other US planes have. (although that's still the subject of the change) So there's still hope. Nonetheless, despite the current limitations, it will certainly be interesting, and if it's just the flying itself :)

 

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On 6/14/2019 at 8:50 PM, Stoopy said:

So hey about that P-38, being a fan of it led me to get Martin Caidin's book about it some years ago and like other authors mentioned above he also got pretty preachy/pitchy about the plane at the end, a fair amount of hyperbole in the closing paragraphs that made me picture him wearing a plaid sportcoat and polyester pants in a used car lot. But an overall good read before that point nonetheless. Making a long-winded  story short, I got the impression that the lack of relative success in the ETO compared to the Pacific was due to some early teething problems, primarily related to cold-weather operations and difficulty with the superchargers at cold, high altitude that affected oil viscosity, leading to supercharger surging and failures, generally neutering the planes at altitude and making them pretty unpopular with pilots (in addition to the lack of creature comforts needed to keep the pilot warm and comfy).

 

By contrast, operations in the Pacific took place at lower altitudes where the superchargers were not quite as critical, or at least sensitive, but also the thicker air allowed pilots to take advantage of the plane’s additional maneuverability down low.  And of course, freezing your buns off wasn’t a big risk there either.

 

In addition, I also have "Hub" Zemke's book about his adventures flying P-47's in the ETO, and he discusses the P-38 a little bit, and certainly not in very glowing terms, referring to similar engine and supercharger difficulties at altitude and in the cold, describing "many" P-38 pilots "leaving formation to limp home trailing blue smoke while cursing the plane under their breath" (or words to that effect), and how he barely was able to avoid being reassigned to a P-38 squadron when transitioning away from the P-47, pulling strings to get into a P-51 group  (ironically his Mustang later breaking apart while diving in pursuit of a ‘109, leading to his capture and internment).

 

I love the airplane and am very excited to see it coming out (twins is where it’s at, man!!), but I'm curious to see how much of these environmentally-related powerplant difficulties may be modeled in the sim for us to deal with.

 

Plus At high alt the lead was separating from the petrol causing it to pre detonate.

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On 6/10/2019 at 10:42 AM, Bremspropeller said:

The chart shows the boosted-aileron P-38 will outroll anything in game above 350mph. It certainly will surprise people that think a 190 can outroll anybody, always.

The P-51B will outroll the 190 above 360mph, but by a lesser margin.

 

Keep in mind that the chart is not measuredl roll-rate, but calculated roll-rate. The actual, achievable rates might differ slightly.

The Early LA5 already surprised everyone in a FW. So why not the P38?
I dont care. VR makes even getting shot down a joy😎

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1 hour ago, LP1888 said:

What will the timers be on it thou 

I really hope the DD thing mentioning fuel octane helps US planes. The old ones and new.  Otherwide Im worried. The P51 I always will love but actually as flight sims have grown more advanced Ive liked her less and found her best qualities dont translate to whoeee fun game stuff. :) the P38 though holds a special place to my heart. Itd kill me if its as hobbled as US planes have been so far.  Thats also why my hopes are on the Tempest so much.

On 6/14/2019 at 3:50 PM, Stoopy said:

So hey about that P-38, being a fan of it led me to get Martin Caidin's book about it some years ago and like other authors mentioned above he also got pretty preachy/pitchy about the plane at the end, a fair amount of hyperbole in the closing paragraphs that made me picture him wearing a plaid sportcoat and polyester pants in a used car lot. But an overall good read before that point nonetheless. Making a long-winded  story short, I got the impression that the lack of relative success in the ETO compared to the Pacific was due to some early teething problems, primarily related to cold-weather operations and difficulty with the superchargers at cold, high altitude that affected oil viscosity, leading to supercharger surging and failures, generally neutering the planes at altitude and making them pretty unpopular with pilots (in addition to the lack of creature comforts needed to keep the pilot warm and comfy).

 

By contrast, operations in the Pacific took place at lower altitudes where the superchargers were not quite as critical, or at least sensitive, but also the thicker air allowed pilots to take advantage of the plane’s additional maneuverability down low.  And of course, freezing your buns off wasn’t a big risk there either.

 

In addition, I also have "Hub" Zemke's book about his adventures flying P-47's in the ETO, and he discusses the P-38 a little bit, and certainly not in very glowing terms, referring to similar engine and supercharger difficulties at altitude and in the cold, describing "many" P-38 pilots "leaving formation to limp home trailing blue smoke while cursing the plane under their breath" (or words to that effect), and how he barely was able to avoid being reassigned to a P-38 squadron when transitioning away from the P-47, pulling strings to get into a P-51 group  (ironically his Mustang later breaking apart while diving in pursuit of a ‘109, leading to his capture and internment).

 

I love the airplane and am very excited to see it coming out (twins is where it’s at, man!!), but I'm curious to see how much of these environmentally-related powerplant difficulties may be modeled in the sim for us to deal with.

 

Seeing how it did so well at low alts In surprised we never sent any to the Soviets ad Im sure we were well aware the Eastern Front airwar was a largely below 15k ft affair

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2 hours ago, Herne said:

 

couldn't see recommended time limits in the manual :-
 

https://www.scribd.com/document/27758155/P-38-Lightning-Flight-Manual

 

 

http://www.avialogs.com/index.php/en/aircraft/usa/lockheed/p-38lightning/to-01-75ff-1-pilots-flight-operating-instructions-for-army-models-p-38h-series.html

 

5 minutes, pdf page 37 for the J.

Edited by PainGod85
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6 hours ago, Sublime said:

Seeing how it did so well at low alts In surprised we never sent any to the Soviets ad Im sure we were well aware the Eastern Front airwar was a largely below 15k ft affair

 

Bit of a guess, but might have been way too expensive.  One P-38 cost as much as two P-51s

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To add to that, available airframes were probably needed more in both the Pacific and Europe..

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They were slower to build than other fighters. More complex. 10,000 were built, and over that same time 15,500 P-47's were turned out. There never seemed enough of them. One unit in the Pacific had to convert to P-47's for several months due to a lack of Lightnings. They weren't happy!

So I'm going to guess that, with Lockheed having enough trouble keeping up with the needs of the USAAF, it wasn't feasable to consider sending any to the Soviets. 

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As long as we're speculating, does anyone have an inkling on whether or not the booms of the P-38 will be mirrored on the template as they were in the old IL-2? Even with the larger size of the templates now it would seem difficult to have both booms available to paint. I'm hoping it's a possibility all the same.

 

5 minutes ago, Poochnboo said:

They were slower to build than other fighters. More complex. 10,000 were built, and over that same time 15,500 P-47's were turned out. There never seemed enough of them. One unit in the Pacific had to convert to P-47's for several months due to a lack of Lightnings. They weren't happy!

So I'm going to guess that, with Lockheed having enough trouble keeping up with the needs of the USAAF, it wasn't feasable to consider sending any to the Soviets. 

 

The P-47 was built in two factories. Until very late in the war, I think it was only in Burbank that Lockheed produced the P-38.

Edited by Rjel
Arggg. Merged replies....

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On 6/17/2019 at 8:02 PM, =475FG=DAWGER said:

I cannot think of another way to twist  a wing.

 

Bending and twisting are normal gust-responses of a wing.

14 hours ago, Poochnboo said:

So I'm going to guess that, with Lockheed having enough trouble keeping up with the needs of the USAAF, it wasn't feasable to consider sending any to the Soviets. 

 

I can't see any use by the Soviets for the P-38s.

They'd probably just posted them to the PVO units around Moscow and have them fly patrols far from the front line.

 

The Lightnings had more operational value at the front-lines in the ETO, MTO, CBI and PTO IMHO.

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