P-38 wing loading?

[gripen]

Well, seems that Caidin used many sources but it also appears that there was no source critic at all. Personally I rate Caidin's works as semi-fictional.

gripen

[GScholz]

Originally posted by OLtos
But the P-38, again according to Dean's stuff, would actually hesitate and balk at changing attitude in the roll axis.  I imagine if you turn the dampening up around 60% on roll for the AH p38 you could see pretty much what he describes.

Well, this is one vice AH doesn't model.

[thrila]

Ok i do't mean to poke holes but here goes-

Tac- How exactly did you pull 4-6 G's @ 70mph in a spit IX?  And how did you manage to give it 2 notches of flaps?  It's either up or down.

AKAK- you know much about the spit XI?  Its a recce plane, it was damn heavy.  It carried lots of fuel- it had a range of over 2000 miles.  A plane for dogfighting by no means.

[Widewing]

Originally posted by gripen
Well, seems that Caidin used many sources but it also appears that there was no source critic at all. Personally I rate Caidin's works as semi-fictional.

gripen

Indeed, some portions of his work are utterly fictional. While it may be fun reading, DO NOT trust anything he says that is not accompanied by footnotes or a bibliographical reference.

My regards,

Widewing

[Furball]

p-38 is, was, looks like and always will be a sack of ****.

I hope my contribution to this thread is both enlightening and educational, have a nice day.

[Furball]

[mold]

What's that ugly thing in the middle of the picture, covering up all the pretty clouds?  Some new species of dung beetle?  

[F4UDOA]

Gents,

I have also wondered why the P-38 is supposed to turn even as well as it does in AH. I have heard many annecdotal stories to that effect but I have never seen the proof. Here are a few points to ponder.

1. Despite the high aspect ratio of the P-38 it had two large engine nacelles acting as spoilers in the wing disrupting airflow and lowering Clmax. This could or should negate the gains achieved by the increased aspect ratio.

2. I have heard many people say that the P-38 had low drag wings. It did not, it had the same airfoil as the F6F, F4U and FW190. It did have low drag flaps.

3. Wells mentioned that the P-38 had a larger wing surface covered by prop wash lowering the stall speed. This is tue but prop wash does not lower an accerated stall just a 1G stall.(I hedge this with the fact that Wells knows much more than me but this is my understanding)

4. For a reason I do not understand the P-38 had the unique trait of having a higher stall speed power on than off.

5. In flight test against the A6M2 the P-38F was no better off in low speed turns than any other allied fighter.

6. In flight test done against the A6M5 the P-38J actually faired worse than the P-51D-5 in low speed turns.

7. In the AFDU test of the P-38F it's turning was even with the P-47B except in climbing turns.

I believe that as is stated in the British report that the aircraft turned well for an Aircraft with high wing loading but not well in comparison with the likes of the Spit, Hurri or A6M.

[Ecliptik]

For one, I don't think anyone in this thread has stated that the 38 could out turn or even turn with an A6M, Hurricane, or Spit, save for perhaps the poorer turning late model Spits.

Second, while all of your points are potentially valid, they are also unsupported and anecdotal, the two things you just complained about.

[F4UDOA]

Ecliptik,

For one, I don't think anyone in this thread has stated that the 38 could out turn or even turn with an A6M, Hurricane, or Spit, save for perhaps the poorer turning late model Spits.

Ever fly WB2? There is an entire comminty that believes a P-38 should be one of the top 5 best turning A/C of WW2. Recently on these boards there was a very long thread about P-38's out turning Spitfires.

they are also unsupported and anecdotal, the two things you just complained about.

Actually nothing I posted is annecdotal. I have copies of every report I quoted. The engines Nacelles in the wing is fact. The stall speeds with power on comes from the 1944 JFC test and the airfoil from the P-38 is NACA series 2300, outer section was series 4400.

[gripen]

F4UDOA,
I'm not sure if the P-38 behaves same way as some other planes in the power on stalls but explanation for higher power on stall than power off stall might be something like this. First we must assume that lift of the wing is generated by air particles which hit the wing in the angle of attack (ie Newton way to explain lift of the wing, lets forget Bernouli for a while). In the power off stall direction of the air flow which hit wing is constant all over the wing span. But in the power on stall direction of the airflow might be different behind propellers because thrust line of the engine might be diffrent than direction of the plane ie propeller bend airflow downwards in the high angle of attack. Therefore air particles hit wing at lower angle behind proppelers than in free airflow and therefore lift behind propellers power on is lower than in free airflow power off.

gripen

[bolillo_loco]

one note where the P-38F is used to compair turning ability against other aircraft is that most P-38F series aircraft did not have the maneouver flap setting. AMT states that around 570 P-38F a/c were produced, of this figure 121 a/c were P-38F-15-LO which had the maneouver flap setting.  

I am sure most are aware of the turn compairison in AMT for the P-63, which states that the P-38J was easily out turned by the P-63 if the J did not use the maneouver flap setting and it was about the same if the J did use this feature. It goes on to state that the P-63 could get on the tail of a P-51D in 3-4 turns and a P-47 in 2.

[mold]

gripen--

Unfortunately you can't ignore Bernoulli or the rest of the fluid flow.  Newton can be used, but you can't limit your analysis to only the particles hitting the bottom of the wing.  The whole system has to be considered--in particular the resulting property of CLmax and the stall beyond it.  In the general case, the power-on prop lowers the effective angle of attack of the wing, which increases the actual AOA before stall, which lowers stall speed.

I don't know either why the 38 has a higher stall with power on.  Wierd.

[gripen]

bolillo_loco,
Relative maneuverability depends also on altitude, the Clmax of the P-38 dropped very quickly when mach number increased if compared to P-47 and P-51. It seems that the P-38 turned quite well at low altitude but not so well at high (with or without using flaps for turning). I don't know if this is modeled in the AH.

gripen

[gripen]

mold,
All I can say that in some cases increasing down thrust of the propeller certainly decreases power on stall speed and that might be the explanation also for stall speeds of the P-38. Otherwise I fully agree that Bernoulli should not be ignored; I'm only offering possible solution for a problem which is true in some cases.

gripen