Recovering From Compression situ's in P.38

[nick172]

Basically the 38 dives really well, you can catch a la in a dive most of the time. It accelerates really well and coming out of a dive is no prob with trim. Its acctually one of my favorite planes to dive because everyone thinks they can just dive away from you and they cant. (Surprize!)

Skyhawk

[bongaroo]

Most compression death dives I see people perform are when they are planning to pork ord at a base and come in from 10k and wait until they get very low to drop their eggs.  You can accurately drop your ord at a high alt with a little practice and you shouldn't get anywhere near compression speeds.

 

[Ack-Ack]

The problem also stems from the fact that a lot do not understand what compressability is and how it affects the P-38.  Below 20,000ft the P-38 will not get into a full compressability state due to the fact that the air flow over the wings will not reach critical mach and the lower you go, the critical mach threshold increases.  It's above 23,000 feet where the threat of a full compressability state is very real as the critical mach threshold is lower than it is at lower altitudes.  The higher you go, the lower that threshold becomes.

It really does help to make a small chart that lists the critical mach for various altitudes and memorize them.  It will help because you'll get a good approximation of where the 'danger zone' is for any given altitude.

Below 10,000ft you can easily get a P-38 into a 475-500mph IAS dive and pull out without having to resort to using auto-trim to recover.

The key is knowing how to control your speed in a dive.


ack-ack

[Bodhi]

I hear that in AH2 that Alt-F4 helps the compression in a '38...

[Sincraft]

I see the methods they use in these documentaries and just don't udnerstand...

It's like as long as you did a VERY basic ACM on an enemy plane, you suddenly became the ACE.

And the recreations are HORRIBLE too.  Makes the pilots in these films look stupid.  I mean come on so the p38's jumped a gaggle of guys and lived to tell?

[Delirium]

Check out this film...

http://www.youtube.com/watch?v=ITRLk9b9AcY

audentes fortuna juvat

I wouldn't normally take a film like that as factual, but it does have Robin Olds there to verify.

[bongaroo]

woo hoo!  P38 dogfights episode.  Watched the first few minutes, I'll get the rest when I get home.

Thanks Del!

(except for you mauling me last night!  After the first I came back for revenge and obviously picked the wrong p38 to pursue, you were the other the promptly nailed me!  I blame the spixtweenie that had rammed me a minute before and spread oil all over my canopy   )

 

[Delirium]

Apologies 420, it wasn't a fair fight, I hate giving people I know well anything but a fair fight.

Unfortunately, the hordes (more so on Tuesdays) aren't always condusive to a good fight. I hope you understand...

[bongaroo]

Oh I know.  I spent most of my time in MW and took a few runs in EW beating up some 68's.

I had 2 runs in the MA and you know how they ended     I still had 3 or 4 scalps each time before you got a hold of me so it was time for a plane with fresh ammo belts and fuel anyways!

<S>

[Cthulhu]

A Highlly Respectfull  to Brig Gen Robin Olds U.S.A.F.(retd)

For anyone who doesn't know already, Robin Olds died back in June 2007. 

[Simaril]

For anyone who doesn't know already, Robin Olds died back in June 2007. 

Which of course means he finally has time to keep up with the AH2 Forums!

[Traveler]

You shouldn't have combat trim on to begin with if you're flying the P-38.


ack-ack

I got to ask, why not take advantage of combat trim?  The advantage of using combat trim is that it keeps the aircraft trimed and flying at it's best possible speed.  Where flying the aircraft out of trim means that the aircraft is not flying at it's best possible speed and thus not giving you it's maximum performance.  You can use trim at any point and if you do, elevator trim will take you out of CT.  You would have to alt x to turn CT back on.    Someone tell me what advantage anyone has flying an aircraft out of trim?  The CT automaticly provides the best most accurate trim for the aircraft weight and balance.  flying with it off, means that after only a few seconds the aircraft is out of trim.  Open up the E6B and watch how the weight changes every second the engines are running.

[Raygun]

I got to ask, why not take advantage of combat trim?  The advantage of using combat trim is that it keeps the aircraft trimed and flying at it's best possible speed.  Where flying the aircraft out of trim means that the aircraft is not flying at it's best possible speed and thus not giving you it's maximum performance.  You can use trim at any point and if you do, elevator trim will take you out of CT.  You would have to alt x to turn CT back on.    Someone tell me what advantage anyone has flying an aircraft out of trim?  The CT automaticly provides the best most accurate trim for the aircraft weight and balance.  flying with it off, means that after only a few seconds the aircraft is out of trim.  Open up the E6B and watch how the weight changes every second the engines are running.

Using CT in the P-38 really limits your dive. CT in the P-38 pushes your nose down when you're diving making it worthless if you are in a compressed dive, in fact it will keep you in a compressed state until you switch to manual.

On some planes CT is fine, the P-38 isn't one of those.

The counter-rotating props make it so that all you have to do is trim the elevator to a little below neutral and you're set.

[Murdr]

I got to ask, why not take advantage of combat trim?  The advantage of using combat trim is that it keeps the aircraft trimed and flying at it's best possible speed.  Where flying the aircraft out of trim means that the aircraft is not flying at it's best possible speed and thus not giving you it's maximum performance.  You can use trim at any point and if you do, elevator trim will take you out of CT.  You would have to alt x to turn CT back on.    Someone tell me what advantage anyone has flying an aircraft out of trim?  The CT automaticly provides the best most accurate trim for the aircraft weight and balance.  flying with it off, means that after only a few seconds the aircraft is out of trim.  Open up the E6B and watch how the weight changes every second the engines are running.

CT obstructs dive recovery in a plane like the P-38 that can suffer compression.  The faster you go, the more it trims nose down, the harder it will be to recover from the dive.  CT is merely a table of trim settings for a standard clean configuration.  If you are maneuvering with flaps, CT will actually have you out of trim.  In the F4U and P-38 specifically, if you are trimmed for cruising speed, and leave it there during combat, as the speed slows down, and flaps deploy, you will generally be close to being in trim.  With CT on, in the same situation, you will become very nose light in the same situation.  This is not optimal for gunnery to be fighting the "balloning" effect and firing while forcing the stick forward.

Try this in a P-38.  Manual trim the elevators to the bottom of the L, reduce speed to 150 and deploy full flaps.  Typically you'll have to push forward on the stick very slightly to keep the nose level.  Now do the same with CT on, and you'll see how far out of trim you really are.

Also, the way trim works in AH, it effectively adjusts the rest point of the virtual stick in relation to the center point of your joystick.  The effect at slow speeds is that you will have less range of motion on your joysticks back stick before reaching stall conditions.

[Traveler]

CT obstructs dive recovery in a plane like the P-38 that can suffer compression.  The faster you go, the more it trims nose down, the harder it will be to recover from the dive.  CT is merely a table of trim settings for a standard clean configuration.  If you are maneuvering with flaps, CT will actually have you out of trim.  In the F4U and P-38 specifically, if you are trimmed for cruising speed, and leave it there during combat, as the speed slows down, and flaps deploy, you will generally be close to being in trim.  With CT on, in the same situation, you will become very nose light in the same situation.  This is not optimal for gunnery to be fighting the "balloning" effect and firing while forcing the stick forward.

Try this in a P-38.  Manual trim the elevators to the bottom of the L, reduce speed to 150 and deploy full flaps.  Typically you'll have to push forward on the stick very slightly to keep the nose level.  Now do the same with CT on, and you'll see how far out of trim you really are.

Also, the way trim works in AH, it effectively adjusts the rest point of the virtual stick in relation to the center point of your joystick.  The effect at slow speeds is that you will have less range of motion on your joysticks back stick before reaching stall conditions.

Murdr,  are you saying that when I change the airfoil shape of the wing by adding flaps  that the CT will not trim out the pitch up?