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View Full Version : P38 Compressability in dives from 1000 meters?



LuftLuver
07-25-2004, 05:19 PM
Why does the P38 enter compressability in thick-air dives from as low as 1000 meters? I've heard of this happening in dives from 30,000 ft maybe.

What we have in FB seems very gimmicky, like an excuse to have a need for dive brakes.

Discuss please.

http://www.pilotlist.org/montagne/images/p38.jpg

β"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Ά
"All your bases are belong to us."

LuftLuver
07-25-2004, 05:19 PM
Why does the P38 enter compressability in thick-air dives from as low as 1000 meters? I've heard of this happening in dives from 30,000 ft maybe.

What we have in FB seems very gimmicky, like an excuse to have a need for dive brakes.

Discuss please.

http://www.pilotlist.org/montagne/images/p38.jpg

β"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Ά
"All your bases are belong to us."

civildog
07-25-2004, 06:05 PM
For compressibility to happen the plane needed to reach around 515 kph IAS. If you can get there from 1000 meters, then you have that problem. Here's a good link for the Lightening:http://www.aviation-history.com/lockheed/p38.html

http://img78.photobucket.com/albums/v304/civildog/CivilDogsignatureMASTER2.jpg

I often think the whole world is out to get me, but then I remember that some of the smaller nations are neutral.

58th AVG "WannaBees" ...We fly where the angels fear to tread!

Dawg-of-death
07-25-2004, 08:06 PM
Needs a little work perhaps but I think in fb air density isnt modled as the speed is for compression.

Bad-MF(Mongrel Fighter) AKA .......Dawg-of-death

LuftLuver
07-26-2004, 12:45 AM
So assuming it's a limitation on the FB model, should this one plane suffer from compressability while the others are completely unbothered by it? My Jug doesn't do this at 800+ KPH. Really, the P38 elevator becomes worthless at relatively low speeds.

Seems like an excuse to have a working dive brake. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-sad.gif

β"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Άβ"Ά
"All your bases are belong to us."

civildog
07-26-2004, 01:14 AM
I'd just stick to the L model and use the brakes then. What's an extra keystroke among friends?

http://img78.photobucket.com/albums/v304/civildog/CivilDogsignatureMASTER2.jpg

I often think the whole world is out to get me, but then I remember that some of the smaller nations are neutral.

58th AVG "WannaBees" ...We fly where the angels fear to tread!

Aaron_GT
07-26-2004, 01:35 AM
"So assuming it's a limitation on the FB model, should this one plane suffer from compressability while the others are completely unbothered by it?"

Other planes are bothered by it, although the P47 isn't one of them. The BI-1, for example, becomes impossible to pull out, even experiencing control reversal (if somewhat above the P38 compressibility speed).

Dammerung
07-26-2004, 02:04 AM
The P-38 experiences Compressability at 400mph... The P-47 does as well, but much higher...

Oh, there are no fighter pilots down in hell...
Oh, there are no fighter pilots down in hell...
The whole damn place is full of queers, navigators, and bombadiers...
Oh, there are no fighter pilots down in hell...

F19_Ob
07-26-2004, 02:53 AM
In the 109 I have been surprised a few times to have a p38 on my tail at 5000m altitude. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif The p38 ofcourse have no probs reaching that hight, but I was surprised to be jumped by such large ac, although its profile is small.

I noticed that a good way to shake it off was to do a bunting dive and when the p38 follows and start shooting U bunt again, hard to a vertical dive. The impulse of the opponent is to roll and go after, and if a p38 does this he probably is overspeeding already or cant pull out of it soon enough.
yaks, La7,spits and p51's might do this mistake too, but they can pull out of it slightly easier.
If sitting in a 109k4 u know that no allied will make 890km/h in a dive and go home. My only problem in the K4 is that I seem to get shot down before I reach 890km/h.
http://ubbxforums.ubi.com/images/smiley/icon_twisted.gif

F19_Olli72
07-26-2004, 04:23 AM
Ob as you know ive been trying some small dive tests in P-51B. It can make 870 km/h keeping it with vibrations but no control surface loss. 860 can be kept for pretty long time. Lost an aeliron at 890 but could still make it. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

http://img70.photobucket.com/albums/v40/Olli72/Forgotten%20Battles/screenshotart/SIG_G50.jpg (http://www.screenshotart.com)