pyro, compressability model is wrong

[Zigrat]

hi ,
i was getting buffet in p38 way below its critical mach of .68 at 25000 ft.

mach number depends on temperature, not density.

for air (perfect gas model) in metric units c=20.1*t^.5 (t in kelvin)

this means mach 1 = 686 mph at 25,000 ft


.68 mach = 466 mph


right now the p38 has buffet far below this speed

thanks

[This message has been edited by Zigrat (edited 04-06-2001).]

[BUG_EAF322]

And fix the funny stall (wing drop left)

thank u

[Glasses]

Make Stall buffeting warning of aircraft to those who had the historically
so we can tell a stall from something else than the cheap horn.BETTER YET kill the horn and make buffeting prior to stall standard on all aircraft.

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Glasses---I may have 4 eyes ,but you only have one wing.
Besser tot als rot

[Animal]

Zigrat,
wouldnt that mean a total rewrite of the flight models?
I have verify my data to see if it matches yours, but if it does it does mean something big.

Also, you are talking only about buffeting right? cause the real P-38 would compress before 466 Mph.

But I hope your data is right, any info that would make my beloved P-38 any better, I welcome.

Now we need those 2k bombs  

[funked]

Let's keep it on topic guys.
Zig I will do some test flying on the P-38 and other birds, and try to compare with published Mach numbers.

[BUG_EAF322]

Widewing or Badboy posted already some numbers long before this .
This is just another repeating off things

I never saw one reaction on it unfortunally

yeah i get tired by that

:rolleye:

[Tac]

Yep, its all been talked, data provided by F4DOA and Widewing and others about the flaps, stalls, etc... no reactions.

The 38 is also extremely fragile as well, many p-38's came home with gaping holes all over and could still land, in AH you get a few .50 pings and the whole damn thing breaks apart. Has HT switched the damage model of the P-38 and the Zeke? Each one behaves like the other should. Zeke can eat and eat and eat and eat lead and still fly.  

[F4UDOA]

Zig,

I think feeling the shock waves before critical mach is reached is accurate. Similar to pre-stall buffeting.

As an A/C approaches critical mach shock waves develope on the leading edge of the wing and work there way down toward the trailing edge. When they reach the elevator portion of the horizontal stabizer is when you loose the ability to pull up and shred your elevator control surfaces. However the pre-compressability can be felt as the shock waves progress down the control surfaces.
Hence the invention of the flying tail to maintain control through mach 1. Once through mach control then returns when the shock waves have moved off of the elevator all together.

There are some great charts out there some where showing wind tunnel test of this.

[This message has been edited by F4UDOA (edited 04-07-2001).]

[BBGunn]

I give up on this one-don't think they want to change it.

[Raubvogel]

 

Originally posted by Tac:

The 38 is also extremely fragile as well, many p-38's came home with gaping holes all over and could still land, in AH you get a few .50 pings and the whole damn thing breaks apart.

Yeah it does seem very fragile. Take a few rounds in the tail and it just falls to pieces.

[Pyro]

The buffet is preceding the actual onset of the compressibility effect.  



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Doug "Pyro" Balmos
HiTech Creations