Maneuvering speed vs. Penetrations speed.

Alchemy

Alchemy

Well-Known Member
Can anyone explain the differences? No dirty jokes please
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My understanding is that maneuvering speed and turbulence penetration speed are the same-the speed at which the wing will stall before structural failure.
 
Well, they're not always the same speed. Some planes only have Va, and some have the additional "Turbulence Penetration Speed". In the M20J, for example, Va is from 97 to 116 depending on weight, but Turbulence Penetration Speed is all the way up at 176! Now, I wouldn't fly in continuous moderate turbulence at 176, but there must be a reason for the difference.

Then only thing that I can think of is that maybe they don't expect you to go all the way to the 3.8 Gs that normal category allows. Maybe they figure, "hey, rough air could give them 2.5Gs, and so at 176 they won't exceed that." EXTREME turbulence might give you 3.8 Gs momentarily, so that might be a good time to pull the speed back to Va, where you'd stall before overstressing the airframe (+3.8 - 1.52 Gs). Also, if you were in utility category, theoretically your plane could handle more turbulence (an additional .6 Gs on the positive side) and aerobatic would allow 2.2 Gs more than normal (limited to 6 Gs on the positive end, and - 4.5 Gs on the negative).

That's my guess.
 
Turbelent penatration speed is not based on stalling, but rather controllability. Usually (any aircraft I have seen), the speed is lower than Va. It is a speed range, and the general guidance is for us to fly towards the higher end of that range. Particularly at altitude, the larger danger is loss of control, and due to the lower q factor in gusts, we are actually below Va even at Mmo. The penatration speed keeps us as fast as we can go without running into the upper buffet constantly in turbulence.

It sounds like GA is using a different definition of the speed, essentially saying the Vno or some such, if I read the above post correctly.
 
Thanks for that Seagull. I've been told the same thing as pscraig.

"TPS" = Va because in both cases you want the plane to stall before structural failure.
 
[ QUOTE ]
Usually (any aircraft I have seen), the speed is lower than Va.

[/ QUOTE ]Thanks for making me dig the books out, I'm going to FSI recurrent next week
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The Citation X's Turb air penetration speed is 300KIAS/.90m
Va at FL410 is between 210 and 280 KIAS (depending on weight). Normal IAS at FL410 is approx 290-300.
 
My understanding was that maneuvering speed was the one to use when *you* were doing the maneuvering (as in doing steep turns), whereas turbulence penetration speed was pretty self explanatory.

In a King Air 200 Va is 181 knots and turbulent air pentration speed is 170 knots.
 
Seagull, sorry. Yeah I got it the first time--and I was agreeing with you. My bad grammer: should've had a : where I had a .
 
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