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Date: Thu, 21 Jan 1999 10:01:19 -0600
From: Snowbird <snbird@ibm.net>
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Subject: Re: Va for 152 seems low?
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St Stephen Ames wrote:

> My plane, excuse me, I fly it so much I think it's mine ;-), the plane > I fly has a little placard that says manuevering speed is 104...That 
> seems pretty low to me...How would you ever get close to Vne(149)?

Saint Stephen,

This sounds like a fundamental confusion about what Vne and Va
mean.

Va has nothing to do with exceeding Vne.  Va is defined as the
speed at which the plane will stall before the G limits for the 
(oh, gee, I'll get this wrong) category in which the aircraft
is certified and being flown, are exceeded.  If you look carefully at
the POH for an aircraft with different normal and utility certification,
I think you'll see different maneuvering speeds listed for normal
and for utility operation (true for C172 POH).  The G limits in 
utility category are higher, this is why Va is higher in utility
category, on the same airframe.

It is very possible to pull multiple Gs at a much lower speed than 
Vne or even normal cruise; this is the principle which makes aerobatic
flight in non-aerobatic aircraft by novice pilots so very dangerous. 
One loop is worth one thousand words trying to explain.

Vne on the other hand has nothing to do with exceeding the G
limits of the airframe, but has to do with a speed at which 
various effects could cause structural damage at lower Gs.

No time to write full explanation, but I suggest you read up on
what Va, Vne, and Vno really mean.  John Denker's online book may
have something. I believe Kerstner's books have a good explanation,
"The Science of Flight, Pilot Oriented Aerodynamics" definately
does.  

This is also the sort of question you ought to ask your CFI.

Snowbird

