Will,
I'm still on the road but here goes.
Short answer:
Q is force, whereas True is just speed.
Long Answer:
Think of it this way. The mono cruises at 175 TAS at 18,000 with a 914. T
he indicated is only 125 ish. You cannot pull enough G to achieve 6 Gs bef
ore you stall or have a vertical gust break the plane. Is the mono above VN
E, at 175 TAS, NO. Heck you are not at Vno or about 131 KIAS which is your
green arc for gust factor(turbulent speed).
That gust factor is what you need to be aware of in the turbulence of the m
ountains.
"Aircraft Performance" by Domash explains it.
So does the FAA. For finding high speed affects, the USAF F104 VN diagram
is on Wikipedia and shows how Mach affects figure in for high TAS.
TAS is important in turn rate, radius, navigation, and determining your Mac
h and Q velocity. But it is your Q (dynamic pressure), aka IAS, that affect
s, flutter, structural deformation, and your stall and not to exceed speed
s. This means what you read on your airspeed indicator is what you need to
know for the plane. TAS and Ground Speed affect your pilotage which is a
different topic.
Again, in mountain flying, you need to know your turn diameter when valley
flying, high altitude patterns (wider pattern necessary), lead turns to a r
adials etc. (especially In high speed aircraft) and in light aircraft in ve
ry high elevations. Engine performance vs airspeed bleed off becomes a fac
tor as well.
Regards,
Bud Yerly
Custom Flight Creations
From: William Daniell
Sent: Friday, January 5, 4:07 PM
Subject: RE: Europa-List: Are Vne and Va IAS or TAS?
Bud
Does this apply even at the upper altitude range ....say 13k or 15k?
Will
On Jan 4, 2018 22:19, "Bud Yerly" <budyerly<mailto:budyerly@msn.com>@msn.co
m<mailto:budyerly@msn.com>> wrote:
Yep Graham,
Airplanes only feel air pressure, not the velocity of the molecule alone.
Dynamic pressure is =BD Density times Velocity Squared or IAS (actually y
ou have calibrated then equivalent) is what the airplane feels. Those RV g
uys got all hung up on this and confused everyone.
Bottom line, what you read on the airspeed indicator counts. TAS is import
ant (actually Mach number) as the skin heats up due to friction which is a
different ball of wax. I was always a slow speed aero guy to match my mind
.
Regards,
Bud Yerly
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From: owner-europa-list-server@matronics.com<mailto:owner-europa-list-serve
r@matronics.com> <owner-europa-list-server@matronics.com<mailto:owner-europ
a-list-server@matronics.com>> on behalf of Pete <peterz<mailto:peterz@zutra
soft.com>@zutrasoft.com<mailto:peterz@zutrasoft.com>>
Sent: Thursday, January 4, 2018 5:49:37 PM
Subject: Re: Europa-List: Are Vne and Va IAS or TAS?
Hi Ivan, just to confirm, Vd IAS @8000ft DA?
Thanks again!
Pete
On Jan 4, 2018, at 5:21 PM, <ivanshaw<mailto:ivanshaw@btinternet.com>@btint
ernet.com<mailto:ivanshaw@btinternet.com>> <ivanshaw<mailto:ivanshaw@btinte
rnet.com>@btinternet.com<mailto:ivanshaw@btinternet.com>> wrote:
All our company aircraft were tested to Vd, 10% over Vne. And not just take
n to the speed but then tested [short stick and rudder raps] to see if any
flutter mode could be excited at Vd. I have performed these tests at/up to
8000ft . We have never experienced any flutter mode. I also tested the tail
plane underbalanced and over balanced with the same results. To my knowled
ge we have not had any reported flutter incidence on the entire fleet. As y
ou mentioned Pete did exceed Vd on a few occasions.
Ivan
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