Not to be argumentative, but as i understand it, Bud's explanation ignores t
he issue reported/described in the other articles, namely that at altitude t
here is less flutter damping for the same reasons Bud explains wrt the struc
tural limits. So for flutter specifically it is TAS that is the determining
limit, and not IAS. Taken to the extreme, the U2 sometimes operates near "
coffin corner" where flutter speed is very near stall speed (IAS is indicati
ng near stall, but they are so high and the air so thin that they are near t
he risk of flutter). It is also why the http://www.perlanproject.org/ glide
r is heavily instrumented to detect the onset of flutter as they go higher a
nd higher in their record attempts.
Taht said, it is comforting to know that Ivan has tested Vd with stick excit
ation to 8000 feet, so i would assume that this could be used as the deratin
g baseline when going to higher TAS's.
Cheers,
Pete
A239
> On Jan 9, 2018, at 7:08 AM, William Daniell <wdaniell.longport@gmail.com> w
rote:
>
> Bud thanks, sets my mind at rest.
>
> William Daniell
> LONGPORT
> +57 310 295 0744
>
>> On Sun, Jan 7, 2018 at 11:09 PM, Bud Yerly <budyerly@msn.com> wrote:
>> 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.
The indicated is only 125 ish. You cannot pull enough G to achieve 6 Gs be
fore 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 g
reen arc for gust factor(turbulent speed).
>>
>> That gust factor is what you need to be aware of in the turbulence of the
mountains.
>>
>> "Aircraft Performance" by Domash explains it.
>> So does the FAA. For finding high speed affects, the USAF F104 VN diagra
m is on Wikipedia and shows how Mach affects figure in for high TAS.
>>
>> TAS is important in turn rate, radius, navigation, and determining your M
ach and Q velocity. But it is your Q (dynamic pressure), aka IAS, that affec
ts, 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 k
now for the plane. TAS and Ground Speed affect your pilotage which is a dif
ferent topic.
>>
>> Again, in mountain flying, you need to know your turn diameter when valle
y flying, high altitude patterns (wider pattern necessary), lead turns to a r
adials etc. (especially In high speed aircraft) and in light aircraft in ver
y high elevations. Engine performance vs airspeed bleed off becomes a facto
r 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?
>> To: europa-list@matronics.com
>>
>>
>> Bud
>> Does this apply even at the upper altitude range ....say 13k or 15k?
>> Will
>>
>>
>>> On Jan 4, 2018 22:19, "Bud Yerly" <budyerly@msn.com> wrote:
>>> Yep Graham,
>>> Airplanes only feel air pressure, not the velocity of the molecule alone
. Dynamic pressure is =C2=BD Density times Velocity Squared or IAS (actua
lly you have calibrated then equivalent) is what the airplane feels. Those R
V guys got all hung up on this and confused everyone.
>>>
>>> Bottom line, what you read on the airspeed indicator counts. TAS is imp
ortant (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
>>>
>>>
>>> Sent from Mail for Windows 10
>>>
>>> From: owner-europa-list-server@matronics.com <owner-europa-list-server@m
atronics.com> on behalf of Pete <peterz@zutrasoft.com>
>>> Sent: Thursday, January 4, 2018 5:49:37 PM
>>>
>>> To: europa-list@matronics.com
>>> 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@btinternet.com> <ivanshaw@btintern
et.com> wrote:
>>>> All our company aircraft were tested to Vd, 10% over Vne. And not just t
aken to the speed but then tested [short stick and rudder raps] to see if an
y 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 knowledg
e we have not had any reported flutter incidence on the entire fleet. As you
mentioned Pete did exceed Vd on a few occasions.
>>>>
>>>> Ivan
>
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