Today's Message Index:
----------------------
1. 03:09 PM - Re: Numbers (dmaib@me.com)
2. 05:27 PM - Re: Numbers (Bob Turner)
3. 07:34 PM - Re: Re: Numbers (Kelly McMullen)
4. 08:34 PM - Re: Numbers (Bob Turner)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Checked today and GRT Hxr allows display of TAS VNE as IAS. So, today at 3500 feet
msl and about 12 degrees C, my VNE was shown as about 191 KIAS. I haven't
had a chance to check that on the whiz wheel, but the number seemed reasonable.
--------
David Maib
RV-10 #40559
New Smyrna Beach, FL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=452319#452319
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
I'm sure Vans' lawyers are telling him to never say anything, but I do wish the
company was a little more forth-coming. Was the prototype dived to some speed?
At what altitude (surely higher than sea level)? This whole business of specifying
Vne as a TAS, when the FARs require specifying it (along with altitudes,
if necessary) in IAS for normally certified aircraft, just bothers me.
PS Dave, your ias/tas conversion looks about right to me.
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=452329#452329
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Van's has a white paper on the subject on their website. Thy physics say
the design flutter speed is a function of TAS. They make the case that
extra horsepower via turbo or other engine mods risks being able to
exceed the number in level cruise at altitude around 12K and up.
Type certified aircraft have to convert that to IAS with some empirical
evidence of margin of safety via dive testing. Doing the testing is
likely to be rather expensive by the time you instrument the airframe,
mount drag chutes, quick release doors and risk loss of the aircraft if
calculations are wrong. While loss of an aileron is relatively benign,
loss of elevator or rudder is considerably more serious.
On 1/26/2016 6:18 PM, Bob Turner wrote:
>
> I'm sure Vans' lawyers are telling him to never say anything, but I do wish the
company was a little more forth-coming. Was the prototype dived to some speed?
At what altitude (surely higher than sea level)? This whole business of specifying
Vne as a TAS, when the FARs require specifying it (along with altitudes,
if necessary) in IAS for normally certified aircraft, just bothers me.
>
> PS Dave, your ias/tas conversion looks about right to me.
>
> --------
> Bob Turner
> RV-10 QB
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=452329#452329
>
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
Kellym wrote:
> Van's has a white paper on the subject on their website. Thy physics say
> the design flutter speed is a function of TAS. They make the case that
> extra horsepower via turbo or other engine mods risks being able to
> exceed the number in level cruise at altitude around 12K and up.
>
>
[/quote]
I've read the white paper. It contains a certain amount of nonsense. Flutter depends
on TAS and air density. IAS depends on TAS and density. So between TAS,
IAS, and density one can choose any two to express the equations. For example,
with lift, we often choose IAS and density, because the density magically drops
out of the equations. Does this mean lift doesn't depend on density? Of course
not. It's included in just the right way in the definition of IAS. Now with
flutter, there are many possible modes, and the relationship between density
and TAS varies from one mode to the next. So it is not possible to define it
away for all cases. You need, in general, two variables. It is not correct to
say "flutter depends on (only) TAS".
This business of higher than standard power is a red herring. Any standard -10,
when light, can climb well into the flight levels. Nose it over to come down,
and you can easily get as high a speed as desired. I would like to know, whether
thru analysis or testing, where certain airspeeds (IAS or TAS) AND densities
need to be observed as limiting.
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=452335#452335
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|