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  #21  
Old 03-29-2018, 11:07 PM
Bevan Bevan is offline
 
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Quote:
Originally Posted by TASEsq View Post
Hi all,

Seems like perhaps the place to ask..

Why do RV’s quote VNE as a TAS?...

...As far as I figured, VNE was an aerodynamic airframe strength issue - so it makes sense that it is based on IAS (I.e: the number of bits of air pushing against the airframe).
Yes, as I understand it... VNE is dictated by airframe strength but the RVs are fast and capable of altitudes higher than other normally aspirated aircraft. So, one of the limiting factors is flutter BECAUSE flutter has to with resonance which has to do with TIMING and natural frequencies of vibration of the structure, particularly the tail feathers. Exciting those frequencies (of airframe vibration) has to do with the ACTUAL speed of the air molecules of air flowing over the surface. That means the airspeed of interest is TAS not IAS. Since there can be quite a difference at the altitudes where our RVs can play, TAS becomes the one to watch. My understanding anyway.

Bevan.
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Last edited by Bevan : 03-29-2018 at 11:09 PM.
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  #22  
Old 03-30-2018, 12:18 AM
hohocc hohocc is offline
 
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Quote:
Originally Posted by Hongie View Post
So who's right (in your opinion)
You, the blue poster.
The other guy is trying to say his bike is faster going downhill than your bike is going uphill. It is, but the argument is nonsense.
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  #23  
Old 03-30-2018, 06:00 AM
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BCP Boys BCP Boys is offline
 
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Wow, isn't this stuff like the ABC's of the Private Pilot training? How could someone argue these points. There is only 1 right answer. If this person was a good friend and I could cut up with them without insulting them I would say, "You can't fix stupid", but If were just an acquaintance then I would respectfully walk away or end this discussion.
Some things are just not meant to be debated. Definitions of TAS, IAS and GS falls in that category.
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  #24  
Old 03-31-2018, 04:13 AM
Hongie Hongie is offline
 
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Wow this blew up! I've been away training in my RV, thanks for your input all. I'm not wanting to insult either of these guys or anything, just wanted to be sure of my arguments. Reassuring that my brain still works sometimes.
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  #25  
Old 03-31-2018, 05:02 PM
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grubbat grubbat is offline
 
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Default Another gee wiz

Another thing that may bewilder the non-Vanís group is that on the Vanís designs, Vno is based on indicated airspeed regardless of altitude and Vne is based on true airspeed. Let them chew on that for a little bit.
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  #26  
Old 03-31-2018, 08:02 PM
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airguy airguy is offline
 
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Quote:
Originally Posted by grubbat View Post
Another thing that may bewilder the non-Vanís group is that on the Vanís designs, Vno is based on indicated airspeed regardless of altitude and Vne is based on true airspeed. Let them chew on that for a little bit.
Well, just like anything else on the interwebz - just because somebody says it, doesn't mean it's accurate.
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  #27  
Old 03-31-2018, 08:24 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by airguy View Post
Well, just like anything else on the interwebz - just because somebody says it, doesn't mean it's accurate.
True

But in this case it is accurate.
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  #28  
Old 04-01-2018, 10:21 AM
TeamFAS TeamFAS is offline
 
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I never could wrap my head around true airspeed until I started flying jets, so I feel the other guy's pain. For the guys who never climb over 4500' I could see it happening.
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