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  #1  
Old 03-28-2018, 11:51 PM
Hongie Hongie is offline
 
Join Date: Sep 2012
Location: Mackay Australia
Posts: 40
Default TAS vs IAS/GS

Hi All, I've had a bit of a facebook discussion with a couple of flying friends regarding aircraft performance, culminating in a question about the TAS performance of one of said friends Tecnam.

Screenshots linked to discussion, it has been anonymized, so please indulge me all the pretty colors.

Let me know your thoughts please, because its driving me a bit insane

https://i.imgur.com/Vn2ZPxI.jpg
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  #2  
Old 03-29-2018, 01:11 AM
hohocc hohocc is offline
 
Join Date: Sep 2008
Location: Christchurch, New Zealand
Posts: 187
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That's just going to keep going around in circles for a long, long time!
I had a similar discussion with a guy about QNH/QFE years ago...
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  #3  
Old 03-29-2018, 01:13 AM
Hongie Hongie is offline
 
Join Date: Sep 2012
Location: Mackay Australia
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Quote:
Originally Posted by hohocc View Post
That's just going to keep going around in circles for a long, long time!
I had a similar discussion with a guy about QNH/QFE years ago...
So who's right (in your opinion)
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  #4  
Old 03-29-2018, 04:49 AM
dwranda dwranda is offline
 
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Location: Jamestown,NY
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I know this doesn't help your discussion but the first thing that came to my head was why not just get an RV? If you're looking for something that goes the speed of an RV it seems like that's the easiest thing to do but maybe I misunderstood the question.
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  #5  
Old 03-29-2018, 05:15 AM
Hongie Hongie is offline
 
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Location: Mackay Australia
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I have an rv. I?m the poster in blue
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  #6  
Old 03-29-2018, 05:33 AM
dwranda dwranda is offline
 
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ahhhh. So someone wants to keep up with RV's without getting an RV. What do you think the reason is for not getting an RV?
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  #7  
Old 03-29-2018, 05:38 AM
Hongie Hongie is offline
 
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Location: Mackay Australia
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haha Not really sure about that.

I'm more questioning their reluctance to talk in TAS. To me, TAS at a give DA is the only true measure of cruise performance. these guys keep going on about GS and IAS. TAS is performance of the aircraft, GS is how well the weather worked out on the day.
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  #8  
Old 03-29-2018, 07:02 AM
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ChiefPilot ChiefPilot is offline
 
Join Date: Jan 2005
Location: Twin Cities, MN
Posts: 1,565
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Quote:
Originally Posted by Hongie View Post
I'm more questioning their reluctance to talk in TAS. To me, TAS at a give DA is the only true measure of cruise performance. these guys keep going on about GS and IAS. TAS is performance of the aircraft, GS is how well the weather worked out on the day.
I agree with you.

Someone needs some quality time with a good CFI at their next flight review. It seems pretty clear that the individual lacks a good understanding of TAS vs. IAS vs. ground speed.
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  #9  
Old 03-29-2018, 08:35 AM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default Resistance is futile.........?

Unless someone is interested in learning it probably is futile.

It is still fairly common for people to walk in to the booth at fly-ins and ask "did you fly one of these airplanes here"? After answering yes they ask "what were you indicating"?
When I answer "137 Kts, but the true airspeed was 165 Kts and with the tail wind I had, since I was eastbound, I had ground speeds of 190 Kts for quite a while." At that point their eyes begin to glaze over.....

There is a lot of the non professional pilot community that has very limited understanding of the difference between IAS and TAS. I guess that is understandable since a lot of the now aged pilots grew up flying airplanes that wouldn't very easily climb high enough that talking in TAS really mattered much. Particularly the ones who flew in the flat lands part of the country.
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  #10  
Old 03-29-2018, 08:50 AM
kaweeka kaweeka is online now
 
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Ever since getting my RV and joining VAF, I have noticed the level of discussion to be leaps and bounds ( with regards to knowledge AND temperament) above those of former owner groups of which I have been involved. There is a professionalism to subjects and a thoroughness of explanation. I'm attributing that to the fact that, when building, one needs a higher level of understanding. I cold be wrong in my assessment but, whatever the reason, this place is GOLD! Thank you for teaching and explaining. I, for one, find the discussions invaluable.
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