Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

What is True Ground Speed?

Wikiposts
Search
Tech Log The very best in practical technical discussion on the web

What is True Ground Speed?

Thread Tools
 
Search this Thread
 
Old 11th May 2004, 12:17
  #1 (permalink)  
Thread Starter
 
Join Date: Apr 2004
Location: Kappis
Posts: 66
Likes: 0
Received 0 Likes on 0 Posts
What is True Ground Speed?

Hy

I`m little confused;
I know TAS, GS, IAS,CAS,EAS etc. but I dont`t have a clue about the "True Ground Speed"!

What is it, I think it's quite simple, can somebody help me?

Thank you guys

W.K.
WhiteKnight is offline  
Old 11th May 2004, 12:29
  #2 (permalink)  
 
Join Date: Jan 1999
Location: Europe
Posts: 341
Likes: 0
Received 0 Likes on 0 Posts
Never heard of it???

Maybe its since you are flying above the earths surface (ground) you are flying a bigger curve than if you were on the ground for the same angular displacement from the earth's centre, so for the same track miles on the ground you fly a longer distance at altitude...

Therefore your speed to cover that distance in the same time must be greater than if you had to fly that angle at the earth's surface.

Managed to confuse myself too...
320DRIVER is offline  
Old 11th May 2004, 13:04
  #3 (permalink)  
 
Join Date: Aug 2000
Location: UK
Posts: 1,914
Likes: 0
Received 0 Likes on 0 Posts
If you fly around the world at 35,000' (or 6nms altitude), how much further do you travel than doing so on the surface? On the back of a virtual fag packet, difference in circumference is 2xPie (R1-R2), ie 2 x Pie x 6=38 miles. In terms of circumference of 25,000 miles, about 0.15% difference.

I've not heard of 'True Ground Speed'. Did he confuse it with 'True Airspeed'?
Notso Fantastic is offline  
Old 11th May 2004, 20:32
  #4 (permalink)  
DFC
 
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes on 0 Posts
Only a guess but;

True ground speed would be the actual speed over the ground.

Indicated ground speed would be the ground speed indicated by something like an INS system which could be different from true (actual) groundspeed towards the end of a long flight but not by very much.

Other than that, the person could be miximg up TAS and GS or TAS and IAS.

regards,

DFC
DFC is offline  
Old 12th May 2004, 03:00
  #5 (permalink)  
 
Join Date: Oct 2003
Location: Canberra Australia
Posts: 1,300
Likes: 0
Received 0 Likes on 0 Posts
Bit like

DEAD Reckoning or

DED Reckoning.

What is it these days?

Then there is g or G for acceleration and cg or CG for centre of gravity

How did they ever become G or CG?
Milt is offline  
Old 12th May 2004, 03:17
  #6 (permalink)  
 
Join Date: Jul 2000
Location: Dubai - sand land.
Age: 55
Posts: 2,832
Received 0 Likes on 0 Posts
Oi you - who's taken my moniker???

The original "White Knight"
White Knight is offline  
Old 12th May 2004, 05:23
  #7 (permalink)  
 
Join Date: Jun 2001
Location: FNQ ... It's Permanent!
Posts: 4,290
Received 169 Likes on 86 Posts
GS = The GS you had on the last sector, as told to everyone in the bar. This speed increases proportionally with alcohol consumed.

True GS = Actual GS achieved.
Capt Fathom is online now  
Old 12th May 2004, 09:04
  #8 (permalink)  
Thread Starter
 
Join Date: Apr 2004
Location: Kappis
Posts: 66
Likes: 0
Received 0 Likes on 0 Posts
Thank you for your replies;


I think I do not confuse the difference between TAS, GS! I just give you a quote of OAT-Notes:

Distance to accellerate/General Principles Take Off:

"From Netwon's laws of motion, the distance required for a body to reach a speed `V` from rest with a constant acceleration 'a' is : Vē/2a

This speed is True Ground Speed, wheras the lift off speed is an IAS."


Best
W.K.
WhiteKnight is offline  
Old 12th May 2004, 16:16
  #9 (permalink)  

Do a Hover - it avoids G
 
Join Date: Oct 1999
Location: Chichester West Sussex UK
Age: 91
Posts: 2,206
Likes: 0
Received 0 Likes on 0 Posts
Perhaps the author could have called it Actual Ground Speed - which it seems to me is what he actually (sorry) had in mind??
John Farley is offline  
Old 12th May 2004, 17:29
  #10 (permalink)  
 
Join Date: May 2003
Location: U.S.
Age: 50
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Looking for "True Ground Speed"

WK,

I'm looking in the FAR AIM 2004, every Jeppeson manual and handbook, and my own notes looking for true ground speed...I'm just not finding anything about it.

There's indicated airspeed, calibrated airspeed, equivalent airspeed, true airspeed, ground speed, all the bloody V-speeds...stall, manoeuvre, NE, NO...uh...I'm running out of places to look.

Is it a term that is used out of the U.S. with which I am not familiar?

I'll keep looking.

MG
MacGriffyn is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.