Replies to This Discussion

3D RoboticsPermalink Reply by Chris Anderson on March 27, 2009 at 1:00pm

That's a good question. I'm thinking 15 (ie, GPS ignores altitude when calculating ground speed) but have never tested that.

• ▶ Reply

Permalink Reply by wayne garris on March 27, 2009 at 1:15pm

definitely worthy of testing if no one has a definite answer

• ▶ Reply

ModeratorPermalink Reply by Gary Mortimer on March 27, 2009 at 1:01pm

Ah well, perhaps better to think of it as groundspeed I think.

So the wind would be more of a factor, ie if its into it or not. 30 knot airspeed into 15 knot wind 15 knots over the ground, turn that around and head the other way you would still be fly at 30 knots but making 45 over the ground.

I think I would be right in saying the only way to measure the airspeed of the airframe would be with a pitot.

Oh I see where you are going with that now I have re-read it.

I think it would adjust, otherwise how else can it stay looking right when I'm flying a real aircraft??

But I stand to be corrected, a better explaination will be forthcoming I'm sure!

G

• ▶ Reply

Permalink Reply by Cody Lewis on April 3, 2009 at 3:20pm

GPS speed (and heading) are calculated from taking sequential recordings of the location (lat and long) and comparing them. Since lat and long are 2D, it follows that speed (and heading) are also 2D.

• ▶ Reply