Finding true vehicle height

[Daishi]

Halp!

Trying to get some schematics designed for my family of launch vehicles - and I'm having a bit of trouble finding out exactly how tall they are. I'm not too sure the altitude readout before launch is very accurate.

Does anyone know of a sure-fire way to measure your creations within the game? I've searched a bit but I cant seem to find anything on the forums or the spaceport.

(also, first post. Woo!)

Edited October 12, 2013 by Daishi
Resolved, thanks :D

[blizzy78]

Hmm, this should work: Place a single pod on the launch pad, note altitude. Next, place pod atop vessel, note altitude. Subtract.

[Daishi]

Brilliant - 68 meter discrepancy. Simple as that

Just noticed though, that decoupling a payload from my rocket while still on the pad, results in no altimeter change. It should have - the rockets lost about 30% of its height. Makes me wonder if height is set based on the position of the command pod, and not what's above it.

[Diazo]

I am 99% sure that the height displayed at the top of your screen is height above sea level for the currently set "Control From Here" part.

To test you could stack two orange tanks with a probe core on each end, then swap "Control from here" between the two cores and the altitude should change.

The only other alternative is that it is from the center of mass of your currently controlled ship, in which case it will not change when you swap between the two cores.

D.

[blizzy78]

Brilliant - 68 meter discrepancy. Simple as that

So, did it work? Not sure what you're trying to say.

[Geschosskopf]

Just noticed though, that decoupling a payload from my rocket while still on the pad, results in no altimeter change. It should have - the rockets lost about 30% of its height. Makes me wonder if height is set based on the position of the command pod, and not what's above it.

If the ship doesn't already have them, add ladders up the side from the highest crew compartment to the very top. EVA a Kerbal and have him climb to the very top of the rocket. Then have him jump off ("for SCIENCE!") and time how long it takes him to hit the ground. Save this value T. Then:

Height = 1/2 * (9.8) * T^2

Once you have the answer, delete the ladders you added to perform this test.

[numerobis]

I am 99% sure that the height displayed at the top of your screen is height above sea level for the currently set "Control From Here" part.

It is from the root part. I've tried; changing the control-from-here pod doesn't change the altitude. It would be handy/cheaty if it did, so that you could get better Isp on liftoff

[Diazo]

Oh. Hmm.

My root part is 99% of the time my control from here part on launch so that's where my logic when wrong I guess.

Good to know.

D.

[Daishi]

If the ship doesn't already have them, add ladders up the side from the highest crew compartment to the very top. EVA a Kerbal and have him climb to the very top of the rocket. Then have him jump off ("for SCIENCE!") and time how long it takes him to hit the ground. Save this value T. Then:

Height = 1/2 * (9.8) * T^2

Once you have the answer, delete the ladders you added to perform this test.

How cruel - I take good care of my flight crews!

Thanks guys - so its measured from the root part, minus 68 meters to account for its altitude above sea level.

I'm going to have to make a few dummy rockets with the root part on top to make these measurements - most of my launch vehicles are controlled from underneath the payload