What is KSP's aerodynamic model?

[martincmartin]

I'm trying to figure out how to do an efficient ascent, and later I'll tackle descent.  During ascent there's gravity, thrust and aerodynamic drag.  Gravity is straight forward, thrust & mass I can get from various panels, but what about aerodynamic drag?  Is it proportional to the square of the velocity times density times the drag coefficient, or something more complicated?  Is there some way I can predict or measure the drag coefficient from various angles?  In real life, the density is a non-linear function of height.  In KSP, is it simply linear with height?

[Vjrcr]

Good question, Ive been wounder about the aerodynamic model lately too, however I just fall back on the old KSP saying, "more boosters and spacetape" but the sometime it just burns my crafts dishes for RemoteTech.

Edited February 20, 2016 by Vjrcr

[soulsource]

Iirc the ambient pressure and temperature follows a scaled version of earth's atmosphere. I have no idea about the drag model though.

Anyhow, if you want more details, I'd consider installing FAR.

[NathanKell]

 

tl;dr we use the drag equation, and Cd * S is calculated per part.

[OnTheHook]

As far as I know in kerbin the most efficient way to launch is straight up until about 10,000 m then begin your gravity turn. Also if possible if you can keep it below 100 m/s you will save the most delta V because the drag increases a lot once you get above that.

 

[godefroi]

5 hours ago, OnTheHook said:

As far as I know in kerbin the most efficient way to launch is straight up until about 10,000 m then begin your gravity turn. Also if possible if you can keep it below 100 m/s you will save the most delta V because the drag increases a lot once you get above that.

 

This hasn't been the most efficient way to launch for a long time (since 0.90?) Usually, nowdays, this will result in a flipping rocket. Best case scenario, it's very inefficient.

Start your gravity turn at ~1000m. Don't try to accelerate too fast in the lower atmosphere. Shoot for a takeoff TWR of ~1.4-1.6 or so. You should cross the 45 degree mark at somewhere around 18-22km or so.

Learn to watch your "time to apoapsis". Keep it at, say, 1 minute or so all the way up. If you start getting closer than 1m, pitch up; if it starts getting way ahead of you, pitch down.

Edit: obligatory Manley:

 

Edited February 21, 2016 by godefroi

[OnTheHook]

I suppose that is why I was losing delta V. Makes sense. Gotta love Scott always informative.