Negative drag

[technion]

Hi,

This sounds (I know I know.. always harder than it sounds) quite easy to implement.

If a nosecone could have, say, -0.2 drag, it would actually HELP the aerodynamics (like it's meant to in real world).

[Smidge204]

So what happens if I build a craft that's essentially nothing but cubic trusses and nosecones?

That's just an easy example of why this is a bad idea. Drag force is proportional to velocity, so with a negative drag that means the faster you go the more negative drag force (ie thrust) these parts will produce. It would be easy to build a craft that approaches infinite velocity with this feedback loop.

=Smidge=

Edited December 11, 2013 by Smidge204

[technion]

I'd imagine.. it would have no engines, no fuel, and no drag Obviously it could cap at 0.

[Nuke]

this sounds less like a flight model improvement and more like a dirty hack to me.

[Deathsoul097]

Or the devs could just make most of FAR stock...

[Whatshtisthis]

Isn't the current drag model something like averaging the drag of the parts? If you did that, the crafts with lots of nosecones would have negative drag, coupled with the current aerodynamics model, the Full-of-Nosecones crafts would have negative drag overall, even if they are shaped in an not-so-aerodynamic way.

[Nuke]

i want to say its a direct (vector) sum. averaging doesn't work because that would only give you the drag of a single part where you want the total drag for the whole system. though they may be able to toy with coefficients such as giving any parts behind a nosecone a cd reduction. it would be effective if its set up so you could never get to a cd of zero. you might do a hard cutoff at %50 of the original cd, so if a cd of 0.4 and -0.5 of cd bonuses it would cut you off at a cd of 0.2. though it might be better to smooth it out on a curve.

though thats fudging it, i have a few ideas about drag models but its too late to get into them.

Edited December 11, 2013 by Nuke

[Eric S]

I'd imagine.. it would have no engines, no fuel, and no drag Obviously it could cap at 0.

The negative drag suggestion has come up before and people have actually experimented with it, and in order for the negative drag to have a noticeable effect on the drag of a real craft, it had to be enough that craft that were built as Smidge suggests could use the force of a single decoupler to reach solar escape velocity.

You could get around this by doing something like "nosecones reduce the drag coefficient of all parts connected below it by X%, but at that point, your asking them to write code for a minor improvement to a placeholder subsystem. The KSP devs know that their current aerodynamic model is at best a gross approximation, and every time the subject of replacing it has come up, if an answer was given, it was that it would be replaced at some point.

[Nuke]

aerodynamics is complicated. its not really something that can be fixed with a few simple hacks.

[frizzank]

Its not that complicated, I can fold a piece of paper and make it fly!

The previous statement was sarcasm for those who don't get it.

[Eric S]

aerodynamics is complicated. its not really something that can be fixed with a few simple hacks.

True, even FAR has it's share of approximations.