Ideal re-entry altitudes/speeds/maths

[NathanKell]

@numerobis square root of denisty, cube of speed. Note however that if you're going too fast in too high density air you'll hit turbulent flow and jack up the convection by a factor of up to 100x, so don't take too much advantage of that sqrt.

[numerobis]

My 3500 seems to be wrong, it's more like 3100-3200:

70km orbit is 2296 m/s. Transfer from there to the edge of the SOI is 938 m/s, a total of 3233.

So if you reenter Kerbin SOI at 0 m/s and drop nearly straight down to skim the atmosphere you'll hit it at 3233 m/s. If you reenter to lower altitude, I'd expect it faster yet; and you didn't reenter the SOI with zero relative speed.

 

[NathanKell]

@numerobis orbital velocity doesn't matter, surface velocity does. You need the velocity with respect to the air around you, not the planet's position.

[numerobis]

3 hours ago, NathanKell said:

@numerobis square root of denisty, cube of speed. Note however that if you're going too fast in too high density air you'll hit turbulent flow and jack up the convection by a factor of up to 100x, so don't take too much advantage of that sqrt.

Oh interesting! So what I said, but "10km" where I said 5km -- unless you hit the wall.

[mrclucks]

On 4/20/2016 at 2:20 AM, KocLobster said:

Wouldn't putting them further and further protected behind the heat shield be directly proportional to their decreased effectiveness? They aren't able to create as much drag if they're hiding behind the head shield because of heating issues, right?

I haven't played 1.1 yet but for 1.0.5 your airbrakes give the same drag regardless of where it is. There is no decreased effectiveness untill they're literally not there anymore

[rodrigoelp]

@KocLobster, though you are right that airbrake parts will overheat rapidly, increasing your surface area while reentry gives you the opportunity to create more drag and orientate your probe/ship. Airbrake is mainly intended as a control surface, is not just for planes, is used to help you control anything within an atmosphere. I tend to use them a lot on extremely light space probes (like small robotic landers) just to get my probe in a stable descent (not intended to be fully toggled on)... plus, isn't KSP about coming out with weird contraptions that will get you fame, glory and Jeb super happy?

The advise @NathanKell gives you is completely true. You need to be careful when using those tidbits. Is always better to plan more aerobraking manoeuvres than a steep insertion that ends on a bang.

PS: I used to love near future technologies... but being a mac user I was extremely limited on my memory usage and had to pretty much cutdown every mod that wasn't essential. If you show your design I can give it a look and try it out, maybe I can think on something to improve it.