Near-vertical reentry?

[rofltehcat]

So I noticed something when I cleared one of my quest satellites: Even when burning all of my fuel to get a near-vertical reentry into Kerbin and accelerate as fast as possible, the aerobraking effect is so strong that the probe got slowed down to very safe speeds. It didn't even produce all that much heat.

I'd have expected it to burn up or break apart but nothing happened. Now I wonder if this is just some freak phenomenon that applies to small probes or if it is something that could theoretically be (ab)used for general reentry.

Here are some pictures of what I did: http://imgur.com/a/G0iOW

Edited June 21, 2015 by rofltehcat

[Old Foxboy]

The probe is too small. The drag/weight ratio is too high to make it pierce through the atmosphere into the denser parts fast enough to let it melt.

[CalculusWarrior]

As of now, the re-entry heating is rather mild; standard Kerbin re-entry speeds will not be enough to damage more than a solar panel or two. If you want to fix this, you can change the heat values in the physics.cfg file in your KSP directory, or temporarily, in the debug menu (ALT+F2).

[Brainlord Mesomorph]

My layman's understanding, is that IRL vertical reentry does not create nearly the same heat as aerobraking.

That's how those sub-orbital parachuting guys don't burn up.

/layman

[Captain Sierra]

My layman's understanding, is that IRL vertical reentry does not create nearly the same heat as aerobraking.

That's how those sub-orbital parachuting guys don't burn up.

/layman

^^

Because you cancelled most of your orbital velocity, You're not actually hitting the atmosphere that fast, and your probe is high drag. It slows down very quickly. If heating wasn't quite so mild as it is currently, you would have definitely incinerated, but as this is a game first, simulator second, the heating is low enough that you survived.

Try a straight-down direct entry when returning from Jool and I promise you'll be going bang real quick.

[Lelitu]

^^

Because you cancelled most of your orbital velocity, You're not actually hitting the atmosphere that fast, and your probe is high drag. It slows down very quickly. If heating wasn't quite so mild as it is currently, you would have definitely incinerated, but as this is a game first, simulator second, the heating is low enough that you survived.

Try a straight-down direct entry when returning from Jool and I promise you'll be going bang real quick.

Hell, with a vertical re-entry and a decently aerodynamic design, may well go bang on the surface.

I've had a couple of overly steep re-entries slam into the ground when there wasn't enough drag.

[Captain Sierra]

Hell, with a vertical re-entry and a decently aerodynamic design, may well go bang on the surface.

I've had a couple of overly steep re-entries slam into the ground when there wasn't enough drag.

What are you diving nose first with a SSTM (single stage to Mun/Minmus) plane? Only thing I've managed to do that with is dropping a class B asteroid on top of R&D.

[Lelitu]

What are you diving nose first with a SSTM (single stage to Mun/Minmus) plane? Only thing I've managed to do that with is dropping a class B asteroid on top of R&D.

Career mode on normal difficulty, dropped a mk1 pod with heatshield and nothing else from the mun.

dead vertical drop, hit the top of a mountain at 1kps.

I've also done it with re-entries between 45 and 90 degrees, if they're fast, and happen to encounter a mountain. That's more a problem of bad aim though.

[Old Foxboy]

Just for comparison: A parachute diver that hops from a balloon (aka "Geronimooooo") will hardly break the sound barrier at Mach 1 (Google Baumgartner Jump).

A spacecraft that reenters earth's atmosphere from LEO will be travelling at Mach 27. See the difference?

[Sharpy]

hit the top of a mountain at 1kps.

That explains a thing or two. It's really some 6km go from 1000m/s down to terminal speed in the lower atmosphere. Had you been in for a splashdown, you'd deploy a chute 1000m above the surface at 500m/s and you'd be fine. The few km of mountain height does make a difference.

[cicatrix]

I tried vertical reentry at 3 km/s vertical speed I specially aimed my trajectory at the center of Kerbin. What can I say, I burned.

Also tried aerobraking at 8 km/s - bad idea.

Really, *IF* Kerbin was the size of Earth reentry heat would be normal.