When Deadly reentry is actually deadly.

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Bill, Jeb, and Bob (who I accidently took to space) died by exceeding g-limit approximately 2 seconds before the capsule (which I forgot to equip with a heatshield) burned up in Kerbins atmosphere after returning from Dres on a highly inclined orbit, entered Kerbin Atmo at slightly greater than 8.0 KM/s.

I'm happy to let the save stand. However, I am interested in learning from the event. So aside from "Don't hit the atmosphere at 8.0 KM/s I'm hoping to see if there is anything else I could have done.

I had a quicksave out past minmus orbit with a pass over Kerbin at 25 KM with about 800 delta V remaining. I tried it multiple times and I couldn't get an altitude at which I could survive without flying out of the Kerbin system at 4 Km/s. I can survive most of the reentry by putting my engine first into the atmosphere and letting it take the heat, but it eventually burns up if I go too low, the whole ship follows shortly thereafter.

I did not have this problem returning from Duna (which I also did without a heatshield...also Minmus and the Mun...I should really edit my workhorse).

What have you learned from using FAR and deadly reentry about returning from interplanetary trips?

Edited November 25, 2013 by [email protected]

[RocketTurtle]

I don't use DR, but I can assume it was sheer speed that killed you. No altitude could help coming in at 8 km/s with no heatshield.

[Galacticruler]

I don't use DR, but I can assume it was sheer speed that killed you. No altitude could help coming in at 8 km/s with no heatshield.

even with one it would'nt help at all.

My suggestion is to save that quicksave elsewhere, and try ending up a ship to intersept and slow down the returning one.

or have them all EVA over to it.

OR you could try burning as long and fast and hard as you can.

[[email protected]]

Right I get that they are dead, I guess I'm more interested in how I should have tried returning from Dres. Was my velocity a result of my terrible orbit, or is this normal when returning from outer planets? and if so, how to deal with it?

[Guest]

When coming in that fast I would suggest a shallow reentry and multiple passes to bleed off speed.

As I understand it, your velocity is a product of how you approached Kerbin. Had you intersected Kerbin orbit with a shape more like its orbit, your velocity would have been less. But I'm guessing it was a highly-inclined or elliptical orbit which means that the difference in vectors adds up to much more relative velocity.

[RocketTurtle]

Well, remembering a heatshield would have helped... then aerobraking to bring your velocity down, then make a final entry.

[henryrasia]

I am not aware of the situation (screenshots, maybe?) but MAYBE you'll be able to do some really weird maneuver and use an inverse gravity assist on the Mun to slow yourself down? (800 m/s of Dv is pretty little though...). Another suggestion would be to have an aerobraking trajectory that does not kill you but just barely puts you into an orbit. Then you can do several passes until the speed safely slows to a safe descent speed. Hope this helped!

Or do it the awesome way: Slow down as much as possible and then leave the capsule stranded in a solar orbit. Then launch a rescue mission to rendezvous with it ASAP around the sun and bring them back!

[I_Killed_Jeb]

I'd do a mun gravity assist, shouldn't take too much dv

[Kasuha]

I'm afraid at 8 km/s there's nothing that can be done except passing Kerbin in the correct direction to get a braking gravity slingshot in combination with deepest possible aerobrake, exit the SOI and enter it again sometime later. By careful burns at apoapsis you might get it done without spending much dv (but spending a lot of time warp). If you're lucky you may even brake by gravity slingshot off something else, such as Eve. After you enter Kerbin's SOI at reasonable speed which will allow you to stay withing the SOI after aerobrake, you can use series of shallow aerobrakes in the atmosphere to get on low orbit and then perhaps try to aerobrake and land from there. Your 800 m/s dv might even suffice for that if you have enough patience.

The question is whether DR will even allow you to land from LKO if you don't have a heat shield.

[Specialist290]

The question is whether DR will even allow you to land from LKO if you don't have a heat shield.

I can confirm that it will, as long as you don't come in too steep (in which case the g-forces will kill your crew even if the heat shield keeps them from burning up). If you're careful, you can even return from the Mun without needing one.

[Savage117]

Kasuha is correct, you have to slow your craft down to about less than 3k m/s at re-entry to survive re-entry, that's assuming you haven't tweaked any of the DR configs. In your current situation 800m/s delta V should be used for manuever tweaking, don't use it for a suicide burn that won't work, you'll just die empty. I have not ever come into the atmo that fast so I'm not sure of what your safe aerobrake altitude limit is, with no component loss, usually its slightly above 35k at 4k m/s.

I would suggest several upper atmo aerobrakes until you get to an acceptable orbit, like somewhere around Minmus's orbit. I was able to bring a whole transfer stage down safely and intact with only the batteries and solar panels on the side exploding from a Minmus orbit. If your speed just slings you outsystem after a minor aerobrake you can use that 800m/s Delta V at the AP to reduce orbit for another aerobrake with the least delta V expended, so you can do it several times if needed. If you are constrained by time, if you have a Life support mod installed, then your gonna have to do a lot of number crunching to get those boys home alive.

Sorry, if it seems like I'm not paying too much attention, watching the SES-8 SpaceX launch live at http://www.spacex.com

[[email protected]]

Its pretty much a lost cause, I've moved on. I've determined any future trips to Dres will pack more fuel for the return. The ship hit 34.4 G's on Reentry and the Kerbals died BEFORE the ship burned up. When I tried and went higher than 28 KM it skipped back out of the atmosphere above escape velocity.

As far as the heat shield...they aren't terribly necessary. I've safely returned from Duna, Minmus, and the Mun without one. All you need to do is point your engines into the atmosphere. Although I will remember to start including one from now on, especially for interplanetary trips.

I'm still fairly new to FAR and DR, loving it though. The added challenge means I have to actually think about how I design my rockets. I've also self imposed a no fuel pumps rule, but I will still use fuel transfers from docking manuevers.

[numerobis]

Skipping out of the atmosphere above escape velocity isn't the end of the world; just do a burn after skipping out (assuming you didn't melt your engines off).

Apollo skipped out and back in to reduce the peak stresses. So you've got pedigree.

[edit: pretend I'm not the type that neglects to read the OP.]

Edited November 26, 2013 by numerobis

[little square dot]

Skipping out of the atmosphere above escape velocity isn't the end of the world; just do a burn after skipping out (assuming you didn't melt your engines off).

Apollo skipped out and back in to reduce the peak stresses. So you've got pedigree.

He was exiting the atmosphere at 4km/s with 800m/s dV remaining. Retro-burning the rest of his fuel would not have helped. Manoeuvring to make use the Mun might have been possible, but at 4km/s following aerobraking, it'd be pretty tough to avoid escape.