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Recover PPD-10?


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Guy,

I need to recover a PPD-10 from LKO.  Is the grabber the only way to do this?  I must assume that successful completion of this contract means I can't have the storage container exploding during rentry?  That is the part that worries me.  I can probably get to a rendezvous and grab it, but I can see this all going bad when it all starts heating up on rentry.

 

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50 minutes ago, Elroy Jetson said:

Guy,

I need to recover a PPD-10 from LKO.  Is the grabber the only way to do this?  I must assume that successful completion of this contract means I can't have the storage container exploding during rentry?  That is the part that worries me.  I can probably get to a rendezvous and grab it, but I can see this all going bad when it all starts heating up on rentry.

 

Use a grabber in a cup of fairing with a heatshield beneath it to protect the cargo from reentry

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You mean a ppd-12 cupola?

Yes, to deorbit and recover almost anything, you use a klaw. Theoretically, there is also a way to use a cargo ramp to do it but I've only seen one person crazy enough to try that. Yes, it needs to land or splash down intact, and then you need to hit the "Recover" button.

You have to decide if you want to do this kind of thing with one ship or two. If you do it with one, it'll be a one-shot deal. If you do it with two, you can use the pair to deorbit many things.

If you do it with one: then the upper stage needs to have a klaw and a decent number of parachutes -- and some extra fuel, if you are concerned about reentry heating. You fly up, grab the thingy, wait until you are above the west edge of the KSC continent, retroburn to 1500 m/s in surface mode (which completely prevents reentry heating), and land really close to KSC.

If you do it with two, then one needs to be a space tug: a robotic craft with a klaw on the nose, and a decent amount of fuel. It goes around in orbit and grabs things, brings them to the other craft, and attaches them.

The other craft needs to be a multi-object deorbiter. Here's one example of something I built a long time ago:

deorbiter.png

I build them slightly differently now, but the idea is the same. That right there can deorbit 9 different things to fill 9 separate contracts. You activate all the parachutes once you are in LKO. You use your spacetug to attach your item to one of those klaws. You retroburn to lower your Pe to maybe 66km. You decouple the arm with the thingy on it. You switch focus back to the deorbiter and raise its Pe back above 70km.

Then you switch focus back to the thingy. The thingy now has activated parachutes, and the little winglets that give it an extremely high drag. You have to watch it while it descends all the way to the surface. The drag from those winglets is so high that you can deorbit just about anything with no heating problems.

Edited by bewing
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On 3/8/2019 at 3:53 AM, Elroy Jetson said:

Is the grabber the only way to do this?

Pretty much, yes.  (There's a mod, KIS, that allows a kerbal engineer to go out with a power tool and attach / detach parts in flight, so in principle that would give you the ability to do it without a grabber.  But in stock?  Yes, you need the grabber.)

On 3/8/2019 at 3:53 AM, Elroy Jetson said:

 I must assume that successful completion of this contract means I can't have the storage container exploding during rentry?

That is correct, yes.

On 3/8/2019 at 3:53 AM, Elroy Jetson said:

That is the part that worries me.  I can probably get to a rendezvous and grab it, but I can see this all going bad when it all starts heating up on rentry.

My guess is that you're probably fine.  Large, lightweight, draggy ships (which is a pretty good description of a PPD-10) generally can reenter from LKO without needing to worry about going boom on reentry, as long as we're not talking about "fragile" parts with low temperature tolerances, such as science instruments.

So I'd say, grab hold with the klaw, retro-thrust to put it on a suborbital trajectory, and pop the klaw ship's parachutes at the appropriate time.  If reentry heating is at all dicey, just use a bit of extra retro-thrust to slow down more before reentry.

 

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