Reusable Tugs in the era of Reentry Heating?

[Srpadget]

I have a quandary. My long-established playstyle involves building up a lot of reusable infrastructure.

I tend to put orbital transfer/refueling stations around pretty much every body I visit, with reusable landers running back and forth from station to surface and back again, spaceplanes moving kerbals and fuel from KSC to LKO, and nuke-powered interplanetary tugs/shuttles hauling kerbals and fuel from one orbital station to another...aerobraking at any destination which allows it.

Conceptually, the whole thing is pretty similar to the infrastructure popularized in the 1950's by Werhner von Braun/Willey Ley/Chesley Bonestell.

It occurs to me that this sort of infrastructure is going to be MUCH more difficult to pull off with the new 1.0.x re-entry heating. Seems Clamp-o-trons don't make very good heat shields, not even Clamp-o-tron Sr's. (Who'd've guessed?) And for obvious reasons, even a redesign that puts a docking port at one end and a heat shield at the other is not going to make for a permanent/long-term reusable vehicle, what with the temporary nature of anything "ablative".

And for equally obvious reasons, I don't want to give up on aerobraking if I can help it--I am ... unfond ... of the idea of keeping 1000m/s dV dedicated to a powered return to LKO (on return from Mun/Minmus/Duna, and even more when coming from further away). But in the absence of ballute-type high-altitude/low-heating deployable/reusable reentry parts, I don't see an obvious way to aerobrake one vehicle many times.

I'm sure some of you clever people out in Forum-land (especially the FAR/DRE users who've been facing this for years) have already worked out suitable approaches to solving this little dilemma. So, any tips/tricks/pointers/clever design concepts? I'm all ears (metaphorically speaking, of course)!

Edited May 13, 2015 by Srpadget
Mark as Answered

[Destroyer713]

I've got my own question. How well do shielded docking ports work with the new re-entry heating? Do they explode like regular docking ports will, or do they tolerate heat better?

[Grumman]

As you noted, powered return is an effective substitute for aerobraking - burning fuel instead of burning ablative shielding to slow yourself to a safe reentry speed.

Another approach you could try is to make the heat shields replaceable. In earlier versions of the game I had a line of SSTO spacefighters with rear-mounted docking ports, and a ground vehicle which could attach various modules to that port. Instead of this:

[spaceship]

[Heat shield]

You could do this:

[spaceship]

[Docking port]

[Docking port]

[Heat shield]

And just swap out the heat shields as they are expended.

[n0xiety]

I am currently using engines as heat shield in 1.02 for my rocket ssto. No need for heat shields with abalative. Sure you won't be able to aerobrake going in with 10km height but you can always touch the edge of the atmosphere (30 to 60km if you wanna push it 25km) and easily survive even a 4000 m/s entry. If you are too fast it might take more than 1 pass to slow down but it generally takes 2 passes max if im returning from a far planet. 1st pass gets me in to orbit and 2nd slows me down to the point where i can land.

[Geschosskopf]

The stock airbrakes do a wonderful job of preventing re-entry heating and also tend to keep the correct end of the ship facing the heat.

[Srpadget]

Hmm...airbrakes. Haven't done anything with those yet, as they're new in this version and I haven't unlocked them yet. Even if I had, I doubt I'd've thought seriously about those for what's basically a deep-space vehicle... but you say they work reasonably well as a high-altitude drag source to allow meaningful apo decreases without dangerous levels of heating?

Replaceable heat shields: I had thought of that, but was hoping someone had come up with something a bit more straightforward. It does add one more thing I have to keep bringing up from KSC, thus makes for more complex logistics--but obviously that doesn't faze me too awfully much or I'd be doing single-launch throwaway Apollo-style missions rather than running an orbital-infrastructure business, right? :-D

Maybe airbrakes as the primary high-altitude braking method, with a replaceable heat shield as emergency backup...? Thanks, folks, I'll give this some thought.

[cybersol]

I second that airbrakes with likely solve a lot of your concerns. Gee, Airbrakes for aerobraking, what will Squad think of next

[adinfinitum]

That's pretty much my favored playstyle, and I wish we had a ceramic heatshield option instead of only ablative. I tried using a heatshield without ablator because the max temp is listed as 3400 degrees. After looking at the heat debugging info it has almost no thermal mass with no ablator, so I'm not sure if it hasn't blown up because it actually works the way I thought, or if aerobraking just isn't that stressful on the craft.

Here's a pic, although not a very good one. Just ignore the station piece it's pushing around, the ship is the fat one with the tiny neck.

I haven't taken it out of the system, but it returns from Minmus and aerobrakes at 32-33km regularly. It's probably got enough dV to return without aerobraking, but that's just so inefficient.

Edited May 12, 2015 by adinfinitum
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[Warzouz]

Thx for that topic. I was wondering the same exactly as inbeta 0.9, I built a large station to explore Jool's moons with various SSTO. It was really fun to play ; much more than throwable missions which only leave debris floating in space.

[magnemoe]

Reentry heat then doing an aerobrake to lower Ap after returning from Minmus is not an serious issue, i tried to use heat shield at bottom however the heat after turning off the LV-N burned most of it away. avoid having vulnerable parts at the bottom part of tug, put them in an service bay.

Airbrakes is very useful but mostly to adjust Ap, I tend to reenter so mechjeb landing autopilot give me an Ap close to 500 km, this end up as 250-300 in 1.0, i then use airbrakes on the last part to increase drag to lower it, airbrakes also overheat.