C-7 Adapter Problems

[Zosma Procyon]

I've been experimenting with different designs for an Eve lander and liftoff vehicle, and keep having the same problem: structural failure between C-7 adapters and what ever they're attached to. They aren't overheating and exploding, they're frequently breaking off and smashing into the heat shield arrays I mount behind them, but are not directly attached to them. Has any else had and solved this problem?

[Cpt Kerbalkrunch]

I imagine they're snapping somewhere between 50-40km on the descent. That's when pretty much everything will start bending and twisting. Adapters are weak points. Cubic octagonal struts and strut connectors will strengthen them. I put them pretty much everywhere. It will raise your part-count quickly, but they really work. I despise autostrut, and never use it.

[foamyesque]

You don't need *that* many struts, but a tank -> engine -> decoupler -> adapter is often wobbly. A pair or trio of struts to bridge the connection between the tank and the adapter will make the connection much less floppy.

[Cpt Kerbalkrunch]

7 hours ago, foamyesque said:

You don't need *that* many struts,

Ordinarily, no. But he's attempting to bring a 700 ton ship down on Eve. It's gonna need some struts.

Edited January 27, 2018 by Cpt Kerbalkrunch

[linuxgurugamer]

18 minutes ago, Cpt Kerbalkrunch said:

Ordinarily, no. But he's attempting to bring a 700 ton ship down on Eve. It's gonna need some struts.

Where does he say 700 tons?

[Cpt Kerbalkrunch]

48 minutes ago, linuxgurugamer said:

Where does he say 700 tons?

He has several other threads here on the forum (in both Gameplay Questions and Discussions) talking about it. He's been working on it for awhile. It's a 7-Kerbal design. Last I saw, I believe he had the Mk1-2 and Hitchhiker Storage Facility. Certainly doable, but not easy.

You know how Eve designs can get away from you. Build it big enough to reach orbit, then realize you need a huge lander. Sort of a viscous cycle.

Edited January 27, 2018 by Cpt Kerbalkrunch

[linuxgurugamer]

22 minutes ago, Cpt Kerbalkrunch said:

He has several other threads here on the forum (in both Gameplay Questions and Discussions) talking about it. He's been working on it for awhile. It's a 7-Kerbal design. Last I saw, I believe he had the Mk1-2 and Hitchhiker Storage Facility. Certainly doable, but not easy.

You know how Eve designs can get away from you. Build it big enough to reach orbit, then realize you need a huge lander. Sort of a viscous cycle.

I wasn't aware, thanks.

yes, I do know how they grow, and grow, and grow, and grow.....

[foamyesque]

Oh, you're going to need *some* struts, certainly. But if you need more than three over any particular connection, you've done something wrong. Three struts can lock a connection down in all six axes of rotation and translation, and I *generally* only ever need those to stiffen up the main stack of a rocket to prevent control point oscillations. Radially connected stacks usually need two max, one nose and one tail (often just one nose, or even none if they're directly bolted to the main stack instead of on decouplers), to keep them oriented to airflow. Wings can require some fiddling, since you can put a lot of aero-loading on them on Eve or with high-speed manouvers on Kerbin.

 

Returning 7 people from Eve is a challenge, to be sure, as it's something of an awkward number. If you're using pods, it's a bit heavy for a Poodle top stage, but not enough to justify a Rhino, so you're probably stuck with a Skipper and its worse Isp, if you want to keep a single stack for the improved structural strength.

Could always use lawn chairs, but that's a bit immersion-breaking.