Push Pull Rocket

[jebisanaggie]

Wondering if designing a rocket that had engines both on top (pull) and on the bottom (push) would help with stability on taller rockets? It seems that it would help by reducing the stress being put on the joints by not forcing the joints to be stretched or compressed. Had anybody tried this?

[Nabiscovinco]

I know for a fact I have not tried this, but here is catch (I'm assuming).

Firstly, how would you detach the payload? You would have to have the payload detach from both engine unit things.

Secondly, you would have to figure out what you are going to do with both engines. Normally, I just have the RCS/solar panels/ASAS/unmanned probe core on the small transfer stage when going to my space station, then deorbiting it. So you you need to make both ends have something like that, or you would have to dock them together and deorbit them as one unit.

Thirdly, getting into orbit. You could, seeing as you have two engine sections, you have twice the thrust. However, if you are creating boosters (especially on the upper engine section) how would they detach WITHOUT hitting anything on the way down?

Sorry to crush your dreams, potentially, but I could see this being hard to do, but I'm bored, so I might try it.

GOOD LUCK! (and post pictures if you make it work, I'd love to see!)

[Ittiz]

I've done it. The big issue is staging them correctly. Most of my push-pull rockets were SSTO attempts. The only successful one (not SSTO) I made had angled aerospike engines attached to the side of every stage and no engines on the bottoms of the stages. That design worked extremely well and allowed for extremely tall stable rockets since each stage was lifting at all times there was no stress on the joints between the stages. Except that caused by the payload on top anyway. Also all the stages were identical making designing the rocket and re-sizing it for any payload a breeze.

[adinfinitum]

I can also confirm that it will work, I've done it before, though not since 0.17.

All I did was add some fuel tanks and rockets onto docouplers near the top of the rocket, and then decouple it at the same time as the bottom stage

[allmhuran]

Yep, works very well but is not needed until / unless you are building really, REALLY heavy or ungainly launch vehicles. For example, if you're trying to get some super long core truss section of a space station into orbit, adding some pull rockets to the top is pretty much mandatory.