Solid Fuel Rocket

[Voyager275]

I had a question about solid fuel rocket stability. I made a rocket with a srb for the first stage. It shakes a lot until stage separation and then after that if the second stage liquid fuel engine doesn't activate immediately, the rocket fails. I was wondering if there was a fix for this. It has cost me a couple of missions, since I play with no reverts and 30 days between launches.

Edited October 12, 2015 by Voyager275

[Kaezan]

SRB's do shake a lot. Try using struts.

If dont feel confident using srb's try starting a new sandbox carrer and try out a little.

KSP is not only a game of shooting rockets. You must know what you're doing and a part of it is to build-fail-redesign.

Go to sandbox, pick any srb and add a remote command and a reaction wheels. See how it behaves. now try it with 4 instead of 1. and so on

[Harry Rhodan]

Fails in what way? A picture of the rocket would also help.

I can only guess that you probably don't tweak down the thrust of the SRB and launch with a relatively high TWR (>2), stage when you are moving faster than Mach 1 at less than 10km and your second stage flips because that stage will suddenly have a lower CoM and no control authority because the second stage engine isn't running.

[Alshain]

Is your staging correct? Why wouldn't the liquid fuel stage activate?

[FyunchClick]

SRBs also don't come with gimbals, so that smoothness you get from LF rockets could just be more control authority. For that reason alone I usually take off on LF and boosters. You can drag your LF engine ignition into the SRB decoupling stage so you don't have that pause between the two.

[Reactordrone]

Sounds like your second stage gets aerodynamically unstable without thrust so you can add the very small fins to the rear of that stage so keep it flying like a dart until you fire the engine or move the engine into the same stage as the decoupler and hot fire to avoid the pause.

[Voyager275]

Is your staging correct? Why wouldn't the liquid fuel stage activate?

It was set to go off after decoupling not at decoupling

[Red Iron Crown]

A pic of the rocket in question would be very helpful in figuring out what's happening.

[legoclone09]

What I would do is get the Kickback from Ven's Stock Revamp, it has a gimbal like the real one. It looks mostly the same as well. Go maker the Ares ships for Constellation!

[Voyager275]

I cut the thrust and it didn't shake as bad. Thanks for all the advice given!

[FyunchClick]

Wat kind of acceleration were you experiencing? For the first 10 km or so something in the area of 2 g should help with a smooth ride.