Can somebody walk me through creating a shuttle system?

[Kagame]

I've mastered all aspects of Kerbal Space Program, from SSTOs for local satellite delivery through to massive SLS replicas capable of.... well, actually, I haven't finished testing those yet (sorry Thoth!), but anyways, the one thing that constantly confounds me are creating shuttle systems. You know, the ones that have an external tank, asymmetrical thrust, and all that other fun stuff? No matter how many different configurations I try, they always end up flipping over at some point. Could somebody walk me through the process of creating a shuttle, please? It'd make an excellent How To article, so you could even post it under a separate thread in this forum under How To and link me in.

[JTpopcorn]

I'm sure there are posts about this, but they are currently quite complicated. Realistically, the big SRB's had trust vectoring, and provided most of the trust on launch. Also, the space shuttle used the big engines while the fuel tank was attached, then switched to two other engines that alinged with the CoM after the big tank decoupled.

[Alshain]

There are plenty of videos and threads on this but the best tip I can give you is wait 3-4 days.

The basic concept is your SSME should aim through the CoM, but we get a real SSME in the next patch. We also get a proper engine mount for shuttles

[Van Disaster]

If you want to try it now, you might want to attempt Shuttle-Saturn instead of the SRB version. The STS is a particularily daft launch system though.

[Alshain]

If you want to try it now, you might want to attempt Shuttle-Saturn instead of the SRB version. The STS is a particularily daft launch system though.

Shuttle-Saturn? You mean a Buran-Energia? The Saturn was never used with the Shuttle.

Edited November 7, 2015 by Alshain

[Van Disaster]

Shuttle-Saturn? You mean a Buran-Energia? The Saturn was never used with the Shuttle.

Look up Shuttle-Saturn or Saturn-Shuttle - I can't remember which way round it was - it was a proposed system which used the parts the name would suggest.

[GeneralVeers]

Another way you could get a shuttle to fly (reasonably) straight at liftoff is to adjust the trim controls. A trim adjustment causes the craft to steer off-center even when you're not touching the controls; you can use that to counter the craft's off-center thrust.

Just remember to zero the trim adjustment once you've dropped the liftoff stage......

[GoSlash27]

Kagame,

This thread is excellent:

http://forum.kerbalspaceprogram.com/threads/132178-how-to-make-space-shuttle

If you wait a few days you'll have the new "vector" engine and it will make all of this much easier.

Best,

-Slashy

[Pecan]

1.0.5 +; the answer to most of our dreams :-)

The simple walk-through though is and will remain; almost any other design is easier, more cost-effective and reliable. If you want to challenge yourself to build something that looks like the North American shuttle then ... well, it's a challenge.

[BudgetHedgehog]

1, Build the orbiter (make sure it's stable when fuel is empty and travelling at re-entry speeds). If you want realism, don't have any LFO on it, have monoprop and use monoprop engines as the OMS. Attach engines to the back too.

2, Attach external tank (ET) to the bottom.

3, Attach 2 x SRBs to the sides of the ET attached in step 2

4, Align CoT with CoM. This is the hardest step - , not only do you have to choose the right SSMEs (usually Skippers and/or Mainsails), you'll have to tweak the thrust levels of the SRBs and the angle of the SSMEs to make a stable launch, but also make sure that when the SRBs are decoupled, the SSMEs will be able to cope with the offset thrust as well as making sure the whole thing has a launch TWR of >1. You can do this by either having SSMEs with large gimbal range, or by tweaking the thrust of the outermost engine in flight (the more the SRBs burn, the more SSME thrust has to be angled downward and not off center. When the SRBs decouple, you need to tweak it back up to cope with the huge offset CoM which will then, with an empty ET, move back towards the orbiter, requiring less thrust on the outer engine). If your SSMEs have a large gimbal range, you can be a bit less precise with CoT/CoM alignment. The KER mod shows thrust torque per stage, use the heck out of that.

In general, think about how the CoM moves at all stages throughout the flight (full SRBs and ET with payload, mostly full ET and nearly empty SRBs (with high TWR) with payload, mostly full ET and no SRBs with payload, nearly empty ET with payload, no ET with payload, no monopropellant without payload, etc etc) and adjust engines (and their angle) and thrust levels until you've got a good compromise on all situations.

Also, yes, Shuttles are more of a novelty than a viable payload launch system, both IRL and in KSP. You're pretty much always better off using disposable launchers, especially if they reply on cheap SRBs as the main source of thrust (say, Kickback core with liquid fuel second stage to finalise and circularise orbit).

Edited November 9, 2015 by ObsessedWithKSP

[Empiro]

My process is similar but I do the following (will still apply when the Vector engines come out, but just be more forgiving). I recommend getting both hyperedit and Kerbal Engineer:

1. Build orbiter, and test landing it by hyperedit into orbit and land.

2. Determine the "average" CoM after booster separation. Do this by attaching expected payload, external tanks (put it high if possible), and boosters. Establish desired TWR at launch, tweaking the thrust of the boosters as needed (you want a TWR of 1.4-1.6 on the pad). Note how much burn time you have after you drop your boosters. Remove your boosters, then set your external tank fuel level so that contains 1/2 of the burn time. If you have multiple external tank segments, you'll also need to watch out for how your fuel drains (I recommend letting it drain evenly from each tank).

3. Minimize "average" thrust torque after booster separation. Adjust the angle of the main engines so that your thrust torque as reported by Kerbal engineer is minimized. Make sure to turn off angle snap, and you'll be able to get it very close to 0.

4. Minimize "average" thrust torque when boosters are attached. Adjust the fuel level of the boosters to 1/2 their full level. Adjust the external fuel tank levels so that they're at the midpoint between full and when the booster separation happens. Move the boosters up and down the main external tank until until the thrust torque is minimized.

5. As a final step, put Vernor thrusters at the bottom (or top) of your shuttle, giving you even more pitch control.

The above steps minimize your average torque and the idea is hopefully make it so that between the engine gimbals and Vernor thrusters, you have enough pitch authority to prevent spinning out of control. When piloting the shuttle, you still may need to adjust the thrust carefully as you're flying. You should definitely keep SAS on the entire time. One thing to do is to look carefully at the pitch indicator on the lower left. If you see it getting close to the extremes, then you may need to reduce your thrust slightly.

Edited November 9, 2015 by Empiro