Rocket SSTO

[Drag146]

Hi,

I guess career mode will soon be released so a recoverable rocket SSTO would be nice to have.

I want to build a rocket SSTO that is capable of launching a 2-5ton satellite to about 150km circular orbit. Any tips on how to build and control it(if it has jets)?

[stupid_chris]

If you're buildding a rocket SSTO, you definitely want to go for Aerospike engines. Experiment with test payloads and Kerbal engineer and you should be able to come up with something nice.

By the way, if you are expecting career in .21, I'm sorry to disappoint you but it's very, very, very, unlikely that it will be available in this update. They'Re only laying the foundations to implement career.

[Drag146]

If you're buildding a rocket SSTO, you definitely want to go for Aerospike engines. Experiment with test payloads and Kerbal engineer and you should be able to come up with something nice.

By the way, if you are expecting career in .21, I'm sorry to disappoint you but it's very, very, very, unlikely that it will be available in this update. They'Re only laying the foundations to implement career.

Thanks for the tip.

I know that career won't come in .21, but I think that it will come soon.

[stupid_chris]

Thanks for the tip.

I know that career won't come in .21, but I think that it will come soon.

I think we can safely set it to .23 or further, which pushes it a bit further out than October. We'll see I guess.

Also, since Aerospikes don't have gimbals, don't forget to pack RCS for control authority at higher altitudes.

[bsalis]

Having a whole single stage taken to a circular 150Km orbit is a lot of mass.

Any satellite will have fuel and a small engine for station keeping right?

Another option is to try out a booster that can get such a satellite to a sub-orbital, with Ap at 150Km. Decouple and round out the satellite. Then switch to the booster and land that with chutes, legs and a bit of thrust just before touchdown.

Edited July 13, 2013 by bsalis

[mellojoe]

((EDIT))

WHOOPS! Just realized you were looking at rocket designs, not plane designs. Forget what I said. But since I already typed it, I'll leave it here.

______________________________________

Jet engines with multiple intakes per engine can get you to 20km altitude and 1,000 m/s or faster. From there it is ensuring you have action groups mapped to switch off the jet engines and turn on the rocket engine. It takes a little bit because you have to sort of dance in the upper atmosphere to keep your air intake above the stall threshold, and a lot of trial and error to tell you exactly what that is for each vehicle design.

I finally had my first successful SSTO plane launch not too terribly long ago. Elliptical orbit but success nonetheless. And made it back to Kerbin and landed safely as well. I missed KSC since I can never seem to pick it out from space, but the theory was successful and the design worked.

GOOD LUCK!

[capi3101]

I'd suggest an LV-T45 center stack engine with radially mounted outboard Aerospikes; that way you've got some steering authority (especially if you couple that with some fins on the outboard engines). If you have three outboard Aerospikes, each stack will need an FL-T400 and three FL-T800 tanks. That'll get you a launch TWR of 1.27 (bit lower than optimal but still enough to get into orbit) and 4,590 m/s of delta-V, and that's assuming a five tonne payload. Two tonne payload, that design will give you 5,133 m/s and a launch TWR of 1.34.

Edited July 12, 2013 by capi3101

[Tobyz28]

You may wish to consider a turbojet engine and radially mounted aerospikes with intakes on them. Launch as high as you can on the jets, as soon as you flame out (or rather a bit sooner before they flame out to maximize the oberth effect) engage the aerospikes! If you're doing unmanned, i would throw some RCS on. If manned you might be able to get away without RCS depending on the ship and payload size

[stupid_chris]

The thing while using jets is that they make for awfully slow takeoffs. Yes they'Re much more effective, but it's very time consumming, and I'm assuming a rocket SSTO is to save time. When launching low payloads, it's not that hard to get a single stage to orbit without jets.

Plus they require extra maintenance, managing the intakes and preventing flameouts.

[UmbralRaptor]

Pure rockets?

The simplest approach would be a Mainsail and 12,800 L of propellant. Maximum payload to a 75 km orbit is ~7 tonnes, so with the smaller payload a 150 km would be doable. Making it recoverable could be a hassle, though.

Several LV-T30s clustered around an LV-T45 would probably be the highest payload fraction, assuming you can solve the recovery issues.

[littlebattler]

The most compact design of a pure rocket SSTO would be pure aerospikes. I have not tried this so I cannot say anything about the amount of fuel needed, but aerospikes have the best efficiency in atmosphere and thus require less fuel than all other rocket engines.

You may want to consider using the rocket simply as a sub-orbital booster and have the payload circularize itself though. Much easier that way.