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arkie87

Anyone Build TSTO's?

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Does anyone else build Two-Stage-to-Orbit vehicles?

I've done a lot of SSTO's, but i tend to get bored during the slow climbs and limited cargo capacity, so ive started to prefer building TSTO's where i just use cheap solid rockets to boost some kind of vehicle into space, drop them like they are hot, and then circularize orbit with the spaceplane stage.

Spaceplane usually looks like so:

http://imgur.com/aM5QdWs

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SSTO rockets don't climb slowly!?

TSTO rockets are pretty normal, as are three- and four- stage vehicles. Unless someone's chasing ultimate asparagus or just special effects I don't think anyone goes further than that though.

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My biggest TSTO was the Cira IV - it puts about 300 tonnes into LKO. It has one MASSIVE lower stage and one smaller but still quite large upper stage, about 25% the size of the first stage. The spaceplane bit at the top seems kind of unnecessary.

Link: http://forum.kerbalspaceprogram.com/threads/88422-Cira-IV-Official-Release!-300-tonnes-to-Orbit!

mhY2zoj.jpg

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I like TSTO's, usually it's one of the ARM Liquid Boosters with some ARM SRBS or maybe some BACCS. Usually these craft have 4000dv w./o boosters, and the way I set it up is, as I throttle down when reaching terminal velocity, my deltaV rises.

Also, mainsail + ARM 1 1/2 tank + Quad Engine =:D

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Even Professor Kerbenstein's wonderous Vertical Propulsion Emporium does quite well as a two stage design to orbit.

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SSTO rockets don't climb slowly!?

TSTO rockets are pretty normal, as are three- and four- stage vehicles. Unless someone's chasing ultimate asparagus or just special effects I don't think anyone goes further than that though.

If you want to utilize air-breathing ISP as much as possible they do... unless im doing something wrong, getting as close as possible to orbital velocity requires climbing slowly so you dont starve the air-breathing engine of air

and yeah, i suppose. but i meant space planes that are launched into space by one booster stage, the idea being to use cheap (in terms of kerbucks) booster rockets to quickly send spaceplanes into space without a slow climb

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I've built SSTO's, also plenty of 2STO's, and a couple 3STO's. Two-Stage-To-Orbit, admittedly, is more fun.

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If you want to utilize air-breathing ISP as much as possible they do... unless im doing something wrong, getting as close as possible to orbital velocity requires climbing slowly so you dont starve the air-breathing engine of air

and yeah, i suppose. but i meant space planes that are launched into space by one booster stage, the idea being to use cheap (in terms of kerbucks) booster rockets to quickly send spaceplanes into space without a slow climb

My main SSTO plane has an listed TWR of 3, real values are less as the jets don't give full effect, it also carries cargo but that tend to be a faction of the plane weight, its mostly for crew and small cargo anyway but has no issues with 5 ton.

Takeoff profile tend to be an 75 degree climb too Ap is 20 km, at this time I usually at 300 m/s, vertical flight while climbing slowly to 32-35 km and 1800-2000 m/s.

Switch rapier to closed cycle and climb to 2200 m/s and 40 km at this time mechjeb anti flameout reduce throttle to 5% and Ap tend to be 80 km so I turn off the turbojets and let mechjeb take it to orbit.

Has an smaller two man SSTO who also is an VTOL tailsitter, design was developed for Laythe but works well enough to be used for an light plane.

Two stage rockets works well but one stage+ srb works just as well and is far cheaper, it let you recover the expensive core while keeping fuel use and size down.

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Here is my way of doing things:

http://www.twitch.tv/othuyeg/c/5154892

So i think you've proved my point about SSTO's taking a while to get into orbit with shallow climb rates etc... :D

That's why ive switched to solid boosters to blast off into space (with mach effects and re-entry heat on exiting atmosphere) so i dont have to spend so much time slow-climbing. Plus, solid boosters are quite cheap in terms of kerbucks:cool:

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Yep it takes some time to launch ssto's into orbit (with DRE ssto rockets are out of question). That's what makes me build shuttles. Mostly two stage designs with many srb's. My regular missions are done by a shuttle strapped on top of a stage that's supposed to be as cheap as possible (piggyback tends to be not reliable enough for hard career mode)

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I personally don't do much real TSTO's, but I occasionally enjoy making spaceplanes with RATO (Rocket Assisted Take-Off). Read: strap SRB's under the wings, make sure the plane has sufficient control surfaces/torque to compensate and blast off! There's just something intensely satisfying about seeing a super-heavy interplanetary spaceplane blast off with less of a third of the runway used.

It's technically two stages, but I usually ditch the SRB's within the first 20 or so seconds of flight. In fact, in one of my iterations I strapped a chute on each SRB, set the chutes to deploy at minimum altitude (50m) and the boosters actually hit the water past the KSC before leaving the physics bubble. Full recovery, even with a stage :) )

Edited by Cirocco

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I usually 3 stage.

1st stage: boosters and main engine running at 50% gets me to 10,000m

2nd stage: boosters dropped, turn to 90 and burn the main engine at 100% to 1000m/s

3rd stage: drop the main and burn the 3rd stage to orbit.

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(about SSTOs being slow)

If you want to utilize air-breathing ISP as much as possible they do... unless im doing something wrong, getting as close as possible to orbital velocity requires climbing slowly so you dont starve the air-breathing engine of air

Yes and no. Most SSTOs would be capable of climbing a lot faster than they do during that stage of the flight. However, the punishment for outrunning your air supply is severe, while playing it safe only means that you take a little longer. So most people prefer to take it slow.

Here's some data from one of my jet ascents:

ssto.gif

Notice the low climb rate near 30km. Notice how slowly airspeed increases in the same timeframe. This is because the ascent follows the standard jet paradigm of getting to 2000m/s in the atmosphere, then proceed to orbit. Also notice what happens next, how the plane has no problem climbing quickly without losing airspeed. I haven't explored this further, but in all likelihood it would be possible to make a much smoother transition, with climb rate never falling quite as low and reaching orbital speeds at much higher altitudes.

What really takes a lot of time is getting to 10-15km in the first place, because SSTOs tend to have a low TWR. For rocket SSTOs, TWR improves as they burn fuel; for ramjets, TWR improves as they gain speed. In either case, boosters are a cheap means to help the impatient.

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So i think you've proved my point about SSTO's taking a while to get into orbit with shallow climb rates etc... :D

That's why ive switched to solid boosters to blast off into space (with mach effects and re-entry heat on exiting atmosphere) so i dont have to spend so much time slow-climbing. Plus, solid boosters are quite cheap in terms of kerbucks:cool:

Build and fly it right and you can get a conventional SSTO spaceplane to orbit in under four minutes: http://forum.kerbalspaceprogram.com/threads/90354-Spaceplane-speed-challenge-shortest-elapsed-time-from-runway-to-orbit

JATO boosters are fun, though. Strap some RT-10s on near CoM and whoosh.

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I don't know if there is a fancy acronym for it, but I'm working on a plane now that takes off, drops it's entire wing body and jet engines in orbit basically converting itself to a lander (1 piece, carefully crafted), goes to the mun, comes back, and docks with it's body for landing. The whole idea was to reduce mass of parts that wouldn't be used for the whole trip. Not sure if it will really have any benefit (or even it it will work at all) but hey, it's something to do.

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The vast majority of my rockets, such as the Mark 2 pictured below, are all two stage rockets. The Mark 2 is my main go-to rocket, and it uses a solid fuel first stage and a liquid fuel second stage, and is extremely simple to build with KW Rocketry. That second stage can push most payloads well into high orbit. Sometimes, depending on the mission, the rocket may have a third transfer stage located in the fairings, but that stage is typically not needed until well into high orbit (it's usually for interplanetary transfers).

Q1cbSGw.png

Note: I use FAR.

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2 STO: includes 6-man transport, full science package, large cargo bay (fill the cargo bay to max and you still have no problem reaching orbit with leftover dV) and 1km/s of dV remaining once in LKO.

(FAR and b9 aerospace). Could use some tweaking I'm sure. Front canards may be unnecessary. Also has a small cargo bay to hide science instruments, solar panel, batteries, sas wheels, etc. Oh and in-line clampotron of course.

w1UhkxS.jpg

Edited by plaerzen

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I don't know if there is a fancy acronym for it, but I'm working on a plane now that takes off, drops it's entire wing body and jet engines in orbit basically converting itself to a lander (1 piece, carefully crafted), goes to the mun, comes back, and docks with it's body for landing. The whole idea was to reduce mass of parts that wouldn't be used for the whole trip. Not sure if it will really have any benefit (or even it it will work at all) but hey, it's something to do.

Superb! THIS is exactly how I keep saying it should be done :-) Like a lot of things it's not such a big thing within Kerbin's SOI but the further you go and the more you do where the 'plane part can't fly the more practical it is to leave them in orbit and redock later to land.

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I built a TSTO in one of my career games fairly early in the tech tree:

dkOV1cC.png

This one only uses basic jet engines to get up to about mach 2 at 15-17km up before separating and letting the payload continue onward. I got it to work at least one into a circular orbit of about 100km. I'm using KCT so I just set the airplane section to open up a set of chutes and I recover back much of the value of the lower stage.

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All my rockets tend to be TSTO, large pair ( occasionally more ) of crossfeeding liquid boosters and something more economical in the centre stage to chug it's way up to orbit from ~14km.

My current big plane family is technically TSTO too, if droptanks count...

15258585854_0ac2c301f3_z.jpg

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Most of my SSTO's are actually TSTO's that can SSTO if they want to. They are also all rockets, and SSTO's make up about a third to half of my rocket designs.

I like to leave 0 pieces of space junk in space and I also like to build minimal rockets for the job at hand. This means that a good break point is just before I circularize. I build a rocket with just enough to get the payload to orbit but then drop the stage during the coast to apoapsis. I know how to do my ascent trajectory so that I typically need less then 200 DV to circularize with it not being uncommon for me to need less than 100. Typically the stage I drop still has 200 DV or so and thus is actually a SSTO. If I expect to have more DV then that I will put de-orbit thrusters and use it like an SSTO but not often.

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