SSTO's, How to make them and how to fly them to SPACE?

[Sharkman Briton]

I've always been interested in SSTO's in this game, like the things that can bring a good payload to orbit and not have to make a good fairing, spend multiple tries to stop it spinning out on gravity turn and not be as annoying to make as rockets, but I'm rather poop at flying planes, and have no clue how I would fly an SSTO or even make one, all I know about it is that its a plane with rapier engines and gets to orbit in one stage, nothing else, so can anyone tell me the answers to my questions so I'm not stuck with annoying rockets that take a good few tries every launch just because it wobbles like Miley Cyrus's *** and I messed up the asparagus and MOAR STRUTS.

Note: I'm on sandbox, and I dont really intend to do the land back on the runway thing, its either decouple a detatchable ascent stage or nothing, I'm not that good at landing planes, oh, yeah, and can MJ autopilot an SSTO Spaceplane?

102t Thank you for any help!

[xtoro]

MJ can sort of autopilot an SSTO if you adjust the ascent path to be quite flat and set roll to zero, but I haven't tried it. Try using one of the larger stock planes, swap out a tank to have some O2, keep the jets and add rapiers. That's how I started out playing with them. You can also download some smaller SSTOs from the spacecraft exchange to learn how they are built.

[Evanitis]

Hint: learning how to design efficient rockets to put stuff to orbit with is much easier than doing the same with an already perfectly engineered SSTO. It's more like a challenge - their only merit is the low operating cost, that doesn't even matter much in a normal career, not to mention sandbox.

Edited July 28, 2015 by Evanitis

[ajburges]

Hint: learning how to design efficient rockets to put stuff to orbit with is much easier than doing the same with an already perfectly engineered SSTO. It's more like a challenge - their only merit is the low operating cost, that doesn't even matter much in a normal career, not to mention sandbox.

Doesn't matter? Tell that to the 100 t, million credit habitation rings I use for station contracts. What did you think I was going to do with the saved funds? Fight a war (or three) like those silly Americans!

(Disclaimer: I am totally a silly American. Just with a different value set than the current Plutocracy)

[Pecan]

Please could you explain what you actually want to do, since the description of the vehicle you're asking for doesn't make any sense.

"SSTO" = Single Stage To Orbit.

Neither rockets, planes nor anything else necessarily need fairings; it depends on your payload design or whether you want to use a payload bay instead.

A SSTO will not be any easier to fly through a gravity turn, especially if you're getting MJ to do it for you.

Spaceplanes are even more fussy about their ascent path than rockets, in general, because they have tighter tolerances.

But then you say "not be as annoying to make as rockets, but I'm rather poop at flying planes" - so how do you expect this thing to fly? Not a rocket and not a plane doesn't leave us much.

Anyway, that's contradicted by " its a plane with rapier engines and gets to orbit in one stage". OK, 'one stage' makes it a SSTO, 'plane' means it is a spaceplane and 'rapier' is the engine-type it uses. Stick some wings on the sides and wheels on the bottom, then test and test and test and test ... it's a lot harder than designing a rocket.

"can MJ autopilot an SSTO Spaceplane?" Yes, if you build and fly it like a rocket OR you really know how to control it and keep updating the MJ settings every minute or so.

"can anyone tell me the answers to my questions" - possibly, if you ask some.

NB: If "102t" is your payload mass then that's REALLY heavy for a beginner, even with a staged rocket. Building a SSTO rocket isn't too bad for that mass but a spaceplane will be very big, complicated and high part-count.

[Sharpy]

Yep, if rockets are annoying you, SSTO spaceplanes are really not for you. They are fun to design and pilot, and occasionally can be used to bring lighter, more regular payloads to orbit, but piloting them takes considerably more effort than a rocket, considerably more time, and landing takes a lot effort too. And it's as easy if not easier to botch the ascent too. Sure try them because they *are* fun, but for launches with actual payloads I recommend a different kind of SSTO - rockets, like the Cygnus family. Less effort than with normal multi-stage rockets, and recoverable too if you're playing career.

BTW, does MechJeb allow for S-shape ascent paths? Because most of SSTOs that don't take ridiculously long to reach orbit utilize something like this. Climb fast to 10km, reach 1000m/s in horizontal flight, then climb rapidly and fire the rockets to reach the orbit, then circularize.

Edited July 28, 2015 by Sharpy

[Pecan]

... BTW, does MechJeb allow for S-shape ascent paths? Because most of SSTOsspaceplanes that don't take ridiculously long to reach orbit utilize something like this. Climb fast to 10km, reach 1000m/s in horizontal flight, then climb rapidly and fire the rockets to reach the orbit, then circularize.

Assuming the correction I made to your quote (SSTO rockets have exactly the same ascent path as any other rocket) ->

From my preceeding post: "can MJ autopilot an SSTO Spaceplane?" Yes, if you ... really know how to control it and keep updating the MJ settings every minute or so. In this case, use SmartASS to keep the thing steady and stable, updating the pitch settings as your rate of climb or speed goes too high or low.

[Red Iron Crown]

Lets just go with the OP's desire to work on a spaceplane and assume that SSTO is shorthand for "SSTO spaceplane" in this thread, please.

[Wolf Baginski]

MechJeb has two different control options. The Spaceplane option would take you to level flight at 10000m, though the climb angle may be too steep for some planes. Then when in high-speed mode start a climb by changing the target height and switch to Ascent Guidance when you switch to rockets. It will likely need a different ascent curve setting.

The transition speed will depend on the plane. The switchover needs to be on an Action Group and needs to be at peak speed. Waiting for a flame-out wastes speed. There's some rapidly diminishing thrust before flame-out, the air-breathing mode losing intake air, and the plane slows down.

1000m/s air-breathing may work out as a little too fast a little too lowâ€â€excess heatingâ€â€and 800m/s with a little more altitude might be a better option. It's possible that the initial rocket-phase climb angle needs to be higher than you had with air-breathing to get out of the major heating.

It's good if the pitch control is balanced, not too slow but not too fast to be precise. With a good design, manual pitch control can do better than MechJeb. Roll and yaw need to be stable. Splitting a control surface into two parts and switching off one part at speed can help. If there's a pitch oscillation with MechJeb excess control authority may be the reason.

Get onto the heading you want early, before you go supersonic.

Time of flight from ground to orbit will be different. That can affect launch times for a rendezvous. Orbital inclination changes can be expensive, Do it right and you will be in the same plane, and simple phasing orbits are all you need

[Pecan]

Lets just go with the OP's desire to work on a spaceplane and assume that SSTO is shorthand for "SSTO spaceplane" in this thread, please.

Trouble with that, as posts 3, 5 and 6 all pointed-out is that the OP says he wants to use a SSTO - of whatever flavour - that's easier to build than a rocket and easier to fly than a plane. That is a pretty tall order, especially for 100t+ of payload, so a spaceplane is almost certainly NOT what the OP wants.

With the added implication that MJ will be used, I'm assuming that "SSTO" is shorthand for "something that MJ can reliably fly to orbit for me".

This, is about the simplest SSTO (rocket) I have for a 102t payload:

Decoupler below payload.

3 stacks of

5 x S3-7200

S3 KS25x4

nosecones and fins to taste

Batteries and RGU on centre stack, SAS units on side-stacks. Has about 500m/s remaining once in 75km orbit, using MJ's default settings (just open Ascent Guidance, set 75km target orbit, click 'Engage Autopilot' and press space to go there). If you want to bring it back it'll need at least a couple of drogue parachutes on there too.

[sal_vager]

Perhaps it's best you give pointers on how to make a small single stage space plane (SSSP), so Sharkman Briton can learn from that, and he can progress to a 100 ton payload monster as his skills improve over time.

[Wolf Baginski]

Lets just go with the OP's desire to work on a spaceplane and assume that SSTO is shorthand for "SSTO spaceplane" in this thread, please.

Multi-stage spaceplanes have been an idea that has been around for a long time, maybe something similar to Pegasus, which has been around for a quarter-century now. It's carried up to 40,000 feet by a modified airline, and is a three-stage rocket with a wing on the first stage. Set the carrier with MechJeb to fly straight and level, decouple the Pegasus-equivalent, and switch to fly that to orbit.

The Pegasus could be a small spaceplane.

I remember seeing pictures of the MUSTARD concept https://en.wikipedia.org/wiki/MUSTARD The plant called "rocket" is part of the botanical mustard family, which makes searches tricky. "English Electric Mustard" works better.

It apparently used asparagus staging, though nobody called it that.

The British aircraft industry had come up with some rather wild ideas in the 1960s. http://www.airforce-technology.com/features/featurehypersonic-mustard-fighter-jet-bae-forgotten-aircraft/

There have been others since.

http://www.armaghplanet.com/blog/10-shuttles-which-never-flew.html

And a lot earlier, though I am not sure that KSP aerodynamics could handle this.

https://en.wikipedia.org/wiki/WaveRider

[Nich]

Actually I have a challenge for this already set up. I have made an SSTO that can get to space with 'z', 't', 'space' all you have to do is back off the throttle so you dont blow up and at 15km follow propagrade. Making one that can do 102t would be a challenge.

Edited July 28, 2015 by Nich

[Sharkman Briton]

Please could you explain what you actually want to do, since the description of the vehicle you're asking for doesn't make any sense.

"SSTO" = Single Stage To Orbit.

Neither rockets, planes nor anything else necessarily need fairings; it depends on your payload design or whether you want to use a payload bay instead.

A SSTO will not be any easier to fly through a gravity turn, especially if you're getting MJ to do it for you.

Spaceplanes are even more fussy about their ascent path than rockets, in general, because they have tighter tolerances.

But then you say "not be as annoying to make as rockets, but I'm rather poop at flying planes" - so how do you expect this thing to fly? Not a rocket and not a plane doesn't leave us much.

Anyway, that's contradicted by " its a plane with rapier engines and gets to orbit in one stage". OK, 'one stage' makes it a SSTO, 'plane' means it is a spaceplane and 'rapier' is the engine-type it uses. Stick some wings on the sides and wheels on the bottom, then test and test and test and test ... it's a lot harder than designing a rocket.

"can MJ autopilot an SSTO Spaceplane?" Yes, if you build and fly it like a rocket OR you really know how to control it and keep updating the MJ settings every minute or so.

"can anyone tell me the answers to my questions" - possibly, if you ask some.

NB: If "102t" is your payload mass then that's REALLY heavy for a beginner, even with a staged rocket. Building a SSTO rocket isn't too bad for that mass but a spaceplane will be very big, complicated and high part-count.

Sorry I might've been unclear, when I said I'm poop at flying planes I meant I gotta learn how to fly it, and when I said "102t thanks" I meant as a term for a massive thanks. Thanks anyway.

- - - Updated - - -

Trouble with that, as posts 3, 5 and 6 all pointed-out is that the OP says he wants to use a SSTO - of whatever flavour - that's easier to build than a rocket and easier to fly than a plane. That is a pretty tall order, especially for 100t+ of payload, so a spaceplane is almost certainly NOT what the OP wants.

With the added implication that MJ will be used, I'm assuming that "SSTO" is shorthand for "something that MJ can reliably fly to orbit for me".

This, is about the simplest SSTO (rocket) I have for a 102t payload:

http://i.imgur.com/fURXN9Pl.png

Decoupler below payload.

3 stacks of

5 x S3-7200

S3 KS25x4

nosecones and fins to taste

Batteries and RGU on centre stack, SAS units on side-stacks. Has about 500m/s remaining once in 75km orbit, using MJ's default settings (just open Ascent Guidance, set 75km target orbit, click 'Engage Autopilot' and press space to go there). If you want to bring it back it'll need at least a couple of drogue parachutes on there too.

I actually meant spaceplanes.

[Evanitis]

Sorry in the name of the other kerbal engineers too if we were rude. Only a really few things can awake such manners amongst the community, unclear requests fall to that category.

Let me point you to my entry in the easy-to-fly SSTO challenge thread. I'm pretty sure there are better entries there, but this one comes with simple, failsafe operating instructions. I'm convinced that you could get it to orbit on the first try. Mind you the described ascent path isn't the best for saving dV, it's just a very simple one to reach orbit. The plane has no cargo-capacity either, the best it can do is some LKO rescue missions.

Mind you, many forumers will agree that designing SSTO planes is more than half of the fun compared to actually flying them. If I were you, I wouldn't skip this process by downloading a working, tested cargo-spaceplane.

Edited July 29, 2015 by Evanitis

[Sharkman Briton]

Sorry in the name of the other kerbal engineers too if we were rude. Only a really few things can awake such manners amongst the community, unclear requests fall to that category.

Let me point you to my entry in the easy-to-fly SSTO challenge thread. I'm pretty sure there are better entries there, but this one comes with simple, failsafe operating instructions. I'm convinced that you could get it to orbit on the first try. Mind you the described ascent path isn't the best for saving dV, it's just a very simple one to reach orbit. The plane has no cargo-capacity either, the best it can do is some LKO rescue missions.

Mind you, many forumers will agree that designing SSTO planes is more than half of the fun compared to actually flying them. If I were you, I wouldn't skip this process by downloading a working, tested cargo-spaceplane.

Okay, Once I (hopefully) fix this bug thats broken my entire game (I posted a thread about it in unmodded installs) I'll try to replicate it and see if I can do it, thanks for the consideration.

[Evanitis]

unmodded installs

Note: the carft file includes a MechJeb Module. Thought I don't have to mention that, because of the MJ related part of the op.

[Pecan]

...I actually meant spaceplanes.

Ah right, sorry I got caught on the implication you wanted something easier then.

Good luck with spaceplanes - they can be interesting if you like flight simulators but really are much, much harder to build and fly than rockets.

[Wolf Baginski]

Here's the .craft file for my latest creation. Its performance surprised me. It should all be stock parts, and there could be a lot of fiddling.

https://www.dropbox.com/s/lr7lb247rucaws1/White%20Arrow%20Spaceplane.craft?dl=0

And here's a picture of the White Arrow in orbit.

I hope the .craft file loads, it should be all stock components.

What startled me was the performance. I was getting 1450m/s in air-breathing mode, and reached a 100km orbit with 980m/s deltaV. Practise might improve that a little. How close do you let things get to overheating during the air-breathing phase? And things were happening fast enough to be worrying.

Anyway, with SAS on it is stable. Pitch and throttle and the only controls you need. I was keeping fuel pumped forwards because earlier planes had bad instability, and it was possibly too much. I could see the canards maintaining nose-up position, and that means drag. But that's the main reason the small fuel tanks and batteries are where they are.

Toggling the Rapier's operating mode and the intake were on an action group.

I started rotation about three-quarters of the way down to runway. Gear up and a gentle climb. between 5 and 10 degrees. Full throttle, of course. It went supersonic between 3000 and 4000m, and I levelled at about 6500m. I think it's a good sign that the nose stuck close to the prograde marker on the navball. Once the speed was in the 600-650m/s range you can start a gentle climb. That's when the acceleration started getting exciting. I started a fast climb, the acceleration continued, and that's when I noticed it was a bit nose heavy.

I ended up cutting back the throttle to stop the speed increasing. I was maintaining the speed. With a rocket you're in the gravity turn at that sort of speed and altitude combination, and I didn't want to pitch up too much. Eventually I was back at full throttle, getting more altitude, and switched to rocket mode as the speed dropped slightly.

After that it was more like taking a rocket to orbit.

I could deliver a small satellite to orbit, and that might counter the nose-heaviness. A radial decoupler in the cargo bay might be enough. It's a one-man craft, and I'm not sure that there would be so much useful science in LKO by the time you had the tech to build it. Could you replace the cargo bay with crew space, and how would you fit a docking port?

Who was that who suggested a couple of command chairs in the cargo bay, and transfers to the space station by an EVA?

The starting point for the re-entry is tricky. If you use SAS to align prograde the deceleration is slow. A ten-degree pitch-up will have some noticeable effects. I've used 90-degree pitch-up above 40km. Starting from the far side of the big desert seemed way too far, but I was way too high as I passed over the big mountains. I got low enough to restart as a jet, with fuel for 15 or 20 minutes of power. Still too high, and I was too nose-down to successfully land. I crashed on the runway.

Remember, the Rapier is an engine that doesn't generate electricity, so you need batteries.

[Captain H@dock]

What startled me was the performance. I was getting 1450m/s in air-breathing mode, and reached a 100km orbit with 980m/s deltaV. Practise might improve that a little. How close do you let things get to overheating during the air-breathing phase? And things were happening fast enough to be worrying.

As close to overheating as possible.

Since reasonable spaceplace have too low a TWR for reaching 1400-1500 m/s in a climb, you'll have to balance heating up with accelerating (in level flight) low enough to have time to pitch-up.

In the end the trade-off is between speed and angle of climb when leaving air-breathing territory. Shallow climb means drag for longer but higher speed means less rocket dV required to reach orbit.

[Frank_G]

The one tip that made my day concerning spaceplanes (thanks again Rune) was, that breaking Mach 1 above 10.000 m is the essential point, no matter how you get there.

R.A.P.I.E.R.s and lots of llifting surfaces are your best friends.

[Wolf Baginski]

The one tip that made my day concerning spaceplanes (thanks again Rune) was, that breaking Mach 1 above 10.000 m is the essential point, no matter how you get there.

R.A.P.I.E.R.s and lots of llifting surfaces are your best friends.

Lifting surfaces produce drag. It's like air intakes. You need enough air, but there's a drag penalty.

It's a toss-up whether to wait to 10000m before Mach 1. At that altitude acceleration can be a bit slow until you're well past Mach 1. The real Concorde usually went supersonic at the equivalent of 6000m.

I had a look at the velocity and atmosphere curves for the engine, and Mach 1.4 looks to be one of the critical numbers. But I am not sure that I am reading them right.

Lifting surfaces will reduce your take-off speed, but high-speed jets can have pretty high take-off speeds.