S.S.T.O questions

[TheAnimePug]

So ive been trying to get an S.S.T.O that could get me farther then just a normal orbit but ive came across some roblems here are the questions:

_is its even possible to have an S.S.T.O that can fly interplanatary without refeuling?

_How do i fix the issue that when ever i make a sligth adjustment in my plane's trojectory it starts to point its nose Up?

_What are the Best engins i must use? (right now im using Turbojet then when im near 0 air intace i switch to chemical since nucliar are not strong enough)

_Would it be more efficient to have an external seat to save weight?

_is there a special way to go when buidling these things sutch as Light and Manovrable or heavy and Fast

If you can help me with this Please do so

Edited December 8, 2014 by TheAnimePug
Post was awnserd

[megatiger78]

you mean SSTO? also spellings fix plz

[Starman4308]

#1: It's quite possible to do an interplanetary SSTO, with Laythe being the usual suspect. It may prove necessary to top off the tanks in low Kerbin orbit or in Laythe orbit: I've never tried it before.

#2: I have no idea what your problem is, so I'm just going to link you here.

#3: Depending on SSTO mass, probably either a mix of turbojets for everything up to ~30km, and a single LV-N for everything past that, or 1-2 Rapiers for light-weight SSTOs.

#4: Technically yes, but that's rather unrealistic for many reasons, thus why I'd prefer to use full-up cockpits or capsules.

#5: Relatively small wings, loads of intakes. I need to save a link the next time I see guidelines for building SSTOs.

The most likely reason you're finding the LV-N insufficient is that you haven't built up enough velocity on turbojets. The typical profile is a dash to 20km altitude, at which point you level off and begin a very slow climb to 30km, gaining as much horizontal velocity as possible, using rate of climb to balance thrust and air intake with drag. Once you're at ~30km and 1500-2000 m/s*, you can switch to LV-N propulsion: you shouldn't need much more velocity from that point.

*The crossover point is basically when you can't get any more horizontal velocity because drag equals thrust, and any further ascent would choke off air supply faster than it reduces drag. Your turbojets are likely to be operating at only a fraction of maximum thrust at this point.

[zxczxczbfg]

It's "SSTO" (Single Stage To Orbit).

1) Possible, but very hard. As in, VERY hard. It's more practical to just refuel on the way.

2) Depends. A few screenshots or a .craft file would be nice.

3) Replace your regular chemical rocket engine with an aerospike for better efficiency. Of course, if you want a total redesign you could just go with the RAPIER engine.

4) No. Even if the seat weighs very little, Kerbals weigh a LOT when they're outside of a command pod. The extra weight of the Kerbal will unbalance your craft.

5) Go for "fast and fuel-efficient". Maneuverability doesn't really matter much. As for weight, just consider what you're trying to do. Are you going for a heavy cargo lifter? A refueling tanker? A science platform?

This post assumes you're talking about an SSTO spaceplane; SSTO rockets are generally simpler but also require a lot more fuel.

EDIT: Ninja'd.

EDIT AGAIN: I reread the original post. I think you've got a CoL (Center of Lift) problem, most likely that it's ahead of the center of mass. You want it to be slightly behind it.

Edited December 7, 2014 by zxczxczbfg

[RainDreamer]

1. Depends. You can dump off most of your useless mass (wings/jet engines/intakes/anything that doesn't work in space) once in orbit and use a very efficient engine to use the rest of the fuel to go to where ever you want. Still very hard, but more manageable. If you intend to keep everything to land at a planet with atmosphere, well, that will be seriously harder.

2. There are dozens of ways that may cause the plane to behave like that. Without further info, that is hard to figure out.

3. Turbojet + chem works. Just try to maximize your turbojet useful time by extending atmospheric flight for a bit for side way momentum, that way once you switch to chem and go to space, you need to spend less fuel circularize the orbit.

4. IMO, not a good idea. Some people makes that design works, but balancing radial stuff is always harder than inline for SSTO, I have found.

5. Maneuverability is only good in atmospheric flight. In space a brick with engine can flight just as well as a sleek space plane. Go with stable and fast. Unless you are designing a fighter plane in atmosphere, you want something that is very stable, able to land safely and capable of getting out of the atmosphere as fast as possible.

[Pecan]

[No baiting of other members - the KSP Forum Moderators]

1. Yes - Single Stage [to orbit] means it doesn't have to stop at orbit. My alarm clock is a torch.

2. Balance the lift and drag correctly relative to the centre of mass. Adjust trim as fuel is burnt and speed and altitude vary.

3. Which engines to use depends on the payload you're trying to lift. The simplest SSTOs use 48-7Ss for small ones, then aerospikes, T30s and mainsails.

4. The trouble with external seats is that you still need a command-pod to get the Kerbal to the seat in the first place. Otherwise ...

5. Light is always the best way to build spacecraft.

Think about why you want to do this in a single stage.

Think about why you want to do it without refuelling.

Do yourself a favour and ditch the wings. If you must take them, at least drop them once in orbit (unless going to Laythe).

ETA for sal_vager's edit: we are having a PM exchange :-)

Edited December 8, 2014 by Pecan

[Wanderfound]

Yes, you can fly SSTOs (spaceplane or not) interplanetary. A demonstration: http://s1378.photobucket.com/user/craigmotbey/Kerbal/Kerboduna/story

[GoSlash27]

_is its even possible to have an S.S.T.O that can fly interplanatary without refeuling?

Yes.

_How do i fix the issue that when ever i make a sligth adjustment in my plane's trojectory it starts to point its nose Up?

Post a screenshot within the SPH with the center of mass and center of lift highlighted.

_What are the Best engins i must use? (right now im using Turbojet then when im near 0 air intace i switch to chemical since nucliar are not strong enough)

Turbojets with (in your case) an LV-N.

_Would it be more efficient to have an external seat to save weight?

Yes, but a pain in the butt, you can't navigate properly, and it's really not necessary.

_is there a secial way to go when buidling these things sutch as Light and Manovrable or heavy and Fast

If you can help me with this Please do so

It's all relative. The way to go about building these is to 1) have everything in the proper proportion to maximize your efficiency and 2) Use the best parts. For each 15 tonnes of aircraft, you want 1 turbojet, .015 m^2 of intake area, and 15 CL worth of wings. It should be stable.

Best,

-Slashy

[TheAnimePug]

Tnx to everybody's help i got a new and improved S.S.T.O and it is now in orbit around the moon (as test flight) its doing amazing thank you everybody

[bitslizer]

1) yes, easily to Duna and Even Jool/Laythe

2) btw SSTO does not mean it must be a spaceplane, it just mean you aren't dumping any part for staging, normal rocket can be SSTO, "wings" are not necessary with SSTO if you got enough Thrust and DV

3) Nuke can be strong enough, you need to learn the correct SSTO profile, typically 8 intakes to 1 turbojet to supply enough air for high alt, build up speed to 2000m/s (2300m/s preferable) at around 30km and that will be orbitial speed, just switch to a little bit of Nuke to raise your AP to 70km, then you can switch back to jet to maintain speed or raise your AP until you are out of the atomsphere, properly done with MechJeb's help turbojet engine can still produce tiny bit of thrust at 68km, which is actually still raising my AP, trick is to not flaming out your engine due to running out of air (ez with mechjeb, harder on manual but there is a trick, last engine added always flame out first, so if you have odd number of engines with the last engine added on the center line, it won't unbalance your thrust when that centerline/last engine flames out)

4) You can, but not necessary, as to its not facing the right direction for control as raised by another user, the trick is to use docking port and "control from here" on the appropriate docking port.

5) both, below I have some links from the user CupCakes, who just recently published some VTOL SSTO tutorial. His design inspired alot of my own build, but some may consider it cheating due to extensive user of air hogging and parts clipping. Its up to you to decide if this is acceptable to you or not.

Threads stared by CupCake

http://forum.kerbalspaceprogram.com/search.php?searchid=3929373

VTOL SSTO Tutorial

http://forum.kerbalspaceprogram.com/threads/93802-How-To-Dropship-%28A-VTOL-Tutorial%29

http://forum.kerbalspaceprogram.com/threads/102023-Building-Dropships-A-VTOL-Tutorial

CupCakes drop ship depot (a bit out of date, but a good overall feel of what is possible, for more up to date check out his updated design in the first link)

http://forum.kerbalspaceprogram.com/threads/27424-Cupcake-s-Dropship-Dealership.

[bitslizer]

*The crossover point is basically when you can't get any more horizontal velocity because drag equals thrust, and any further ascent would choke off air supply faster than it reduces drag. Your turbojets are likely to be operating at only a fraction of maximum thrust at this point.

I want to point out that there exists another cross over point, once you use the nukes to kick your AP up to Orbit(i.e. 70k) you may still be slowing down due to drag in between 30k-70k after you shut off the nuke, to conserve LF/OX you can switch back and feather your turbojet throttle to continue gaining horizontal speed, but its tricky to do manually without flame out and unbalance thrust spin out.

[panzer1b]

So ive been trying to get an S.S.T.O that could get me farther then just a normal orbit but ive came across some roblems here are the questions:

_is its even possible to have an S.S.T.O that can fly interplanatary without refeuling?

_How do i fix the issue that when ever i make a sligth adjustment in my plane's trojectory it starts to point its nose Up?

_What are the Best engins i must use? (right now im using Turbojet then when im near 0 air intace i switch to chemical since nucliar are not strong enough)

_Would it be more efficient to have an external seat to save weight?

_is there a secial way to go when buidling these things sutch as Light and Manovrable or heavy and Fast

If you can help me with this Please do so

_is its even possible to have an S.S.T.O that can fly interplanatary without refeuling?

yes, yes, and YES! Every one of my SSTOs that isnt a parasite fighter, is capable at a bare minimum of 4K dV, meaning duna and back, or landing at duna, and my more recent ones have been flying to laythe and landing there with close to enough fuel to take off again.

_How do i fix the issue that when ever i make a sligth adjustment in my plane's trojectory it starts to point its nose Up?

make sure ur center of thrust is BEHIND but nto too far being the center of mass. This is a very common rookie mistake that causes instability and a tendency to picthup/down

_What are the Best engins i must use? (right now im using Turbojet then when im near 0 air intace i switch to chemical since nucliar are not strong enough)

I will say that for pure efficiency, you want a nuke for space travel, and rapiers/jets depending on how many intakes you have. Once in space, unless it is a lightweight below 10t, the nuke will ALWAYS give you the best range. For super lightweights, a rapier can actually give higher dV, but it has to be very small for this to be true.

_Would it be more efficient to have an external seat to save weight?

its extremely theoretical. for starters, kerbals have mass when outside of a command pod. While it is still LESS then a command pod, i dont think the effort of setting up command seats is worth a negligible benefit (it may help for extremely long range vessels but its quite possible to drag a 1 ton command pod to laythe and land it there).

_is there a secial way to go when buidling these things sutch as Light and Manovrable or heavy and Fast

My recent SSTO is manuverable and fairly fast, but id say at least for beginners, maneuverability is not the priority. Stability and minimizing drag/unneeded mass is key.

A few tips:

for someone who isnt very experienced with SSTOs, here are a few general tips on building something that WILL get into orbit at the bare minimum, and can easily go farther if needed:

1 jet for 10 tons (you can get away with 1 for 15 with a very large amount of wings), or 1 rapier for around 8 tons.

Have at least some wings. While some SSTOs are technically wing stabilized rockets (i tend to build this way recently), the best efficiency during ascent is with enough wings to be able to fly somewhat straight at low altitudes. The more cargo capacity and mass, the more wings you will need.

Aerospikes or LVT-30s are good for short range, but are only 13% more fuel efficient then rapiers, and still make little sense over a nuke that have around 200% the fuel economy of a aerospike.

Have at a bare minimum 0.03 intake area per engine with a medium sized 10-20t SSTO, but i myself tend to bring around 20 on most builds to let me get some thrust above 50km with either jets or rapiers. If its very small/light, one ram may very well suffice.

If you plan to dock, bring RCS/ports, but if you dont intend on docking, leave it out to save mass (and remove monoprop from teh cockpit).

Overall, cut out anything that isnt deemed essential to the mission. The less mass, the more range and the easier it is to get in orbit.

keep center of mass IN FRONT of the center of lift at all times (need to compensate for shifting CoG due to fuel drain.

On average, you want 2/3 LFO, 1/3 jet fuel, although this can vary greatly on mission requirements (need more fuel when going to laythe for ex), and also on your ascent profile (rocket like sstos generally use less jet fuel and get in orbit faster but need more rocket to circularize, whereas more classical planes spend alot more fuel on jets, and get to a faster orbit on jets, using less rocket fuel to circularize).

[bitslizer]

yes, yes, and YES! Every one of my SSTOs that isnt a parasite fighter, is capable at a bare minimum of 4K dV, meaning duna and back, or landing at duna, and my more recent ones have been flying to laythe and landing there with close to enough fuel to take off again.

Did you mean 4K DV left AFTER achieving/circularizing orbit? 4K total DV in the traditional rocket sense may not even make LKO orbit.

[theend3r]

_How do i fix the issue that when ever i make a sligth adjustment in my plane's trojectory it starts to point its nose Up?

The CoL is probably in front of CoM. ->

Post a screenshot within the SPH with the center of mass and center of lift highlighted.

[panzer1b]

Did you mean 4K DV left AFTER achieving/circularizing orbit? 4K total DV in the traditional rocket sense may not even make LKO orbit.

I dont bother calculating dV in atmo, its got too many factors to mess with. yeah, its in space dV, once i achieve LKO (70-100km orbit)

And who would use a rocket in a SSTO in atmo (until theyre above the engine cutoff)?

[Pecan]

...who would use a rocket in a SSTO in atmo (until theyre above the engine cutoff)?

Me.

Most of my SSTOs are rockets, for construction and flight simplicity and part-count.

When I use jets my Single Stage TO ORBIT vehicles separate the (rocket) space vehicle once they are IN ORBIT.

Who would carry excess, useless, heavy, wings, jets and landing-gear across interplanetary distances?

[KerikBalm]

"Who would carry excess, useless, heavy, wings, jets and landing-gear across interplanetary distances? "

Indeed, I don't. I go to LKO with a spaceplane (no a rocket), and detach a payload.

With some ISRU modding, it may be worth it to take a similar craft (no separation events) to laythe for example, to lift large amounts of fuel to a fuel depot

[theend3r]

Who would carry excess, useless, heavy, wings, jets and landing-gear across interplanetary distances?

Me and anyone who wants to build a 100 % reusable craft.

[GoSlash27]

Me and anyone who wants to build a 100 % reusable craft.

This gets into personal preference, but from a standpoint of maximum efficiency...

SSTO spaceplanes are really only optimized for making the trip from KSC to LKO and back with kerbals and/ or supplies. Any mission beyond that is best- served with a craft optimized for the task.

If I'm going to Laythe, I will

1) Lift the sections of a Kerbin-> Laythe mass mover and assemble them in orbit using an SSTO bulk lifter

2) Lift a Laythe SSTO spaceplane as payload using an SSTO bulk lifter

3) Get the crew and supplies into orbit using an SSTO spaceplane

4) Use the mass-mover to handle interplanetary logistics.

Of course, the beauty of KSP is that it allows you the freedom to tackle the challenges as you want.

Best,

-Slashy

[Pecan]

Me and anyone who wants to build a 100 % reusable craft.

I have learnt to re-dock before de-orbit ;-0

However, my space vehicles are mostly reused by refuelling in space. Why come all the way back down just to go all the way back up again?

Yes, I have to lift the fuel, but just the fuel, with a light Single Stage To Orbit not the whole vehicle that has to go interplanetary.

I wreck my efficiency by using Moho-capable tugs to take stuff to Duna sometimes. If you want to take your 'plane all the way you can do that too. Neither of us should pretend it's efficient to take mass you don't need where you don't need it though.

[TheAnimePug]

Me and anyone who wants to build a 100 % reusable craft.

so me basicly

[Wanderfound]

Who would carry excess, useless, heavy, wings, jets and landing-gear across interplanetary distances?

Me. As you know.

There's more than one way to define "efficiency", and there are also valid considerations besides efficiency. Runway to Laythe to Runway in something that flies like a fighter (and looks as below...) without needing to drop parts or transfer passengers has definite advantages.

The control surfaces and intakes give me precision aerobraking abilities, the turbojets provide high-efficiency atmospheric thrust, the RAPIERs give high TWR vacuum power, the LV-N's handle high-efficiency vacuum propulsion. Vernors provide low-G VTOL, while the wings and landing gear handle high-G landings (and combining the Vernor VTOL jets with the monoprop retrothrusters allows for VSTOL landings on rough terrain).

Is it as fuel efficient as an ultralight probe? Hell no. But why should I care? It only costs a couple of thousand √ to fly it, and with spaceplane tankers it only takes about √20,000 to put an orbital fuel depot around any planet you choose (√1/unit to put the fuel in orbit, plus a tank, a probe core, a docking port and an LV-N, all of which can also be spaceplaned to orbit for pocket change).

Spaceplane economics are somewhat broken at the moment.

Edited December 9, 2014 by Wanderfound

[Pecan]

Me. As you know. ... Runway to Laythe ...

Yes, I do know. Many other people do too. Laythe is a special case, of course, since the jets, etc. are not 'excess, useless' there. None of those advantages apply to other bodies, especially those that are in vacuum, or are easier than using a simpler design. 'Planes look cool, of course, but mostly because of that and their RL impossibility so many KSP newbies get the idea they are "THE" way to do things. I'm just trying to stress the benefits of the alternatives here, since hardly anyone ever does.

so me basicly

Many people want to create 100% reusable vehicles. Don't make the common mistake of thinking that means it has to complete the mission in a single stage. Separating and re-docking is prefectly valid, as is keeping special-purpose vehicles in space. Take-off, orbit, transfer, injection, de-orbit, landing ... and all the way back in one big lump, or Launch/Recover, Transfer, Lander with three specially-designed vehicles? The best thing about KSP is that it allows you to choose.

Edited December 9, 2014 by Pecan