I need help building a Space Plane (SSTO), that can function as a refueling station

[Gauss H2K]

While I am no beginner to the complexities involved in SSTO building, as I've built several one man Stock SSTO's that can get to Laythe with refueling. However I am having difficulty scaling up to a space station that can work as a central refueling hub and carry 10+ Kerbals, as expected since its mildly difficult to build a non SSTO version. While its tempting to just ask for a craft, I want to do this on my own for the satisfaction of completion.

This is basically going to anyone who's built large space bus like SSTO's, any tips or tricks to make this possible?

I also ask for ways to minimize part count as my computer can barely handle 500 parts.

Edited August 1, 2013 by Gauss H2K

[Amoun]

Im going to be monitoring this.

I am trying to make a fuel....deliver....er...to my wannabe refueling station in Kerban orbit.

[AnalogAddict]

Check the Showcase: Post your SSTOs here.

Like you, OP, I have created several SSTOs that can get anywhere in the Kerbol system, but payload haulers, refuelers, and busses are foreign to me.

Threads like these have helped me insurmountably with ideas and techniques for building planes that aren't my traditional style. Especially since you're wanting to do the work yourself.

[IWantSumCrusha]

An SSTO station eh? That sounds difficult; i cant help but will also keep tabs on this as im interested to see where it goes! The bestbof luck to you!

[antbin]

to anyone who's built large space bus like SSTO's, any tips or tricks to make this possible?

I had a big "How To Build Heavy Spaceplanes" thread that got eaten by the last forum update. I think you'll learn best by watching others' creations (I just posted a .craft in the SSTO Showcase thread) and by trying yourself. My advice:

* Start with a fuselage that lets you attach the gear near the center of mass and with enough ground clearance. I like upside-down Mk3-Mk2 adapters, but you can also use strutted-up gear. Nothing worse than tail strike.

* Wings are the hardest thing to get enough of. Spam them.

* If a biplane, strut your wings together at the tips for more strength. Strut un-connected wing segments together too (hover over them in the VAB - connected 'child' wings will be highlighted together).

* Put fuel towards the middle of the plane, jets towards the back, and anything you can towards the front. When fuel runs out, if your rear-mounted engines are the only heavy thing left on the plane, you will re-enter flipping backwards.

* Intakes are the 2nd hardest thing to get enough of. Spam them too.

* ~4 intakes per turbojet and always use odd-numbers of jets. Use action groups to turn them off 2 at a time as you climb out of intakeair at 25km.

Edited August 3, 2013 by antbin

[Sauron]

I'm in the same boat here. I can make the little ones fine (10-30 tons), but figuring out how to get enough lift (and how much lift is necessary) is proving to be quite a problem for anything big enough to haul useful payloads.

[Gauss H2K]

Sooooo I've tried this idea I had and its failing...

Here it is in the hangar

Here it is on the runway

Now I followed some advice, and did as much to ensure that this thing would fly.

It has 12 turbo fans, and weighs about 151 tons. It's CoL is right behind it's CoM. It has extended landing gear designed to prevent tail strikes. It has almost half its mass in lifting force. (it only slightly <2 RAM intakes per jet engine, but as it can't get off the runway that's a mute point). The main problem I had was that it doesn't want to lift its nose, even with RCS and rear landing gear just behind the CoM, control surfaces are also a fair distance away from the CoM, so the torque from everything combined should at least allow it to lift its nose...

Here is the download link if people want to take a look at the actual vessel (you'll need the latest version of Mech Jeb) http://kerbalspaceprogram.com/recs-utah/

[allmhuran]

Use more than one layer of wings.

When building very large aircraft I tend to have two sets of wings. The upper wings angle down towards the tip, and the lower ones angle up. I then strut them together in a couple of central places and at the tips. The triangular geometry this creates is very resistant to flexing and allows you to build very large wings.

In the parlance, this is a combination of a dihedral and anhedral wing structure.

It also gives you space inside to hide fuel, air intakes, etc.

Don't put wings on backwards. Well... you can, but based on the movement of the centre of lift in the editor, I think reverse-facing wing parts do not generate additional lift.

Example of wing geometry:

[Gauss H2K]

After trying for a couple days now, I've decided to save my sanity, and give up on this project. The requirements for the design I had required too many small engines to be practical. I have no doubt that I could complete my design if there were was a bigger jet engine and a bigger Nuclear Engine, however since there isn't any in the stock version I give up;.;

[carazvan]

In my attempt to build large payload SSTOs I've found that there are really 3 different stages you should consider as far as engines go:

1) atmosphere jet ascent

2) rocket ascent

3) circularization

For most smaller SSTOs you can usually combine the engines for one or more of the stages but for a large SSTO you really need to have them individual. The suggestions that I can offer are:

- use 1 turbojet / 10t .. the more air intakes the better but this is a matter of choice. Think 2-3 would be minimum to get correct benefit out of jets up to at least 15-20k

- use NERVAs for circularization. There is no reason once you have the Ap above the athmosphere to look for large TWR but rather look to efficiency. You do need to ensure you have enough TWR to get your orbit circular so I'd say having 1 NERVA / 40t should be enough

[Gauss H2K]

In my attempt to build large payload SSTOs I've found that there are really 3 different stages you should consider as far as engines go:

1) atmosphere jet ascent

2) rocket ascent

3) circularization

For most smaller SSTOs you can usually combine the engines for one or more of the stages but for a large SSTO you really need to have them individual. The suggestions that I can offer are:

- use 1 turbojet / 10t .. the more air intakes the better but this is a matter of choice. Think 2-3 would be minimum to get correct benefit out of jets up to at least 15-20k

- use NERVAs for circularization. There is no reason once you have the Ap above the athmosphere to look for large TWR but rather look to efficiency. You do need to ensure you have enough TWR to get your orbit circular so I'd say having 1 NERVA / 40t should be enough

Yeah Constructing previous SSTOs has led me to build better booster for rockets easily. The ones I've built used actually about 1 turbofan per 15 ton, and utilized about 6 RAM intakes per Engine, which allowed them to got to 26Km+ and 1500 m/s+, then I use the Nukes+Radial engines to climb to 30-36km where a TWR of .5+ (just Nukes) and a speed around 1800 m/s is able to keep the vessel climbing to orbit. At which point circularization becomes easy since the delta v of just nukes was usually around 4500 m/s, and I was usually left with ~800 m/s delta v after circularization. The biggest one I made was 42 tons, had 3 turbofans, and 4 nukes.

However when I tried to make a 10+ Kerbal VTOL SSTO Thats when the problems hit. To get enough fuel for IP travel (Which to me was a must), the vessel started to weigh 100-200 tons. This wouldn't be a problem if it wasn't for the fact that 30 engines (with Ideally around 60 intakes for the Jet engines) taxes my computer too much to be practical (I can't even play with the aerodynamic effects because they crash my computer). Basically I'm not able to do this project with Stock KSP.

[Captain Sierra]

I'm actively working on a ship that can launch a standard fuel can (1 orange rockomax, 1 jumbo RCS; about 40 tons) to orbit. It is not SSTO and is rocket launched. I also have an 8 man crew shuttle. You want pics?

[Gauss H2K]

Go ahead an post pics plus the craft file if other people want to take a look. However the challenge (and "perceived" impossibility) go out the window when it's not SSTO, since the problems can be easily solved by adding more throw away boosters.

[Captain Sierra]

Yeah, lifting 40 tons isn't easy SSTO style. I have to do it rocket launch. I can do crew SSTO though. Then again, I'm not the greatest SSTO builder.

[allmhuran]

This one will put two (well, 1.8) orange tanks into orbit, but the tanks can't be decoupled.

The key to the design is twofold

1) On the runway the landing gear is directly under the heavy parts... ie, the orange tanks and the central fuselage. This prevents the craft from buckling and beinding while taking off, meaning you won't start veering wildly or scraping bits and pieces.

2) The heavy parts are also spread across the lifting structures. You can see that the orange tanks are about a third of the way out along the wings. If all of the mass was down the middle the aircraft would sag drastically once airborne because all of the upwards lifting forces of the wings would be a long way away from the mass in the middle. Spreading the mass out keeps the wings from bending or breaking off the fuselage.

[lammatt]

you can safely fly the B9 stock shuttle plane (the one with name started with H______ and has a crew capacity of 6) to a 100km orbit with ~300 LF and 360 oxidizer left

and it can hold ~2000 unit of LF at max.

i think 2000unit is pretty decent already

so...

if you want to make a plane which can act as a fuel station

try modifying it.

- replacing the 2 crew tanks with empty LF+O tanks

- remove the air brakes

- replace with lighter cockpit (probably using the stock Mk2)

- remove the inline port and add the port at the nose of the cockpit (if u change it to a Mk2)

- more lights

- less landing wheels

- stronger RCS thrusters

- a few gigantor panels

[camulus777]

I like using the flying fuselage design it looks like a flying pizza slice. You can do a fuel variant or a transport. The transport is kinda cool cause you can put like 20 kerman in it. The fuel can is good because you use a fraction of the fuel to get it into orbit. Rockets are just inefficient as fuel carriers because they use 7/1 fuel to get into orbit. A plane uses 4/1 or even 5/1 if you fly it right. This became a bit more difficult with the latest patch but it is still doable. in fact you can make an entirely rocket free space program if you know what you are doing. Im starting a youtube series dedicated to simplifying SSTOs an space plane based launch platforms. I'll put the link up here when i get my PC fixed in a few days. If it helps let me know, I'll dedicate an early episode to fuelers and transports.

[allmhuran]

in fact you can make an entirely rocket free space program if you know what you are doing.

For any launch vehicle, the periapsis of its orbit can never be higher than the highest point of thrust. If you are only using air breathing engines then this means your periapsis must still be in the atmosphere. How do you stay in orbit without rockets?