Large spaceplane construction: Tips and tricks, as I uncover them.

[Whackjob]

I've just begun a new project, for however long my ADHD holds out.

As many of you SSTO old hands know, smaller is better, and large aircraft tends to wibble and wobble all over the place. Not to mention the commonplace rapid unplanned disassembly. I've taken the lessons I've learned with the Arkingthaad series of large tower landers, and am currently applying this to SSTO construction. Provided I can manage this, I will build an SSTO variant of the Arkingthaad lander.

So, yeah. Big plane. Here's a screenshot of what I've put together thus far:

As I build, I make it a habit to launch it, even if it's seriously far from complete, as in this case. The reason is quite simple. Does it fall to pieces the second physics kicks in? How much sag is there? Do two parts that have no business being so close cause problems? What does this button do?

In this case you can see the bi-wing set I'm working on. Utilizing the truss and strut method, I've managed to make it superbly rigid. There's still flex in there, as I note when physics went, but she holds like a champ. You can see the center just-in-case wheels are largely pointless. I may retain them for belly-flop bad landings.

More screenshots and construction discoveries as I get there.

#EDIT: I forgot, you can't see the wheels tucked under the center tanks from that screenshot. But they're there and off the ground.

#EDIT2: I don't even have an overall plan on how this will turn out. Just kind of... winging it.

Edited January 14, 2014 by Whackjob

[Captain Sierra]

Oh dear God whack. May God have mercy on your processor.

EDIT: So planes is what got you out of the rut eh? Just had to pick one of the hardest things KSP has to offer, no biggie.

now, Supersize it baby!

XD lol.

Whack, please give us both pics of that in orbit when you can get it there.

[Whackjob]

#EDIT: Redacted.

Thank you kindly for correcting my thread!

Edited January 14, 2014 by Whackjob

[vexx32]

Moved it back. Not sure what went on there.

When you've got a good compilation of tips and tricks, you might want to consider compiling a comprehensive guide for the Tutorials section.

[Whackjob]

Thank you, Vexx32!

I'm kind of at a loss as to how to take it from here. Right now I've got the fore-center section completed. Do I put the primary wings to the fore, or aft? Kethane refinery's gotta go inside also.

And how will I put her down on the Mun? Arse first? If I do it that way, how will I flop it over so it sits regularly? Do I throw landing thrusters underneath?

I think I'm just going to keep building and not stop and see what happens.

Got front tank tops in the open yet. I suppose I could put a pair of stowaway containers there, provided I properly reinforce the attachment points. Or put the kethane refineries there.

Here you can see the landing gear trusswork. This has proven suspiciously stable; I put three mainsails on the back of this thing, and ran it off the runway and across some rough grass. Got airborne quite a few times, at a high rate of speed, and the gear stayed put, even at ~150kph+.

#EDIT2: I'm considering a dual tail boom and large wing up front.

Edited January 14, 2014 by Whackjob

[ferram4]

If the landing truss is really that strong, you should be able to land it on the Mun by flying backwards, angled slightly above retrograde, using the engines to provide "lift" to keep you from slamming down too hard. Then you can use the brakes + engines to do nothing but slow it down.

[ArmchairGravy]

That's genius truss-work on the wing segments. I just found out the joy of jet-powered rovers using trussed landing gear. I'll definitely try that wing design!

[numerobis]

That wing design seems extremely heavy; surely you could get away with strutting only every other or every third wing? Otherwise you've converted your 50 kg wing part into a 300 kg wing segment made of 5 parts.

[Arsonik]

I haven't built a big plane since .19 with B9, I play mostly mod free now.

What I wanted to contribute was that I've had great success with bi-plane wing setups on small-medium planes. Don't be afraid to start over now and rebuild to where you are with your current design plan. You can work out existing redundancies and improve things that you already have found can be done better. It's never to late... Don't get burnt out on another big project Whack!

Just make sure you have center of lift/thrust behind center of mass. Usually the primary wings are near the arse end to balance the bulky weight of the engines. Be sure to disable yaw on all your wings but tail wings. It will rip a big multi-part plane apart trying to use to many control axis on a single control surface. Try making multiple control surfaces for individual functions (pitch/roll/yaw). Landing should be easy. Land on the engines, gently use SAS to flip it onto the wheels, or RCS. Those landing gears are strong, don't be worried about dropping on them. I actually made a pretty ******edly large rover back in the day out of the Modular Multiwheels mod that I forgot all about. It was slightly smaller then what you have there and landed on the mun (and returned, punching it up a mountain to get a return trajectory LOL) with that profile. The entire thing was made out of entirely cheater parts (Modular Multiwheels, Deuterium, B9/TV Wings, etc). but the proof of concept exists IMO. Good luck

Edited January 14, 2014 by Arsonik

[Col_Jessep]

I think you can get away with less structural elements for the amount of fuel you want to carry. But I only build large planes with B9. Everything larger than Mk1 brings out the ugly in stock...

[Jon Tash]

With just what you just showed us, my computer would probably blow up, can't run so many parts at once.

[Whackjob]

Still mulling over how to build out from here. I think what I'll end up going with, will be the large wing up front, and extended dual tail booms. Also need to figure out how I'll do the jet engine clusters.

#EDIT: Inspiration strikes! Why not simply integrate the air collection and fuel bus system for the non-jet engines directly within the wing itself? Lots of space in there!

Edited January 14, 2014 by Whackjob

[Moar Boosters]

Thats kinda similar to my design for big planes. A sandwich with wings for the bread and fuel tanks for the filling.

My design is pretty simple really....I stuck the fuel tanks together first, and add a few girders to them above and below. The wings are attached to the center line of girders, and then diagonally strutted to the fuel tanks to stop them flapping. Then I created a diagonal series of braces between the girders over the top, and the same on the bottom. It's this bracing that really stops the wobble. There's not that many struts, but having them in the long diagonal/diamond formation makes them very good at resisting flex, and believe me, with all those engines this thing wants to flex.

You should be able to get away with quite a lot less bracing if you use less up/down struts, and brace diagonally instead.

[katateochi]

Oh look the sun is being eclipsed by a moon..no, wait...that's just a WhackJob plane going overhead. Going to watch this with interest (and some trepidation).

I agree with Col_Jessep & Moar Boosters thou, you prob don't need so many structural parts.

[Whackjob]

I'm still practicing for the actual build. I think I'm going to make it look something like a frigate, and less like a plane. Still mulling over ideas.

[Seshins]

I think I'm going to make it look something like a frigate

i like this idea alot. Love your work.

[Moar Boosters]

I also figured out a good way to attach the engines for large spaceplanes when you're using multiple types.

Instead of each type having its own fuel tanks, this method effectively gives you one massive fuel tank which every engine can access all of the fuel.

All the fuel tanks drain into the middle tank. Instead of the engines attached to the tanks directly, each one has an octagonal strut and then a 2x2 plate which the engines attach to. The middle fuel tank drains into the middle 2x2 plate, and then that drains outwards into the 2 plates next to it, and so on.

It works quite well for balancing the fuel load as well. The tanks drain from the out-side inwards, so depending how you design your plane, you can minimise weight-shift as the fuel drains. You can even put tanks in pairs, one set upside-down, and then there will be amost no weight-shift at all as they drain.

[LostElement]

Built bigger... much much bigger...

[Whackjob]

I'm thinking of taking the hexagonal pattern from the Gossamer and applying it to the frigate. This will give me much more fuel storage. I think the way I'll have to go will be to build the majority in the VAB, then move it to the SPH, to add on the lifting surfaces. I think I can weave the actual wing segments in between the hexogram, and still have the lift direction being more or less the right way.