Do off-center (?) spaceship designs work at all?

[ErevanGaming]

Hi everybody,

I have recently design a large tanker to ferry LF+Ox and MP to my science space station orbiting Mun. I initial got an inspiration to design it off-centered like the image below:

Earlier test launches and space flights were okay, with and without fuel as cargo. Then I decided to add it's own heavy fuel shuttle/tender which would dock with any space station transferring fuel from the large tanker. This messed up everything (hehehe =">). I ended up going back to traditional designs, using one big tank from the SpaceY mod. =P

If you have tips for such designs, I surely would appreciate it! =) I really would want to have such styled ships stable/flyable with my career save. =)

 

Regards and thanks in advance =)

[Blaarkies]

Least effort: Have an array of small engines. Turn off a few engines on the side of the ship that has the least mass. This will move your center-of-thrust inline with the center-of-mass.

Some complication: Get fuel from many fuel tanks, but set their fuel flow priority so that they alternate using tanks from left and right...in the end you should have the same amount of mass of the left side as you do on the right side

The cargo being off-center brings up a new problem. My solution was to have the cargo in the center of the ship. With B9 HX parts thats easy. With stock parts, play around with the 3.75m Payload Faring's truss sections. You can build really strong structure with it, without even adding much to the part count.

 

[tg626]

The key is thrust through center of mass, the shuttle was an asymmetrical design, and that's why the rear engined on the shuttle are in the angle that they are.  Shifting center of mass is why they have a large gimbal range, to keep the center of thrust pointed thru the center of mass.  (Remember, main shuttle engines did not fire when the external tank was jettisoned)

[Wadusher0]

You might want to use RCS Build Aid to help balance your array of engines around the center of mass. It'll show exactly where and how much torque your engines put out, which is invaluable in an asymmetrical craft.

 

[ErevanGaming]

Thanks for your tips and comments guys! =)

By the way, this is what I was working on =">

Edited February 20, 2017 by ErevanGaming

[foamyesque]

That's pretty neat-looking. I assume it's purely for use in space, though?

[ErevanGaming]

2 hours ago, foamyesque said:

That's pretty neat-looking. I assume it's purely for use in space, though?

Yes, purely space use only, warranty void if used in an atmosphere =D

[steuben]

The advanced readouts in KER will help as well. You'll want to balance it against full and empty. You might be able to position or rotate the engines a bit to balance some of the torque you get from them, and load up on reaction wheels to balance the rest. 

[foamyesque]

Another option would be to exaggerate the U bend of the main spar, moving the tanks closer to the centerline and reducing your CoM shift. If those are vectors at the back, you've got tonnes of gimbal range; if they aren't, a set of thuds at the back, front, or both could help you as well. Another possibility is to move to a LFO RCS system, which'd give you considerably more oomph to keep the thrust aligned.

[tg626]

I'd put the black tanks in the middle for the ascent, then assemble in orbit...  make it less asymmetrical.

[Tyko]

You might want to check out @dboi88 and his work on an asymmetrical freighter http://forum.kerbalspaceprogram.com/index.php?/topic/155452-wipcoyote-space-industries-cargo-freighter/&page=1

[dboi88]

[Jarin]

It's massive overkill just for thrust balancing (like using MJ for just dV readouts), but TCA will do this with no trouble.

[ErevanGaming]

Thanks for your tips and suggestions guys!

• position/rotate engines
• moving tanks closer to centerline
• add smaller engines
• use LFO rcs for more power
• place black tanks properly for ascent, assemble/redeploy in orbit

My personal take on cargo freigher... it is a.w.e.s.o.m.e. =D