Splace plane with adjustable COM and COL?!

[Arugela]

I'm building a very large cargo space plane. I have build a ballast system and movable tail fins.

With center weighted cargo(balanced symmetrically front to back) I can make the COM/COL balance be almost completely in the rear position, half way in the rear, just behind the center, probably just in front of the center or directly over the top, halfway to the front of the COM, and almost completely to the front.

Has anyone built something like this or know what it could be useful for. I'm assuming some of the use is simply different cargo positions during missions. Not sure what else.

The only other use I can think of is for the asymetric boosters I've designed for it. It gives options to help balance it if it even helps.

I'll get picks later.

Edited January 25, 2021 by Arugela

[vv3k70r]

19 minutes ago, Arugela said:

Has anyone built something like this or know what it could be useful for.

Yes. But if You are about to keep vessel (without leaving in back for funds in KSC) robotocs will turn into crap (position, rotation) after some gameloads. Escpecialy landed. World stabiliser do not help in such case.

Robotics in game is for fun, to complicated dependency for this phy.

[Guest]

I distribute fuel tanks evenly around the CoM. I can shift the CoM by pumping fuel around.  Never used robotics for that purpose, although I have considered making a cargo bay with a piston-mounted docking port that would allow me to position the cargo for optimal CoM.

In general I design my planes to be CoM-invariant, or as close to it as feasible. Fewer surprises that way.

[Incarnation of Chaos]

IRL Concorde pumped large amounts of it's fuel to shift the COG to account for "Mach Tuck" while underway and at speed. Stock KSP Aero won't have you needing such things, but FAR if i recall does model it to some extent.

So you could use a system like that to achieve the same in KSP.

COM in stock KSP should affect the stability of the plane, so you could make it more or less unstable by shifting your COM. Which could be interesting for a fighter/stunt plane, both because instability makes it easier to maneuver and get into a flaming wreck.

[KerikBalm]

20 hours ago, Brikoleur said:

I distribute fuel tanks evenly around the CoM. I can shift the CoM by pumping fuel around.  Never used robotics for that purpose, although I have considered making a cargo bay with a piston-mounted docking port that would allow me to position the cargo for optimal CoM.

In general I design my planes to be CoM-invariant, or as close to it as feasible. Fewer surprises that way.

Same here. 

As I think you know, I love to build large cargo carrying spaceplanes, and that cargo is often very large, and can shift the CoM, I often have significant excess fuel storage to allow for fuel redistribution to account for varying CoM depending on what payload is positioned.

When I restrict myself to a mk3 cargobay, it generally matters less. Also, my cargos tend to move the CoM forward.

Lastly, I do sometimes employ a method for changing the dry CoM, after payload deployment, by undocking and redocking some engines:

Spoiler

Runway:

Orbit:

Docking to move CoM  a bit forward:

 

 

Since moving to 2 stage recoverables on 3 or 4x Kerbin, it doesn't matter one bit really. I have a large carrier plane, with the payload + second stage slung underneath just behind the CoM. The 2nd stage always has its CoM shifted forward by the payload, but upon release its aerodynamics don't really matter. Its aerodynamics only really matter when landing with no payload:

Spoiler

Most of my robotics on space planes are for ones with plenty of dV, and deal with landing on Duna ... or are for flying on eve (if you count rotors as robotics). Dunno if you want to count aircraft designs for flight on other worlds as spaceplanes (space being anything outside of kerbin's atmosphere, or anything outside any atmosphere).

Spoiler

Never really needed more CoM shifting than what I get from fuel transfer, or redocking parts after payload release. Using robotics dynamically is quite... floppy. Its not so bad if you can get to space, unlock the joint, move it, relock it, and autostrut.

I did try some designs with robotics moving an ore can to balance out some VTOLs, but I prefer just designing it well balanced and with enough control authority from thrust vectoring/aerodynamics(in the case of rotorcraft).

So... I tried that, but I did not find it attractive considering other alternatives.

[Arugela]

Here is my current design: (Very laggy. 1k tons cargo. 3668t /wboosters 3216/woboosters)

I think for me this is a lazy convenience thing. It also gives a lot of options potentially for cargo loadouts and adjusting mass. Although I haven't tested this thoroughly.

CraftFile:

Boosters: https://www.dropbox.com/s/bcnczsra33ko7eo/KB-52 1_11_0_3045 x108 9_1_8 MB PI.craft?dl=0

No Boosters: https://www.dropbox.com/s/mi9jfglyguzuhng/KB-52 1_11_0_3045 x108 9_1_8 LB PI.craft?dl=0

https://imgur.com/a/1Qcl2zU

If I changed the cargo around I could get the COL all the way to the front of the COM.

Edited January 27, 2021 by Arugela

[KerikBalm]

@Arugela  a part count of 1160! very laggy indeed. My large 3x SSTOs were reaching about 1000 tons, but they were only 200 parts or so....

Good grief... my laptop could not handle that, even a part count of 200 makes it nearly too laggy for me.