I need help with a MK3 SSTO

[Nansuchao]

Ladies and Gentleman, from the very first days of KSP 1.0 I was trying to build a proper MK3 SSTO, with bad results until now. I'm used to play with FAR, but it's not updated yet, so I tried with the stock aero. Yesterday finally I discovered the beautiful "Instell Incorporated Experimental Technologies" that provided me with the mighty Scramjet Engines. After a couple of try with some small planes, I tried for a proper MK3 cargo plane.

The problem is that this ship is unstable at high altitude. It seems that the engines are aligned with the CoM, but my nose continue to fly by itself. Can someone please help me?

Craft Download: https://www.dropbox.com/s/qqmfi6kdk8gih22/SSTO%20Test%20III.craft?dl=0

Mod Requested: TweakScale http://forum.kerbalspaceprogram.com/threads/112693

Instell Incorporated Experimental Technologies http://forum.kerbalspaceprogram.com/threads/119735-1-0-2-Instell-Incorporated-Experimental-Technologies

Edited May 8, 2015 by Nansuchao

[stardog573]

Problem is that CoM of your craft moves toward rear as fuel is consumed. Because jet engine consumes fuel evenly from all fuel tanks, short tank at front will be empty when long tank at rear is half-empty. Even if you put long fuel tank in front of cargo bay, CoM still will be moved because front tank is farther from CoM than rear tank. Try to maintain position of CoM during your flight.

And if you don't locate CoM of spacecraft at center of cargo bay, same kind of problem will be happened while you load/unload cargo.

Edited May 8, 2015 by stardog573

[Nansuchao]

Yes, for that reason I use TAC Fuel Balancer, but no solution with that.

[Hodo]

Yes, for that reason I use TAC Fuel Balancer, but no solution with that.

I am looking at your design, and seeing as I have already given up on the new stock aero and am using the NuFAR dev build I can't offer much advice.

The problem is the air up higher gets much thinner now, so airhogging just doesnt work as well as it once did. So once you lost your jets to provide gimble force to keep the nose down you are now relying on very thin canards to try and keep the nose under control. I would suggest using RCS thrusters to help with that in stock. Also I would stay lower till you get your speed up then use that to transition to a higher altitude.

Oh and as a long time FAR user you will LOVE the NuFAR!

[Nansuchao]

Thank you very much Hodo. I downloaded nuFar, but I was scared from bugs. For the first time from when I discovered the mod's world, my KSP install it's almost stable :-)

Soon I'll try.