Antonov An-955 Calina, cant get her off the ground.

[fcdrifter13]

I am Having a little trouble with a build I am trying. I really wanted to build my next space station by getting all the parts up with a very large space-plane. This should lift what I need in larger sections if I did my math right, my problem is I cannot even get it off of the ground. I have build large planes before that can hold a 20k altitude all day long that weigh more than this but for some reason this one empty or loaded does back flips, veers wildly out of control, or wont catch lift until the end of the run way. I have tried shifting weight front to back and vise versa and where it is right now is as far as I get with it. I am looking for any suggestions, heck call me a fool for all I care I am just stuck.

Everything is B9 Aerospace, with a mechjeb 2 pod on top for load info.

and the craft file

https://www.dropbox.com/s/8wwcr6l83gc3eft/SSTO%20heaviest%20Lifter.craft

[Rune]

The pic is worth more than a thousand words: look at that thrust vector, and the position relative to the the center of mass. It wants to backflip, right? And you are trying to balance that out aerodynamically, when you problem is an off-center thrust. Even if you do, you will have problems once you run out of air, move those engines upwards!

And while we are at it, you know that you will need a very rigid and well placed landing gear, right? I find I-beams mounted on the center fuselage can usually be rigidized enough.

Rune. Good luck!

[deskjetser]

look at that thrust vector

Rune is right, while that position of thrust is very good for getting your nose up off the tarmac, its a nightmare for control.

Also just remember to strut your stuff!

[fcdrifter13]

The pic is worth more than a thousand words: look at that thrust vector, and the position relative to the the center of mass. It wants to backflip, right? And you are trying to balance that out aerodynamically, when you problem is an off-center thrust. Even if you do, you will have problems once you run out of air, move those engines upwards!

And while we are at it, you know that you will need a very rigid and well placed landing gear, right? I find I-beams mounted on the center fuselage can usually be rigidized enough.

Rune. Good luck!

I have tried them on top, they were their before they were on the bottom, I could not get any lift at all loaded with them on top no matter the attack angle. Could the problem be to little lift? and when I do manage to get the nose up it is just catching the air and flipping it backwards? When I get off from work I will try again moving it around and I will try to double the amount of lift.

Can I use regular rover wheels as bigger landing gear or will they cause too much drag. Right now I am just trying to get her up with 2 orange tanks plus a little extra I think that is about the most weight that I would carry. I have a different design in the making for trying to lift 300tons.

[NASI Director]

Also just remember to strut your stuff!

That has two meanings!

[fcdrifter13]

Well I finally got her into stable flight. I do not have enough lift, operating mass is 137t empty. I took 20 F119 Turbofan engines to get it going fast enough so slight lift, I can only turn up to 26* before it starts to stall so I am back to the drawing board.