space plane question

[fancycat]

I am having trouble getting my center of lift just behind my center of mass without having my wings in the very back of the aircraft or my engines in the very front. Also if i do manage to get that part right my planes seem to have no power to pull up at all, they just leave the run way, pull up to a max angle of 5 degrees and slowly descend into the ocean.

Anyway I was hoping someone might be able to give me some design advice to help with this.

[sickboy]

what you want is the center of lift to be quite behind the center of weight, not dramatically, but more than just a little, or else you'll lose fuel and that'll shift it too much. You don't need only the center of lift to be behind, you also need LIFT itself, if you can't lift early enough, add control surfaces.

[White Owl]

First, get Ferram's Aerospace Research. The stock game's aerodynamics are nonsensical, and therefore the only aircraft that fly well are the ones that make no sense.

If you don't have enough lift, you need more wing area and/or more thrust. If you can only pitch 5 degrees up, it sounds like you don't have anywhere close to enough pitch authority; try moving the control surfaces farther away from the center of the plane in order to increase the leverage exerted. More control surfaces or larger surfaces can also help.

[fancycat]

ill give this a try

[RSwordsman]

The others have it pretty much right. CoL behind CoM is a good start, but you also need the wing area and speed. All the control surfaces in the world won't help you if you're going too slow and at too steep an angle of attack for them to work well.

[lammatt]

fuel tanks and engines!

fuel tanks are the heaviest things in a plane.

you can manipulate the center of mass just by shifting the position of the tanks.

usually, you dont want the CoM being too in front tho' because this is make your take off very hard. (to avoid tail strike)

also, if you want to have the center of mass more in front, you can use lighter engines. (aero spike is 1.5t at 175kN, while the 215kN engine is 1.25t)

also, monopropellent tanks are pretty heavy too, you can use them to play with the CoM position.

[fancycat]

ok so I added the farr mod but now my rockets all tip over in flight.. no matter how much thrust vectoring or canards or RCS i use they always uncontrollably tip over at about 5000 to 10000 km up. every single rocket so far no matter how small or how big has failed in this way

[Hodo]

ok so I added the farr mod but now my rockets all tip over in flight.. no matter how much thrust vectoring or canards or RCS i use they always uncontrollably tip over at about 5000 to 10000 km up. every single rocket so far no matter how small or how big has failed in this way

Simple, do you have nose cones on them? Are they aerodynamically sound? Or are they a bunch of bricks with rockets slapped on the back.

If the rocket isn't aerodynamically sound as soon as it gets near the speed of sound, 300m/s (+/- a few meters). It will flip to the more aerodynamic side, which is often the engines themselves.

So the trick is with rockets, is keep the speed to around 180-220m/s till you complete your gravity turn at around 10-14km altitude.