Spaceplanes and air buoyancy

[Axel]

I noticed that when I get to a certain height my spaceplane will start to loose its stability. It then plummets back to Kerbin, until it gets low enough for the plane to retain buoyancy.

What can I do to counter act the low air buoyancy in the higher atmosphere?

Inb4 'MOAR BOOSTERS!'

[Rico88]

I think the problem is that you get so high that the atmospheric engines stop working efficiently, because the atmosphere becomes thinner (if you use atmospheric engines).

[Axel]

Yeah, that does make sense. It\'s what I meant with air buoyancy. As the atmosphere gets thinner, my spaceplane starts to loose flight stability.

Is the only possibility to just add more boosters/engines or is there a design trick that could work?

[TerranCmdr]

Longer wings maybe? I don\'t really know, I\'m still playing around with ideas myself.

[RedDwarfIV]

Hah. I know this one.

The difference between my early Harrier aircarrier, which was supposed to put a spaceplane into near-orbit, and the current Harrier, is that I used the same wing configuration as one of my early triumphs, the Ibis Munar space plane. Let me get this straight - these are BIG craft. So at first, I used the biggest wings I could on the Harrier. You know, the really long ones. It just flips, goes crazy, and falls out of the sky.

With Ibis configuration - having the wings close to the spaceplane, covering as much of the length of the spaceplane as possible - you get the same, if not more lift, and it makes it a lot more controllable.

So do this:

P

C F C

WFW

WFW

WFW

WWFWW

Rather than this:

P

C F C

WWWFWWW

WWWFWWW

C F C

P - Pod

C - Canard

W- Wing

F - Fuselage

The second thing. In the upper atmosphere, your control surfaces will lose their effectiveness. At that altitude, you need RCS to keep you stable.

[White Owl]

It is time for a new meme around here. More boosters is no longer the only answer. Now we also need more wings!

[Axel]

thanks! I used your blueprint.

However whenever I launch, my plane somehow gets pulled towards the left, even though my plane is in perfect balance.

I try and correct and then my plane tilts and crashes mid start.

[RedDwarfIV]

thanks! I used your blueprint.

However whenever I launch, my plane somehow gets pulled towards the left, even though my plane is in perfect balance.

I try and correct and then my plane tilts and crashes mid start.

More SAS.

The design works, but you do need something to keep it on course. Why it would pull left is something I don\'t have the answer to. Can you post an image of your craft?

[Axel]

I got it to work. Thanks!

Apparently adding wheels in such a way that they aren\'t at a 90° angle makes them pull the plane left or right. ???

[ianken]

Symmetry is good.

I had a wicked space plane that would just tumble once it got too high. Even with a vectoring rocket motor lighting off it could not keep it flying straight. Jet engines on pods (like on an A-10) that are offset from the wings just cause all sorts of problems once there\'s no air for the control surfaces to bite into.

Basically the rocket motor axis of thrust is not aligned with the center-line of the craft.

[0muffins0]

I have a space plane that can fly happily at 15km, though it takes four engines at near full throttle, 540ms speed, and feels like skating on ice. The higher you go, the faster you must go for your wings and flight surfaces to work.

:-*

[Mr_Orion]

I have a space plane that can fly happily at 15km, though it takes four engines at near full throttle, 540ms speed, and feels like skating on ice. The higher you go, the faster you must go for your wings and flight surfaces to work.

I believe this is inaccurate. Although this would be the case in real life, in the game it currently does not support this. I hear a new wing and control surface module may come sometime, however, with more realistic physics.

[Axel]

Yeah, currently I think all they did was just add wheels and the possibility to build horizontally.

Planes still fly like rockets. As in no real gliding, up-draft etc.

[Temstar]

No no, speed and air density are taken into account by the game.

If speed wasn\'t taken into account, your plane will be as maneuverable sitting on the runway as it is flying through air

If air density wasn\'t taken into account then either:

[list type=decimal]

[li]control surfaces will continue to work outside of the atmosphere[/li]

or

• [li]there is a sudden point during the ascent where the game treats your plane as having 'entered space' and you instantly lose effect from all your control surfaces[/li]
  

Since neither happen and we do in fact slowly lose use of control surfaces as we climb, it means the game just be taking speed and air density into account.