Deorbiting and landing a spaceplane

[XenonSpark]

Hi everyone,

I have just recently started building spaceplanes, and I think I have a pretty decent grasp of how thrust, mass, and lift all combine to make something flyable. I've made a few great little creations in the SPH that handle well and are fun to play with in the atmosphere.

Today I decided to try building a VTOHL. It launches in a vertical configuration on top of one of my standard lifters. I take it up to an 80x80 orbit around Kerbin and detach the horizontally-designed payload (pic below), and then do a quick de-orbit burn. As you can see I am using B9 Aerospace parts in conjunction with stock. I also have the Ferram Aerospace plugin running.

My problem is that as soon as my plane reaches 33,000m it stalls and spins wildly out of control. ASAS does nothing to help. My airbrakes only worsen the spin, and parachutes simply alter my trajectory to become completely vertical, which of course means I'm completely screwed. Are there any obvious errors I'm making, perhaps in the design of my craft or the way I'm flying it?

Edited July 2, 2013 by XenonSpark

[Rradley]

Concerning your problem space planes when no designed correctly will destabilize in low air, to fix this increase the speed of the aircraft or find a way to switch from air intake engines to rocket fuel. I do not have the mods so i cannot accuratly say what your issue may be

[Tex_NL]

The reason your aerobrakes won't work is simple; you've put them way to far forward.

Currently they do increase the total amount of drag but it is all centered near the CoG. If you place them as far back as possible they create drag there and will function like the fletching on an arrow, keeping the nose pointed in the right direction.

Besides your aerobrake placement your entire design looks pretty unstable to me. It's very stubby and compact, has only small wings and no vertical stabilizer. Longer, narrower designs with more control surfaces tend to be more stable and easier to control.

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Concerning your problem space planes when no designed correctly will destabilize in low air, to fix this increase the speed of the aircraft or find a way to switch from air intake engines to rocket fuel. I do not have the mods so i cannot accuratly say what your issue may be

Your suggestion is totally irrelevant. First of all XenonSpark's problem is concentrated around re-entry and descent. Switching from airbreathing to rocket is an issue related to ascent. And second of all; his design DOES NOT EVEN HAVE JET ENGINES!

Edited July 2, 2013 by Tex_NL

[XenonSpark]

The reason your aerobrakes won't work is simple; you've put them way to far forward.

Currently they do increase the total amount of drag but it is all centered near the CoG. If you place them as far back as possible they create drag there and will function like the fletching on an arrow, keeping the nose pointed in the right direction.

Besides your aerobrake placement your entire design looks pretty unstable to me. It's very stubby and compact, has only small wings and no vertical stabilizer. Longer, narrower designs with more control surfaces tend to be more stable and easier to control.

Ah, that all makes sense. I think I'll add a vertical stabilizer and move the airbrakes. Probably lengthen things a bit too. Thanks.