Lifting bodies and small spaceplanes

[voleurinconnu]

TLDR; I need help with a Hermes type VTHL shuttle.

In all this time I've had the game I haven't really done all that much with spaceplanes, but with the new SAS and downloading FAR I thought I'd give it a try.

Anyways, I'm working on a Kliper/Hermes/Dream Chaser type spacecraft, and I'm running into some issues. Whenever I launch one of these on a rocket, it will just flip uncontrollably once I reach about 1000 meters.

I'm trying to build one with a shorter wingspan, maybe do I can fit it under a fairing, but it can't seem to produce enough lift to keep it's nose up when going less than 2-300 m/s. Canards would surely help, but I'm trying to avoid those.

[Frederf]

Sounds like a CoL/CoM arrangement issue in both cases. One has negative stability and the other has too much positive.

[espm400]

Personally, I had some problems with my own lifting body designs a while back (using FAR as well). I ended up settling on more blended body designs. Unfortunately, most of the 'ready-made' ones (such as Bobcats Kliper, etc.) don't really react to FAR that well. Personally, for a while there I was using a 'Dyan-Soarer' design for crew transfer to and from my main station (back in .20), but haven't done too much in the lines of lifting bodies since then. However, another mod that can help you out is pWings. Otherwise known as Procedural Wings, this mod allows you to create your own wing shapes, tailor made to your craft. One of the functions of the mod (one I'd like to figure out how to circumvent somehow) is that expanding the wing root length-wise, also increases the wing's thickness. From your standpoint using this function correctly, you can make some pretty good lifting body shapes.

Sorry for the uncharacteristic lack of example pics, but I just found 'X3-Albion Prelude' and have been playing that in most of my free time over the last few days...

[CalculusWarrior]

I don't believe lifting bodies work in KSP. However, launching a winged plane on top of a rocket requires some extra control. Ideally, you want the centre of lift behind the centre of mass (yes, even if it's launched vertically), otherwise it will be inherently unstable in flight. Possible solutions would be to put quite a few canards/winglets on the very, very bottom of your rocket, make sure your engines gimbal and can compensate for such instability, or simply slap a buttload of RCS/SAS units on the rocket to keep it locked in place.

[espm400]

I don't believe lifting bodies work in KSP.

~snip~

Although I can't speak for pure lifting bodies (you'd have to make an actual model for those), blended wing bodies work just fine with FAR installed. To put it mildly, they're a bit hard to control on re-entry...