How to Balance/Land a Space Shuttle?

[Mr. Peabody]

Basically I've been working on a shuttle lately. I have most aspects complete (including the launch system) but the glide balance is really throwing me. I'm not sure whether I should bring the COM closer to the COL or vice versa. The below screenshot details the situation when the rear LF tank is nearly empty, as it will be after re-entry.

So how do I balance this thing? Also, what exactly is the best way to land a shuttle? Any help will be appreciated. Thanks.

[Geonovast]

10 minutes ago, The Dunatian said:

Also, what exactly is the best way to land a shuttle?

Nose forward, wheels first. 

I can't help with math or best practices, but here's mine in landing condition.  Lands very nicely.  Note the two drogue chutes on the bottom in the back.  They're tied into the brakes, and help make sure the nose stays down during deceleration.  (Not really a problem on the runway, I just end up putting them down in the grass once in awhile)

[GoSlash27]

Bring the CoL closer to the CoM.

 The SPH doesn't show your pressure center; where the drag acts relative to CoM. If you have the CoM and CoL in the back, the light, draggy nose makes it want to fly backwards at high speeds.

As for how to land it... You will have some trial and error while you get the hang of it. You find a reentry burn landmark and Pe that will put you long of the airfield into the ocean. Then you use steep banking turns to soak up the excess energy. You will have to find landmarks to judge your speed and distance so you know whether you're fast or slow.

You want to maintain not more than 5° AoA on your final approach to the runway so you don't stall it, which may require a fairly steep glideslope. Aim for the leading edge of the runway, then flare when you hit 100m.

HTHs,
-Slashy

 

[KerikBalm]

Send it up empty on top of some SRBs, to about 10 km, and then try to land it... no need to go all the way to orbit to test its landing. IRL they stuck the orbiter on top of a 747 and released it in flight to test it:

https://en.wikipedia.org/wiki/Space_Shuttle_Enterprise

I don't have many pics from my shuttle designs (which I have basically abandoned since I play 3x, but with stock parts STS style shuttles don't work so well)

With no fuel, they land fairly slowly. With the heavy main engine(s) at the back, its the wings also need to be pretty far back for stability... this also works well for ascent with fuel and payload in front of the wings, so that they act like stabilizing fins.

Spoiler

This shuttle design was before we had vectors, and I think they nerfed the Rhino a bit since then... I think its mass used to be 6.5 tons, now its 9

 

[bewing]

In general, it's much easier to move the CoL (by just moving the wings forward) than it is to move the CoM. Additionally, as slashy said, the farther back the CoM, the more likely it will swap ends at high speeds.

However, the other vital criteria is that the CoM does not move behind the CoL at any time during flight. Not when it's full of fuel, or empty, or full of cargo, or empty. You can mitigate this during flight if you are willing to pump fuel around to maintain some balance.

 

[Capt. Hunt]

With the KSO, I start the deorbit burn over the desert.  I do tend to use MJ's landing autopilot just for the prediction, however you have to keep in mind that it assumes a vertical descent for the last few thousand meters.  I usually burn until the predicted landing site is the summit of Mt. Woopstoshort, from there the KSO can still glide to the runway.  If you're coming in high or fast, a few s-turns can bleed off speed.

 

Drogues won't be too helpful, they're designed for high speed and high altitude.  If you have real chutes, the Drag chute is useful for slowing you down once you're on the ground.