Space Shuttle reentry headache

[Spyderborg]

This is my space shuttle:
http://steamcommunity.com/sharedfiles/filedetails/?id=813107644

It seems like it's impossible to get this thing to land. As it is, it nosedives once I reach landing speed and I can't pull up. Obviously this is because the center of mass is so far forward. But if I move the center of lift forward at all, it flips out on re-entry for no apparent reason (all I'm doing is following prograde; I'm not pulling up too hard or anything) even though the CoL is behind the CoM.

Can anyone make sense of this? It's extremely frustrating.

EDIT: Forgot to mention, all fuel tanks are completely empty when I'm re-entering

[blodsub]

Airbreaks?

[Spyderborg]

Originally posted by Jebediah Kerman:

Airbreaks?

I have those as well. But I don't have any problems slowing down. The problem is when I get down to landing speed (100m/s or so), the CoM is too far ahead for it to glide properly, so then it just nosedives.

[Jabroni Slayr]

Try moving your CoL closer to your CoM. That looks quite a bit farther back than I would make it myself, expecially since as you mentioned your CoM is shifting forward on landing so you aren't getting enough lift/flight control at that point.

[Spyderborg]

Originally posted by Jabroni Slayr:

Try moving your CoL closer to your CoM. That looks quite a bit farther back than I would make it myself, expecially since as you mentioned your CoM is shifting forward on landing so you aren't getting enough lift/flight control at that point.

I tried that, but as I said in the OP, if I move the CoL any closer, the whole thing flips out for no reason at all during reentry (even though the CoL is still behind the CoM)

[Jabroni Slayr]

Hmm. Have you tried canards on the front?

[Semaj]

http://steamcommunity.com/sharedfiles/filedetails/?id=790667308 - try my wing design, it might help. Then again though, I wouldn't trust mk3 parts to be particularily aerodynamic. I once read somewhere the real shuttles were like flying bricks, lol.

[TotallyAverageGamer]

Drain the fuel out of it and see where the COM is, it probably shifts forward when its almost empty and thats why you nose dive.

[Spyderborg]

Originally posted by Jabroni Slayr:

Hmm. Have you tried canards on the front?

I could, but I just don't know of any canards that are large enough to have a significant effect on the massive, heavy Mk3 parts, unless I try to custom-make some out of smaller parts.

Originally posted by Semaj:

http://steamcommunity.com/sharedfiles/filedetails/?id=790667308 - try my wing design, it might help. Then again though, I wouldn't trust mk3 parts to be particularily aerodynamic. I once read somewhere the real shuttles were like flying bricks, lol.

I'll definitely try out different wing configurations, but I'd also like to know why it's flipping when the CoM is ahead of the CoL

Originally posted by Capt. Odysseus:

Drain the fuel out of it and see where the COM is, it probably shifts forward when its almost empty and thats why you nose dive.

All fuel is drained out in the picture. What you see there is exactly the state it is in during reentry.

EDIT: Whoops, realized that the link in the OP was wrong. Fixed it

[john1352]

The horizontal tail fin that can't move is going to be a large contributor to your problem. Anything that far back needs to be a control surface, otherwise you end up with a dart. Big-S Elevons can be attached to the fuselage and offset to be in the correct position, giving you an all moving tail.

Otherwise RCS or reaction wheels can be used for stability during reentry, but RCS means extra mass for the fuel, and reaction wheels are a bit cheaty.

[AoD_lexandro]

Bad balance setup for a start. You should have the same size fuel tank in the back as the front with your gargo bay slap bang in the middle. Balance the Mk4 cabin with the mass of your main engines. Your CoM should be as close to the exact center of the cargo bay as possible. That means when adding or releasing cargo it wont affect your aircrafts balance.

Also flatten the wings, Big-S wings are dehidral in shape and dont need high angles. You should only need a maximum of 5 degrees up-lift at most with those. Also with the tail fin, click the move tool and turn off angle snap, then pull the tail fin down in to the fuel tank until the "wedge" end of the rudder is at the hull.

When you place every control surface on, the CoM and CoL should be near identical positioning. Then just slide your main wing rearward using the move tool until your CoL is stradelling the back of the CoM ( it should look like an number 8 shape). From there you can set your trim angle (to keep the nose level) with either your flaperon/spoileron or with a high tail T section.

And lastly, add some flaps. All aircraft use flaps to control lift levels under different flight regimes. Any aircrat you make should have FOUR sets of control surfraces.

1.) Pitch
2.) Roll
3.) Yaw
4.) Flaperon/spoileron

[Spyderborg]

So...I tested it some more and it appears that it only happens when I'm using physics warp...I guess I should just be patient and wait out the whole descent?

[Semaj]

Lol, warp is terrible in this game for the physics...

Originally posted by Propane Accessory:

So...I tested it some more and it appears that it only happens when I'm using physics warp...I guess I should just be patient and wait out the whole descent?

[TotallyAverageGamer]

Originally posted by Propane Accessory:

So...I tested it some more and it appears that it only happens when I'm using physics warp...I guess I should just be patient and wait out the whole descent?

That puts you on an "on rails" simulation where physics arent really calculated so youre basically hoping the kraken doesnt decide to attack.... Game of pure luck when you warp in atmospheres either entering or exiting.

[=BB= Misophist]

Originally posted by Propane Accessory:

So...I tested it some more and it appears that it only happens when I'm using physics warp...I guess I should just be patient and wait out the whole descent?

Warp in atmosphere is essentially saying "meh, I didnt like this craft anyways"

[Operation40]

Originally posted by Propane Accessory:

Originally posted by Jabroni Slayr:

Hmm. Have you tried canards on the front?

I could, but I just don't know of any canards that are large enough to have a significant effect on the massive, heavy Mk3 parts, unless I try to custom-make some out of smaller parts.

the advanced or standard canards are fine -- it doesn't need to be big, but plane basics demand 2 sets of aero-controls, 1 in front and 1 in back. it creates some kind of lever effect, iirc.. I'm surprised you can take off without 2 sets?