Getting this glider into orbit..

[Panzerbeard]

Hey all. I've got my first eve launch window coming up soon in my career mode save, and I wanted to get some science done in the atmosphere. Normally I'd just make a conventional landing probe with parachutes and all the usual gubbins, but I thought I'd take a stab at making a glider instead. I've not done much more than an eve flyby before, and I'm not exactly an expert when it comes to planes/atmospheric flight, but the glider itself seems to fly really well on Kerbin, and, I assume, should be just as good on Eve (as I understand it, I'd be getting much more lift due to the thicker atmosphere, right?).

The issue, however, is getting it into orbit. Every time I strap it onto a rocket the entire thing spins out and wobbles around madly like Jebediah on crack, once I get too fast. I've tried multiple rocket designs, but it just doesn't work; I assume this is due to the lift from the wings causing problems, but I don't how to counteract that. Any ideas?

screenshot:

I know the glider itself isn't the best thing on the planet, but it works, so I'm happy with that. It's just getting it into space that's the problem, ideally on a rocket if at all possible. I'm not using FAR, DR, or KW/B9.

cheers,

Ash

[Landge]

Are you mounting the rocket inline to your glider or on the side? Looks like there's a small rockomax hiding behind the rudder.

Check your center of mass (CoM) to make sure it's in front of your Center of Lift (Col). That's usually the cause. Add a bit more length to the nose and see if that helps.

Edit: do you have ASAS on the glider AND on the rocket? That may help stabilize the launch too.

Edited January 26, 2014 by Landge

[Panzerbeard]

Are you mounting the rocket inline to your glider or on the side? Looks like there's a small rockomax hiding behind the rudder.

Check your center of mass (CoM) to make sure it's in front of your Center of Lift (Col). That's usually the cause. Add a bit more length to the nose and see if that helps.

Edit: do you have ASAS on the glider AND on the rocket? That may help stabilize the launch too.

I've tried both ways, I've mostly been mounting it inline, since I need to get it plus the fuel+nuke engine for the interplanetary transfer into orbit, I was treating it like any other payload. That small engine on the glider is just for short bursts to extend my glide time a bit, or to get in the air again if I land.

I've checked the CoM and CoL, the CoL is always behind the CoM on the glider. I've tried doing the same for the rocket, but even with a bunch of tail fins it still wants to flip about when it gets above 100m/s or so. As I said, the glider itself works fine on its own, it just doesn't like being on the rocket at all. I've used multiple reaction wheels on the rocket, I can't fit one onto the glider since the body is made of the tiny probe parts, and I want to keep the weight down anyway.

[DeMatt]

Maybe try taking it easier as you boost. Larger fuel tanks, less engine thrust, until you get clear of the atmosphere, so the atmospheric surfaces don't affect your trajectory.

Could also try mounting two gliders, one on each side, and facing opposite each other. Be sure to right-click the gliders' control surfaces and turn 'em off.

[Landge]

How about mounting 2 gliders on opposite sides of the rocket. Let your rocket be the main craft to get into a parking orbit over Eve then detach your gliders separately.

Edit: Ninja'd

[Panzerbeard]

I was hoping to avoid adding a second glider, but I guess they're light enough that the extra mass shouldn't impact my dV too badly; I'll just use the second one to explore a different area on the planet. Obviously Eve doesn't actually have biomes yet, but one can pretend, I guess. Or I could attach a satellite of a similar mass to the other side instead of a second glider, and just stick wings on using a decoupler, and ditch them once I'm out of Kerbin's atmosphere. Thanks for the tip, I'll give it a try

On a slightly related note- how will the wings affect aerocapture? If I'm trying to capture the entire rocket into an Eve orbit, with the glider(s) attached, I guess I'd need to have a slightly higher periapse for the aerocapture than I would normally, due to the extra drag from the wings?

[Landge]

2 is better than one. Better to have a backup for those oh crap moments.

This isn't a glider but here's a 2 jet transport ship I made for the journey to Laythe. It's one of my favorite ships in my fleet. I like ships that multi-task.

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[Claw]

You have a lot of wing area for a small craft (which is fine). But all that lift is probably what is causing your rocket to tumble. Just stapping wings to the bottom of your rocket might not fix that. I would guess it isn't your CoM/CoL design of the glider, but the assembeled rocket that might be the problem. Once you strap a rocket to the bottom, I'm sure the CoM shifts back.

Also realize the CoM indicator in the SPH lies to you once you put landing gear on. In flight, they actually have zero mass or drag (ignored by physics). So do all your CoM/CoL designing with landing gear off, then put the gear on. If you didn't do this already, you might want to check it out because based on the size of this thing I'm guessing you have very little CoM/CoL margin.

You have more than enough control surfaces on there. So that might also be why you don't have problems till 100m/s.

[numerobis]

Main options I can see:

1. Build a 3-stage plane. Jet in the back with wings; midsection is a rocket; front section is your glider.

2. Send two gliders, on either side of the rocket.

3. Use two rockets, on either side of the glider.