Need to get this Rover/Lander into orbit and not spin before doing so

[Benie]

Again I feel like "it's not good enough" for the physics engine of this game. Also, I'm using ingame cheats and MechJeb. So anyway, I got to get this...

into at least an orbit around Kerbin. It's mostly Stock parts except for the fuel canisters of the rover. On liftoff, it's fine. But when I go to do my Gravity Turn, it spins out of control even with ASAS on.

I don't get it. The Center of Mass is perfect (I think). I can't get the rockets higher, as that's where the landing gear is.

And I read somewhere, that you want the engines to be low for landings. But I can't even get this thing into orbit, let alone land it.

Please understand that I'm not even using MechJeb to fly this. I'm doing it manually.

Please help me out here. I know I cheat, but I'm begging. I want to enjoy this game my way, and watching something I spent hours trying to think of a design of, go horribly wrong like this, isn't helping.

If it helps, here's the Rover/Lander in the VAB, showing the Center of Mass and Thrust.

I know the thrust is tilted because it thinks the rocket of the rover is a rocket of the lander, but my staging keeps that rocket from firing.

Edited July 5, 2013 by Benie
Finally resolved! :D

[Tex_NL]

Add some control surfaces. Aerospikes can't gimbal so they can not correct for any errors and pod torque alone isn't strong enough.

[stupid_chris]

Add some control surfaces. Aerospikes can't gimbal so they can not correct for any errors and pod torque alone isn't strong enough.

Though he would lose control after going a bit higher because the control surfaces won't supply enough force after a while. He's also gonna need an RCS system once you get further out of the atmosphere.

[Guest]

I tend not to use aerospikes very often just because of the flipping around issue. Maybe try using some winglets to give mechjeb a little help controlling the rocket while in the atmosphere? Placement of the winglets can be a little tricky also. You might need to experiment some to find ideal placement with regard to center of mass.

edit : wow. 3 posts in 4 minutes

edit 2 : I also didn't read the post right. Winglets may help when flying manually also. Time for sleep.

Edited July 4, 2013 by Otis

[Tex_NL]

Though he would lose control after going a bit higher because the control surfaces won't supply enough force after a while. He's also gonna need an RCS system once you get further out of the atmosphere.

He already has RCS onboard.

[Benie]

I actually didn't expect any posts. The reason I decided to use Aerospikes is a need a good engine that won't be too powerful.

My other, smaller Rover/Launcher uses 4 of the Mark 55 Radial Mount Engines. They seem good for most of my landings, and they're also quite powerful.

Would you recommend I try 4 LV-T45's? It's what I used of my first Rover to the Mun.

[stupid_chris]

I'm not sure but I think LV-909s would maybe do the job.

[NoMrBond]

When I was trying to lift a big crazy rover (nearly 9 tons, just to the Mün), I ended up loading a (symmetrical) pair of them (facing forward, parallel) as it was just impossible to have the single one slung underneath, while a a pair was at least balanced, so moar boosters worked.

Edited July 4, 2013 by NoMrBond

[Benie]

Well, I just found one problem that may be causing this to happen. The rockets aren't symmetrical. I took care of that problem.

I'm also trying to balance it better by raising the struts to be in the middle of the rocket, which in turn is shifting the Center of Mass near the center.

Also got to fix the landing gear, so my rover can get out, and latch on to the Docking Port.

Edited July 4, 2013 by Benie

[Johnno]

I don't see any fuel lines. Without fuel lines your rockets won't be able to utilize the fuel in the middle.

Also, if you're using ingame cheats just toggle infinite fuel+rcs and hack gravity. Should be near impossible to not get it into orbit. Beyond that I think it'd even be easier building a proper launcher for it, if you're having trouble getting it to orbit *with* cheats try doing it the proper way.

A few more thoughts on your design - I'd advice you to attach the parachutes onto the fueltank, otherwise they're likely to just rip the top off. Also moar struts, specifically stabilize the engines stacks and I'd probably strut the center stack as well, any tilt while deploying those parachutes (even if they're on the tank) may result in the top parts falling off. Landing legs - shouldn't need that many. 4 if you're comfortable doing a soft landing, 8 at a stretch. To save mass you could swap the large probecore for a small one attached to the fueltank with a octocube strut. Also the nosecones are currently deadweight, I'd remove those unless you want them for looks. Docking ports can 'undock' items attached to them, so no need for decouplers. Decouplers are good for cutting off fuelflow but beyond that not much need when attaching to docking ports.

Hope some of that helps.

[rryy]

Aerospikes for some reason tend to cause your rocket to spin out, so try using the LV-T30 or LV-T45 engines instead. Also, check the position of the center of mass of the rover and make sure it is alinged with the docking port you attached. The craft's CoM may look centered on takeoff, but as you burn fuel, the CoM may shift.

If that doesn't solve the problem, do the gravity turn earlier at around 5 km and gradually turn over, staying pointed near your prograde vector.

[Aragosnat]

Have to agree with rryy assesment. Even if it looks balanced the rover could be just the tinest bit off. And that is all it needs for it to spin out of control. The only thing I can sugest is. Pulling the rover by the nose. In short change the rover CoM to the other plane one as that will allow you to use a nice docking port there. But, I understand your reason for doing it like you have.

[Benie]

Hi again. I got another problem, and I think it's being caused by Quantum Struts. I'm using KAS instead of docking ports, since I've spent so much time raising and lowering the landing legs to get both ports at a good height that they'll connect.

Yet when they do, I'm not getting the magnetic pull I'm supposed to. My rover just goes right by it like it doesn't exist, and both ports are the same.

So now I'm using a Vertical Winch (standard), and a Radial Connector Port on top of where the Micro-ASAS and the strut that's holding it in place. I also have two Quantum Struts that lock the rover in place (since without them, the connection between the strut and my rover is like an invisible spring).

Now I can't get this damn lander to turn. I think it's the struts. They probably think they're supposed to be glued to the ground, even though they're attached to the rover.

I tried putting the struts on the rover, but after I EVA to place the cable in the connector (Undocked) and pull the winch in, the struts aren't being activated.

[Tex_NL]

After undocking ports need to be separated a few meters in order for them to reset. Only then will they re-engage.

Normal struts are 'single use' After they are disconnected they are useless. Docking struts and Quantum struts can be reconnected.

[Benie]

I finally got this thing into orbit! All of this time, it was the cubic strut holding the Micro-ASAS in place that was screwing everything up.

Thanks loads to HoY, and the guy that made Quantum Struts. I'm so happy.