How are you landing your rovers?

[GalaxyGryphon]

even though mine isnt that off balance, when i apply thrust, it goes out of control, ive tried skycrane method but i just cant control this damn thing!!

what do you guys do?

[llamatoes]

That is off balance, although some sas would help.

[satcharna]

Try turning on the center of mass and center of thrust indicators. Align the two so that the arrow from thrust points straight along/past/through the center of mass. This balances your lander.

[GalaxyGryphon]

Try turning on the center of mass and center of thrust indicators. Align the two so that the arrow from thrust points straight along/past/through the center of mass. This balances your lander.

ok its off like an inch, but i would have expected the thrust vectoring to take care of that no?

Edited May 24, 2013 by GalaxyGryphon

[Qumefox]

i'll post pics of the delivery of the last rover I sent to Mun when I get home. Though mine might be a tad complicated, since it involved droptanks, etc, but it still worked successfully the three variants I sent to Mun.

[Wabur]

ok its off like an inch, but i would have expected the thrust vectoring to take care of that no?

An inch is all it takes.

[Qumefox]

ok its off like an inch, but i would have expected the thrust vectoring to take care of that no?

Thrust vectoring won't help much if CoM and CoT aren't aligned pretty much exactly.. ASAS isn't really smart enough to correct for much imbalance purely with vectored thrust.

[GalaxyGryphon]

I am noticed something very very odd..... if i remove the ASAS it flys almost perfectly, as soon as i put it back on the ship is uncontrollable..... a glitch?

edit: i think it has something to do with activating it before launch. as i put it back on and didn't use it, and it once again flew fine.

Edited May 24, 2013 by GalaxyGryphon

[satcharna]

Not at all. The purpose of ASAS is to "lock" your steering, so that your vessel will continue pointing the same direction. It does this by manipulating your controls and overreacting in every direction, wasting momentum and RCS.

[Shrike42]

I've been avoiding skycranes. I have a ship that can land and drop off two small rovers and take off again, and a few manned rovers that have a landing stage and separate upon arrival.

Edit: To clarify, the landing stage is under/inside the legs of the rover. That way I just have to line it up with the CoM, and carefully weight the rover.

Edited May 24, 2013 by Shrike42

[GalaxyGryphon]

I've been avoiding skycranes. I have a ship that can land and drop off two small rovers and take off again, and a few manned rovers that have a landing stage and separate upon arrival.

my only problem is: once i land the vehicle i need a way to get the rover off the top of the ship without dropping it :/

[Shrike42]

Well, how about using that same rocomax tank, putting on landerlegs and ASAS, and put the rover on top? Once you land, you retract the lander legs on the tank, and drive off.

Hmmm... How about this: your rover is REALLY low slung. Could you put another set of panels on top of all the sensitive bits to protect 'em from overhead impact, strut together for strength in a structural plate sandwich, then put a lander leg on top so that if the rover flips over, you can extend the leg to right yourself again?

With this approach, you could sandwich your lights and sensors and batteries safely inside the rover, put a few solar panels on the outside (if not a few reactors on the inside) and have a solid little system that could handle the drop.

[Frederf]

I am noticed something very very odd..... if i remove the ASAS it flys almost perfectly, as soon as i put it back on the ship is uncontrollable..... a glitch?

edit: i think it has something to do with activating it before launch. as i put it back on and didn't use it, and it once again flew fine.

I've heard that ASAS doesn't handle if the COM and COT are reversed from normal.

[Shrike42]

Oh, I see the chair now. Hm. Well, you could use panels or pylons or i-beams to give it a roll cage. Probably not a bad idea in any case, since that light little thing is going to accelerate pretty dang quickly.

[CosmicX1]

Currently I'm just sticking my rover at the very top of the lander with a docking node and then the plan is to spin the wheels a lot until the rover falls off in the right direction... well that was the plan anyway. Instead the entire lander bounced on impact and tipped over allowing me to just detach the rover and drive away while pretending nothing had happened

[Stealth2668]

I have the same question. I have my CoT and CoM perfectly lined up and i still start tipping...

[satcharna]

This is how I build most of my rovers. Basically, I make a low design, and then put a lander on top of it with a docking port. You do a powered or parachute descent, land on your wheels, pop the landing gear so the module lifts the rover off of the ground, and then decouple the docking port. When I want to take off again, I just drive the rover back under, lower the landing gear, and blast off. Maybe it could give you an idea?

[ZedNova]

I have the same question. I have my CoT and CoM perfectly lined up and i still start tipping...

You should have the COT lower than the COM.

[Pulstar]

I land them attached to the bottom of a landing hanging assembly. Once it lands I just decouple it and drive away. You just build a wide structure with the engines and fuel above the rover.

Kind of like this below only make the legs longer so that the rover can be taller.

The idea is that the rover doesn't take the impact of the landing and doesn't get obstructed by the structure. You can put a structural fuselage below the 6-way node and then another pair of 6 way nodes and the legs proper. Preferably the thing should be H shaped when looking from the top so that the landing structure has a wide base.

Edited May 24, 2013 by Pulstar

[satcharna]

You should have the COT lower than the COM.

Not always. If you're a big fan of stability, like me, putting the thrust over the mass makes it "balance" on its own. It fights your commands, but it does so to keep pointing upward.

[rryy]

I like to use skycranes for landing rovers. For asymmetric rovers, I would place a radial decoupler over the center of mass and put an I-beam on top of the decoupler as close as I can get it to being above the center of mass. Then, I build a skycrane on top of that.

[Stealth2668]

What exactly is a skycrane?

[satcharna]

A stage mounted on top of the rover with thrusters that slow it down, hover it slightly above the ground, and then decouple. The rover drops down safely, and the skycrane flies off and crashes somewhere.

[lobsterbark]

I just use a skycrane. I've never had any issues with them.

[GalaxyGryphon]

aaawww yeah...

not as complex as some people would have done it.... but its good enough

what do you guys think?

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