Catching an E-class

[Sokar408]

Alright so I sent up a vessel that ended up encountering an E-class asteroid while still have 8.4k DeltaV and as expected when I struck it head up, it went done to about 270. However it would still have been enough if it wasn't for the fact that as soon as I turn on the engines, the whole thing starts shaking wildly. I even brough 60 struts with me (KAS), reloaded the quick save, strapped every single one the the vessel (evenly ofc), and it helped absolutely nothing. The vessel stroke free 1 side of all the struts after the shaking got too bad, and end up ripping itself apart even though I desperately shut down the engines.

How the hell do you guys do catch these behemoths?

[_Aramchek_]

"Balance in all things."

You have to find the asteroids CoM and thrust accordingly.

[Vanamonde]

Long burns at low thrust work for me. At lower G loads, SAS does a better job of keeping your heading.

[Tex]

Remember that the AGU gimbals, unlike standard docking ports, and you can lock said gimbal. I hope by "shaking" you mean your craft wobbling violently at this connection point, otherwise I would assume you mean that the entire asteroid is flipping end-over-end, which is unlikely.

Hope this helps!

[Sokar408]

"Balance in all things."

You have to find the asteroids CoM and thrust accordingly.

I am ofc focusing the CoM. What happens looks like the same situation, as when you have a rocket that is too long, and once it starts shaking to one side, trying to compensate just makes the oscillation worse.

Long burns at low thrust work for me. At lower G loads, SAS does a better job of keeping your heading.

I guess I could try fewer engines. I was using 6 nukes though, which given the size really shouldn't be too bad. I think its the torque forces that is causing the shaking, but I sense RCS isn't really the way to go when trying to maneuver an asteroid

[cantab]

There has been a bug reported where craft vibrate themselves to destruction with no specific cause, especially with stuff clawed to asteroids I believe. If you're experiencing the shaking getting worse even after you've shut down engines and SAS, that may be the problem. The resolution is to completely close and restart KSP, though even that may not cure a ship that has already picked up the issue.

[Caelib]

There needs to be a fine-tuning of COM on large asteroids because I don't think sending up a ship with 20 reaction wheels is very realistic.

[CalculusWarrior]

I've never tried it, but I heard of a strategy where one docks multiple smaller probes which are basically extra RCS ports to help with stabilization.

[theend3r]

I too used a six LV-N ship to move my E class, albeit it had a lot more than 270 dv since I needed to move the asteroid from a highly inclined orbit to an equatorial LKO in one go. It had about 100 000 units of fuel (7x the largest tank) and I didn't experience much wobbling. As to the job of keeping the heading, it didn't even have any SAS, RCS only, which was a stupid decision since I ran out of it near the end of the mision. Still managed it somehow but if I were to redo it I'd definitely bring some SAS along.

[CatastrophicFailure]

.... There's a reason big rig trucks move 100,000 lb loads by pulling from the front vs pushing from the rear....

[SpaceSphereOfDeath]

This seems to have been caused by the gyrokraken, but I thought it had been fixed‽

How many reaction wheels did you have on your space craft and was the claw fixed or free to move?

[Uncle Mort]

After wrestling with a couple of Es and a D I've decided that pulling is the way to go. Mainly because if you don't get that CoM just right any manoeuvre causes drift off the correct path. However, A, B and C I'll continue to push.

[Random Tank]

I pushed an E class with a ship that had only 3 Nerva's, and used RCS to steer; it was pretty easy actually!

Here is the Grabotron Mk1 and its Class E roid; granted it does have 2 claws though.

And here's the newer Grabotron Mk2 with a Class C; it now comes with a small drone to latch on the other side for additional maneuverability.

Edited April 22, 2014 by Random Tank
Uploaded pics

[Mazlem]

I've spent the last two weeks wrestling off an on with an E-class, getting it into orbit using a couple different pusher designs. Now I'm working on putting it in an equatorial orbit. A pusher design with small torque arms (little arms with SAS / RCS) on each side didn't help any. I finally set up a puller design and that's working much much better; another thread about working with class D/E's showed using a long arm on your ship, with the claw at the end and the pivot freed while thrusting, along with engines set to pull.

A couple times when I sent a refueling ship up there, even though it wasn't docked, the ship / asteroid did some pretty weird stuff:

-One time the asteroid puller ship and torque arms were responding directly to my inputs while I was moving the refueling ship.

-Another time the asteroid / ship parts started wobbling and turning on their own, while I was controlling the refueling ship nearby.

-Three times the asteroid puller ship has spontaneously exploded; the last time while controlling the refueler - it had moved away and was set to de-orbit; the second I turned on time warp, that ship and the asteroid puller blew up.

That weird behavior is really making me re-think setting up a fuel station on the asteroid, at least until the devs can get this stuff with the larger asteroids figured out.

[Kasuha]

Best approach to catch E-class (or generally any) asteroid according to my experience:

You need a lot of torque to turn and steer that thing, and you need to put that torque on the asteroid itself. When steering, you need the asteroid to turn your pusher, not the other way around. Proportional to the asteroid mass, get some probes with a claw, some RCS and 3-4 torque wheels each (warning: it drains electricity like crazy!) and attach them directly to the asteroid. Your pusher alone should rely on engine gimbal rather than torque for steering.

Make your pusher long enough. You need the engine gimbal to be able to compensate for your ship grabbing the asteroid slightly off-center, eventual imbalance caused by your torque probes and any wobbling that may happen in your ship and its connection to the asteroid.

Edited April 22, 2014 by Kasuha

[samiamthelaw]

Best approach to catch E-class (or generally any) asteroid according to my experience:

You need a lot of torque to turn and steer that thing, and you need to put that torque on the asteroid itself. When steering, you need the asteroid to turn your pusher, not the other way around. Proportional to the asteroid mass, get some probes with a claw, some RCS and 3-4 torque wheels each (warning: it drains electricity like crazy!) and attach them directly to the asteroid. Your pusher alone should rely on engine gimbal rather than torque for steering.

Make your pusher long enough. You need the engine gimbal to be able to compensate for your ship grabbing the asteroid slightly off-center, eventual imbalance caused by your torque probes and any wobbling that may happen in your ship and its connection to the asteroid.

I've tried this. I had about 20 reaction wheels attached to an E-class asteroid, but it was still very difficult to turn or steer the thing. The approach that worked for me was to mount engines on each side of the thing (an FL-T800 with LV-909's on each end). They make turning my E around pretty easy.

[Kasuha]

Turning is difficult. Or rather, takes time. But once the asteroid is properly oriented, with enough torque and engine gimbal, it's possible to let the SAS work through the burn.

Using engines to perform quicker turns is not a bad idea but you must account for random changes to your trajectory they may cause. So if you decide to turn your asteroid using engines, you may need to reset your maneuver once you're done. Maneuvers in general do strange things when handling heavy asteroids and to my experience, using torque only is the safest way to avoid messing them up.