Creating an Asteroid Wrangler

[Zero Serenity]

So I'm trying to get an asteroid miner together and sofar I am having severe problems getting it to fly properly. For some reason the original version just falls apart. Like, put it on the launch pad and the side engines just come off. 

Here's the ship.

I somehow got it fixed by spacing out the side engines from the main body, but during testing the ship can't fly straight. After maybe five seconds or so of full burn it seems to lose control, even with RCS on and no asteroid attached. Is there something I'm doing wrong here?

Some other thoughts: Four drills are still capable of mining more than sixteen refineries can keep up with, so I'd like to keep that as a central feature if I can. Otherwise the ship is largely available to change. Cheers.

 

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[Gianni1122]

@Zero Serenity

Sounds like you might need to add "structural hard points" or radial decouplers(?). I would also add some struts. In the bottom right of the screen, I see you have engines + fairing + decoupler on the same stage. This will cause all three things to "activate" at the same time. If this doesn't help, let me know and we can keep troubleshooting. 

Welcome to The Forum 

[Zero Serenity]

Thanks for the welcome. I put some hydraulic manifolds on the connection point (disabling staging in the process) and while it's holding together as a piece, it still doesn't fly straight. Like it's unbalanced but the CoM is perfect as far as I can tell. The craft has been updated if you want to look.

[bewing]

It looked like the same craft to me. I'm not sure you quite got the important point that Gianni1122 was making. Generally, when you launch a rocket, you want the engines to fire first. Then you want the rocket to go up a ways, and then maybe you want to decouple something. Once you are almost out of the atmosphere, you maybe want to get rid of your fairings. So you need to set up 3 stages -- one stage for each of those things. And then you activate the 3 stages by hitting the spacebar at the appropriate times. The rocket in the picture will fire its engines, decouple the decoupler, and dump the fairings all at the same instant, the moment you launch the rocket off the pad. Even if you have the "falling apart" issue covered, this seems like it's going to be bad for drag.

So that's the next point. When rockets have proper CoM and they don't fly straight, it's because there is too much drag at the front end of the rocket, and not enough at the back. And not enough control surfaces at the back to prevent flipping.

 

 

[Zero Serenity]

I got the point about staging. This rocket is incomplete anyway (no launch vehicle, TWR is about 0.7). But if I crack the debug menu, throw it into orbit and then fire the engines, it doesn't fly straight. That's the problem I'm having.

[bewing]

3 hours ago, Zero Serenity said:

But if I crack the debug menu, throw it into orbit and then fire the engines, it doesn't fly straight. That's the problem I'm having.

Oh. OK, thanks for the clarification. What is your control point when you fire the engines? The little cupola? Is gimballing turned on for the engines? Do you have any extra reaction wheels on that monster anywhere? What happens if you select one of the Klaws and choose it as your control point?

 

 

[Zero Serenity]

8 hours ago, bewing said:

Oh. OK, thanks for the clarification. What is your control point when you fire the engines? The little cupola? Is gimballing turned on for the engines? Do you have any extra reaction wheels on that monster anywhere? What happens if you select one of the Klaws and choose it as your control point?

 

 

Huh. I changed to having the claw being the control point (at least I think this is what you mean by "control from here") and now the wobbling is gone. No wild wobbles, nothing. What I was doing before was controlling from the station housing but doing everything in reverse. Like, if I wanted pro, I burned retro. To answer the reaction wheels question, I have sixteen between the mono-prop tanks and batteries (look near the refineries).

[bewing]

Yeah, I've heard reports before of people having trouble controlling SAS in backwards mode, but doing that hasn't bothered me yet. -- But that's why I suggested you try it.

 

** Actually -- if you could post a savegame of that ship in orbit, I'd like to make a formal bugtracker report for the backwards SAS issue so that the devs can fix it someday.

 

Edited December 26, 2016 by bewing

[Zero Serenity]

The save is specifically "Miner in Space", but everything of my save file is in here if you have some advice or anything.

https://1drv.ms/f/s!As5DYck_hFS-t757-piJ7flKsn3hlQ

[bewing]

Thank you for posting all of that. I will make a bug report about your ship for the devs to fix.

It turns out that if you set the "Gimbal" to "Locked" on the engines, that the problem goes away also. But you will probably need the gimbal set to "free" when you have grabbed the asteroid. You may actually need to put the klaw on the end of a girder to get it further away from your ship, in order to grab the asteroid.

 

[Zero Serenity]

I have tested the miner on an asteroid and it does spike in pretty fine. The launch is going to be expensive (like, over $2 million) but once its in space I don't have to do it again. Just wrangle new asteroids as they come by and such.