I don't understand what in the hell is going on

[Catthedragon]

I'm a moderately-experienced player, I've made it as far as crash-landing on Vaythe with single-launch rockets, now I'm trying to dock for the first time so I can expand my horizons. But there's something really, really wrong with this particular rocket.

I've already got the top half of my docking rocket (cockpit and landing unit) into orbit, now I'm trying to get the main fuel tank up there as well. But for some reason, this rocket will randomly stop responding to controls at varying points throughout its flight. Sometimes it will happen in the lower atmosphere just as the solid fuel boosters are about to expire, just now it happened as I was trying to migrate from a sub-orbital trajectory to a full orbit.

The effects of this phenomenon vary. Sometimes the game won't let me activate stages or use the engines, but it will let me turn the aircraft. Other times, it will let me control the engines and progress through stages, but it won't let me turn.

Now, I'm piloting this craft with two Stayputnik MK1s (Stayputniks so they can be detached and discarded after docking, two to counterbalance weight as one cannot be put on top of the docking port), and of course my first thought was that they ran out of power. But nope, they're each equipped with batteries and solar panels, and they were each at 100% power as my ship was spiraling out of control.

Can someone explain to me why this is happening? Is it a bug? Pic related, it is the problematic craft.

(Also unrelated question, but do adapters have fuel crossfeed? That small fuel tank on top is for smooth transitioning between the parts of the finished craft, but I'd like to know if it can feed into the orange tank or if it's just dead weight)

Edited January 18, 2015 by sal_vager

[7499275]

Pictures of this craft will be a huge help! However, (educated guessing here) sounds like you might be running out of electricity on the probe thus loosing control, or maybe not enough control surfaces and torque. Again, pictures will really help us out!

Also adaparts (NOT DECOUPLERS) do have fuel cross feed enabled. (I'm fairly certain)

[Catthedragon]

Pictures of this craft will be a huge help! However, (educated guessing here) sounds like you might be running out of electricity on the probe thus loosing control, or maybe not enough control surfaces and torque. Again, pictures will really help us out!

Also adaparts (NOT DECOUPLERS) do have fuel cross feed enabled. (I'm fairly certain)

I did have a picture in the OP, but it was weird and bugged. I fixed it.

[Scoundrel]

It's a bug where, near as I can tell, keyboard inputs stop. I don't know what causes it, as it is intermittent, but I have experienced it several times. The only way I know to fix it is to quicksave then restart KSP.

[Norpo]

The image in the OP isn't showing up for me, luckily I got a (weirdly cropped) version to show up, here ya go.

Took me going into the developer screen in Google Chrome to find it

[CrisK]

It looks like there are no batteries on your rocket. SAS uses battery power. When your power runs out, you lose control. Power drains especially fast if you're using one of the new unmanned tracking functions.

[Catthedragon]

It looks like there are no batteries on your rocket. SAS uses battery power. When your power runs out, you lose control. Power drains especially fast if you're using one of the new unmanned tracking functions.

There is a battery on each side-fuel tank just below the Stayputniks, you can see one in the image.

However, the solar panels are on the main rocket, on the adapter.

I do not think power is an issue, though. I mentioned in the OP that both Stayputniks were at full power as I lost control.

[Norpo]

Hm, is it somehow possible the stayputniks are getting detached from the rocket prematurely?

Other than that I can't think of anything other than a power issue.

[MircoMars]

hmm from the (suboptimal) pic I can't see anything wrong. which one is the root part? have you tried an two node probe core right under the dockingport (my standart)? or perhaps KSP is confused by the off-center probecores, try right-click on dockingport and "control from here".

you're not using RemoteTech, are you?

[Catthedragon]

hmm from the (suboptimal) pic I can't see anything wrong. which one is the root part? have you tried an two node probe core right under the dockingport (my standart)? or perhaps KSP is confused by the off-center probecores, try right-click on dockingport and "control from here".

you're not using RemoteTech, are you?

I don't know what RemoteTech is, just playing the vanilla game.

Controlling from the docking port actually sounds like a good idea, I'll try that and get back to here. Thanks.

- - - Updated - - -

I don't know what RemoteTech is, just playing the vanilla game.

Controlling from the docking port actually sounds like a good idea, I'll try that and get back to here. Thanks.

Nope, it happened in the lower atmosphere this time. The boosters were at about 30% and the thing started tipping over no matter how much I mashed QAS. And the liquid engine on bottom was going full blast, so I should absolutely have had control over the vehicle. This is after I had closed the game and come back in.

You said the picture was suboptimal. I was trying to get the entire rocket in one picture. what would be a better angle?

[LethalDose]

Are you running out of the electrical charge? I see a small solar panel and maybe two tiny batteries. If you're getting oriented away from the sun during docking, you could easily be losing change causing the vessel to become unresponsive.

Also, watch your language in the forum (e.g. your thread title). Any kind of foul language isn't tolerated and the mods tend to be pretty heavy-handed.

[Norpo]

You said the picture was suboptimal. I was trying to get the entire rocket in one picture. what would be a better angle?

I think he/she might be referring to the picture I grabbed, it's low-res; the picture in the OP doesn't work for me (not sure if it does for anyone), if I follow the image URL now it just gives me a dropbox 403 error "It seems you don't belong here? Maybe you should try logging in?" so maybe only you can see it?

[CrisK]

Catthedragon, Stayputniks do not have any SAS. That means that your rocket will spin around wildly out of control unless it is very simple and perfectly symmetrical. The only thing that you can once your Stayputnik-driven rocket spins out of control is throttle your engine.

Does that sound like what you're experiencing?

[SRV Ron]

The Stayputnik in KSP 0.90 Beta is strictly a radio receiver for your control commands. It has no built in stability or control function and has no ability to control anything external such as an SAS. You have to constantly fly it or it will promptly tumble out of control.

[Catthedragon]

I have found the solution:

First, to settle once and for all whether or not it was an energy issue, I tried replacing the Stayputniks with manned cockpits. The same thing happened. So energy issues could be completely ruled out.

My clue came when, as I was spinning out of control, increasing fuel flow to the main engine actually decreased my control over the vehicle. That's when I realized it was a structural integrity issue. The top of the ship was tipping over at its weak point, the docking port just under the orange tank (you can see a small space there in the first picture). I rectified the issue by attaching some bars from the side tanks to the adapter to help hold it together. This worked perfectly, and the bars came off without any issues when it came time to disconnect the Kerbodyne engine/fuel tanks. I also moved the boosters a bit lower down the rocket because they were having issues with colliding with the Kerbodyne tanks when jettisoned. With these changes, the rocket made it into orbit, with (hopefully, I'm assuming) enough fuel left to make the dock.

I don't know why the dropbox link is not working for people, or why I can't just post attachments, but here are tinypic links to the "before" rocket that was in the OP and the "after" rocket that did its job correctly after the modifications.

http://tinypic.com/view.php?pic=1zy7hk&s=8#.VLw1iUc4aFU

http://tinypic.com/view.php?pic=21jbxgn&s=8#.VLw1pUc4aFU

Changing "unanswered" to "answered".

However, one question still remains. This explains why I was losing control of the craft at random stages of the launch, but not what was happening the times when I could not manipulate the engines (pressing shift or ctrl would simply do nothing to the slider). That may have been a bug.

[match]

I can pick out one SAS module in that picture (There may be another large one toward the middle... if it is, then its placement close to COM is dubious). As the SRBs burn they are producing the same amount of thrust while having less and less mass. While that stabilizer may provide enough torque for control at the beginning of the burn, it is overwhelmed as the burn continues until it is non-responsive. Once the SRBs are spent and ejected, control authority may be reestablished, depending on the current thrust/weight ratio.

Mixing in engines with gimbals can help reduce the effect.

Edit: Almost forgot... keep your mouse cursor off of the stages during flight. I've lost too many ships trying to figure out why nothing works only to discover I had left my mouse hovering on top of them.

Edited January 18, 2015 by match

[DBT85]

Can I suggest that if you haven't docked before (have you even had to do rendezvous?) then trying to dock with a small nimble craft with RCS is the best place to start. And Docking Port Alignment Indicator.

[Liowen]

As far as not know what is happening when you lose control hitting F3 might answer that, it will show you if anything has broken or undocked. I made a similar craft with a few minor tweaks, I however did not see the post about the docking port on the bottom but that can be edited in later. One thing I did differently during launch is I did not fir the main engine until the solids had completely burned out. While it did tip a bit near the end of the solids I believe it is due to the weight transfer as they empty out, but once the main engine fired it corrected itself and all was well. FOrgive the HotRockets mod (the LFO engines might need to be changed before launch) but I just love the prelaunch smoke . I included the .craft file if you want it, also a picture from the launch pad is your best spot to see thing the VAB is hard to get a good angle.