Sticky ship?

[StormKat]

I started a career game in .90 but the last few craft I have built seem to "stick" on the launch pad for a second or two before actually taking off.

Here's my latest example:

I got a rescue mission and built a craft that's 37 tons. KER says the first stage has a 1.78 TWR.

Yet when I hit the spacebar, it sits on the pad for a full 3 seconds and then suddenly leaps into the air.

It's almost like the engine bells are getting stuck in the launchpad's grill.

Has anyone noticed this behavior?

Edited December 21, 2014 by StormKat

[Tex_NL]

Did you throttle up to 100%?

At 50% your TWR is only 0.89. Burning for three seconds could burn off enough fuel to reach a TWR >1.

[Anquietas314]

That's actually a bug. I've had it happen a few times; rockets with enough thrust or multiple engines seem to be able to overcome the sticking though. Another workaround is to raise it off the pad a bit with launch clamps.

[The Yellow Dart]

I've had that bug as well, I remember it was due to a mod but I can't remember which one. If it persists, try uninstalling mods until it stops.

[MarvinKitFox]

Bug, sortof.

At that sort of mass, you really should be using the launch clamps, which remove the problem.

What is happening is that your engines are penetrating the surface, just a bit.

Add another couple dozen tons, and your launchpad will self-destruct from the load.

use launch clamps.

[Anquietas314]

I've had that bug as well, I remember it was due to a mod but I can't remember which one. If it persists, try uninstalling mods until it stops.

Nope, it's a stock issue, although it's quite possible mods make it more likely.

Add another couple dozen tons, and your launchpad will self-destruct from the load.

Only a couple dozen tonnes? I found it took hundreds of tonnes to make that happen

[StormKat]

Tex_NL, I was at full thrust. Usually an overweight craft will slowly rise off the pad once TWR goes above 1. This one sits there, then pops right off the pad.

armagheddonsgw, I haven't unlocked launch clamps yet.

I think MarvingKitFox has it right, but I'll have to figure something else out.

[monophonic]

I got this with one design too. Didn't have launch clamps either, but I put a stack decoupler under each engine. Staged them with the engines and got a clean take-off. The decouplers were left behind stuck into the launch pad.

[StormKat]

Yay! Finally got launch clamps!

monophonic, I ended up switching to the Mark 55 engines and raising them above the bottom of the fuel tanks.

It would be nice if there was a note in the F3 information mentioning that the rocket is embedded in the pad.

[Cerberus738]

Had this too. Mine never did take off. Burned all my fuel with the engine bell barely stuck in the launch lad. Guess it considers it blocking thrust? Raising the rocket just a bit with launch clamps solved the problem

[nekogod]

If you haven't unlocked launch clamps yet you can use a stack decoupler and a girder under each engine and put the decoupler in the same stage as the engine.

[LethalDose]

This is a bug. DasValdez ran into it during his stream the day after 0.90 dropped. The OP's image pretty clearly shows the vessel in the VAB above the ground, but on the launch pad, the bells are stuck below the grate.

[Claw]

As LethalDose said, there's a bug with the pad. Specifically it's a bug with the tier 2 launch pad colliders which cause certain mass/engine combinations to stick to the launch pad.

To fix it, you can (as others have posted):

1) Increase your TWR a little (such as activate your core engine for just a moment to get off the ground)

2) Use launch clamps

3) Add some girder segments onto your boosters along side the engines to pick them up off the pad slightly.

I'm working on a fix for this, but it's been difficult to do without inadvertently destroying the ship.

Also, the "exploding pad due to overweight vehicles" bug has been fixed in 0.90.

Cheers,

~Claw

Edited December 22, 2014 by Claw

[Mister Kerman]

I was having this problem too. I used lander legs to pop myself out of the pad. My ship was a single engine, very small and light rocket. I don't know why this happens.

EDIT: My landing legs were stuck when I added them to counter the problem. The ship would pop out when I'd retract them!

[Anquietas314]

JHadden123: Yeah, lander legs have their own problems on the pad. The number of times I've had a larger lander fall over during tests because of glitchiness...

[Zargg]

I had this problem last night, and since I was at 30 parts already I had no option for adding anything to prop up my ship. So in the VAB I moved my rocket far off to the side, and when I hit launch it placed my ship off to the side of the pad, where there was no problem taking off

[Anquietas314]

I had this problem last night, and since I was at 30 parts already I had no option for adding anything to prop up my ship. So in the VAB I moved my rocket far off to the side, and when I hit launch it placed my ship off to the side of the pad, where there was no problem taking off

Nice job finding a workaround That can be quite tricky to get right and it's a bit dodgy on Hard difficulty if you leave quicksave/revert disabled (which makes designing spaceplanes in stock physics a bit of a nightmare but never mind); you could accidentally place the rocket on the sloped part of the (tier 2) launchpad... which for some rockets is not a good idea

[Claw]

If anyone is still looking for a fix to this (and isn't opposed to using add-ons), I have added a fix for this to my stock bug fix add-ons.

http://forum.kerbalspaceprogram.com/threads/97285-KSP-v0-90-Stock-Bug-Fix-Modules-%28Release-v0-1-7-23-Dec-14%29

Cheers,

~Claw

[tater]

I'm using that fix, and I had that last night. Mainsail and SRBs on rocket that lifted a station section earlier, now lifting something smaller stuck to the pad, all rockets burning. Got it aloft with clamps...

Put it around minmus, and the lander (and a fuel tank for minmus station)… dock, and decide to take lander down, now the LANDER is stuck to the station, uncouple… nothing. Accelerate time, and they separate, go to normal time, and the lander explodes, then anything debris brushes on station also explodes. Weird.

Pad facility totally upgraded, BTW.

Edited January 7, 2015 by tater

[SRV Ron]

It is a bug very noticeable with mods and even some stock. Using launch stabilizer clamps eliminate that issue.

In addition, some of the larger KW Rocketry and NovaPunch liquid fueled engines take a second or two to reach full power. Therefore, fire them up first, then release the launch clamps. Otherwise, those rockets will drop to the pad before the engines have developed their full power. Likewise, they take a second or two to power down when used for maneuvering in space.

[tater]

The 2d stick was a lander docked to a station. Once free it explodes.

[Claw]

I'm using that fix, and I had that last night.

I need pictures, log files, and preferably .craft files (if they are stock). It's extremely difficult for me to replicate and fix a bug (or make my fix more robust) if I don't know what happened.

I'm especially interested if your craft was on the Mun and still hitting the pad, because that could possibly be related to the bug that destroys space planes.

Cheers,

~Claw

[tater]

It was minmus. The craft was stock parts, but I have DRE/FAR/PF, and the stock bugs fixes, etc installed.

Have to see if I still have logs, but I can replicate it. I added hyperedit to try and put a replacement nearby to rendezvous, and I could put just the lander on the pad, pop it in orbit with HE, and it would instantly explode. I will try and replicate it with a stock copy of 0.90 and let you know.

The one that stuck on the pad, however, was not stock as it had a PF fairing.

Edited January 8, 2015 by tater

[Claw]

The one that stuck on the pad, however, was not stock as it had a PF fairing.

If you can just leave off the fairings, that would be handy.

~Claw

[tater]

I just PMed you the log and craft file. Sorry, fairing was on.

My career might be corrupted, I think.

I tried building it in a clean stock build, and it worked.

I will move the craft file and see if that sticks in stock...

- - - Updated - - -

The stuff I sent you was loaded up in the modded install, but in sandbox, not my career… so it is the mod constellation (DRE/FAR/KJR/PF/SBFM) not my save game.