Please test this .craft

[klesh]

My dudes, I have a weird one here.

 

Trying to answer a question in the help forum, I made this ship in a big ol modded install and found some very weird happenings on the runway.  Just letting the ship load in results in it wiggling itself to destruction within 10 seconds.

Fair enough, mods probably to blame.   Grabbed a fresh install on steam, and plopped in this .craft and tried it stock.  Same problem.

Recreated the ship manually in the stock install, get same results.

 

Its nothing fancy, clearly it is to test the drag characteristics of different nosecones.  Launch and compare, right?

 

Can you try this and see if the same thing happens to you?

 

https://www.dropbox.com/s/haztaguz4bqc7mt/Wiggle.craft?dl=0

 

 

[qzgy]

I'm testing this at the moment, but does seem to wiggle more than it should.I think this was a bug from sometime ago, I'm not sure. Seems if you just autostrut or use some struts, it should stop wiggling.

Also, for testing, try putting the decoupling force at zero - should help align everything.

 

Edited April 22, 2017 by qzgy

[Alshain]

It's a very long standing issue with attaching the girders to one another.  Just move your clamps.

However I do not think this design is going to help you test the drag.  You probably just want to take one of those, put a probe on it directly and launch it 4 times with a different nose and record how far it gets.  Also, you may want to use the Flea as the hammer will destroy itself going straight up at full power and fuel.

EDIT: Also you need to account for varying masses, which might actually be easiest if you edit them to be equal, if you just want drag results.

 

Edited April 22, 2017 by Alshain

[technicalfool]

It's unfortunately a known issue with joint physics. Long dangly stuff can wobble, and sometimes it gets possessed by the Kraken. Adding a 4x symmetry set of struts should fix the wobble.

Or change the clamps as shown above. Heh.

[klesh]

Okay, thanks for the replies fellas!

I didn't know it was a longstanding issue.  I've built little tree launchers like this before without issue, guess I was lucky then.

I didn't even get to the point of adjusting decoupler forces (probably should have inline ones on the bottom anyway), or fiddling with fuel or thrust at all.  Slapped the thing together and checked it quickly on the launchpad and was taken aback so much by the Kraken forces that I didn't even get to seeing which cones worked best.  The guy asking about it in the Help forum got a very thorough answer anyway from someone else.   I was simply going to post a picture at some altitudes showing one is able to faster or further than the others.

 

 

This was shortly before the thing tore itself apart:

Edited April 22, 2017 by klesh

[ARS]

Watch Danny 2462's video about this: