Fairing from engine plate even at 5% force destroys everything

[Daze]

I've tried making a Saturn V interstage by using engine plate + a reversed decoupler, but for some reason even if i put the force of fairing at 0% it will destroys everything except the engines, why?

Screenshoots:

https://imgur.com/a/yPEpO

Edited March 30, 2018 by Daze

[klesh]

Is it perhaps using the ejection force of the engine plate’s built-in decoupler? Its hard to tell from the screenies. 

If you upload the .craft file I will give it a look ingame. 

[Daze]

They are both at very low force

At the moment I can't send you the craft file, when I will return home I will post it 

[klesh]

I've recreated this to what I think is an accurate degree, but in vacuum testing I'm not seeing anything unexpected.

Perhaps since your decoupling is happening fairly low in the atmosphere (28km), its drag that is pushing it back at unexpected speeds?

 

 

 

 

Edit:   When I rerun the test performing the decoupling in the atmosphere, indeed I do see what you're experiencing.  The interstage shoots retrograde at a rapid pace, and slams into the 1st stage.  Since this only happens in the atmosphere, I am going to posit that atmospheric drag is the culprit. 

Edit#2:   From what I learned about drag values being displayed in the PAW's in this thread, it would appear the drag values on the interstage 5m decoupler are astronomical, resulting in the pullback you're seeing.  Observe in the following screenie the YP value of the interstage 5m decoupler being at 19.48. The shroud part of the interstage is not right-clickable, so I don't know what values it might have, if any.  Perhaps @DMagic would be kind enough to confirm what I'm seeing and/or offer an opinion as to whether this YP value is off the charts or expected.

 

Edited March 30, 2018 by klesh

[DMagic]

Hollow parts like decouplers are weird about drag and usually need custom handling to work right. There was thread way back about drag cubes where it was suggested that you would just copy the Y values for the drag cube from a similarly sized fuel tank or other part with flat ends. I guess you could compare it other decouplers, or see what it looks like for the decoupler alone, but that might be a normal value. Looking at the PartDatabase those values seem to be reasonable for a 5m part.

And shrouds are another problem entirely. I would guess that the shroud contributes zero drag effects once it's separated from the engine plate, since it's probably not really a part at that point. Maybe it still has mass though and that makes it behave funny, who knows, it's a weird setup.

Edited March 30, 2018 by DMagic

[klesh]

Thanks for your input, my man. I'm all out of likes today.

Edited March 30, 2018 by klesh
ohhh, new batch of available likes I guess.

[Daze]

4 hours ago, klesh said:

I've recreated this to what I think is an accurate degree, but in vacuum testing I'm not seeing anything unexpected.

Perhaps since your decoupling is happening fairly low in the atmosphere (28km), its drag that is pushing it back at unexpected speeds?

 

 

 

 

Edit:   When I rerun the test performing the decoupling in the atmosphere, indeed I do see what you're experiencing.  The interstage shoots retrograde at a rapid pace, and slams into the 1st stage.  Since this only happens in the atmosphere, I am going to posit that atmospheric drag is the culprit. 

Edit#2:   From what I learned about drag values being displayed in the PAW's in this thread, it would appear the drag values on the interstage 5m decoupler are astronomical, resulting in the pullback you're seeing.  Observe in the following screenie the YP value of the interstage 5m decoupler being at 19.48. The shroud part of the interstage is not right-clickable, so I don't know what values it might have, if any.  Perhaps @DMagic would be kind enough to confirm what I'm seeing and/or offer an opinion as to whether this YP value is off the charts or expected.

 

Thanks a lot! It's indeed like this, I've tried again putting the rocket in orbit with the cheats and it worked flawless, hopefully it will be patched soon  

[klesh]

1 minute ago, Daze said:

hopefully it will be patched soon

 

It very well may be intended design.  Only time will tell.