Tanks pushing inward when staged

[NecroBones]

 

There used to be a problem with in-atmosphere staging of radial decouplers, such that the stronger the ejection charge, the harder the booster would get shoved inward. They fixed that (or so we thought), but I wonder if there's still some residual effect along those lines that can happen when the circumstances are right.

 

Originally I made the sepratron-decouplers in SpaceY because of that bug. Not only could I not trust normal ejection charge, but because SpaceY had much larger parts, it needed to be a bigger charge, which made the bug worse. This was a great work-around, and I liked it so much that I steered away from ejection charges altogether for a while.

 

[Snark]

15 minutes ago, Nich said:

I did a couple tests with the smallest decouplers and it was still smashing the center tank even with low center of mass and sepratrons.  I suspect there is some unseen clipping as mentioned before that is forcing the tanks to pop out on the bottom even though the decoupler is on top.

Yah, if there's a likelihood that clipping is going on, definitely use some sort of "stand-off" decoupler (like the TT-70) to get some clearance, as FancyMouse suggests.

[ineon]

Wooo, I'm in space. 

Thanks everyone for your help. I think the problem was that the bottoms of the engines were clipping into each other. I did also remove the fins from the boosters and rotate the boosters around the centre tank by 45 degrees so that the main tank has fins on the N, S, E & W sides and the boosters were on NE, NW, SE & SW sides. I'm sure this didn't hurt.

I did a small test with the slanted nose cones. It looks like the boosters do go in the direction that the nose points, but the force is so miniscule that it is nothing compared to sepratrons. 

[Nich]

On March 6, 2016 at 9:00 AM, ineon said:

Wow everyone thanks for the feedback . I don't think I'll have a chance to try anything out until Tuesday, but I'll comment on some of what is above. 

Regarding decoupler placement, I think the decoupler is a far up as it can be. I have seen others suggest this as good advice and tried to generally follow it. But as @FancyMouse points out I've got 2 separatrons shop the decoupler force is minimal. What I didn't show in the imgur album is the one time that I got to space - when I staged the other set of engines at about 60km - the main thing that they did was spin rather than be pushed further out. 

Regarding placing them lower down and further out, I will definitely give that a go. Regarding nose cones, I changed to sloping because my intuition is that it should push them out - the nose cone pushes air into the middle and the (equal and opposite) reaction pushes the tank out. Is that not the case? And what is wrong with the intuition? I'll also try rotating them around. @rhomphaia which was did the rockets turn in you experiment - towards the direction that of the slope or away? 

Finally regarding the wings, it appears my intuition is at odds with the community here again. I would have thought that the CoM and Cod are both in the moved outwards by the tail (compared to just the tank on its own), but that the trail would move the drag more than the mass,  and this would induce a rotation outwards. What am I missing? 

Thanks once again everyone. 

Bernollis equation yes when you attempt to move more air on one side of the body the air will speed up and lower pressure creating lift in that direction