How to stop a spinning block spinning the main cube.

[Bad!]

I want to have it so that there's spinning blades at the bottom of my heli, but when I try it spins the main cube and not the blades

[tom]

add a same ammount of equal spinning blades on top of it, it might work

[Petrus1904]

action = reaction. simple as that. but since the blades have a higher combined inertia (if you dont know what that is, its something that describes the mass distribution with respect to the distance from the rotation center), they will spin lower. the starting block has a low inertia and will therefore spin fast. to get rid of this effect, you can do 2 things:

1. build stuff on the starting block, preferable the further away, the better. then it will still rotate, but much slower than the blades. to counter that, add a flying block at the end and set it to automatic. tune the value to counter the rotation. (this is the realistic approach, helicopters have this too)

2. in besiege we can completely neglect the rotation by putting a unpowered wheel between the spinning block and the cube. since the spinning block has a low inertia, it will now spin very fast instead of the blades or the cube. to solve that, put a few braces from the inside of the wheel to the outside of the wheel (use blocks to place those, then remove blocks). make sure the braces are symmetrical to prevent unstable vibrations.
Hope you still follow me here, but at this point you have a spinning block with blades, connected to a wheel with braces and that wheel is in its turn connected to the cube. make sure all 3 parts can rotate individually and you should be good to go. in case you dont understand me completely, check out any helicopter of propeller plane from the workshop. as good as any model uses this method to get rid of the counterrotation.

[Bad!]

Originally posted by Petrus1904:

action = reaction. simple as that. but since the blades have a higher combined inertia (if you dont know what that is, its something that describes the mass distribution with respect to the distance from the rotation center), they will spin lower. the starting block has a low inertia and will therefore spin fast. to get rid of this effect, you can do 2 things:

1. build stuff on the starting block, preferable the further away, the better. then it will still rotate, but much slower than the blades. to counter that, add a flying block at the end and set it to automatic. tune the value to counter the rotation. (this is the realistic approach, helicopters have this too)

2. in besiege we can completely neglect the rotation by putting a unpowered wheel between the spinning block and the cube. since the spinning block has a low inertia, it will now spin very fast instead of the blades or the cube. to solve that, put a few braces from the inside of the wheel to the outside of the wheel (use blocks to place those, then remove blocks). make sure the braces are symmetrical to prevent unstable vibrations.
Hope you still follow me here, but at this point you have a spinning block with blades, connected to a wheel with braces and that wheel is in its turn connected to the cube. make sure all 3 parts can rotate individually and you should be good to go. in case you dont understand me completely, check out any helicopter of propeller plane from the workshop. as good as any model uses this method to get rid of the counterrotation.

I did in fact put an unpowered wheel there, but then when I tried doing the same on top it started spinning again