Secondary engine balance 3

[Deividas]

Hi! I can't understand, why seconadary forces are 2x per revolution? why from 0deg to 90deg secondary force curve goes down, and from 90deg to 180deg curve goes up? can someone explain?

 

[gruntguru]

Correction to an earlier post of mine where I said "Each sine wave is twice the frequency of the previous.
"

Should be "the frequency of each sine wave is a multiple of the fundamental frequency"

Engineering is the art of creating things you need, from things you can get.