Quote:
Originally Posted by Turtle
Erhmmm...no; I disagree. Spinning a floating sphere in still air will cause it to move directionally. Moreover, properly gymbaled, any vector for the axis is achievable and so any direction of travel achievable as well.  |
No, that is not the case.
Both wikipedia article and the link you originally posted say that sphere has to be moving trough the fluid, or fluid flowing by it
. If fluid has no velocity compared to the sphere, the problem has no reynolds number! And hence no wind, no magnus force.
To correct your first post, jet engines have better efficiency than piston ones. It says it in the same article you linked there. On page 22, there is a comparison between pistons and jets, it clearly shows that jet planes have lower energy per seat than piston ones. Thats why piston curve stops at 1970, as it seems piston engines haven't improved since.
