@prchakal: You can't expect help if you only say "it doesn't work, what should I do?" It's always better to look at the tutorials, give us some example code, try to give us the most descriptive explanation of what's happenning. The Irrlicht community can always help, they helped me on every topic, it's about the way you ask. Why would anyone bother writing you the same you could find in the tutorial #7?
No one forbids you to post here and ask, but search a little before you do.
About your problem, instead of changing ellipsoid radius, try changing the ellipsoid translation. If you have translation of (0, -10, 0), try changing it to (0, -5, 0) or something similiar and that should solve the problem.
@Geomaster - thanks for solutions. Is very hard to find a good tutorial ou material about irrlicht about advanced things.
@others - if have more decent/good materials/tutorials i dont need come here to disturb anyone, but i dont find information about it. but sorry, next time i will search for a month before post.