Description of helicopter torque effect. From the FAA Rotorcraft Flying Handbook.
<a href="https://it.wikipedia.org/wiki/Utente:EH101" class="extiw" title="it:Utente:EH101">it:Utente:EH101</a>
<a rel="nofollow" class="external free" href="http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083-21.pdf">http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083-21.pdf</a>