Tom22 Posted June 27, 2009 Report Share Posted June 27, 2009 (edited) I wanted to discuss the vibration felt during approach at slow speeds around effective translation lift. I think that it comes from unsteady airloads resulting from blade tip vortices coming close to or striking the other blades in a condition identified as blade vortex interactions (BVI) and not flapping caused by transverse flow effect as the Rotorcraft Flying Handbook explains. I wanted to provide some awareness to this situation insofar as I think BVI is more convincing and it has not been discussed on this forum before. J. Gordon Leishman discusses unsteady airfoil behavior and BVI in Principles of Helicopter Aerodynamics. Leishman’s book is an engineering book so BVI is unfortunately not discussed from a piloting perspective. Also, see the link at the bottom of the page, which is a study from The Pennsylvania State University Department of Aerospace Engineering. What I am expressing is in the introduction so reading the whole study is not necessary. There is more research on BVI out there, as it is a large source of helicopter noise and vibration. http://www.uweb.ucsb.edu/~brian_munsky/AHS_BVI_2002.pdf Edited July 1, 2009 by Tom22 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.