Originally Posted by
jellycopter
I’ve not seen the R44 crash video that many have discussed on this thread. However, I’m not so sure that many of the so called ‘Vortex Ring’ crash videos are actually Vortex Ring at all.
I was always taught that Vortex Ring was a combination of Root Stall on the inner portion of the disc and loss of lift on the outboard portion of the disc due to increased induced flow caused by the vortex. As Rate of Descent increases into fully developed Vortex Ring State, the stalled portion and the vortex section have expanded laterally, potentially to meet each other, rendering the rotor system ineffective at producing lift and hence control. Please feel free to correct me if I’ve got this wrong!
My reasoning is that if a Rotor disc, or more accurately a rotor blade, is experiencing Vortex Ring State, it is effectively no longer producing lift. If that’s the case, the coning angle would surely reduce? Most of the crash videos I’ve seen that are passed off as Vortex Ring State actually show an increase in coning angle, often just before impact. More a case of HTG (as a result of poor energy management and over-pitching) than VRS in my opinion.
I’d be interested to see the R44 video discussed earlier if anyone can point me to a link.
JJ
Sadly, the only place I've ever seen that video is at the Robby Course (been there six times), and (even sadder) since they've doubled the price of that course I doubt I'll ever see it again,...unless you've got $1,500 bucks I can have, lol.