LSP_Ron Posted September 19, 2020 Share Posted September 19, 2020 Trak-Tor and D.B. Andrus 2 Link to comment Share on other sites More sharing options...
Dave Williams Posted September 19, 2020 Share Posted September 19, 2020 I had seen that video. It’s interesting seeing the angle of the blade change as it’s advancing and retreating, but what are those two balls at the blade root that float up and down for? Link to comment Share on other sites More sharing options...
LSP_Ron Posted September 19, 2020 Author Share Posted September 19, 2020 I wondered that also Link to comment Share on other sites More sharing options...
rjones726 Posted September 19, 2020 Share Posted September 19, 2020 Some type of dampener/harmonic balancer to counteract vibration??? Just a a guess. I'm sure someone who knows will jump in and enlighten us LSP_Matt 1 Link to comment Share on other sites More sharing options...
chrish Posted September 20, 2020 Share Posted September 20, 2020 I should put that on a 10 hour loop on the computers at work and see who falls off their chairs... LSP_K2, dmthamade and LSP_Ron 2 1 Link to comment Share on other sites More sharing options...
dmthamade Posted September 20, 2020 Share Posted September 20, 2020 1 hour ago, chrish said: I should put that on a 10 hour loop on the computers at work and see who falls off their chairs... I lasted 10 seconds.... Don chrish 1 Link to comment Share on other sites More sharing options...
MikeMaben Posted September 20, 2020 Share Posted September 20, 2020 Link to comment Share on other sites More sharing options...
ChuckD Posted September 20, 2020 Share Posted September 20, 2020 10 hours ago, dmthamade said: I lasted 10 seconds.... Don Same. Barf. Link to comment Share on other sites More sharing options...
LSP_Matt Posted September 20, 2020 Share Posted September 20, 2020 14 hours ago, LSP_Ron said: I wondered that also Apparently they're called pendulum vibration absorbers. I found an explanation on reddit "My understanding of them is that they simply passively flop up and down, out of phase (due to their weight/inertia) with the vibration of the rotor blades, and thus reduce the vibration of the blade." Jonesy was on the money with his intuition that it was a kind of dampner. Here's a link on the theory. https://en.wikipedia.org/wiki/Tuned_mass_damper This is a fascinating area of engineering. This is the most spectacular example I can think of that demonstrates why controlling vibration is essential. I forget when I cam across the need for helical vanes on cylindrical chimneys but now everytime I go past one I notice them and recall it as a critical feature. Even my kids know the concept now...lol One of those...hey look at the window at that. amazeballs huh? D.B. Andrus and LSP_K2 2 Link to comment Share on other sites More sharing options...
rjones726 Posted September 20, 2020 Share Posted September 20, 2020 LOL, A lucky guess. On a side note, I rode my bike across that bridge yesterday. Well, actually that bridge is several hundred feet underwater...I rode on the new bridge next to its replacement. LSP_K2 1 Link to comment Share on other sites More sharing options...
LSP_Matt Posted September 20, 2020 Share Posted September 20, 2020 1 minute ago, rjones726 said: LOL, A lucky guess. On a side note, I rode my bike across that bridge yesterday. Well, actually that bridge is several hundred feet underwater...I rode on the new bridge next to its replacement. Wow. Imagine that coincidence. Gave me a chuckle...strange world eh. Cheers Matty Link to comment Share on other sites More sharing options...
LSP_K2 Posted September 20, 2020 Share Posted September 20, 2020 5 hours ago, LSP_Matt said: I forget when I cam across the need for helical vanes on cylindrical chimneys but now everytime I go past one I notice them and recall it as a critical feature. Very similar in concept to the WWII German habit of winding a steel cable around the periscope mast of submarines, to reduce wake turbulence, I suppose. LSP_Matt 1 Link to comment Share on other sites More sharing options...
LSP_K2 Posted September 20, 2020 Share Posted September 20, 2020 I had assumed the steel spheres were some sort of free-wheeling torsion/vibration counteraction/absorption devices of some sort, but really wasn't sure. LSP_Matt 1 Link to comment Share on other sites More sharing options...
rjones726 Posted September 20, 2020 Share Posted September 20, 2020 51 minutes ago, LSP_K2 said: Very similar in concept to the WWII German habit of winding a steel cable around the periscope mast of submarines, to reduce wake turbulence, I suppose. I spent 30 years on Subs and never heard that before. I now have some homework to do It just goes to show that no matter how much experience you have, there is always more to learn. LSP_Matt 1 Link to comment Share on other sites More sharing options...
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