Go Back  PPRuNe Forums > Aircrew Forums > Rotorheads
Reload this Page >

Video - Flapping to Equality / Dissymmetry of Lift

Rotorheads A haven for helicopter professionals to discuss the things that affect them

Video - Flapping to Equality / Dissymmetry of Lift

Old 24th Jun 2019, 11:41
  #1 (permalink)  
Thread Starter
 
Join Date: Nov 2008
Location: UK
Posts: 57
Video - Flapping to Equality / Dissymmetry of Lift

Great video showing pitch changes of the MR blade during a revolution. Check how the advancing blade reduces pitch and the retreating blade increases pitch. Pause the video to show the pitch increase towards the tail and then the pitch decrease as it advances towards the front. Perfectly displaying flapping to equality.

I put a GoPro on my Rotor Head Assy so you can see exactly what a Main Rotor Blade does on EVERY revolution in the experimental BO-105 helicopter. (Shot at 240fps slowed to 30fps)

How cool is that
Mitchaa is offline  
Old 24th Jun 2019, 13:11
  #2 (permalink)  
 
Join Date: May 2002
Location: Wanaka, NZ
Posts: 1,990
I'm surprised by the movement of the pendulum dampers.
gulliBell is offline  
Old 24th Jun 2019, 13:51
  #3 (permalink)  
 
Join Date: Dec 2001
Location: Here 'n' there!
Posts: 257
I'm just surprised - period! See the current thread One Nil; Cellphone vs Robinson!

Now, not saying you can't! I believe as a "Temp Fix" the FAA leave it up to the PIC - but I'm no expert on FAA rules so don't listen to me. But I did work in Mil Trials myself several times and we used to stick all sorts of stuff all over the place - and even convince the odd TP to go fly it to see if it worked!

Fitting something to the MRH? Sporty! Hope this doesn't encourage your ave GP and R22 owner - given the comments in the other thread and the Safety hoops we had to jump through for even a small trial fit. But Chuck Aaron looks OK...... and I'm sure there is more to this in terms of how it all came about!

And looks cool!! H 'n' H
Hot 'n' High is offline  
Old 24th Jun 2019, 14:00
  #4 (permalink)  
 
Join Date: Dec 2001
Location: Here 'n' there!
Posts: 257
Too late!
Seems well strapped on.....! H 'n' H
Hot 'n' High is offline  
Old 25th Jun 2019, 01:58
  #5 (permalink)  
 
Join Date: Oct 2007
Location: A better place.
Posts: 1,562
OK.
Intriguing to see, but am I alone in thinking this is insanely dangerous?
You put a Go-Pro on a rotorhead - for real?
Are you a licenced aviation mechanical engineer?
What if it had cut loose?
What if it caused said rotorhead to be slightly out of balance?
I'd be interested to hear further details.
tartare is offline  
Old 25th Jun 2019, 02:02
  #6 (permalink)  
 
Join Date: Sep 2002
Location: Great South East, tired and retired
Posts: 2,313
Sorry, Mitchaa, but it ain't "Flapping To Equality". It is "Blades flapping as dictated by the swash plate."

FTE will only happen when the cyclic is neutral and a puff of breeze causes a differential in relative airflow between advancing and retreating blades. The advancing blade will flap up, and the retreating blade flaps down, the opposite of what is shown on this video. This FTE makes the disc tilt backwards, and the helicopter would then move backwards - but then the relative airflows are then reversed, the disc flaps the other way, and you are into the realm of dynamic instability.

BUT! The pilot sees that the disc is flapping back right from the start, when he wants to go forward, so he uses cyclic to make that happen. End of FtE. The aircraft does what the cyclic tells it to do. Advancing blade goes down instead of up, disc tilts forward, total rotor thrust points forward, and away he goes.

Nice video, though, and the pair of balls flapping away is doing its job of absorbing vibes.
Ascend Charlie is online now  
Old 25th Jun 2019, 02:09
  #7 (permalink)  
 
Join Date: Sep 2018
Location: California
Posts: 160
Originally Posted by Mitchaa View Post
Great video showing pitch changes of the MR blade during a revolution. Check how the advancing blade reduces pitch and the retreating blade increases pitch. Pause the video to show the pitch increase towards the tail and then the pitch decrease as it advances towards the front. Perfectly displaying flapping to equality.



https://youtu.be/Pu48f7s5Ru8
All that did was make me dizzy
Robbiee is offline  
Old 25th Jun 2019, 02:40
  #8 (permalink)  
 
Join Date: Feb 2008
Location: New York City
Posts: 298
Originally Posted by tartare View Post
OK.
Intriguing to see, but am I alone in thinking this is insanely dangerous?
You put a Go-Pro on a rotorhead - for real?
Are you a licenced aviation mechanical engineer?
What if it had cut loose?
What if it caused said rotorhead to be slightly out of balance?
I'd be interested to hear further details.
You must not be familiar with the name Chuck Aaron, the creator of the video. A quick Google search may answer your questions. The fact that his BO-105 is in the Experimental category supports the legality as well.
MikeNYC is offline  
Old 25th Jun 2019, 03:12
  #9 (permalink)  
 
Join Date: Aug 1999
Location: Gold Coast, Australia
Age: 71
Posts: 4,085
Originally Posted by tartare View Post
OK.
Intriguing to see, but am I alone in thinking this is insanely dangerous?
You put a Go-Pro on a rotorhead - for real?
Are you a licenced aviation mechanical engineer?
What if it had cut loose?
What if it caused said rotorhead to be slightly out of balance?
I'd be interested to hear further details.
Seriously? Are we so risk averse that we can't accept that someone may actually know what they're doing

Previous films (yes, with cameras with film stock inside) show how blade technology has changed over the years. And explain why the Bo105 and others are known as rigid rotor systems

1946, and the film that is claimed to dissuade pilots from flying rotary


S-56, sometime in the late 1950s


I think this is the S-56 footage, as originally shot


Mil-8, more recent footage



A modern BERP blade shown from 1:28 onwards. Seeing Colin Hague is a blast from the past!


John Eacott is offline  
Old 25th Jun 2019, 06:24
  #10 (permalink)  
 
Join Date: Oct 2007
Location: A better place.
Posts: 1,562
Nope - no way of me telling simply from viewing the link on the forum that the poster is Chuck Aaron.
If he knows what he's doing - and clearly he does - and is flying an experimental category machine, then that's fine.
All I saw was someone unknown, strapping a Go-Pro to a rotorhead.
tartare is offline  
Old 25th Jun 2019, 06:29
  #11 (permalink)  
 
Join Date: Nov 2006
Location: After all, what’s more important than proving to someone on the internet that they’re wrong? - Manson
Posts: 1,489
All I saw was someone unknown, strapping a Go-Pro to a rotorhead
Really? I didn’t see that in the video. Must have missed something. Just watched it again. Didn’t see “someone”.
RVDT is offline  
Old 25th Jun 2019, 10:06
  #12 (permalink)  
 
Join Date: Feb 2000
Location: UK
Posts: 1,206
John E - "Colin Hague a blast from the past", indeed. Worked with him at Boscombe in the 70s. He was D Sqn SPLOT (or some such Dark Blue terminology) when the Icing trials Wessex had a camera fitted with prisms to monitor each blade in flight. I believe this was a first and the resultant viewing was 'interesting'!!
Cornish Jack is offline  
Old 25th Jun 2019, 13:51
  #13 (permalink)  
 
Join Date: Feb 2019
Location: Ct USA
Posts: 6
John E:
The S-56 video is deceiving. The camera was mounted on the rotor hub inboard of the flapping,hunting, and pitch hinges so you see much more than blade bending. Later on a camera was mounted on the pitch horn of the S-61F which only showed blade bending, both flatwise and edgewise. It was very benign. This was also repeated on a CH-53 with the same results.
Al M is offline  
Old 29th Jun 2019, 11:53
  #14 (permalink)  
RMK
 
Join Date: Aug 2008
Location: London
Posts: 179
Scariest one on this thread is post #4 which shows a gyrocopter MRB is held on by nothing more than a few hex bolts - damn?

For our resident RHC fans, in comparison, that makes an R22 look like its built like a CH53.
RMK is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.