#41  
Old 10-12-2017, 10:45 AM
DG_player DG_player is offline
Birdie Member
 
Join Date: Apr 2013
Posts: 389
Niced 56 Times in 45 Posts
Default

Quote:
Originally Posted by sidewinder22 View Post
What happens when your slatted wing is rotating really fast like a disc-wing? ---->
I expect it would enhance the effect of the roughened leading edge.

This thread got me to thinking, so I pulled up potts&crowther paper to see what they found the effects of spin were, as well as different Reynolds numbers.

As expected they did find some side force due to the magnus effect, but it was indeed very small. The coefficient of was less than 0.1 even at the maximum advance ratio* (1.04) and speed (55pmh) they tested for.

They also found a slight decrease in pitching moment at higher advance ratios. Due to precession this would result in the disc acting slightly less over stable.

The third finding was a slight negative roll moment (roll to the left) as advance ratio increased. This would cause the disc to experience a slight pitch down precession throughout it's flight.

In regards to Reynolds number, they found the forces and moments on the disc appeared to be independent of Reynolds number. Keep in mind though their test conditions were not identical to typical disc golf throws (different disc geometry, metal replica vs plastic, higher release speeds of pro disc golfer, etc.).

*advance ratio is spin/speed, an advance ratio of 1 represents the rotational speed of the discs rim equaling the forward velocity of the disc.
Sponsored Links
Reply With Quote
  #42  
Old 10-12-2017, 11:11 AM
lyleoross's Avatar
lyleoross lyleoross is offline
* Ace Member *
 
Join Date: Feb 2009
Location: Houston, TX
Years Playing: 21.8
Courses Played: 2
Posts: 3,357
Niced 455 Times in 298 Posts
Default

Why is it that whenever I read one of these threads it's always doof calling people names or making fun of other's thoughts?

Also, I sincerely hope that Throw and Sidewinder are already married, cause boy are you guys deep into geek. Please note, the tone is jealous, not ridicule.
Reply With Quote
  #43  
Old 10-12-2017, 11:13 AM
lyleoross's Avatar
lyleoross lyleoross is offline
* Ace Member *
 
Join Date: Feb 2009
Location: Houston, TX
Years Playing: 21.8
Courses Played: 2
Posts: 3,357
Niced 455 Times in 298 Posts
Default

I always thought Potts and Crowther were using a lid? They seem very different in side profile to a disc? Was I wrong? By the way DG, you get a geek shout out too. I did see your caveat on the P&T experimental design. Just want more info from you experts.

Last edited by lyleoross; 10-12-2017 at 11:15 AM.
Reply With Quote
  #44  
Old 10-12-2017, 01:33 PM
DG_player DG_player is offline
Birdie Member
 
Join Date: Apr 2013
Posts: 389
Niced 56 Times in 45 Posts
Default

Quote:
Originally Posted by lyleoross View Post
I always thought Potts and Crowther were using a lid? They seem very different in side profile to a disc? Was I wrong? By the way DG, you get a geek shout out too. I did see your caveat on the P&T experimental design. Just want more info from you experts.
I'm not sure exactly what the definition of a lid is, but I would describe what they use as a standard frisbee profile. They do do a comparison between that design and ones with a flatter profile (something more similar to a disc golf putter or mid-range) as well as a flat disc.

The main finding of the comparison was that as you become more flat the pitching moments (in both directions) became larger. Additionally the AoA where you went from negative pitching to positive pitch decreased.
Reply With Quote
  #45  
Old 10-12-2017, 02:19 PM
lyleoross's Avatar
lyleoross lyleoross is offline
* Ace Member *
 
Join Date: Feb 2009
Location: Houston, TX
Years Playing: 21.8
Courses Played: 2
Posts: 3,357
Niced 455 Times in 298 Posts
Default

Quote:
Originally Posted by DG_player View Post
I'm not sure exactly what the definition of a lid is, but I would describe what they use as a standard frisbee profile. They do do a comparison between that design and ones with a flatter profile (something more similar to a disc golf putter or mid-range) as well as a flat disc.

The main finding of the comparison was that as you become more flat the pitching moments (in both directions) became larger. Additionally the AoA where you went from negative pitching to positive pitch decreased.
Thanks, yeah, I call a lid a standard frisbee. I had also thought that the flat discs they used were just that, flat? Not really disc golf discs. I must have missed the putter/midrange experiments.

If I read you correctly, this suggests that flatter discs are inherently less stable that lids or frisbees, tending to pitch. That would make sense to me.
Reply With Quote
 

  #46  
Old 10-12-2017, 08:37 PM
DG_player DG_player is offline
Birdie Member
 
Join Date: Apr 2013
Posts: 389
Niced 56 Times in 45 Posts
Default

Quote:
Originally Posted by lyleoross View Post
Thanks, yeah, I call a lid a standard frisbee. I had also thought that the flat discs they used were just that, flat? Not really disc golf discs. I must have missed the putter/midrange experiments.

If I read you correctly, this suggests that flatter discs are inherently less stable that lids or frisbees, tending to pitch. That would make sense to me.
Well, not to actually pitch, the pitch moment causes precession. So the flatter discs will fade more and sooner in the flight.

You are correct though, the discs tested are not really golf discs because they do not have the traditional bottom bevel around the rim. The flattest one they tested was not really a disc, it was just a flat plate.
Reply With Quote
Reply

Thread Tools

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

Forum Jump


All times are GMT -4. The time now is 07:07 AM.


Powered by vBulletin® Version 3.8.10
Copyright ©2000 - 2017, vBulletin Solutions, Inc.