Frisbee Aerodynamics

[bertusgeert 1]

So here is a question google wont answer.

CW- Clockwise
CCW- Counter Clockwise

Why does a frisbee released with a backhand (angular momentum CW as seen from above) curve CCW along it's directin of travel.

A frisbee released CCW (as from above) curves CW along it's direction of travel.

I understand gyroscopic effect, but it is only an effect, not a force. What is the FORCE that cause the rotation?

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As jy dom is moet jy bloei!

[GeordieSkydiver 0]

Centripedal force, at a guess.

Lee _______________________________

In a world full of people, only some want to fly, is that not crazy?
http://www.ukskydiver.co.uk

[Lostinspace 0]

i guess

[GeordieSkydiver 0]

They are the wrong way around.

Lee _______________________________

In a world full of people, only some want to fly, is that not crazy?
http://www.ukskydiver.co.uk

[manifestRyan 0]

It depends on what angle you release the frisbee. You can make it curve what ever way you want.

[Lostinspace 0]

i guess

[pilotdave 0]

coriolis force.



Dave

[bertusgeert 1]

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coriolis force.

yeah....not quite....
So... according to the theory that (like a softball that curves) the frisbee is faster on one side and slower on the other due to angular momentum and therefore curves left or right, the frisbee would curve along its path, but it wouldn't rotate along the direction of travel, (which, as a result produce the effect of the frisbee swerving left or right because of the princples of lift as in the picture)

So the question is still in the air....

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As jy dom is moet jy bloei!

[rhanold 0]

On the edge of the Frisbee for the clockwise rotation the air is traveling relatively faster on the left then the right from the thrower's point of view. This will push the Frisbee left as it travels. This force will be much smaller than the curve from the slight tilt or breeze so you are probably witnessing the result of a consistent non level through.

[bertusgeert 1]

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On the edge of the Frisbee for the clockwise rotation the air is traveling relatively faster on the left then the right from the thrower's point of view. This will push the Frisbee left as it travels. This force will be much smaller than the curve from the slight tilt or breeze so you are probably witnessing the result of a consistent non level through.

Yes, like you and I both said, this force is neglegable, especially considering the amount of surface are the edge of the frisbee presents.

But. Regardless of the angle I release the frisbee at, and regardless of the angle of attack, the frisbee ALWAYS curves left with a backhand, and ALWAYS curves right with a forehand, therefore DIRECTLY linking the direction of angular momentum with the direction the frisbee will veer.

Go and throw one and see what I mean. It's kind of puzzling!

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As jy dom is moet jy bloei!

[Lostinspace 0]

A rotating cylinder will produce lift.

why are you so concerned about angular momentum ?

[pilotdave 0]

I can throw a frisbee straight. Just practice more.

I haven't exactly studied frisbee aerodynamics, but if your observations are correct, it could be caused by the lower relative wind velocity on the retreating side causing slightly less lift on that side. But my observation is that a frisbee thrown flat flies straight.

Dave

[AggieDave 6]

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if your observations are correct, it could be caused by the lower relative wind velocity on the retreating side causing slightly less lift on that side. But my observation is that a frisbee thrown flat flies straight.

Sure, but what about an aerobe?

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[blueVTsky 0]

I get the physics part but I think the forces we are dealing with here are in fact mostly areodynamic and it all depends on its bank angle, after all a frisbee is just a round airfoil in flight isn't it?

[Lostinspace 0]

Look up Flettner rotor ship

sorry to quote Breakaway but ... "Im outta hear ...."

[bertusgeert 1]

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I get the physics part but I think the forces we are dealing with here are in fact mostly areodynamic and it all depends on its bank angle, after all a frisbee is just a round airfoil in flight isn't it?

All these forces are valid, and yes, they do affect the frisbee's direction, but not to the extent or direction I am talking about.

One. If the Frisbee produced more lift on one side and therefore curved because it is faster on one side than the other, then a backhand released frisbee (CW angular) would produce more lift on it's left side, and therefore it would curve right. THis is the exact opposite of what happens in reality. Also, you have to apply gyroscopic effects, which means more lift on the left of a CW rotatinf disc will produce the effect of the lift on the front end of the frisbee. In any case, this does not explain the puzzling curve.


Two. As with Flettner's ship and a baseball, this does not affect the rotation of the frisbee. It does have a very minimal effect (because of the minimal edge of the frisbee) on the path. In any case, neglegable.

Third. YES, A frisbee can be observed as a wing in flight in certain aspects. It is symmetrical from all horizantal viewpoints however. - The bank angle does not make a difference on the veering of the frisbee. PITCH does determine how fast the frisbee climbs or falls, but does not affect the veering. ROLL does determine HOW MUCH and HOW FAST the effect of the veering takes place. --- A backhand frisbee released with an initial rightwards roll angle will take LONGER to have the effect take place, but it still takes place. A backhand frisbee released with an initial leftwards roll angle simply veers more agressively. The bank therefore does not DETERMINE the veering and is therefore not an answer to the problem..

Although all three of these theories do play a part in aerodynamics, they do not determine why a backhand frisbee curves left and a forehand frisbee curves right.

Still wondering....

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As jy dom is moet jy bloei!

[Lostinspace 0]

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I can throw a frisbee straight. Just practice more.

im bored with frisbees.

but i can think of a fun game for a high wind day at the dropzone. it would involve creepers, round plastic trash cans and the motor from the golf carts and lawn mower.

and power tools

[Lostinspace 0]

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All these forces are valid, and yes, they do affect the frisbee's direction, but not to the extent or direction I am talking about.

Conclusion: you throw like a girl ...

[genoyamamoto 0]

http://www.disc-wing.com/ICASposter.pdf

Gotta go... plaything needs to spank me
Feel the hate...
Photos here

[bertusgeert 1]

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http://www.disc-wing.com/ICASposter.pdf

Awesome friggin link....thanks....

It somewhat answers my queries. It also seems to indicate that: If thrown with a posisitve angle of attack, gyroscopic effect will cause the rotation. Theory number two in my previous post might be valid. I think I have an answer for now!

THANKS AGAIN. I can go sleep now.

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As jy dom is moet jy bloei!

[Skyliving_Dave 0]

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Regardless of the angle I release the frisbee at, and regardless of the angle of attack, the frisbee ALWAYS curves left with a backhand, and ALWAYS curves right with a forehand

Dude, I think that's just your throwing. I can huck a disc dead flat or curve it either way, whether I'm throwing forehand or backhand.

I know you can get discs with a built in curve for playing disc golf. As you probably don't have one of those I guess your disc is bent or you're throwing it with a curve without realising.

*thinks* maybe you're always stood on a slope when you throw it

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'Everybody needs a mate called Dave'

[blueVTsky 0]

excellent I'm glad this was resolved, now back to discussions of titties and beer! *** ITS ALL PIPES! George Costanza

[Peej 0]

Head...sore...from...trying...to...under...stand...just...throw...the...damn...thing...already!

Advertisio Rodriguez / Sky

[shropshire 0]

I found this...http://www.afda.com/skills/physics.htm

It would appear that the direction of the curve in the flight path is attributable to the slant (Roll) given to the disc...
Roll, or bank, refers to the angle of the disc rotated about the direction of travel. This means whether the outside edge of the disc is held up or down. The amount of bank on the disc mainly determines the flight path, and can be used to good effect to throw around players who are between thrower and target. The disc will curve in the direction of the lowest edge of the disc.

This doesn't explain the cw/ccw aspect, unless the roll is induced by the way that you throw the disc (maybe?)

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[bertusgeert 1]

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Regardless of the angle I release the frisbee at, and regardless of the angle of attack, the frisbee ALWAYS curves left with a backhand, and ALWAYS curves right with a forehand

Dude, I think that's just your throwing. I can huck a disc dead flat or curve it either way, whether I'm throwing forehand or backhand.

I know you can get discs with a built in curve for playing disc golf. As you probably don't have one of those I guess your disc is bent or you're throwing it with a curve without realising.

*thinks* maybe you're always stood on a slope when you throw it

NO, it is NOT my throwing. It is a constant that ALWAYS happens. I actually have a bag full of disc golf discs that is perfectly flat and symmetrical. And NO, you cannot throw a disc so it curves left or right, it will ALWAYS end up curving left for a cw angular momentum.
Modern Playing frisbees are designed to be very stable and to counter this effect. they have a thicker profile/edge giving it a lot of weight on the outmost edge, so that centrifugial forces will stabalize the disc. Go throw some disc golf discs and watch. Thanks for the contribution though. (I am being blunt for clarity's sake).

As for roll, I absolutely agree, BUT, what CAUSES it to roll is what I am asking. The fact that direction of roll affects veering is established, just like a plane will turn left with left bank angle. But what CAUSES the roll to the left with a cw angular momentum and a right roll with ccw angular momentum?

Wow....this is some crazy stuff. I have an answer worked out though, and will post it as soon as I am done studying for my math exam.

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As jy dom is moet jy bloei!