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Magnus Effect (Read 5156 times)
CanDo
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Re: Magnus Effect
Reply #30 - Feb 15th, 2006 at 6:23pm
 
water ballons are hard to aim!!

does the spin really impact accuracy? i think that a waterballon in flight would be squashed because of the force anyway. it seems to me that an amorphous blob like a water baloon, without seams (like on a tennis or baseball),  would not be heavily impacted by spin.
i think that it's actually the force exerted on the ballon which causes the spin (that bit of friction at the moment of realease) which makes a noticiable veer.

anyone who's actually taken a physics course know what effect it would have?
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Matthias
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Re: Magnus Effect
Reply #31 - Feb 15th, 2006 at 7:17pm
 
I'm surprised you can spin a water balloon. Usually the water inside (having no particular reason to start spinning in the first place) is more than happy to just slosh around a little. I bet leaving the pouch sets up all sorts of crazy oscillations though, which "probably" won't really impact accuracy too much.

siguy's bottle sling might do the trick. Ideally I suppose you want something that conforms to the resting shape of the balloon as much as possible during the windup, and then releases cleanly without causing the ballon to fold in half or any such craziness...

Matthias
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CanDo
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Re: Magnus Effect
Reply #32 - Feb 15th, 2006 at 7:38pm
 
ha, exactly what I was thinking, but didn't want to bring up. Theres no reason for the water to spin (and if it did, so what?).

The balloon itself could spin though (even if slowly) because of so much friction it can create with the pouch.

Question for phsyics people:
Can the energy/momentum of spinning itself cause an object to change flight? Or is it only the spinning's interaction with the air that can do that? (If an oboject were spinning in a vaccuum would the spin impact trajectory??) I personally don't think it would, but thought it would be nice to hear from someone who knows that they're talking about.

W0W this has gotten off topic.

I think it's safe to say that you should cast water ballons with a style that gives you the best accuracy/range, and to not worry so much about spin.

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Matthias
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Re: Magnus Effect
Reply #33 - Feb 15th, 2006 at 7:59pm
 
Not really. Since you have spin, if you could somehow influence a change in attitude you could deflect the shot. The only way to do that though is aerodynamically, so it is a bit of a chicken/egg problem. In a vacuum, and ignoring the earth's spin. the glans would just carry on merrily in a nice clean parabola.

Further reading - google ballistics and precession, and don't believe everything you find Wink

Matthias
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CanDo
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Re: Magnus Effect
Reply #34 - Feb 15th, 2006 at 8:02pm
 
woa... .the whole time i thought this was the water ballon war thread....

Thanks Matthias for clearing that up Smiley
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AjlouniBoy
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Re: Magnus Effect
Reply #35 - Feb 15th, 2006 at 8:24pm
 
MiniMagnus Balloonster

Try a staff sling with short cords

AjlouniBoy
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Like tying a stone in a sling is the giving of honor to a fool.&&Proverbs 26:8
 
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Re: Magnus Effect
Reply #36 - Feb 15th, 2006 at 8:41pm
 
AjlouniBoy, ....please tell us more about your grip/release!!  An overhand thumb release with the thumb up and pinkie down should put topspin on the ball, not backspin, if I have the geometry right.

In fact, underhand and sidearm with thumb release with thumb up should do the same.

What's different about your overhand, etc?  Inquiring minds want to know!!

Many thanx!
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Unsapien
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Re: Magnus Effect
Reply #37 - Feb 16th, 2006 at 12:29pm
 
Thanks, for the comments/ suggestions.
I realize that this veers off the topic alot, so I'll take the topic up in tthe water ballon thread.

Interesting thoughts though. Thankls for th imput.

-Unsapien
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AjlouniBoy
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Re: Magnus Effect
Reply #38 - Feb 16th, 2006 at 12:44pm
 
I dunno, it seems counterintuitive to me as well.  I'm not sure what factors are at work, particularly what the final pouch orientation is at release.  We need some high speed video to study.

With a palm forward release, thumb to Lt and pinkie to Rt, I was getting some backspins, but a lot of side spins and topspins.  The percentage of backspins inproved dramatically with the thumb up, pinkie down.  I don't know if that additional wrist flip has anything to do with it.

With a "Greek" start having the cords on tension I think we get more consistency in pouch orientation at release, but there is still enough variation in spins that I think the pouch pivots on the long axis of the sling during windup.  An "open" grip with retention loop on ring finger should help minimize the pivot.  A lot happens during windup that I still need to learn to control.  Time to get another bag o balls and try to watch.  Must get quality video.

All that to say I don't entirely know.  Try it out and see what you get.

AjlouniBoy
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Like tying a stone in a sling is the giving of honor to a fool.&&Proverbs 26:8
 
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Re: Magnus Effect
Reply #39 - Feb 17th, 2006 at 12:47pm
 
Another round of golfballs using figure 8 technique with Thumb up, pinkie down "Handshake" release "fishing rod cast"wrist flip gave 12 beautiful backspin 180m throws in a row.

I don't think I have thrown 12 beautiful anythings in a row before.

This must have something to do with figure 8 technique.

Switching to Greek overhand with the same Thumb up handshake I got the topspin plungers we would expect.

Will keep after it , eager to hear of other's experiences and observations.

Nwmanitou, Yurek, Tint & other Figure 8 powerhouses--Any similar or different observations?

AjlouniBoy
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« Last Edit: Feb 18th, 2006 at 5:28am by AjlouniBoy »  

Like tying a stone in a sling is the giving of honor to a fool.&&Proverbs 26:8
 
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Chris
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Re: Magnus Effect
Reply #40 - Feb 21st, 2006 at 9:59am
 
Would someone care to write up a little snippet about the Magnus effect.  I've created a "Magnus Effect" Section under "Physics of the Sling"

http://www.slinging.org/wiki/

Chris
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Matthias
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Re: Magnus Effect
Reply #41 - Feb 21st, 2006 at 2:04pm
 
hint... hint...


We have lots of material in the archives. I'll see what I can do, and if anyone wants to get a head start, that would be good. Any collaborators?

ChuckRocks' link takes me back... Maybe we'll should aim for an explanation that *doesn't* make most slinger's eyes glaze over Tongue...

Matthias
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