Chief Delphi - Linear Path Shooter vs. Circular Path Shooter?

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Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- Technical Discussion (http://www.chiefdelphi.com/forums/forumdisplay.php?f=22)

- - Linear Path Shooter vs. Circular Path Shooter? (http://www.chiefdelphi.com/forums/showthread.php?t=110682)

CalTran

08-01-2013 12:59

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by Jeffy (Post 1210714)

My understanding of this is that he means the very short contact time and small contact area that a wheel and a linear wall creates compared to a curved wall and a wheel.

Oh.

dheerm

08-01-2013 20:08

Re: Linear Path Shooter vs. Circular Path Shooter?

Related Physics Question:

Take 2 different sized wheels with the same material making the outer edge.

Wouldn't the bigger wheel cause the frisbee to exit the shooter faster due to faster tangential velocity on the wheel?

Ether

08-01-2013 20:21

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by dheerm (Post 1211031)

http://www.chiefdelphi.com/forums/sh...2&postcount=16

dheerm

08-01-2013 21:00

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by Ether (Post 1210612)

It translates into approx 21 mph, assuming no slipping.

3600 rpm / 60 min/sec = 60 rev/sec

60 rev/sec * pi*4/12 ft/rev = 62.8 ft/sec

62.8 ft/sec / 2 = 31.4 ft/sec

31.4 ft/sec * 3600 sec/hour / 5280 ft/mile = 21.4 mph

Why did you only multiply by pi and not by 2pi? Also why did you divide by 2?

(I might just be missing something but I thought linear velocity was Angular Velocity(in radians) * r?

dheerm

08-01-2013 21:06

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by Ether (Post 1211043)

http://www.chiefdelphi.com/forums/sh...2&postcount=16

Also, I understand that linear velocity at the edge of the wheel increases with a bigger wheel. I was unsure about whether that entire increase would still go into the frisbee

Ether

08-01-2013 21:37

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by dheerm (Post 1211058)

Why did you only multiply by pi and not by 2pi?

because the wheel circumference is equal to pi times the diameter

Quote:

Also why did you divide by 2?

because the speed of the exiting frisbee is theoretically half the speed imparted to the frisbee's circumference (assuming, as stated in the post, that there is no slipping, i.e. the frisbee is rolling along the non-motorized edge)

Quote:

(I might just be missing something but I thought linear velocity was Angular Velocity(in radians) * r?

That's correct. Punch the numbers and you'll get the same answer.

Ether

08-01-2013 21:41

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by dheerm (Post 1211060)

Also, I understand that linear velocity at the edge of the wheel increases with a bigger wheel. I was unsure about whether that entire increase would still go into the frisbee

The faster the tangential velocity, the more likely that the explicitly stated "no slipping" assumption won't be entirely accurate.

dheerm

08-01-2013 21:45

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by Ether (Post 1211081)

The faster the tangential velocity, the more likely that the explicitly stated "no slipping" assumption won't be entirely accurate.

So in other words, a bigger wheel "might" speed up the frisbee's exit velocity?

Dr Theta

08-01-2013 22:44

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by dheerm (Post 1211085)

So in other words, a bigger wheel "might" speed up the frisbee's exit velocity?

And that is why you prototype ;)

dheerm

08-01-2013 23:13

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by Dr Theta (Post 1211124)

And that is why you prototype ;)

Exactly what I'm working on tomorrow :) Reason I was asking these questions was so that I could have some direction in the modifications I make to my prototype, but oh well :P

Ether

08-01-2013 23:18

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by dheerm (Post 1211085)

So in other words, a bigger wheel "might" speed up the frisbee's exit velocity?

It's highly likely, everything else being equal*.

* same wheel speed, same compression, same wheel material, etc etc

billbo911

08-01-2013 23:53

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by AdamHeard (Post 1210722)

When making prototypes, keep in mind there are more variables than just linear versus curved.

Our linear prototype currently worked AWESOME, and our curved is merely pretty darn good.

We're smart enough to realize we haven't proved anything yet, and need to explore more.

As Adam stated, there are many variables that need to be identified and worked out before any designs are made. The following video and the one posted yesterday are proof that prototyping works.

The four things that changed between yesterday and today are:
Larger wheel (6in to 8in).
Different tread to reduce slippage.
Much more solid backing to the wall.
[Edit] Added traction tape to the wall to stop slipping. [/Edit]

The result is, we can run the wheel at a lower RPM and get much longer and repeatable flights. This will allow us to also have more headroom in the drive for faster spin up and shorter recovery time.
Can anyone say "Bang Bang" Speed Control"?:yikes:

Yesterday's
http://www.youtube.com/watch?v=Wa6pc...ature=youtu.be

Today's
http://www.youtube.com/watch?v=_iqd_...ature=youtu.be

Bruceb

09-01-2013 00:28

Re: Linear Path Shooter vs. Circular Path Shooter?

NIce video but w a y to m u c h s l o w m o

billbo911

09-01-2013 00:50

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by Bruceb (Post 1211221)

NIce video but w a y to m u c h s l o w m o

I'll pass that on to the editor.
But remember, we are using these for analyzing a prototype, not for entertainment. :)

dcarr

09-01-2013 00:59

Re: Linear Path Shooter vs. Circular Path Shooter?

Quote:

Originally Posted by billbo911 (Post 1211235)

I'll pass that on to the editor.
But remember, we are using these for analyzing a prototype, not for entertainment. :)

They are very useful. But a bit long to get through :P

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