DC Motor for frisbee launcher

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LentzWC
 
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DC Motor for frisbee launcher

Post by LentzWC »

Hey, Y'all! I'm a designer working on an iteration of a DIY frisbee launcher, and I could use a little help.
First, here are some examples:

https://www.youtube.com/watch?v=ewesDBSRASw

https://www.youtube.com/watch?v=mCn-YSVi3-A

https://www.youtube.com/watch?v=0UklfX38tfY

https://www.youtube.com/watch?v=8KVK8svZzbI

I'm miniaturizing this thing to a "desktop" size using a 4.5" disc. It'll have a similar structure to the third sample video. It won't have tracking or a mechanized feed. The discs will just be gravity fed or placed in one at a time and I'm going to control the thing using servos and a wii nunchuck via Arduino. Right now, I'm collecting parts while working on designing the way the structure needs to function. My biggest concern for parts is picking up the correct motor size. A lot of full scale versions of this just use an electric drill... But that's not ideal for a desktop. Can anybody help?

I'd like it to be variable speed to control distance more accurately. And at top speed I think it would be awesome if I could get 20ft.

Disc (projectile) dimensions:
diameter = 4.5"
circumference = 14.13"
weight = 38 grams

I look forward to hearing from anybody with two-cents to give that might help push me in the right direction!

Best,
Will

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Re: DC Motor for frisbee launcher

Post by adafruit_support_bill »

What is the intended power source for this launcher?

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LentzWC
 
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Re: DC Motor for frisbee launcher

Post by LentzWC »

adafruit_support_bill wrote:What is the intended power source for this launcher?
I am willing to use whatever power source is necessary. Battery power and portability is not something I'm looking for. So a standard wall outlet is probably what I'll end up using.

W

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Re: DC Motor for frisbee launcher

Post by adafruit_support_bill »

Your disks are about 1/5 the mass of a regulation Ultimate disc, so you probably will need something with about 1/5 the power of the larger rigs to get similar acceleration. To some extent, you can get by with less power using a larger flywheel. The tradeoff is that you need more time between launches to get back up to speed.

Do you have any details on the motors and power supplies used in the videos?

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Re: DC Motor for frisbee launcher

Post by LentzWC »

No, I can't find any of those numbers. People didn't do a great job of posting their values. I'll see what I can find. But in the meantime if you've got any pointers on how to choose the right motor, I'd appreciate the help!

Will

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Re: DC Motor for frisbee launcher

Post by adafruit_support_bill »

What forward velocity do you need on the disc coming out of the launcher? Driving the disc from the rim on one side as in the videos means that the speed of the driven side of the disc need to be twice the speed of the center of the disc as it exits the launcher.

So, you will need to choose a motor and drive wheel combination that when spun up to speed, the periphery of the drive wheel will reach (or exceed) that speed.

You will also need to choose a motor with enough power to accelerate the disc to that speed. You can select a motor (and power supply) that can apply that power directly. Or you can have a lower powered motor spin up a flywheel and have the flywheel transfer its stored energy to the disc. If using the flywheel approach, you will need to account for the drop in speed as the flywheel transfers its energy to the disc.

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Re: DC Motor for frisbee launcher

Post by LentzWC »

I'll get back to you as I figure some things out. But I think the flywheel method is what I'll end up using. This thing doesn't need to spit out discs rapidly. So, if it can spin up to speed inside of a handful of seconds, it'll be just fine. Forward velocity is not something I've figured out yet. I'll get back to you after I've done some more research into existing projects. Thanks for all the help you've given me so far. It's been a big help. I'll see if I can't find info on velocity from those other projects and let you know what I've figured out. I'm on a quick deadline, so I may overshoot a little bit on power and not worry about efficiency. I'm in Becky Stern's class at SVA and we're on a deadline. I'll post photos and things as this comes along a little more.

Thanks Bill!

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