Mousetrap Cars.....

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VH_man
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Thu Sep 04, 2008 7:35 pm

Well, im in a grand-old physics class, and i have been assigned to construct a mousetrap car...

its the usual competition... 5 meters in the fastest time gets the best grade.

I want to have a plan for a car that will kick the holy living hellll out of everyone elses car. Ulike everyone else, i plan to use mathematics to CALCULATE the optimum tourque and speed to give the maximum acceleration without wheel slippage.

Anyway, just wondering if anyone has ideas/ the most importat...

What is the Average force exerted on the end arm of a mousetrap? I lack the equpiement to measure this.

Thanks in advance.
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Hotwired
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Thu Sep 04, 2008 7:43 pm

It would vary a fair bit between designs tbh.

You could take force readings with one of those springy scale things that you hold or hang up and attach whatever you're weighing to the hook like a bag or a fish or something. In this case the trap arm being pulled back.
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VH_man
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Thu Sep 04, 2008 7:57 pm

you know... i didnt think of that.........

haha i feel like an idiot now. Thank ya!

anyone know the dimensions of a mousetrap? Im doing some Scale Drawings for my "partner in crime" (tehehehehe)
brother361
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Thu Sep 04, 2008 8:50 pm

they have a video on make.com youtube site from a guy named kipkay that made one
microman171
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Fri Sep 05, 2008 1:50 am

Just go into your local hardawre store and buy the size you are looking for (in NZ they come in 3).
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littlebro05
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Fri Sep 05, 2008 4:10 am

Hey dude!...

I made one of these back in grade 8,

Anyway what i think is important will be using big wheels for rolling, i dunno how to explain it... I used CD wheels for it.

Friction on the axle of where the mouse trip produces a spin on the axle. Too much will not make it go, to little will give little acceleration.

and a slick design is all i can think of
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Carlman
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Fri Sep 05, 2008 4:33 am

and very light..

these are fun!
oh and if you wnt to win switch out the spring with a different one lol
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potatoflinger
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Fri Sep 05, 2008 5:14 am

You could also put rubber bands around the wheels for extra grip.
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microman171
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Fri Sep 05, 2008 6:19 am

Biger wheels should be good for distance as they will act like a flywheel. Do anything to reduce friction and you should win for sure
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TwitchTheAussie
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Fri Sep 05, 2008 8:13 am

Slicks (previous mentioned big wheels with rubber on them) and for optimum speed keep the back end heavier to get the grip going. Keep the acceleration as best as possible.

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Antonio
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Fri Sep 05, 2008 8:46 am

I did this project as well a long time ago. I used cds as the wheels with big rubberbands along the edges for grip. If you make the vehicle as light as possible you will have a higher acceleration so I would go for that:) Further keep into account that the mousetrap doesn't give a linear force. As it has an arm you can get a buildup of force or a decrease in force( and lots of force in the beginning). So if you go with big diameter wheels I would go for the last. Lots of torque in the beginning and once it rolls u don't need it any more>
Rokmonkey
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Fri Sep 05, 2008 11:36 am

Use a rat trap, Small wheels give you the acceleration you need, My suggestionw ould be small wheels, as you only have torque for so long. Large wheels give you the top speed though...
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Fri Sep 05, 2008 1:04 pm

I have participated and won several of these type contests...in the adult world, engineering week typically in Feb of every year. Do everything you can to use the rules to your favor. Focus on what the rules specifically say and don't say in designing your car.

You're looking for speed rather that distance so be careful not use too large wheels...you won't get the torque you need out of a large wheel. You'll get lots of torque out of a small wheel but the land speed may not be enough to win or go the full distance.

Assuming they aren't dictating the wheel size and type for everyone (something I think they should do BTW), try different sized wheels to get the optimum speed for your car design.

Remember, you are going for SPEED in a certain distance. Focus on that in your design. That's going to inherently call for a light weight car. Keep the profile and center of gravity as low as possible. Make sure your wheels are squarely aligned, not toeing in or out.

Also, look for any tips used in pinecar derby designs. Many design problems will be the same.
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Pilgrimman
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Fri Sep 05, 2008 1:49 pm

You could try using lego wheels. Ready made traction!
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VH_man
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Fri Sep 05, 2008 9:47 pm

What i plan to do is use my friend's dad's metal lathe/milling machine and make the thing out of aluminum tube (swis cheesed of course). Ball bearings on all axle points, and 3 wheels for minimum rolling friction.

i plan on using 2 rails, put in a triangular shape under the mousetrap, using the mousetrap as part of the body itself to conserve weight. After this, however, i need the diameter of the axles im using and the tourque of the Mousetrap in order to calculate my optimum wheel diameter to insure the car accelerates as fast as possible WITHOUT the wheels slipping.

for wheels i plan on using "spoked" basswood (for less weight), with the rubber bands from lobster claws for the "traction"
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