Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

ddrueckhammer

macrumors 65816
Original poster
Aug 8, 2004
1,181
0
America's Wang
For my Physics 2 class, we were asked to create a self propelled gondola that would traverse a 3/16” total diameter rubber insulated wire across a 70’ span approximately 20’ above the ground. Below is a link to my website with further information, schematics, and pictures of the project.

http://web.mac.com/ddrueckhammer/iWeb/Site/Mono Wire Racer Project.html

I have designed an aluminum enclosure and wired my batteries so that my motor is at max capacity. (18 V, 2.4 A, 18000 RPM w/ load). I haven't weighed it yet but I think my total weight is under 1 pound. Unfortunately, I am restricted to Alkaline batteries so the weight can't be cut significantly without cutting power to the motor.

I am getting a propeller adaptor so that my 2mm shaft can fit bigger props. My questions are:

Can anyone recommend an RC Airplane or Hobbyist forum where I can get some help?

Would I benefit from using a front mounted gear-box on my motor? I think that this would cut the RPMs but add more torque. What are the benefits in general for gear-boxes?

What sort of prop should I be using? From the little research I have done, it looks like a 7-9 inch pusher prop would be good but I'm not sure whether a flat pitch or a deeper pitch is appropriate. Also, would I benefit from using a 3 or 4 blade prop?

My max lwh is 25cm x 15 cm x 25 cm and my max wight is 2.2 lbs.
I am limited to a max of 2 motors and only ones available through Radio Shack.
And my max voltage is 18 V from Alkaline batteries.
 
Or to be even less helpful...you could make a 'cotton rocket.'

Liquid nitrogen (cheaper than bottled water) can be used for this. Blow up a balloon and drop it into liquid nitrogen. The oxygen will condense into a cool blue liquid. Pack cotton into a cardboard tube. Pour the liquid oxygen from the balloon into the cotton. Strap the tube down strongly...apply flame and stand back.

P.S. I recommend a long fuse or something to get you far away when the thing goes...lots of power.

P.P.S. I don't actually recommend doing this...it's just so freaking cool.
 
Thanks for the replies. I finished my project and got an A on it. My design finished third out of a feild of eight. Pictures, schematics, and information about the project is located on my website at:

Mono Wire Racer Project

Thanks again for your help!
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.