Hey guys, Today I have an odd request…sort of. For a school project, I am going to build a small vehicle though Inventor. This vehicle will carry with it six magnets in any position I choose, and must levitate above a magnetic track…sounds simple right? But here is the catch, this vehicle will be powered by a small 12v motor by an off board power supply. So the object is to make a motor that will spin a propeller, that I must also design in Inventor, and that will push the cart across the track. Fastest time wins, and winner gets the best grade. But how the heck do I make a propeller??Any tips to getting a more efficient cart and propeller?? All parts will be 3d printed
Thanks
p.s. if I am missing any info you may need, feel free to ask in the comments
One presumes that your Inventor creations will be 3D printed? If not, this post is a good bit off topic. One can, however, 3D print propellers that will operate below the rpm of destruction.
Larger slow moving propellers with proper pitch will be more efficient than smaller high speed ones. The fastest human powered watercraft used a propeller that was ten feet in diameter, twice as tall as the rest of the craft. It also used hydrofoils to reduce drag in the water, something that won’t help you much.
You can do a search with your favorite search engine for “low speed propeller design” and have a deluge of information. You may also have better luck looking into the world of radio control aircraft. Park flyers are designed for low speed high efficiency propellers.
You can also search for “autodesk inventor propeller design” which will result in another bundle of returns.
If your craft is to levitate above the track, will you have contact brushes to transfer the off-board power to the cart? Is the magnetic track constructed of energized coils or fixed magnets?
Are you permitted to use the power of the track’s magnetism to power your cart? It appears from the description that the answer to that question is no, if an electric motor drive is a requirement.
That’s an interesting method of providing power. It must mean that the track is of a limited length. I hope you won’t have to drag a power line behind the cart and the spool will unwind from the cart, not from a fixed location.
@Fred_U From what i gather the track is only 8 feet long with 4" sides to guid the craft, lots of friction will ocuur on the walls of the craft and guides. And agian i belive that the spool is in a fixed location and the cart must pull the wire it needs
The magnets on the cart have to be considered along with those on the track. I’ve not played with linear motors in any form, but find the topic fascinating. Rotary motors work by changing polarity of coils in a proper sequence to react with other coils or fixed magnets. Linear motors work the same way, but the coils and magnets are arranged in a straight line.
I’m not quite sure how one manages magnetic levitation without an active track configuration. This link:
will present a number of different design configurations. I suspect you’ll have the greatest success if your cart is not levitating until it reaches the appropriate speed, but that also implies magnets or coils in the track.
If the power spool is in a fixed location, you have additional drag if the line is pulled out as you run. If the rules allow, have the power spool at the finish, with the line stretched to your cart. Even if you are not permitted to create a take-up spool on your cart, you’d have to drag only half as much line behind you by having the spool at the finish. If you can have a take-up spool with a commutator of sorts (slip-ring) you would really have a low-drag advantage.
Does the motor have to spin a prop? Personally, I’d probably try to use the magnets themselves as the propulsion, using a linear motor setup; you need some sort of controller for a linear motor so if you’re not allowed to us an Arduino or Pi or somesuch, you might be able to use the motor to act as a rotary selector for the parts of the linear motor.
Mind you, I also usually argue that simple works best and going down the route of a linear motor could be a lot of pain for little gain (if any, it may never work!).
I’m concerned about the cable though; as others have suggested, that seems a huge possible problem with drag/fouling, etc.