MagLev Vehicle B/C

[personasaurus rex]

do you know those cars' masses?

My guess would be 201g... there's no point in making them any heavier than necessary, right?

yeah, but it's hard to get them down to minimum mass without sacrificing a little speed...

[Primate]

The top three run times were 2.07s, 2.25s and 2.37s at WLI regionals - the test was rather easy and didn't really affect the score. Basically, it was the fastest that won.

10th grade, no Physics yet - what should I study?

Propeller: got a good one by dissecting an old computer

Try learning some physics anyway; it was a huge component of our test. It's really not all that complicated; just learn the basic equations for relating magnetic fields to electricity. (Here's a great introduction, and SparkNotes to sum it up.)

Are you sure a computer fan is the best option? They're generally designed to circulate air, not for propulsion.

[Flavorflav]

The top three run times were 2.07s, 2.25s and 2.37s at WLI regionals - the test was rather easy and didn't really affect the score. Basically, it was the fastest that won.

10th grade, no Physics yet - what should I study?

Propeller: got a good one by dissecting an old computer

Try learning some physics anyway; it was a huge component of our test. It's really not all that complicated; just learn the basic equations for relating magnetic fields to electricity. (Here's a great introduction, and SparkNotes to sum it up.)

Are you sure a computer fan is the best option? They're generally designed to circulate air, not for propulsion.

Newton's Third - move air out the back and the car will move forward. The real problem is that computer fans are designed to be quiet, which is likely to reduce their efficiency.

[Primate]

10th grade, no Physics yet - what should I study?

Propeller: got a good one by dissecting an old computer

Try learning some physics anyway; it was a huge component of our test. It's really not all that complicated; just learn the basic equations for relating magnetic fields to electricity. (Here's a great introduction, and SparkNotes to sum it up.)

Are you sure a computer fan is the best option? They're generally designed to circulate air, not for propulsion.

Newton's Third - move air out the back and the car will move forward. The real problem is that computer fans are designed to be quiet, which is likely to reduce their efficiency.

Well, sure, but the shape can drastically effect efficiency as well. You want to minimize drag while maximizing thrust, optimizing pitch, etc, etc.

Of course, prop design isn't consequential until you get down to the three-four second range. The difference between a 45 second run and a 5 second run is all balance.

[Flavorflav]

Well, sure, but the shape can drastically effect efficiency as well. You want to minimize drag while maximizing thrust, optimizing pitch, etc, etc.

Of course, but a shape that is good for moving air is good for moving air, is what I am saying. It shouldn't really matter whether the assembly is on a fixed platform or not. The big problems are that fans are missing some design considerations (like weight) and have others (like quietness) that are likely to make them suboptimal. I have seen at least one really good maglev with a ducted fan, though.

[personasaurus rex]

So since a lot of competitions have passed, I was wondering if people had maglev times to share? What mass was the sled at your competition and what was your time?

[bchero]

I was just assigned to this event and I have no idea about the actual construction of the car. I know most of the electricity and magnetism behind the event, but the construction is ticking me off. Anybody have any suggestions? Where should I start?

[quizbowl]

Does anyone know what exactly would be on the test?

[Primate]

Does anyone know what exactly would be on the test?

Anything remotely related to magnetism is fair game. History, important scientists (know these!), physics (magnetic fields, current through wires, etc), and just plain old common sense about how magnets behave. Know paramagnetism and dimagnetism too.

Sample question from our test--I'm not sure what the answer is:
You're given three rods. One is a permanent magnet, one is brass, and one is steel. How can you determine which is which, using only your hands and the three rods?

[Flavorflav]

I was just assigned to this event and I have no idea about the actual construction of the car. I know most of the electricity and magnetism behind the event, but the construction is ticking me off. Anybody have any suggestions? Where should I start?

1. Get some motors, propellers and a bunch of nine volt batteries. You are going to suck a lot of them dry doing time trials.
2. Build a very simple platform for them - I like aircraft plywood, myself.
3. Get some velcro strips to attach the magnets to the bottom. These are a lifesaver - a small adjustment of your magnets can produce a huge reduction in friction.

You are going to need to elevate the prop, unless you use a really small one (which I do not recommend).