MagLev C

[wlsguy]

The side walls are 27mm high.
The molding is 30mm on inside and the magnets are 3mm thick.
Since the rules allow for 2~5cm (20~50mm) this puts it on the low side a little bit from the median of 35mm.

The brick mold cross section is 30mm x 50mm.
I am considering rotating the molding 90 degrees to make the track 50mm high to see the difference.

From your experience, what is the "best" dimension?
Or better, what are the pro's / con's to high vs low track heights?

Thanks.

[chalker]

Mr. Chalker (not sure which one), can you please update the Maglev page on soinc.org? I remember someone saying that instructions to build your own track would be made available on the national website, but nothing has been uploaded as of now. Thanks

The MagLev event page on soinc.org has been populated now. Be sure to check out the wonderful track construction guide Andy Hamm created: http://soinc.org/maglev_c

[Flavorflav]

Chalker, would you care to give your unofficial opinion about the ducted propeller-motor combinations? If a student uses their own motor and a separate ducted fan, is the motor allowed to go up to 65 cm, or does that larger size apply only to commercial ducted fans with integral motors?

ETA: oops, make that 60 mm.

[wlsguy]

Chalker, would you care to give your unofficial opinion about the ducted propeller-motor combinations? If a student uses their own motor and a separate ducted fan, is the motor allowed to go up to 65 cm, or does that larger size apply only to commercial ducted fans with integral motors?

I think a better question would be;

Is the duct on a ducted fan considered part of the propeller or part of the vehicle?

If it is part of the propeller, it would be allowed to extend outside of the track rails (the only exception to the width rules) and the 6cm limit would be significant in limiting the size of the motor/prop combination.

If it is part of the vehicle it cannot and would be limited to the width of the track (65.09mm on a 2 9/16" track or 76.2mm on a 3" track) since no part of the vehicle is allowed outside of the sides of the track.

[chalker]

Chalker, would you care to give your unofficial opinion about the ducted propeller-motor combinations? If a student uses their own motor and a separate ducted fan, is the motor allowed to go up to 65 cm, or does that larger size apply only to commercial ducted fans with integral motors?

I think a better question would be;

Is the duct on a ducted fan considered part of the propeller or part of the vehicle?

If it is part of the propeller, it would be allowed to extend outside of the track rails (the only exception to the width rules) and the 6cm limit would be significant in limiting the size of the motor/prop combination.

If it is part of the vehicle it cannot and would be limited to the width of the track (65.09mm on a 2 9/16" track or 76.2mm on a 3" track) since no part of the vehicle is allowed outside of the sides of the track.

Unofficially, the duct is part of the vehicle. It is not allowed outside the track rails (hence the 6cm width of it, which was originally put in to account for the standard width track, then we forgot to update to account for the wider/narrower range allowed for team provided tracks).

Regardless, the reason behind the rules is that we want to limit the overall size of the motors to help try to avoid too powerful motors that could cause injuries. Since there are commercially packaged ducted fan/motors available, we realized it might be hard to directly measure the diameter of the motor, so we put in the 6cm limitation to ensure teams didn't have to disassemble their devices to be checked (the assumption being that the duct blocks the motor from being easily measured). Thus the language specifies ducted motor/propeller. If the propeller is the only part ducted, then you can easily measure the motor and the normal limit applies.

[Flavorflav]

Thanks, Chalker. That's what I figured, but I thought it was worth asking.

[Mr_J]

Anyone know of a place to get a cheap track for this event? I tried building one a long time ago and it never worked out very well, but $150 or more is way out of our budget...

If you plan to build, I found 25 feet of Magnetic tape online at walmart for $9 including shipping

[illusionist]

Anyone know of a place to get a cheap track for this event? I tried building one a long time ago and it never worked out very well, but $150 or more is way out of our budget...

If you plan to build, I found 25 feet of Magnetic tape online at walmart for $9 including shipping

Would that be appropriate for maglev purposes though? Kelvin also sells some magnetic tape that is cheaper than the designated maglev one, but they clearly state that it is not suitable for maglev purposes. Anyone else have any thoughts?

[_HenryHscioly_]

http://www.walmart.com/ip/Magnum-Magnet ... 5/13432532

http://www.amazon.com/Magnum-Magnetics- ... Descending

The product has not-so-good reviews and ratings on amazon.
I cant find if it is the kind where it is magnetic on one side and barely magnetic on the sticky side, where the magnetic side has both north and south pole attraction along the strip. But that could be the case.

[chalker]

I cant find if it is the kind where it is magnetic on one side and barely magnetic on the sticky side, where the magnetic side has both north and south pole attraction along the strip. But that could be the case.

In all likelihood it is magnetic on just one side since it's adhesive on the other. This is called a Halbach array (see the good wikipedia article on it: http://en.wikipedia.org/wiki/Halbach_array ) and is generally preferred in most applications where you are trying to use the magnet to hold an object onto a metal surface because of the stronger field.

However it's NOT recommended for MagLev tracks because it's essentially lots of alternating North and South magnets lined up. Note that you wants magnetic tape with North on one side and South on the other side, as sold by Pitsco (and others): http://www.pitsco.com/store/detail.aspx ... 1&c=&t=&l=

As an aside, here's a fun quick experiment you can do. Take 2 flat fridge magnets and put them face to face (magnetic side touching magnetic side). Slowly slide them back and forth past each other, then rotate one of the magnets slightly in relation to the other. Rinse and repeat this process until at some point you'll feel the magnets 'clicking' in small steps when you try to slide them past each other. You've now aligned the Halbach arrays with each other and what you are feeling is the attraction when the North and South poles align, versus the repulsion when the like poles align. If you use a ruler you can count the number of steps over a 1cm and figure out the actual width of the magnetic domains.