MagLev C

[twototwenty]

I may be repeating opinions already voiced here (in fact, I know I am), but I just want to strongly emphasize my feelings about this event for next year.

Firstly, safety is undeniably an issue for this event; unprotected blades which competitors are doing their best to make go as fast as possible are intrinsically dangerous. Many of the "better" propellors are meant to be used for R/C airplanes, where there is a far smaller risk of slicing your fingers up than with a compact MagLev car, where switches are forced to be very close to the blades. I have numerouse cuts on my own hands to prove this point, and I was using ducted fans for most of the year. In general, this is a very good reason to keep the battery limits as are; I agree with many of erikb's poinits about the safety topic.

However, the bigger problem I have with this event is the money. To begin with, I believe someone suggested removing the "no integrated circuits" rule. Do not do this, please. This allows brushless fans, which essentially immediately makes this event a boring "richer team wins" competition.
Even as is, this event is facing a problem (at least in New York, where it has been run as a trial event for a VERY long time) of the winners being the team which is able to afford the best materials (is able to get good motors, good propellors, and make a good track). This, as I understand it, occurs because teams have already figured out the event pretty well, and thus being the best depends largely on the materials the team is able to get. The best way to solve this, obviously, is to radically change the event. Iwonder listed various ideas for this; in particular, I liked his idea of having to travel a distance in a specific time. This, I feel, would really require competitors to rethink the event, take care of the need for expensive materials (if the cars have to travel 4 ft in exactly 30 seconds, the most powerful motor is not at all necessary), and also remove some safety risks (for the same reason).

One other idea for changing the event that I thought of would be offering some very large bonus, similar to the chinook helicopter bonus of last year, for some similar handicapping of the car, such as requring it to have only one fan blowing air towards where the car needs to go, or some ridiculous (and fun) engineering problem like that.

[Schrodingerscat]

To begin with, I believe someone suggested removing the "no integrated circuits" rule. Do not do this, please. This allows brushless fans, which essentially immediately makes this event a boring "richer team wins" competition.

However, the context of this suggested rule change was to make a certain distance the goal, which would be preferable to some degree of electronic control. This modified event could be made so spending money on brushless motors would not give any benefit. However, the problem with making it a slow target time or a certain stopping distance is that it removes the event from the original context of the problem, as it would actually encourage inefficient tracks with high friction. Perhaps the event could be redesigned to run on a finite amount of energy, such as elastic power, which would place the event in the context of a more "real world" problem of energy efficiency.

[twototwenty]

To begin with, I believe someone suggested removing the "no integrated circuits" rule. Do not do this, please. This allows brushless fans, which essentially immediately makes this event a boring "richer team wins" competition.

However, the context of this suggested rule change was to make a certain distance the goal, which would be preferable to some degree of electronic control. This modified event could be made so spending money on brushless motors would not give any benefit. However, the problem with making it a slow target time or a certain stopping distance is that it removes the event from the original context of the problem, as it would actually encourage inefficient tracks with high friction. Perhaps the event could be redesigned to run on a finite amount of energy, such as elastic power, which would place the event in the context of a more "real world" problem of energy efficiency.

Hmm, you bring up a very good point. And I like your "finite energy" idea...

Imagine, if the rules stayed exactly the same, except for the addition of a 5x vehicle score bonus for using no electricity. That would certainly make things interesting.

[mrsteven]

Multiplier for no electricity? I like it too! Some sort of mechanical device to use gravitational potential energy with counter weights.... I can already start seeing that being very fun

brushless motors turn everything around. You have to buy the ESC, motor, likely some sort of transmitter & reciever... Turns pricy for an event that I think is currently run at a level where little money but a fair amount of physics intuition pays off big time. Not to say money doesnt help though

[chalker7]

Just to interject another opinion from the side, I think everyone can agree that investment and expenditure of resources is what creates performance, but I believe many people focus on two aspects of those inputs and outputs; money and whatever metric is relavent to the event as chosen. That is to say, money doesn't necessarily buy a gold medal in any event. Of course it helps, but there are other resources you can invest, such as time, finding and utilizing quality mentors/coaches, developing personal expertise, finding and learning how to use unique tools, etc. Once again, of course having financial resources helps with all of that, but it isn't implicit. If a "poor" team spends 500 hours perfecting their cheap vehicle, they are likely to beat the "rich" team who builds the vehicle the night before.

More importantly, the outputs are not consistent. Resources don't only provide you with improved speed/mass pulling capacity, but they can also provide you with more consistency (or whatever else you're being judged on.) If one team makes their vehicle by taping together popsicle sticks while another uses a precision CNC mill to craft an exacting frame, it's very likely the latter will be more predictable on the track.

All of this is to say, of course these issues are ones the "rules writers" think about all the time. The problem is that the issues are more complicated than you might think, once you think you've solved one problem, another arises. To me, as someone who contributes to this process, safety is the biggest concern in this event. And I don't mean safety on competition day, but more importantly safety throughout the year when teams are building and practicing and don't have a supervisor around to tell them they can't use a dangerous device. So, for whatever it's worth, that is the part I have been and am actively advocating for above all else.

One final interesting point. Pretty much this whole thread has been dedicated to the vehicles, while that's only 50% of the final score. Teams can dedicate 100% of their resources to that section and still perform extremely poorly in the event as a whole. Does anyone have any opinion about the test component?

[erikb]

First the cost:

For regionals and invitationals, i limited the kids to AA batteries and flexible propellers, for safety. Even if they nicked an area outside the gloves it was a scratch not a deep cut. They averaged 800g in .6 seconds

For state they used lipo's but still flexible blades. 1900g in .6 seconds

For nationals they are going to use lipo's and apc blades. While it is tough to estimate the times at nationals, (since we are at over 5200 feet and it is at 700). We expect over 2k at less than .6 seconds.

The difference between the events.

For both state and regionals.
Same motors: 2x$5:86
Same propellers: 2x$1

Regionals: 20 pack, AA Batteries from wal mart for $8.97 (used 8), battery holder from radio shack $4
State: Lipo batteries. $26 and $100 for the charger and accessories for lipo.

So total cost for a mag lev before state:
Motors: 2x$5.86
Propellers: 2x$1
Batteries: $8.97
Battery holder:$5
Total: less than $50

For state
Motors: 2x$5.86
Propellers: 2x$1
Batteries: $126
Total: over $140

You can use the same motors and propellers, at different amps. But limiting the amps makes the price to compete drop by 2/3

So the only reason i can see to complain about limiting the amps is that you have already spent the money or you understand that limiting the amps levels the playing field and next year it will be more competitive.

On a side note: this "have to start over if we limit the amps" logic is broken. Propeller and motors work just fine with voltage and amp differences. However, At nationals we are taking all the possible propellers that we could find and that fit within the rules. Why? because the density of air has more of an impact on what propeller to use than voltage and amps.

Safety:

Throwing red herrings out about safety is silly.

I would like to see the table saw that has the on/off switch inside the painted red area around the blade. Better yet, between two spinning blades. Plus, you don't have to hold the table saw blade back with a pencil. (or now something safe)

Comparing the two is not the same. One has decades of technology and knowledge behind it and to make it safe for use. The other by design, places the hand in harms way. I really don't understand this logic of "it has not maimed enough so we should not change it" or comparing it to something that has had decades of safety initiatives behind it.

Furthermore, to keep the amps and forcing the addition of safety features to the mag lev is an another economic burden and technological hurdle. You might as well call it a "schools with the resources only event"

Finally:

All the suggestions so far will force re-engineering.

Pulling a sled will change how the weight is distributed. Thrust then can be more evenly distributed between the propellers. Since a portion of weight will be behind the sled the rear propeller won't push the sled up or down as much so it's thrust can be equalized and increased.

Limiting to one propeller will change everything. Currently, one prop is pushing air into the other, while the other is creating a vacuum behind the first. They effect on each other. Causing them both to spin faster and generating more thrust then the combined individual thrust. So this year you can run props and motors that would not be competitive in a single prop/motor event.

Distance for time. Will change everything since the committee will have to set the fastest times to be a reasonable time for the all schools. Including the ones that can't compete with lipos. So the fastest times should be at least over 1.5 seconds for the .95 meter and for a good spread under 3.5.

On a side note i am most in favor of the time and distance style event. As long as the times are reasonable for all schools to achieve.

Back to my point, No matter what, any of the suggested changes will force a reevaluation of the motors/propellers to be competitive.

So your arguments boil down to: we have already spent the money, so make everyone else spend as much to compete

In conclusion, by limiting the total wattage available lowers the bar to compete, increases safety and will force teams to focus on physics if they want to win.

[erikb]

One final interesting point. Pretty much this whole thread has been dedicated to the vehicles, while that's only 50% of the final score. Teams can dedicate 100% of their resources to that section and still perform extremely poorly in the event as a whole. Does anyone have any opinion about the test component?

The test portion is not exactly 50%. Since the sled score is percentage of the score based on performance in comparison to competitors. However, i do like the way it is set up since a team that knows the information can overcome a strong sled to win.

The way it is set up now, they have to engineer a competitive sled and learn the material to earn medals. I like that more than just building, since a lot of building can be done without having to learn about the principles behind it.

I think the academic test should stay in the formula format like it is now, next year.

[mrsteven]

The test is difficult to study for, the writers are so different and cover completely different things, more so than other events.

Example, invites most of those tests were a good mix of E&M Physics, real maglev trivia and magnetism stuff, but my regional test was entirely random trivia from maglev trains and the state test was entirely a AP Physics E&M Magnetism test. I think next year if the test stays, the topics should be limited. With so many topics on it, few supervisors actually know or are willing to research to write a good, well rounded test.
I think that it should be limited to direct calculation magnetism questions (like AP Physics) and maglev trivia and write out all those other random things that few supervisors even use but are in the rules as something that should be covered.


Perhaps add in some additional scoreable points (like extra credit or something) for a multi-part calculus driven derivation from Gausses Law of Magnetism or other other things of the like. Most people doing the event in my experience are in AP Physics C ( or at least 1 of the duo to deal with the physics question). Something genuinely difficult instead of the usual F=ilbsin(o) and radii of electron in a uniform field.
I know calculus is usually taboo in SO but I think it would be a good challenge and allow people more ability to LEARN to complete it by learning calc (or in most cases they already know).

[twototwenty]

One final interesting point. Pretty much this whole thread has been dedicated to the vehicles, while that's only 50% of the final score. Teams can dedicate 100% of their resources to that section and still perform extremely poorly in the event as a whole. Does anyone have any opinion about the test component?

I have to say, I do like the testing component quite a bit; I think it makes MagLev a more comprehensive event in regards to the material (magnetism) that it is supposed to cover. However, the only problem I have with it is that the tests I've seen can be somewhat...all over the place, for the lack of a better term, especially when compared to the highly organized and regulated tests that we see in "testing-only" events. If future rules could be more exact in describing test structure and content, it would be much appreciated.

So your arguments boil down to: we have already spent the money, so make everyone else spend as much to compete.

This was not the argument I was trying to make, I apologize.

What my argument above for the need for a change in the building part of the event "boils down to" is really something more like this: The building part of this event has already become very "even", to the point of making that part of the competition very dull and pointless. I'm guessing that I feel this more than you might, as New York has already had this event for several years and, unfortunately, many of the designs I saw at states this year were very similar. When competition reaches that point, in my opinion the best thing to do is to toss in a twist to the rules, as discussed above.
In summation, cars are very similar, which means event winners can come down to pointless things such as money or luck instead of legitimate ingenuity on the part of the competitors. To remedy this, simply alter the rules such as to encourage more ingenuity.

[erikb]

What my argument above for the need for a change in the building part of the event "boils down to" is really something more like this: The building part of this event has already become very "even", to the point of making that part of the competition very dull and pointless. I'm guessing that I feel this more than you might, as New York has already had this event for several years and, unfortunately, many of the designs I saw at states this year were very similar. When competition reaches that point, in my opinion the best thing to do is to toss in a twist to the rules, as discussed above.
In summation, cars are very similar, which means event winners can come down to pointless things such as money or luck instead of legitimate ingenuity on the part of the competitors. To remedy this, simply alter the rules such as to encourage more ingenuity.

With the success of one, many will follow. It is the way of all competition.

I agree with you. If they keep it the same then next year, more vehicles will be identical.

However, In New york next year, things will be different. Ward Melville 1022g @ .808. The top run scores were clustered around 1200-1500. (i did see one team in the 2300 range but they must not have made it to state) In colorado they would not have been in the top 5, where the top run scores clustered around 2200-2500. @ over 5200 feet.

What it looks like happened in New York is someone built a sled for speed (from scores at other states, i think the same thing happened in other places also) It was successful and everyone else copied it. Thus, all the scores bunched up around that design.

Mag lev is like gliders. If you read a book on aerodynamics and never talk to an AMA guy your glider will fall like a brick because no one deals with the low reynolds number designs but the duration folk at AMA and the people making solar planes. The vast majority of information is on high reynolds numbered flight design.

If you build a mag lev like it is a racing plane. The advice you would get from a hobby store attendant or a plane builder. Your mag lev will be built for a duration race not a tractor pull. Mag levs built for speed will be hundreds of feet short of reaching their potential by the time they hit the end of the mag track. In addition in mag lev issues that effect planes, like turning are not an issue. You don't care if your propeller causes the sled to move only in a straight line because the track does not curve. The agility of a mag lev is not an issue. It will never do a spectacular bunt to a roll out.

Next year, all the teams that want to compete nationally, will look at their mag levs and those that built for speed will realize it will fail them and switch to pure thrust. In order to get to nationals they will have to compete at regionals and state. And other teams will have to switch to be competitive, soon everyone will have the same design. (I think that is why they change the rules every year and rotate the events.)

And there is my worry, all those high rpm motors will be thrown out for moderate rpm motors with more horsepower and at the end of those motors will be knife sharp propellers that can cut through leather gloves easily and don't slow down when they hit flesh.