MagLev C

erikb
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Re: MagLev C

Postby erikb » April 25th, 2013, 6:31 am

I disagree with limiting batteries at this point. Those of us who have already spent considerable resources should not be required to buy new batteries, motors, or switches because a few people haven't figured out how to make thier device safe. I really doubt simply changing the battery type will prevent someone from designing a dangerous device.
You have proven my point.

Given the students an option to just purchase the most power available it is creating a dangerous situation and blocking other teams from competing because of money.

Here is calculator so you can play with volts and amps to see that if you limit the number of amps the amount of work that can be done is a fraction of what is possible:

http://www.calcunation.com/calculators/ ... Horsepower

As an example i will use one of our sleds.
7.4 volts and 30 amps gives over .3 a horsepower.
9 volts and 2 amps less than .02 horsepower

That is a magnitude of over 10. Physics limits the possible work, thus safer propeller speeds.

In addition, your school has the money to purchase lipos. lipo chargers and everything else but they can't spring for $20 for rechargeable batteries a battery case and a connector. I would have a talk with the budget people.

Or is your point, since you have already purchased the items the event can't be changed because it would inconvenience you next year?
The rules already prohibit unsafe devices. Now we just need to consistantly enforce them.
I really don't think you understand this event. The goal is to make an unsafe device. Remember, the fastest most powerful device wins.
Unless the kids have figured out a way to insure they will not contact the blades, don't let them run.
By your logic no one can do this event. There is no way to guarantee that an accident does not happen. By design the students have to put something in front of an object that can generate more than 2 times the force needed for low earth orbit. That same object has rotating blades that can shred clothes and cut deep into the tissue. There is no way to make the event safe. This year by design, it is unsafe.

However, i do like your idea of making it a time to distance event.
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Stingray355
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Re: MagLev C

Postby Stingray355 » April 25th, 2013, 6:43 am

While I definately support changes to make MagLev safer I hope the changes don't force teams to discard much of the hardware they have purchased for this season. This years rules favor performance and we spec'd the motor(s), batteries , magnets and props accordingly. Changing battery requirements will also impact motor and prop selection and at some point you are building from the ground up again.

I would prefer changes to address the safety issues, there are a number of simple and effective ways to cover this. The other changes , to mix up the scoring parameters, I would hope will be consistent with the hardware teams have already purchased.
As I have commented before in our Region we have lost some great competitors to lack of funding. We also have schools fielding partial teams in part because of a lack of funding for all events. Often times the build events consume much of the available funds so they can be the first ones impacted. We also compete against schools that field multiple teams at invitationals so this is not universal. Our school district is one that provides minimal support for academic endeavors like Science Olympiad, robotics and others. From my conversations with coaches and parents from other districts this is not uncommon. I am not in favor of handicapping the schools with better resources and support, good for them and they are able to expose more kids to SO. I would like to see the cost burden discussed as part of any considerations for changes to existing events or new events. I think we can all agree that anything we can do to get more schools/kids involved in Science Olympaid is a good thing.

I think there are plenty of ideas on how to change MagLev for next year that will allow teams to keep most or all of their current hardware but still have to reevaluate/redesign their device to be competitive next season.

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Re: MagLev C

Postby wlsguy » April 25th, 2013, 7:26 am

I agree, the current rules are written where the goal is to make an "unsafe" device.

Anytime you have a 1.5kg device moving at 1m/sec it has enough energy to smash fingers, etc.
Add in the fact it is propeller driven and the potential exists for injury.

This event, however, is no more risky than others if proper safety precautions are taken. (we use saw, drills, and power tools to build everything)
Making a device you can turn on and off safely is one of the engineering challenges of the event and something faced in the real world every day.

My original opinion is unchanged. Make kids create a safe device first and enforce the safety rules already in place.
If the kids cannot show how they can operate their device without cutting their fingers, don't let them run.

No one can predict every possible dangerous situation so accidents can still happen.
The rules writers need to put enough limits in place to prevent as many injuries as possible.

Now, with respect to changing rules;
Unless the vehicles are lightened and slowed, they will still be somewhat dangerous.
The easiest option is to only allow 1 propeller. This prevents kids from reaching between 2 operating props to turn the device on / off.
The more involved measure would be to change the focus of the event from speed / weight based to speed / time based (and give an ideal time).

Our team has the money to spend regardless but I think other schools may not. These are the schools I worry about.

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Re: MagLev C

Postby iwonder » April 25th, 2013, 7:28 am

I don't understand the idea of limiting the types of batteries people can purchase. It doesn't necessarily make the event much safer, as I have an 8.4v rechargeable NiMH pack right now and it can still seriously injure someone's finger(or take a large chunk of wood out a pine dowel), LiPo's may be more dangerous, but anything is dangerous, so it doesn't really get you very far. Sure, I may only slice two or three mm into my finger instead of five or six, but it doesn't stop someone from hurting themselves. Furthermore, my understanding is that people like chalker try in every event to make sure it doesn't become a contest of who has the most money(which is why there's a time prediction component), but limiting the materials that students can buy and use to try and level the playing field is not the appropriate solution. If you limit everything down so that now one can get away with spending more money, we'd all walk into the competition with basically the same device, everyone would use the same batteries, same cheap motor, same cheap propeller, etc. as a competitor I can tell you there's no fun in that. I want to go to competition and see what the teams with tons of money have come up with, and see what other teams have designed as well. Walking into a room full of cheap highly similar maglev vehicles just isn't the same. A better solution is to change the event rules so that it doesn't matter how much money is spent, and scores are improved by spending more time in the event. Things that do this have been discussed. How about one of these instead of battery and money limits.

-Pulling a weight behind the sled with a heavy time prediction
-Being given a target time to hit
-Traveling a specified distance(sort of like the old electric vehicle)

Admittedly that last one would be difficult, but personally I think it'd be a lot of fun to try. You'd probably have to remove the integrated circuit restriction to deal with it.

Basically, I don't see how limiting the type of battery makes it safe, it'd be safer, but it's still dangerous, it's the teams responsibility to make sure no one gets hurt, it's not NSO's job to constrict the rules and limit us so we can't hurt anyone. No one complains about 2M HCl in events like forensics, but that's just as dangerous. And the solution to the money problem isn't limit what we can use, it's making sure that money spent isn't so directly related to score.
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Re: MagLev C

Postby joeyjoejoe » April 25th, 2013, 7:52 am

While I understand the need for safety, I disagree that sweeping changes need to be made to secure it. Our students had to use several tools during the construction of their devices that were immensely more dangerous than any spinning prop. A radial arm saw was used to cut the wood for the track base. A table saw was used to cut plywood for the car base not to mention they drive 2000 lb vehicles to and from school each day. It should be up to the coach to insure that a sufficient safety briefing is performed for the students tailored to their event. I agree that it is hard to convince them to ignore the desire to reach for the car that they've put their heart and soul into before it crashes to the ground after bypassing the stop position for some reason but that's why I have them say over and over: "don't worry, we can always make a new one".


Edit: And yes, I realize the irony that this is coming from a coach who has already admitted (on this very thread!) to cutting himself with the prop. Once we realized the power of the vehicle, we treated it with the respect it deserved.

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Re: MagLev C

Postby twototwenty » April 29th, 2013, 9:32 am

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.

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Re: MagLev C

Postby Schrodingerscat » April 29th, 2013, 11:51 am

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.

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Re: MagLev C

Postby twototwenty » April 29th, 2013, 12:26 pm

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.

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Re: MagLev C

Postby mrsteven » April 29th, 2013, 3:01 pm

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
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Re: MagLev C

Postby chalker7 » April 30th, 2013, 7:01 am

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?
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