Kinda stupid question...
 

A while back, someone suggested filling the inside of the robot with helium to save weight. Is this legal?

Re: Kinda stupid question...
 

This is one for the GDC. You should ask it in the Q&A.

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Tell my teammates that HELIUM IS NOT FLAMMABLE!!! (long story)

Even if it was legal, getting it inside might be tough...

Re: Kinda stupid question...
 

Michael,
I can't help but notice that you are the 'rules expert' - so ... well, you know...

Now I'm having visions of thousands of balloons and a grumpy old man. Oh, and a talking dog. No talking dogs on the field. Grumpy old men are ok - sometimes.

Re: Kinda stupid question...
 

Well, I think it would only be a last ditch move to get under 120 lbs, if necessary. I don't think it will actually happen.

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Maybe the first thing to do is to calculate how much weight you'll save per volume of He. If one cubic foot of air is displaced by one cubit foot of He, how much savings would you get?

Greg McKaskle

Re: Kinda stupid question...
 

Let's see here... density of air is 1.204 kg/m^3, which converts to 0.0789 lb/ft^3; and density of helium is 0.1786 kg/m^3, which converts to 0.0117 lb/ft^3. So we are saving 0.0672 lb/ft^3 by replacing air with helium. I.e., not a big difference.

Re: Kinda stupid question...
 

That is about 1/16th of a pound, or an ounce. Five US quarters weigh an ounce. Not much savings, especially once you factor in the weight of the balloon or whatever will hold in the He.

Greg McKaskle

Re: Kinda stupid question...
 

Participating on a robotics team provides amazing opportunities to think through problems and possible solutions. That is not a bad thing but a good thing.

One Saturday not long ago, I was watching a student use the whiteboard for working through some ideas that he had regarding the kicker. I don't know if he was in the problem part, the possible solution part, or the testing part. What mattered was that he was using trigonometry and calculus and that he "was very happy". He spent 45 minutes going between the kicking mechanism and the whiteboard.

To observe a student using all the tools available to him/her, including 'doing the math', can provide moments of deep inspiration to the mentors. That is no small thing.

Re: Kinda stupid question...
 

As long as the pressure stays with in recs (sorry if some one else poasted this i just skimmed it.

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If you need to lose weight, soak your robot in a solution of Slim-Fast. I've seen it said that if you follow their guidelines you can lose up to 2 pounds a week.

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When we are overweight, we take lines of code out to reduce the weight.

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I'm surprised nobody has brought up that Hydrogen is half the weight of Helium, and would be a much more efficient weight-loser.
I also noticed somebody brought up the weight of the balloons that would hold the He/H. If you cover them in tape first, they won't tear when you swiss-cheesify them.

Re: Kinda stupid question...
 

Might I suggest some intelligently placed 3/4" lightening holes? The best ways of losing weight involve removing matter from your robot, either via lightening or more efficient design.

Helium is not a very practical solution, hate to burst your bubble... or blimp.

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So I kinda heard about bloated code, but you mean I could save postage by mailing CDs with efficient code? That makes me a happy pup!

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Hydrogen is only half the weight of Helium, but since buoyancy is proportional to the difference in density, the gain in buoyancy is only ~9%. Not to mention if you plan on filling your robot with hydrogen, you better be darn sure your robot won't short anywhere -- that would be quite the show. :cool:

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we change all of our colons in our codes to semicolons and use size 8 font to conserve weight... we lost a good 20 lbs with the font change alone :D

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Well, that works when I use floppies!

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helium is inert, not only is it not flammable, it isn't at all reactive (with a few possible exceptions, of course). If its in the last row of the periodic table, it won't burn.

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das hindenberg!

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I keep telling our team to use 0 instead of 1 in the code for this very reason. :D Since a 0 in electronics terms is a hole. :D

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I really like how this thread, while "silly" / "not serious", involves students taking wild ideas and doing calculations to figure out how or why they're unfeasible. Applying what you've learned to challenge even the most sensible conventional wisdom is something great to get used to doing. I wish I did it more often.

You never know when you'll run the math for something you're convinced you'll never work. Just a few days ago, the team was convinced that the tension needed in a piece of string would not be generated by a window motor powered winch, since it was so hard for a human to do. If any of us ran the numbers to challenge rather obvious seeming conventional wisdom, we'd have known a week ago what we know now.

How much weight is needed to make a chassis airtight? Weatherproofing Lexan shields, and making a hinged weatherproof door should get you close enough, assuming the design was within the rules (it isn't).

Re: Kinda stupid question...
 

If you really want to use a fluid density change to make your robot lighter... just remove the fluid.

You need to pull a vacuum....

that would eliminate all of the air...
Unfortunately... do beef up your robot to do this would put it overweight ...
by a HUGE amount...

As an aside... I wonder if all of our equipment would work in a vacuum?

I know that some interesting things would happen to all of the pneumatics...

:yikes:

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doodling during the kickoff webcast back in January....Steve reminded me that I took a picture of this

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Popular myth about the famous accident associates hydrogen with the disaster. All that flame you see is from OTHER things burning. A spark inside a pure hydrogen vessel will not ignite anything. If the gas leaked out, it would escape the area by being pushed aside by in-rushing heavier gas (air) so the igniting spark would have to be very close to the leak to cause problems. Is there a Mythbusters episode about this?

BTW, German engineers knew full well of the flammability dangers of hydrogen but were prevented from using helium by a U.S. embargo that prevented selling the safer gas to Germany.

Re: Kinda stupid question...
 

As long as you keep the hydrogen concentrations above 95% or below 2% (IIRC) hydrogen won't ignite. It's used in electrical generators (think ConEd, city-sized generators) under positive pressure to dissipate heat from the internals because hydrogen is more thermally conductive than air. Crazy, right?

Using it to loose weight on a robot is just silly.

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Yep, there is. I've seen it. I just checked the schedule; should be on again on 3/6; time listed as 5 ET/PT.

What they figured out with several models was that neither the cover nor the hydrogen was fully responsible. Both of them were culprits. Hydrogen made the cover burn better; the cover makes the hydrogen burn better.

Re: Kinda stupid question...
 

not to mention, that when it burns, it creates water that'll short out your robot

Re: Kinda stupid question...
 

but won't the water put the fire out? :p

/sarcasm