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-   -   Kinda stupid question... (http://www.chiefdelphi.com/forums/showthread.php?t=83163)

Ian Curtis 20-02-2010 20:59
Re: Kinda stupid question...
 
Quote:
Originally Posted by Taylor (Post 924765)
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.
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:

Nigel 20-02-2010 22:10
Re: Kinda stupid question...
 
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

pSYeNCe 20-02-2010 22:24
Re: Kinda stupid question...
 
Quote:
Originally Posted by Dick Linn (Post 924840)
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!
Well, that works when I use floppies!

PAR_WIG1350 20-02-2010 23:00
Re: Kinda stupid question...
 
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.

jmanela 20-02-2010 23:39
Re: Kinda stupid question...
 
Quote:
Originally Posted by iCurtis (Post 924869)
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 you're robot won't short anywhere -- that would be quite the show. :cool:
das hindenberg!

fsgond 21-02-2010 09:03
Re: Kinda stupid question...
 
Quote:
Originally Posted by Nigel (Post 924947)
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
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

Chris is me 21-02-2010 09:15
Re: Kinda stupid question...
 
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).

Bob Steele 21-02-2010 18:27
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:

MrForbes 21-02-2010 19:07
Re: Kinda stupid question...
 
1 Attachment(s)
Quote:
Originally Posted by JaneYoung (Post 924528)
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.
doodling during the kickoff webcast back in January....Steve reminded me that I took a picture of this

Bill_B 25-02-2010 11:39
Re: Kinda stupid question...
 
Quote:
Originally Posted by jmanela (Post 925032)
das hindenberg!
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.

JamesCH95 25-02-2010 11:55
Re: Kinda stupid question...
 
Quote:
Originally Posted by iCurtis (Post 924869)
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:
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.

EricH 25-02-2010 12:06
Re: Kinda stupid question...
 
Quote:
Originally Posted by Bill_B (Post 928481)
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?
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.

joek 27-02-2010 21:04
Re: Kinda stupid question...
 
not to mention, that when it burns, it creates water that'll short out your robot

JamesCH95 27-02-2010 21:29
Re: Kinda stupid question...
 
but won't the water put the fire out? :p

/sarcasm


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