Hovercraft B/C

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Hovercraft B/C

Post by bernard » June 16th, 2016, 10:00 pm

"One of the ways that I believe people express their appreciation to the rest of humanity is to make something wonderful and put it out there."

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Re: Hovercraft B/C

Post by rvonhof » September 12th, 2016, 11:20 am

Does anyone know of a good place to buy relatively cheap motors for an event like this, hopefully a place more concrete than ebay auctions?

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Re: Hovercraft B/C

Post by chalker » September 12th, 2016, 6:45 pm

rvonhof wrote:Does anyone know of a good place to buy relatively cheap motors for an event like this, hopefully a place more concrete than ebay auctions?
FYI, there is a different Hovercraft thread where we discussed this already. Here's my post, which should help:
http://scioly.org/phpBB3/viewtopic.php? ... 4&start=75#

Note: The linked thread discusses details from proposed rules. Always consult final rules when preparing for competitions.
Last edited by bernard on September 12th, 2016, 9:32 pm, edited 1 time in total.
Reason: See note.

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Re: Hovercraft B/C

Post by chalker » September 13th, 2016, 5:12 am

FYI, we just posted the Hovercraft clarification about brushless motors:

https://www.soinc.org/official_rules_clarif

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Re: Hovercraft B/C

Post by windu34 » September 13th, 2016, 5:10 pm

So I have managed to levitate a craft of the max weight with pretty low friction with the ground, but I cant seem to figure out the propulsion aspect. Of course propelling a craft with relatively low mass (and thus inertia) isn't all that complicated, can someone work out the CFM requirements and/or explain how to calculate the propulsion fan requirements for a 2kg mass?
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Re: Hovercraft B/C

Post by chalker » September 13th, 2016, 8:26 pm

windu34 wrote:So I have managed to levitate a craft of the max weight with pretty low friction with the ground, but I cant seem to figure out the propulsion aspect. Of course propelling a craft with relatively low mass (and thus inertia) isn't all that complicated, can someone work out the CFM requirements and/or explain how to calculate the propulsion fan requirements for a 2kg mass?
If you have very low friction, then the most fundamental of Physics equations applies: F=ma. Figure out the acceleration you want based upon the track length and target time, plug in 2kg for mass, and that tells you the force the fan needs to exert. To find out the thrust of a fan, you need to know the mass flow rate (CFM) through it and the velocity. Nasa has a good page explaining that here: http://wright.nasa.gov/airplane/propth.html

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Re: Hovercraft B/C

Post by PHXcoach » September 16th, 2016, 2:00 pm

I am not sure that I follow rule 6.e. where a penalty is applied to the timing score of any run that has a competition violation. All the competition violations that I see result in a failed run (i.e. TS = 0) so what are the competition violations that don't cause a failed run and would trigger this rule ?

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Re: Hovercraft B/C

Post by chalker » September 16th, 2016, 4:50 pm

PHXcoach wrote:I am not sure that I follow rule 6.e. where a penalty is applied to the timing score of any run that has a competition violation. All the competition violations that I see result in a failed run (i.e. TS = 0) so what are the competition violations that don't cause a failed run and would trigger this rule ?
That's kinda our catch all way of ensuring we didn't miss anything. One example might include touching the vehicle during a succesfull run (5.m.)

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Re: Hovercraft B/C

Post by PHXcoach » September 17th, 2016, 1:09 am

chalker wrote:
PHXcoach wrote:I am not sure that I follow rule 6.e. where a penalty is applied to the timing score of any run that has a competition violation. All the competition violations that I see result in a failed run (i.e. TS = 0) so what are the competition violations that don't cause a failed run and would trigger this rule ?
That's kinda our catch all way of ensuring we didn't miss anything. One example might include touching the vehicle during a succesfull run (5.m.)
Ok - catch all makes sense.

BTW I thought that touching the vehicle is an unsuccessful run according to 5.m. so does not hit this catch all.

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Re: Hovercraft B/C

Post by chalker » September 17th, 2016, 6:22 am

PHXcoach wrote: BTW I thought that touching the vehicle is an unsuccessful run according to 5.m. so does not hit this catch all.
No. You have to parse that sentence carefully. It's saying yo can't touch it until it passes the finish line or is declared a failed run. It's NOT saying that if you touch it the supervisor declares it a failed run.

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