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### Hovercraft B/C

Posted: June 16th, 2016, 10:00 pm

### Re: Hovercraft B/C

Posted: 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?

### Re: Hovercraft B/C

Posted: 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? ... &start=75#

Note: The linked thread discusses details from proposed rules. Always consult final rules when preparing for competitions.

### Re: Hovercraft B/C

Posted: September 13th, 2016, 5:12 am
FYI, we just posted the Hovercraft clarification about brushless motors:

https://www.soinc.org/official_rules_clarif

### Re: Hovercraft B/C

Posted: 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?

### Re: Hovercraft B/C

Posted: 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

### Re: Hovercraft B/C

Posted: 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 ?

### Re: Hovercraft B/C

Posted: 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.)

### Re: Hovercraft B/C

Posted: 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.

### Re: Hovercraft B/C

Posted: 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.

### Re: Hovercraft B/C

Posted: September 17th, 2016, 8:05 am
Is this event considered a trial event, and is subject to change at any time?
Simply said, this event can be removed and previous work done will constitute as useless.

### Re: Hovercraft B/C

Posted: September 17th, 2016, 11:00 am
PandaDevs wrote:Is this event considered a trial event, and is subject to change at any time?
Simply said, this event can be removed and previous work done will constitute as useless.

No, this is not a trial event. That being said, I believe every competition site has the right to remove any event.

### Re: Hovercraft B/C

Posted: September 17th, 2016, 3:12 pm
While not common at the state level, they may drop an event and substitute another. For some poorly explained reason, Florida is doing it this year.
I do not like it as it puts FL teams behind other states in experience for this event at Nationals.
It is somewhat common for regionals to substitute as they may not be able to support a given event.

### Re: Hovercraft B/C

Posted: September 17th, 2016, 4:23 pm
So as far as the definition of levitation goes, I feel I may be given a construction violation for what I have. I'm levitating barely .5mm off the ground, but as far as performance goes, its pretty good and very frictionless. Do I need to build a skirt system so that I levitate higher or do you think ES will be okay with it? (I know all competitions are different, etc)

### Re: Hovercraft B/C

Posted: September 17th, 2016, 4:55 pm
windu34 wrote:So as far as the definition of levitation goes, I feel I may be given a construction violation for what I have. I'm levitating barely .5mm off the ground, but as far as performance goes, its pretty good and very frictionless. Do I need to build a skirt system so that I levitate higher or do you think ES will be okay with it? (I know all competitions are different, etc)

The rules clearly define how to demonstrate levitation. Does your device rise when pushed down? Is the rise readily apparent to an objective observer? If so, it meets the criteria.