Hovercraft B/C

[chalker]

New user to this forum. Working to get ready to run this event at an invitational.

Can anyone provide info on how to economically buy or construct a photo-gate system (including related software that would work with a laptop or tablet) suitable for use with this event? The ones I see online are close to $200 with tax and shipping and that's not in the budget especially since I'll need 2 of them in order to run 2 simultaneous tracks.

Thanks for any help.

They are expensive! I'm sure someone can post a DIY guide on making your own with some inexpensive laser pointers and photoelectric components and programming skills, but, there's a good chance you're as short on time as money ... Suggestion: ask any physics teachers you can find if they know where you can borrow some. If you email the host school or coaches from participating schools, chances are high someone has a set sitting in a closet somewhere.

This. Push come to shove, you can always utilize manual timers. If you setup a laser pointer for the dowel rods to 'break the beam', manual timers can be relatively accurate.

[TheDabbingMC]

I have a question regarding the 9/12/2016 Rules Clarification. It states "Brushless motors and integrated circuits are not permitted, unless they are an integral part of and are imbedded into a commercially available electronic or computer cooling fan". Is it meant to be read as commercially available electronic fan, or as electronic cooling fan?

Thank you!

[windu34]

I have a question regarding the 9/12/2016 Rules Clarification. It states "Brushless motors and integrated circuits are not permitted, unless they are an integral part of and are imbedded into a commercially available electronic or computer cooling fan". Is it meant to be read as commercially available electronic fan, or as electronic cooling fan?

Thank you!

Can you clarify?
As per my knowledge, it is meant to legalize computer cooling fans that utilize brushless motors and integrated circuits inside, but only require a power supply (input to fan is only Voltage and Ground)

[sciolysaurus]

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?

radio shack has cheap motors

[sciolysaurus]

Can someone help me understand what they mean by "it is recommended that the vehicle be adjustable to accommodate variations in track rail width and height" ?
Are they saying the dimensions of the hovercraft should be adjustable when the proctor gives us a new track rail or the skirt should be adjustable or something?

[windu34]

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?

radio shack has cheap motors

The motors at radioshack have proven to have too low of an rpm for my liking. Try amazon or your local r/c shop (they usually carry a few brushed motors)

[Unome]

Can someone help me understand what they mean by "it is recommended that the vehicle be adjustable to accommodate variations in track rail width and height" ?
Are they saying the dimensions of the hovercraft should be adjustable when the proctor gives us a new track rail or the skirt should be adjustable or something?

They're basically just saying to account for variations, i.e. if the track width is 20 cm, build a device at ~19.5 cm in case the event supervisor didn't make the track perfectly (which is a bit unusual, the rules generally don't say stuff like this; probably something happened when they were trialing at nationals last year that they felt they needed to include this). As far as I know, the Hovercraft dimensions don't need to be adjustable.

[windu34]

I have been considering adding wheels horizontally to the device to roll along the sides of the track to improve consistency and smoothness, but I am unsure whether it will be a problem as at as size measurements because they would be spring-loaded and push outside the 19.5 cm unless I implemented a stopper

[keslerscience]

I've got a few questions. I'm running Hovercraft at an invitational in a few weeks and am also the judge at our state competition.

1. I realize that photogates are more accurate for data collection, but it seems like there is a lot of room for error with getting the dowel to pass through the gates.
a. I can see the craft going left or right and the dowel missing the gate. What happens in this case? Rely on stopwatch data?
b. What happens if the dowel hits the gate and stops or slows down the craft?
c. I'm assuming the gates need to be moved for each particular craft to the correct height?
d. They are terribly expensive to get all setup. The gates themselves aren't that pricey, but you start adding in adapters and software this becomes quite expensive.

2. I can't seem to find any shared tests for the exam portion. Would you suggest I maybe purchase or a AP Physics study guide and use those questions as "inspiration" for my own? What about Division B?

I've read through this thread and feel pretty confident with all the other parts of the competition. It should be a fun one.

Chris

[windu34]

I've got a few questions. I'm running Hovercraft at an invitational in a few weeks and am also the judge at our state competition.

1. I realize that photogates are more accurate for data collection, but it seems like there is a lot of room for error with getting the dowel to pass through the gates.
a. I can see the craft going left or right and the dowel missing the gate. What happens in this case? Rely on stopwatch data?
b. What happens if the dowel hits the gate and stops or slows down the craft?
c. I'm assuming the gates need to be moved for each particular craft to the correct height?
d. They are terribly expensive to get all setup. The gates themselves aren't that pricey, but you start adding in adapters and software this becomes quite expensive.

2. I can't seem to find any shared tests for the exam portion. Would you suggest I maybe purchase or a AP Physics study guide and use those questions as "inspiration" for my own? What about Division B?

I've read through this thread and feel pretty confident with all the other parts of the competition. It should be a fun one.

Chris

Not official, just my opinion. Hope this helps
1a.) Yes rely on stopwatches in this scenario
1b.) Count it as a failed run? (Not really sure - maybe chalker can weigh in here)
1c.) Check the dowel height requirement in the rules - dowel height will be at least 30cm for all teams
1d.) Try asking around - other tournament directors may know where you can borrow a setup
2.) AP Physics is certainly a good starting point for basing questions off of - just make sure you get a good range in difficulty of the questions. For div B, pick easier questions and maybe throw in some multiple choice