Hovercraft B/C

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Re: Hovercraft B/C

Post by antoine_ego »

Considering that no one has asked this yet, what scores have y'all gotten when testing your hovercrafts?
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Re: Hovercraft B/C

Post by Adi1008 »

antoine_ego wrote:Considering that no one has asked this yet, what scores have y'all gotten when testing your hovercrafts?
I think it's hard to tell because of the mass score. It depends on the heaviest device at the competition, so people's scores will vary. At a very competitive competition, someone might have a low mass score, while at an uncompetitive tournament they might have a very high mass score
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Re: Hovercraft B/C

Post by HandsFreeCookieDunk »

Adi1008 wrote:
antoine_ego wrote:Considering that no one has asked this yet, what scores have y'all gotten when testing your hovercrafts?
I think it's hard to tell because of the mass score. It depends on the heaviest device at the competition, so people's scores will vary. At a very competitive competition, someone might have a low mass score, while at an uncompetitive tournament they might have a very high mass score
I think it's pretty safe to assume that most competitions will have at least one 2kg device.
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Re: Hovercraft B/C

Post by JonB »

Patrick Yepes wrote:
windu34 wrote:
HandsFreeCookieDunk wrote:I did an estimate by scaling down larger hovercraft propellers and found that you'll need about 50 CFM to go full speed with a 2kg craft. Does this sound reasonable?
Very reasonable, but keep in mind our hovercrafts will not be very comparable and youll likely need much more CFM. There is a fan on amazon with 200 CFM for a reasonable price.
I attached a grate/mesh over the propulsion fan that I laser-cut out of acrylic. Reduces thrust by ALOT. Might have to look for a different solution.
What have you guys tried as far as materials for the grate?

Isn't it against the 'rules' to laser cut something for the hovercraft since the students don't have a hand in the design, programming, or using the machine to cut said part?

Asking for a friend... ;)

As the coach, I can confirm that he does all of his own work, from start to finish. The laser cutter is available for student use in my classroom. I am here to make sure we don't all catch on fire and to fix it when it breaks.
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Re: Hovercraft B/C

Post by HCCoach »

windu34 wrote:
RJohnson wrote:
sciolyqa wrote: What is the part number of the motor from digi-key that suffice? We have been there and must have missed that.
Here is the link: http://www.digikey.com/product-detail/e ... ND/2560506
That is a really good looking blower! Specs are definitely above the requirement

Hello, Has anyone used this fan for lift?
Isn't this a bit too big?
Thanks!
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Re: Hovercraft B/C

Post by keslerscience »

I ran my first hovercraft event at an invitational recently and a few questions came up.

1. There was one hovercraft that had about 16 9.0v batteries in a parallel circuits. The voltage never exceeded 9.0 across either of the circuits so it appeared to be in line with rule 4H. Is that right?

2. Some teams completed 1 successful run and on their second run wanted to stop their craft before the finish if they didn't think it was going to beat their first run causing a failed attempt. This doesn't seem allowed per Part 5 m. Correct?

3. Can the competitors run their device on the floor or behind the starting gate to test it during their 8 mins?

4. Per part 5 q it states that a failed attempt is triple the target time. Even if we saw that the device was crawling along the track and wouldn't make it in 51 seconds (target time 17) we were making them wait until 51 to turn it off. Any proctor discretion here? I didn't want it all of a sudden to pick up steam and cross the line before 51 seconds. The problem is that the juice on their batteries really get eaten up during this time.

5. The last, and maybe most important one, has to do with scoring. I used the spreadsheet on scioly (thanks by the way). I do see a problem with TS (time score) is calculated though. A run of 5.0 would score no time at all if the target time was 17. However, I run of 39 seconds would actually get a decent amount of points. I think it was nearly 13 points which is huge in a close competition. Clearly 5.0 is closer to the target time than 39. Is this by design?


thanks
Chris
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Re: Hovercraft B/C

Post by RJohnson »

HCCoach wrote:
windu34 wrote:
That is a really good looking blower! Specs are definitely above the requirement

Hello, Has anyone used this fan for lift?
Isn't this a bit too big?
Thanks!
That is the fan I use. It fits well within the physical bounds set by the rules. Hope that helps!
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Re: Hovercraft B/C

Post by MrGood »

What would be the CFM needed to create enough propulsion to levitate a 2kg(the max weight) hovercraft.
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Re: Hovercraft B/C

Post by windu34 »

MrGood wrote:What would be the CFM needed to create enough propulsion to levitate a 2kg(the max weight) hovercraft.
You are not looking for CFM in a levitation fan, you are looking for static pressure. At least 20 CFM to be safe though (that isn't much at all)
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Re: Hovercraft B/C

Post by windu34 »

keslerscience wrote:I ran my first hovercraft event at an invitational recently and a few questions came up.

1. There was one hovercraft that had about 16 9.0v batteries in a parallel circuits. The voltage never exceeded 9.0 across either of the circuits so it appeared to be in line with rule 4H. Is that right?

2. Some teams completed 1 successful run and on their second run wanted to stop their craft before the finish if they didn't think it was going to beat their first run causing a failed attempt. This doesn't seem allowed per Part 5 m. Correct?

3. Can the competitors run their device on the floor or behind the starting gate to test it during their 8 mins?

4. Per part 5 q it states that a failed attempt is triple the target time. Even if we saw that the device was crawling along the track and wouldn't make it in 51 seconds (target time 17) we were making them wait until 51 to turn it off. Any proctor discretion here? I didn't want it all of a sudden to pick up steam and cross the line before 51 seconds. The problem is that the juice on their batteries really get eaten up during this time.

5. The last, and maybe most important one, has to do with scoring. I used the spreadsheet on scioly (thanks by the way). I do see a problem with TS (time score) is calculated though. A run of 5.0 would score no time at all if the target time was 17. However, I run of 39 seconds would actually get a decent amount of points. I think it was nearly 13 points which is huge in a close competition. Clearly 5.0 is closer to the target time than 39. Is this by design?


thanks
Chris
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1.) That is legal - kinda a waste of money
2.) Correct
3.) I don't see why not if the supervisor permits it
4.) What you did was correct. Teams may bring spare batteries (I think don't quote me on this) if needed
5.) I'm not fit to answer this
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