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by fxsandiego
December 15th, 2018, 2:05 pm
Forum: Roller Coaster B
Topic: Roller Coaster B
Replies: 76
Views: 16344

Re: Roller Coaster B

My students are just back from a invitationals. They are demoted to Tier 3 because of "non-impound device." They did impound their devices. However they are told "1) they didn't have and data/notes to impound; 2) they didn't fill out some paperwork." From what I read in the rule, data/note are not r...
by fxsandiego
October 30th, 2018, 2:15 pm
Forum: Roller Coaster B
Topic: Roller Coaster B
Replies: 76
Views: 16344

Re: Roller Coaster B

One way would be to use a sweep. for 1/2" PVC it would have about a 4 " radius.
Thanks!
by fxsandiego
October 29th, 2018, 10:41 am
Forum: Roller Coaster B
Topic: Roller Coaster B
Replies: 76
Views: 16344

Re: Roller Coaster B

Hello, New coach of this event this year. I have a very basic technical question. I am planning to let my students build their tracks using PVC pipes (split half). What would be a good way to make a smooth 90 degree turn? Thanks.
by fxsandiego
November 17th, 2017, 10:19 am
Forum: 2018 Lab Events
Topic: Hovercraft B/C
Replies: 627
Views: 70480

Re: Hovercraft B/C

I am guessing the logic is capacitors provide larger instantaneous current than batteries hence your craft accelerates faster. However, to make it work, you would need a very very large capacitor. Large capacitors are heavy and dangerous to play with.
by fxsandiego
November 16th, 2017, 11:14 am
Forum: 2018 Lab Events
Topic: Hovercraft B/C
Replies: 627
Views: 70480

Re: Hovercraft B/C

Our crafts seem very sensitive to the penny roll placement. The difference is working vs failing. Wondering what kind of design flaw this indicates?
by fxsandiego
October 16th, 2017, 11:06 am
Forum: 2018 Lab Events
Topic: Hovercraft B/C
Replies: 627
Views: 70480

Re: Hovercraft B/C

Like this, https://www.digikey.com/product-detail/ ... ND/3283580?

Current rating is 3.2A. Need a really big battery to run it. The self weight of the craft is going up.
by fxsandiego
October 15th, 2017, 9:03 pm
Forum: 2018 Lab Events
Topic: Hovercraft B/C
Replies: 627
Views: 70480

Re: Hovercraft B/C

I think that is allowed. only stand-alone brushless motors (the ones that have three leads) are banned. BTW, the fan in your link has a static pressure rating at 625 Pa. Do we need such powerful fans? Let's say, the whole craft, including 16 penny rolls weighs 2.5kg ( 2kg of penny rolls + 0.5 kg of ...
by fxsandiego
October 13th, 2017, 5:07 pm
Forum: 2018 Lab Events
Topic: Hovercraft B/C
Replies: 627
Views: 70480

Re: Hovercraft B/C

Another new coach here. I am wondering, if two fans have the same static pressure spec but different diameters. Would the diameter make a difference, ie, the one with bigger diameter performs better or vise versa? I saw in last year's posts some people were using fans rated at 900Pa+. Does the fan n...

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