Hovercraft B/C

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Re: Hovercraft B/C

Postby SPP SciO » December 10th, 2017, 8:00 am

geniusjohn5 wrote:This may sound like a really dumb question but I'm an extreme newbie to this event. Does the hovercraft float on the air-contained skirt or is there a little bit of plain open air beneath the skirt?


The skirt inflates with air, levitating the craft, but the skirt will stay in contact with the surface. That effectively reduces (but does not eliminate) the weight of the craft. And the air escaping through holes in the skirt reduces friction enough to where the propulsion fan can accelerate the vehicle horizontally.

Think of air hockey table - the puck stays on the table, but can slide along with minimal effort because of the little jets of air coming through the table holes. The hovercraft is sort of like an upside down version of that set up.

I hope that analogy is helpful but definitely do a little research - Wikipedia always a great place to start!
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Re: Hovercraft B/C

Postby reed303 » December 10th, 2017, 9:20 am

geniusjohn5 wrote:This may sound like a really dumb question but I'm an extreme newbie to this event. Does the hovercraft float on the air-contained skirt or is there a little bit of plain open air beneath the skirt?


Some reading here may help.

https://scioly.org/wiki/index.php/Hovercraft#Skirt

We are having good results with a "wall" skirt. Which is basically a bag skirt with one largish square hole in bottom of bag. You want some air escaping out from under the craft.
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Re: Hovercraft B/C

Postby NilaiVemula » December 10th, 2017, 6:46 pm

What is a good cfm for a blower fan?
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Re: Hovercraft B/C

Postby dmis » December 12th, 2017, 6:48 pm

NilaiVemula wrote:What is a good cfm for a blower fan?

It depends on your design. Some designs are better with a fan optimized for static pressure, others for one with a high cfm.

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Re: Hovercraft B/C

Postby Zioly » December 12th, 2017, 7:11 pm

reed303 wrote:
geniusjohn5 wrote:This may sound like a really dumb question but I'm an extreme newbie to this event. Does the hovercraft float on the air-contained skirt or is there a little bit of plain open air beneath the skirt?


Some reading here may help.

https://scioly.org/wiki/index.php/Hovercraft#Skirt

We are having good results with a "wall" skirt. Which is basically a bag skirt with one largish square hole in bottom of bag. You want some air escaping out from under the craft.


I second the wall skirt... they effectively minimize friction consistently and are easy to build and get working with a bit of creative tinkering. A lot of it just takes messing with the balance of the craft and where to cut larger openings, etc.
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Re: Hovercraft B/C

Postby shrewdPanther46 » December 12th, 2017, 7:31 pm

Zioly wrote:
reed303 wrote:
geniusjohn5 wrote:This may sound like a really dumb question but I'm an extreme newbie to this event. Does the hovercraft float on the air-contained skirt or is there a little bit of plain open air beneath the skirt?


Some reading here may help.

https://scioly.org/wiki/index.php/Hovercraft#Skirt

We are having good results with a "wall" skirt. Which is basically a bag skirt with one largish square hole in bottom of bag. You want some air escaping out from under the craft.


I second the wall skirt... they effectively minimize friction consistently and are easy to build and get working with a bit of creative tinkering. A lot of it just takes messing with the balance of the craft and where to cut larger openings, etc.


I'm curious as to what you mean when you say "where to cut larger openings." From my limited experience last year, all we did was create a large rectangle centered on the bottom of the skirt so the air escapes evenly from underneath, and that seemed to work fine for us atleast.
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Times/weights?

Postby Randomperson11 » December 16th, 2017, 1:45 pm

Hello! I'm new to this forum, and even scioly itself.

What times and weights have you been getting with yours? I'm having trouble getting mine to lift. I'm using a small axial fan for lifting and blowing. it's about 30cmx20cm.

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Re: Times/weights?

Postby Random Human » December 16th, 2017, 4:56 pm

Randomperson11 wrote:Hello! I'm new to this forum, and even scioly itself.

What times and weights have you been getting with yours? I'm having trouble getting mine to lift. I'm using a small axial fan for lifting and blowing. it's about 30cmx20cm.

-randomperson11

Hi Random Person

First off...welcome to the forums. And... thanks for practically copying my username. ;)

We are holding all they weight, but are getting overloaded on thrust. Mainly, a good experimentation for fans and motors is the most important. And make sure that your design is efficient as possible. We've built 3 prototypes already.
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Re: Hovercraft B/C

Postby geniusjohn5 » December 16th, 2017, 7:55 pm

Even though the width of the track is much wider, which means the Hovercraft is expected to be much wider, would a significantly smaller Hovercraft, such as something from last year's Hovercraft event, be effective this year? And would "hugging" the sides of the track work effectively?
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Re: Hovercraft B/C

Postby Randomperson11 » December 16th, 2017, 7:58 pm

random HUMAN, if you're comfortable sharing with me, what fans are you using to blow? also what base design?

I'm just using a bag under it that covers everything up. we have problems not getting air to leak :\
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Re: Hovercraft B/C

Postby antoine_ego » December 17th, 2017, 6:23 am

geniusjohn5 wrote:Even though the width of the track is much wider, which means the Hovercraft is expected to be much wider, would a significantly smaller Hovercraft, such as something from last year's Hovercraft event, be effective this year? And would "hugging" the sides of the track work effectively?


Since the size of the hovercraft is always less than the width of the track, a hovercraft from last year could be effective assuming that you can hold full weight. Hugging the tracks is probably the way to go because any rotation of the craft will screw up consistent timing.
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Re: Hovercraft B/C

Postby geniusjohn5 » December 17th, 2017, 8:30 am

Can someone explain what "hugging" the track means? I know this is a stupid question, but I really need a clarification.
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Re: Hovercraft B/C

Postby arv101 » December 17th, 2017, 8:31 am

shrewdPanther46 wrote:
Zioly wrote:
reed303 wrote:
Some reading here may help.

https://scioly.org/wiki/index.php/Hovercraft#Skirt

We are having good results with a "wall" skirt. Which is basically a bag skirt with one largish square hole in bottom of bag. You want some air escaping out from under the craft.


I second the wall skirt... they effectively minimize friction consistently and are easy to build and get working with a bit of creative tinkering. A lot of it just takes messing with the balance of the craft and where to cut larger openings, etc.


I'm curious as to what you mean when you say "where to cut larger openings." From my limited experience last year, all we did was create a large rectangle centered on the bottom of the skirt so the air escapes evenly from underneath, and that seemed to work fine for us atleast.


I think we are doing the same thing but can you explain what "wall" skirt means?
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Re: Hovercraft B/C

Postby SciolyMaster » December 17th, 2017, 12:23 pm

Does anyone know where to find a potentiometer that's lightweight yet can bear a strong current?

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Re: Times/weights?

Postby ftf841 » December 18th, 2017, 5:11 pm

Randomperson11 wrote:Hello! I'm new to this forum, and even scioly itself.

What times and weights have you been getting with yours? I'm having trouble getting mine to lift. I'm using a small axial fan for lifting and blowing. it's about 30cmx20cm.

-randomperson11


20x30cm fan? Are you sure it isn't mm? because that's pretty big. I would recommend a blower fan such as https://www.digikey.com/product-detail/ ... ND/2560506 with a high static pressure as a lift fan, and a brushed dc motor with a propeller and a duct around it as a thrust fan. With this set up, my craft carries around 6 pennies.
i'll work on my events eventually

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