Hovercraft B/C

Tesel
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Re: Hovercraft B/C

Postby Tesel » February 23rd, 2018, 5:56 am


I might try that out - not sure how that would work compared to completely hugging the wall, since I would imagine hugging the wall would have a straighter path. Thoughts?
The wheel thing reminded me of a design last year. Someone put ball bearings on the side so it hugs the wall with less friction.
-snip- Maybe something like this could be an easy-to-try solution. (If the image doesn't work, it's a picture of shower curtain rings with rolling beads to reduce friction). They would probably be easy enough to clip on somehow.
Interesting...

I actually tried using ball bearings earlier this year. They worked pretty well with my old design, I'm not sure how they'll work with my current hover. However, at our competition, they ended up riding on top of the side of the track. They slowed down the hover enough for an excellent score... but obviously that isn't a feasible technique. I've got enough room within spec to try it on improved designs, so I'll let you all know how it goes. (Or maybe not, if it's too good of an idea :P )
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arv101
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Re: Hovercraft B/C

Postby arv101 » February 24th, 2018, 11:07 am

But there will be varied amts of friction between the hover and railings...
That's been a really big problem for us, eventually our hovercraft just stops moving because of the friction.
Honestly, I've kind of given up on timing and am heavily relying on weight scores, and our hovercraft moves well enough that friction isn't a problem. Even with the friction, ours almost always goes too fast.

If you have time, try making a hovercraft with more thrust and then just brute-force your way through.

But if you want a more precise timing mechanism and also no spin by hugging the walls, you could just test with multiple barriers. (Or if you area is like mine, just test with the barriers all the proctors use.)
What do you mean by brute force your way through?
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Re: Hovercraft B/C - Batteries

Postby royT » February 24th, 2018, 12:21 pm

Can anyone clarify if the 2 motors must be powered by the same battery or if the 2 motors can have separate batteries - meaning battery 1 powers only motor 1 for the downward propeller, and battery 2 powers motor 2 for the forward motion?
The rules say multiple batteries may be connected together, but do not say if separate batteries can be used for the 2 motors. The voltage would still be less than 9V across any point.
Thanks

shrewdPanther46
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Re: Hovercraft B/C

Postby shrewdPanther46 » February 24th, 2018, 12:33 pm

Separate batteries may be used. Your interpretation of the rules is correct. That was the intention of saying voltage across any point/node..

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Re: Hovercraft B/C

Postby bt03 » February 24th, 2018, 5:41 pm

Hi,
First time competing in this event. Just curious on some aspects of the hovercraft:
1. How many rolls of pennies do people manage to place on their craft?
2. What solutions are there to prevent the hovercraft from "caving in" after the weights are generally placed on the center of mass of the craft? Small wooden supports seemed to do the trick, but the belly of the hovercraft eventually drags on the track after extensive use.
Thank you!
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Re: Hovercraft B/C

Postby MattChina » February 24th, 2018, 7:29 pm

ive seen many people who are able to put 16 penny rolls on their hovercraft
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shrewdPanther46
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Re: Hovercraft B/C

Postby shrewdPanther46 » February 25th, 2018, 6:02 am

Hi,
First time competing in this event. Just curious on some aspects of the hovercraft:
1. How many rolls of pennies do people manage to place on their craft?
2. What solutions are there to prevent the hovercraft from "caving in" after the weights are generally placed on the center of mass of the craft? Small wooden supports seemed to do the trick, but the belly of the hovercraft eventually drags on the track after extensive use.
Thank you!
2) dont build your base out of those garbage foam trays all the kits come with.. problem solved.

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Re: Hovercraft B/C

Postby sciduck » February 25th, 2018, 10:10 am

That's been a really big problem for us, eventually our hovercraft just stops moving because of the friction.
Honestly, I've kind of given up on timing and am heavily relying on weight scores, and our hovercraft moves well enough that friction isn't a problem. Even with the friction, ours almost always goes too fast.

If you have time, try making a hovercraft with more thrust and then just brute-force your way through.

But if you want a more precise timing mechanism and also no spin by hugging the walls, you could just test with multiple barriers. (Or if you area is like mine, just test with the barriers all the proctors use.)
What do you mean by brute force your way through?
Make the hovercraft powerful enough that it goes forward regardless of friction. For us, this meant getting a better battery and changing our skirt design.
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Tesel
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Re: Hovercraft B/C

Postby Tesel » February 25th, 2018, 11:03 am

To add to that, weight scores are much more consistent than time scores. Once you get to the point where you have a powerful hovercraft, you can guarantee the weight score is successful. Time score is less consistent; obviously, it is important, but not as important as being able to handle all 16 rolls of pennies.
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LittyWap
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Re: Hovercraft B/C

Postby LittyWap » February 25th, 2018, 2:03 pm

To add to that, weight scores are much more consistent than time scores. Once you get to the point where you have a powerful hovercraft, you can guarantee the weight score is successful. Time score is less consistent; obviously, it is important, but not as important as being able to handle all 16 rolls of pennies.

I wouldnt say it is "not as important as being able to handle all 16 rolls of pennies", far from it. Science Olympiad is all about relative performance: you don't have to be good, just better than everyone else. If your tournament is riddled with foam tray crafts, then mass score becomes more important. If however, when your team goes to the regional, state and possibly national level, all teams will have mastered the mass score, and time scoring becomes the critical deciding factor. To handle this additional 2kg, I would highly encourage you all to build your craft out of wood: while it is a time investment, it is much less likely to variation and fragility. It isn't a good mass score that makes your proctor gawk, its the accuracy to which you can predict your time. Any Neanderthal can over-engineer a craft to carry 2kg and consistently reach inaccurate times.
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