Hovercraft B/C

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Re: Hovercraft B/C

Postby antoine_ego » January 31st, 2017, 7:09 pm

Hey, guys. Me and my partner built a hovercraft, and it works great, except when we put the shield on (which unfortunately is a requirement). Any ideas on how to reduce shield weight?
For me, fan grills worked out very well (about $5 on Amazon). They do reduce the fan output, but not significantly. I've seen other teams use plastic screen/mesh material, but personally I think fan grills are easier to deal with.
The issue with that is that I've been able to get through the shielding with a 1/4 dowel, especially around the edges of the shield.
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Re: Hovercraft B/C

Postby SPP SciO » February 1st, 2017, 3:11 am

A minimalist approach to shielding - you can take thin wire, and carefully wrap it in a spiral. A tiny dab of superglue can hold it to the plastic frame at each point of contact. It takes a long time to do it right and may not be worth the effort vs other methods, but it barely has an effect on performance. It should pass the ES test, unless they intentionally bend the wire to force a dowel in.
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Re: Hovercraft B/C

Postby funnybunny48 » February 1st, 2017, 5:04 pm

I was wondering if Rule 5.m. could be used as a loophole during competition.

"Teams must not touch the vehicle after motors are turned on until the vehicle passes the finish line or the event supervisor declares the run as a failed run."

If, for example, we realized the Hovercraft was going too fast/too slow during its run, could we intentionally touch it to make it a "failed run" (which we get 5 of) to readjust the vehicle and make another attempt?

It doesn't seem like the most sportsmanship-like thing to do, but the rules seem to allow it.
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Re: Hovercraft B/C

Postby maxxxxx » February 1st, 2017, 5:28 pm

I was wondering if Rule 5.m. could be used as a loophole during competition.

"Teams must not touch the vehicle after motors are turned on until the vehicle passes the finish line or the event supervisor declares the run as a failed run."

If, for example, we realized the Hovercraft was going too fast/too slow during its run, could we intentionally touch it to make it a "failed run" (which we get 5 of) to readjust the vehicle and make another attempt?

It doesn't seem like the most sportsmanship-like thing to do, but the rules seem to allow it.
Generally doing something that goes against the spirit of the competition is a bad idea, and if the supervisor catches wind you could be penalized.
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Re: Hovercraft B/C

Postby chalker » February 2nd, 2017, 5:13 am

I was wondering if Rule 5.m. could be used as a loophole during competition.

"Teams must not touch the vehicle after motors are turned on until the vehicle passes the finish line or the event supervisor declares the run as a failed run."

If, for example, we realized the Hovercraft was going too fast/too slow during its run, could we intentionally touch it to make it a "failed run" (which we get 5 of) to readjust the vehicle and make another attempt?

It doesn't seem like the most sportsmanship-like thing to do, but the rules seem to allow it.
Generally doing something that goes against the spirit of the competition is a bad idea, and if the supervisor catches wind you could be penalized.

This ^. Keep in mind that the general rules (https://www.soinc.org/code-ethics-general-rules) allow for the event supervisor to apply arbitrary penalties for spirit of the rules violations since we can't account for every situation in the event rules.

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Re: Hovercraft B/C

Postby SPP SciO » February 2nd, 2017, 7:38 am

I'll be honest, when I first read the rules, I had thought that students would be allowed to decide a run has "failed." However, it's quite clear, only the ES can declare a failed run. Rule 5.m states that students must not touch the vehicle - implying to me that it's a forbidden act. Rather than invoking sportsmanship / spirit of the rules / ES judgement calls, why not add a clarification to scoring, so that touching the vehicle incurs a large penalty? If Scrambler students saw that their egg was about to crash into the bucket and break, and ran onto to the track to prevent that (similar spirit/sportsmanship violation), they'd be penalized in the scoring.
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Re: Hovercraft B/C

Postby MCbigminer » February 2nd, 2017, 12:12 pm

(keep in mind I'm pretty new to this forum so please point out any mistakes I make)

So i'm currently working on hovercraft and I have already bought a good 24000 RPM brush motor and have made a wooden fan for testing, but i'm planning to 3D-Print a better one in the future for the final craft. I need some tips for the actual method of hovering, any ideas?

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Re: Hovercraft B/C

Postby Zioly » February 2nd, 2017, 12:43 pm

(keep in mind I'm pretty new to this forum so please point out any mistakes I make)

So i'm currently working on hovercraft and I have already bought a good 24000 RPM brush motor and have made a wooden fan for testing, but i'm planning to 3D-Print a better one in the future for the final craft. I need some tips for the actual method of hovering, any ideas?
I'd look through the previous discussions on this thread... they've been really helpful to me. Also, look through the wiki and find examples of hovercrafts on the internet.

Then, if you have specific questions, feel free to ask and start a new discussion.
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Re: Hovercraft B/C

Postby chalker » February 2nd, 2017, 2:39 pm

I'll be honest, when I first read the rules, I had thought that students would be allowed to decide a run has "failed." However, it's quite clear, only the ES can declare a failed run. Rule 5.m states that students must not touch the vehicle - implying to me that it's a forbidden act. Rather than invoking sportsmanship / spirit of the rules / ES judgement calls, why not add a clarification to scoring, so that touching the vehicle incurs a large penalty? If Scrambler students saw that their egg was about to crash into the bucket and break, and ran onto to the track to prevent that (similar spirit/sportsmanship violation), they'd be penalized in the scoring.
We have a general policy of not issuing clarifications in the middle of the season unless it's to address a truly event shattering issue. This clearly doesn't fall into that category, since everyone can fall back on the General Rule #1 which prohibits actions that violate the spirit of the rules.

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Re: Hovercraft B/C

Postby andrewp » February 3rd, 2017, 10:18 am

I do have a quick question:

With say NIMH batteries (say 8.4v), fully charged they will show 9.5v (say) on the multimeter. This will burn off under 9 soon enough. Even a fresh 9v alkaline cell will report 9.2 - 9.5v unloaded fresh out of the box.

How literally are we to take the rule "no point in the circuit must exceed 9v"? Are we supposed to make sure all batteries are discharged down to this to make sure we don't get hit up on impound/review?

Thanks,

Andrew

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Re: Hovercraft B/C

Postby maxxxxx » February 3rd, 2017, 10:30 am

I do have a quick question:

With say NIMH batteries (say 8.4v), fully charged they will show 9.5v (say) on the multimeter. This will burn off under 9 soon enough. Even a fresh 9v alkaline cell will report 9.2 - 9.5v unloaded fresh out of the box.

How literally are we to take the rule "no point in the circuit must exceed 9v"? Are we supposed to make sure all batteries are discharged down to this to make sure we don't get hit up on impound/review?

Thanks,

Andrew

Rule 4. h. says that voltage must not exceed 9V as labeled, so that's as literally as the rule should be interpreted.
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Re: Hovercraft B/C

Postby antoine_ego » February 3rd, 2017, 12:13 pm

I do have a quick question:

With say NIMH batteries (say 8.4v), fully charged they will show 9.5v (say) on the multimeter. This will burn off under 9 soon enough. Even a fresh 9v alkaline cell will report 9.2 - 9.5v unloaded fresh out of the box.

How literally are we to take the rule "no point in the circuit must exceed 9v"? Are we supposed to make sure all batteries are discharged down to this to make sure we don't get hit up on impound/review?

Thanks,

Andrew

Rule 4. h. says that voltage must not exceed 9V as labeled, so that's as literally as the rule should be interpreted.
I interpreted as that even if your batteries are overcharged, so long as the rated voltage (voltage on the label) is below 9V, it should be allowed.
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Re: Hovercraft B/C

Postby dragonfruit35 » February 3rd, 2017, 12:20 pm

I do have a quick question:

With say NIMH batteries (say 8.4v), fully charged they will show 9.5v (say) on the multimeter. This will burn off under 9 soon enough. Even a fresh 9v alkaline cell will report 9.2 - 9.5v unloaded fresh out of the box.

How literally are we to take the rule "no point in the circuit must exceed 9v"? Are we supposed to make sure all batteries are discharged down to this to make sure we don't get hit up on impound/review?

Thanks,

Andrew

Rule 4. h. says that voltage must not exceed 9V as labeled, so that's as literally as the rule should be interpreted.
I interpreted as that even if your batteries are overcharged, so long as the rated voltage (voltage on the label) is below 9V, it should be allowed.
There's a similar rule in Electric Vehicle/Robot Arm, and that's how I interpreted it as well.
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Re: Hovercraft B/C

Postby maxxxxx » February 3rd, 2017, 4:22 pm

I do have a quick question:

With say NIMH batteries (say 8.4v), fully charged they will show 9.5v (say) on the multimeter. This will burn off under 9 soon enough. Even a fresh 9v alkaline cell will report 9.2 - 9.5v unloaded fresh out of the box.

How literally are we to take the rule "no point in the circuit must exceed 9v"? Are we supposed to make sure all batteries are discharged down to this to make sure we don't get hit up on impound/review?

Thanks,

Andrew

Rule 4. h. says that voltage must not exceed 9V as labeled, so that's as literally as the rule should be interpreted.
I interpreted as that even if your batteries are overcharged, so long as the rated voltage (voltage on the label) is below 9V, it should be allowed.
Oh whoops, that's what I was referring to by "it". I hope I didn't cause any confusion.
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Re: Hovercraft B/C

Postby NyeSpy » February 6th, 2017, 11:38 am

Does anyone know if a rotary dimmer would work to vary the speed of the push fan? We will be using two 7.2v NiCd RC racing batteries, one for the lift fan and one for the push fan.

Push fan - http://www.digikey.com/product-detail/e ... ND/5209819
Rotary dimmer in question - https://www.lowes.com/pd/Lutron-Rotary- ... er/1059607

Thoughts?


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