Hovercraft B/C

maxxxxx
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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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Re: Hovercraft B/C

Postby antoine_ego » February 6th, 2017, 11:49 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?
Since rotary dimmers are basically variable resistors, assuming you can connect them, you should be able to use them. Since you are running 7.2V batteries, and these dimmers are meant for maximum 120V, I would think they would work.
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Re: Hovercraft B/C

Postby 0ddrenaline » February 6th, 2017, 2:21 pm

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?
I believe that we considered a dimmer but it had an integrated circuit. I think the dimmer in that link will work if it doesn't have an integrated circuit.

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Re: Hovercraft B/C

Postby andrewwski » February 6th, 2017, 10:14 pm

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?
Since rotary dimmers are basically variable resistors, assuming you can connect them, you should be able to use them. Since you are running 7.2V batteries, and these dimmers are meant for maximum 120V, I would think they would work.
Dimmers are typically *not* variable resistors (rheostats/potentiometers). If they were, they'd have to dissipate a LOT of heat when the light was dimmed, and would get very hot.

Dimmer switches are used in AC, and they essentially "chop" the sine wave. When the polarity switches direction (crosses zero), it cuts the power supply until the wave reaches a certain voltage, at which point it allows it back through. This voltage is what you're controlling through the dimmer.

Most dimmers contain integrated circuits, which are not allowed in this event. But they won't work on DC anyway.

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Re: Hovercraft B/C

Postby keastman » February 7th, 2017, 8:02 am

In regards to "vehicles must have an electric switch to permit safe starting"... If you are using two motors can they each be turned on with a separate switch or do they have to be linked to a single switch to turn it on?

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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » February 7th, 2017, 9:02 am

In regards to "vehicles must have an electric switch to permit safe starting"... If you are using two motors can they each be turned on with a separate switch or do they have to be linked to a single switch to turn it on?
Disclaimer: This is one man's opinion and is in no way an official rules clarification.

I can't imagine that would be a problem. As long as you are safely starting all your fans, I don't see why a supervisor would care what order you do it in.


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