Air Trajectory B/C

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power123
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Re: Air Trajectory B/C

Post by power123 » March 2nd, 2015, 11:20 am

I have a question regarding the triggering device. At our last invitational last week the supervisor thought our device may be illegal. He didn't tier us or penalize us but pointed out that we may want to fix it before our regionals.

Our weight drops via a lever with a hinge at the base. A stick is placed at various points along the bottom to hold up the lever at different heights. A string is tied to it so we can stand back outside the launch area and pull the stick out. The stick is a simple 1/4" dowel rod, about 8in long. He said since when we pulled the stick out it came out of the launch area that was illegal. But the rule reads below as follows:

"The triggering device is not considered part of the device and must not contribute energy to the launch. It must extend out of the launch area, allow for competitors to remain at least 1.00m away from the launch area, and does not need to return to the launch area after launch. The triggering device must not pose a danger to anyone due to flying parts or excessive movement outside of the launch area."

I think our trigger meets these rules. What do you think? Do I need to redesign?

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Re: Air Trajectory B/C

Post by drcubbin » March 2nd, 2015, 4:10 pm

Power123, that sounds good to me.

I am having a different problem. The rules say, "All air device chambers must start launch at ambient air pressure and must automatically return to ambient pressure." We are using a red rubber "dodge ball" that begins at ambient pressure, gets deflated during launch, thus returning to ambient pressure - but not the original shape of the ball - meaning it does not "re-inflate." Is it expected to "re-inflate" to the original shape or if deflated ambient pressure ok and then we just blow into the tube to return into the original shape?

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Re: Air Trajectory B/C

Post by bernard » March 2nd, 2015, 5:55 pm

drcubbin wrote:Power123, that sounds good to me.

I am having a different problem. The rules say, "All air device chambers must start launch at ambient air pressure and must automatically return to ambient pressure." We are using a red rubber "dodge ball" that begins at ambient pressure, gets deflated during launch, thus returning to ambient pressure - but not the original shape of the ball - meaning it does not "re-inflate." Is it expected to "re-inflate" to the original shape or if deflated ambient pressure ok and then we just blow into the tube to return into the original shape?
If the pressure of the ball at the start and end is the same as the pressure of the surrounding room, then it is ok. Disclaimer, this is unofficial opinion.
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Re: Air Trajectory B/C

Post by vid_123 » March 3rd, 2015, 8:06 am

Thanks goodcheer. I like the broom/cane idea for the triggering device.
I think we will go with that.

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Re: Air Trajectory B/C

Post by bernard » March 3rd, 2015, 8:20 am

power123 wrote:I have a question regarding the triggering device. At our last invitational last week the supervisor thought our device may be illegal. He didn't tier us or penalize us but pointed out that we may want to fix it before our regionals.

Our weight drops via a lever with a hinge at the base. A stick is placed at various points along the bottom to hold up the lever at different heights. A string is tied to it so we can stand back outside the launch area and pull the stick out. The stick is a simple 1/4" dowel rod, about 8in long. He said since when we pulled the stick out it came out of the launch area that was illegal. But the rule reads below as follows:

"The triggering device is not considered part of the device and must not contribute energy to the launch. It must extend out of the launch area, allow for competitors to remain at least 1.00m away from the launch area, and does not need to return to the launch area after launch. The triggering device must not pose a danger to anyone due to flying parts or excessive movement outside of the launch area."

I think our trigger meets these rules. What do you think? Do I need to redesign?
I think your trigger meets the rules. I asked the event supervisor at our recent invitational and he said that my cotter pin I was pulling out was allowed to hit the ground.
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Re: Air Trajectory B/C

Post by Type » March 3rd, 2015, 4:10 pm

I have finally figured out my device and got it to work. The only problem is, it is hard to re-inflate the kickball I am using. Would it be against the rules to use an air pump for an air mattress to fill it? I know the rules say that you can not have anything electrical as part of your device, but technically, this is separate and would not affect the distance the ping pong ball would travel since it would get inflated without it.;

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Re: Air Trajectory B/C

Post by sjwon3789 » March 3rd, 2015, 4:39 pm

Type wrote:I have finally figured out my device and got it to work. The only problem is, it is hard to re-inflate the kickball I am using. Would it be against the rules to use an air pump for an air mattress to fill it? I know the rules say that you can not have anything electrical as part of your device, but technically, this is separate and would not affect the distance the ping pong ball would travel since it would get inflated without it.;

It has to reinflate it by itself. So you cannot use any mechanism to re-inflate it, I believe. When I attempted to use the kickball, we just switched to using a soda bottle because it was really irritating to work with.
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Re: Air Trajectory B/C

Post by bernard » March 3rd, 2015, 4:45 pm

sjwon3789 wrote:
Type wrote:I have finally figured out my device and got it to work. The only problem is, it is hard to re-inflate the kickball I am using. Would it be against the rules to use an air pump for an air mattress to fill it? I know the rules say that you can not have anything electrical as part of your device, but technically, this is separate and would not affect the distance the ping pong ball would travel since it would get inflated without it.;

It has to reinflate it by itself. So you cannot use any mechanism to re-inflate it, I believe. When I attempted to use the kickball, we just switched to using a soda bottle because it was really irritating to work with.
Could you direct me to the rule that suggests that or explicitly says it? All I see is the rule about ambient air pressure, which could be met even if it is re-inflated with a bike pump.
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Re: Air Trajectory B/C

Post by chalker » March 3rd, 2015, 4:51 pm

bernard wrote:
sjwon3789 wrote:
Type wrote:I have finally figured out my device and got it to work. The only problem is, it is hard to re-inflate the kickball I am using. Would it be against the rules to use an air pump for an air mattress to fill it? I know the rules say that you can not have anything electrical as part of your device, but technically, this is separate and would not affect the distance the ping pong ball would travel since it would get inflated without it.;

It has to reinflate it by itself. So you cannot use any mechanism to re-inflate it, I believe. When I attempted to use the kickball, we just switched to using a soda bottle because it was really irritating to work with.
Could you direct me to the rule that suggests that or explicitly says it? All I see is the rule about ambient air pressure, which could be met even if it is re-inflated with a bike pump.
Correct, there is no requirement in the rules to 'reinflate by itself'. Only to remain at ambient air pressure, which is a completely separate thing. General rule #1 applies: http://soinc.org/ethics_rules However note that you can't expect there to be a power socket available to plug your air pump into, so I wouldn't count on using that.

As always, this is not the place for official comments of clarifications though.

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Re: Air Trajectory B/C

Post by bernard » March 3rd, 2015, 4:54 pm

Type wrote:I have finally figured out my device and got it to work. The only problem is, it is hard to re-inflate the kickball I am using. Would it be against the rules to use an air pump for an air mattress to fill it? I know the rules say that you can not have anything electrical as part of your device, but technically, this is separate and would not affect the distance the ping pong ball would travel since it would get inflated without it.;
Could you use a handheld bike pump or ball pump to do it?
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