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Re: Paddle Wheel Task
Posted: March 1st, 2012, 5:50 pm
by chalker7
GoNerdHerd wrote:chalker wrote:hogger wrote:According to the rule, the paddle is attached to an axle that in turn attaches to a string that wraps around itself as the wheel turns. Does anyone think that the string can be hoisted up high and hung off an anchor before attaching to the mass? Would that be illegal and considered a pulley? Or maybe pulley is allowed at this point since rule (2) in part m only prohibits attaching pulley where the wheel connects to the axle.
FYI, there have been numerous questions submitted to soinc.org about things like this. The general response is NO PULLEYS at all in the final task. Of course if you want an official response to your specific design, feel free to submit a clarification request on soinc.org
. Sorry, I'm still not quite sure of the answer to this. Would a "anchor" be illegal?
Quoting from the official clarification page: 02/16/2012 - 16:26 Does the axle need to lift the mass directly, or can it operate a pulley system to lift the mass?
Yes, the string wrapping around the axle must lift the mass directly. A pulley must not lift the mass. No pulley system! That is part of the challenge."
In particular, "the string wrapping around the axle must lift the mass directly."
Re: Paddle Wheel Task
Posted: March 1st, 2012, 6:21 pm
by GoNerdHerd
Alright thank you. I asked because on the Maryland Mission Possible coaches guide, a diagram specifically shows the paddle wheel attached to an anchor. I also wasn't sure because it seemed if the paddle wheel lifted the mass directly the granular material would fall onto the raising mass.
Re: Paddle Wheel Task
Posted: March 1st, 2012, 6:56 pm
by chalker
GoNerdHerd wrote:Alright thank you. I asked because on the Maryland Mission Possible coaches guide, a diagram specifically shows the paddle wheel attached to an anchor. I also wasn't sure because it seemed if the paddle wheel lifted the mass directly the granular material would fall onto the raising mass.
The mass can be off to the side.. there isn't a limit on the length of the axle. And technically it's the AXLE lifting the mass directly.
Re: Paddle Wheel Task
Posted: March 2nd, 2012, 7:15 am
by hogger
Do you think if we use a very thick string, like .5cm diameter, and tie it directly to the axle with wooden discs sandwiched tightly on both side as to guide subsequent winding on top of each other such that when we tie the string to the axle, the diameter of the axle is theoretically increased by 1 cm and more as the axle is turning. Would this be violating the spirit of the rule?
Re: Paddle Wheel Task
Posted: March 2nd, 2012, 10:30 am
by chalker
hogger wrote:Do you think if we use a very thick string, like .5cm diameter, and tie it directly to the axle with wooden discs sandwiched tightly on both side as to guide subsequent winding on top of each other such that when we tie the string to the axle, the diameter of the axle is theoretically increased by 1 cm and more as the axle is turning. Would this be violating the spirit of the rule?
Interesting idea. Unofficially, no, that is within the spirit of the problem since just the string involved. However keep in mind you are trading off distance for torque in this situation (i.e. you won't have to spin the paddle wheel as many times, but you will need more weight on the paddles to get it to spin.
Re: Paddle Wheel Task
Posted: March 6th, 2012, 9:30 am
by hogger
How about using a winch on the axle? Are we allowed to add a winch to not let the axle spin backward the other way?
Re: Paddle Wheel Task
Posted: March 6th, 2012, 11:11 am
by chalker
hogger wrote:How about using a winch on the axle? Are we allowed to add a winch to not let the axle spin backward the other way?
Are you sure you are thinking about a winch? I'd think you'd want a ratchet in that situation:
http://en.wikipedia.org/wiki/Ratchet_%28device%29
Unofficially, I think a ratchet is fine, but you don't need to have one. Note this FAQ:
http://soinc.org/node/897
Re: Paddle Wheel Task
Posted: March 6th, 2012, 11:56 am
by hogger
Yes, I mean ratchet, thank you. I am aware of that FAQ. We have been testing it and our granular material dispenser sometimes slow down to the point that the wheel reverses the spin a little bit. When that happens, we just loose a lot of progress made and wasted a lot of granular material. We will first tweak the dispenser and probably will not add a ratchet but we are just kind of thinking out loud at the moment.
Re: Paddle Wheel Task
Posted: March 12th, 2012, 4:58 pm
by mattravn
hogger wrote:Yes, I mean ratchet, thank you. I am aware of that FAQ. We have been testing it and our granular material dispenser sometimes slow down to the point that the wheel reverses the spin a little bit. When that happens, we just loose a lot of progress made and wasted a lot of granular material. We will first tweak the dispenser and probably will not add a ratchet but we are just kind of thinking out loud at the moment.
As another data point. We have a fixed gear on our wheel that has a flapper plate that prevents backwards rotation and did not have an issue at regionals. As long as it does not help drive it on any way it sounds like what you describe would be fine. One opinion
Re: Paddle Wheel Task
Posted: April 6th, 2012, 5:20 pm
by Cheese_Muffin_Man
Can anyone lift the full 1 KG?