Dry Ice on Robot?

[dtengineering]

Originally Posted by Jeff Pahl

My opinion would be that if it is doing anything useful (providing cooling) then it is an illegal energy source, as the energy for creating the dry ice did not come from any of the allowed sources of energy that may be used on a robot, and the dry ice effectively becomes a stored energy device.

Hmm... I like the illegal energy source interpretation, but really... wouldn't it be a perfectly legal energy sink? Thermodynamically, energy would flow from the warm chassis and motors into the ice... the robot itself would be an energy source. <edit... I see a few other thermodynamically-inclined respones to this idea popped up while I was writing this!>

Further to this thought, even if dry ice were to be considered an "energy source", would it not be included under the "deformation of robot parts". After all, the energy would come from the thermodynamic expansion of a gas, which is specifically legal in a closed-loop gas shock... which means the gas is a robot part and it is allowed to deform. I challenge anyone to find a rule prohibiting phase changes!

A logical thought experiment... would it be legal to leave the dry ice on the motors while queuing, then remove it immediately before going on to the field? I'd say "yes"... which means that having thermal gradients is legal.

(An interesting thought... for teams using off-board compressors... chill the air in your aluminum storage tanks, and place them above your warm motors... as the match goes on you might get a bit more energy out of them.)

If we really wanted to find excuses to not allow Dry Ice on the robot, we could try classifying it as "compressed air", and as it was compressed by a source other than the compressor then it might not be legal. However since "air" is primarily nitrogen, and Dry Ice is CO2, that would really be stretching it.

In short, however, if the dry ice was handled safely, and placed on the robot in a secure manner, unlikely to injure competitors or officials, and unlikely to damage the field or other robots.... it would be up to the event officials to explain under what rule they were disallowing the dry ice. If they couldn't do that, then they would be obliged to rule the dry ice legal.

And why not? I mean, it's just dry ice! I shared the same "gut feeling" as the cat at the top of the page, but after looking at all the rules... I'd have to pass it at inspection.

Jason