Air Trajectory B/C

[bernard]

[creativecurio]

Can anyone confirm: students are required to use a #2 pencil to trigger the launch of their machine. Can they simply tie a string around the pencil and have that string release the weight? Is that enough to meet the requirement for "triggering" the device with a pencil?

[Krish2007]

Can anyone confirm: students are required to use a #2 pencil to trigger the launch of their machine. Can they simply tie a string around the pencil and have that string release the weight? Is that enough to meet the requirement for "triggering" the device with a pencil?

It's a bit unclear what you mean here; is the string or the pencil being pulled? The only part of the device that can be touched during activation is the pencil, so pulling a string to launch would violate rule 5.d.. If they were to pull the pencil, it would be allowed, but they would have to be careful to not have the string reach outside of the launch area, as no part of the device other than the pencil can leave the launch area (see this FAQ). It doesn't matter whether it's the string or the pencil that releases the weight as long as the device is triggered while only touching the pencil without contributing significant energy to the device.

[knightmoves]

Rule 3f says that the device must remain in ready-to-launch configuration without human intervention, so they can't stand there holding a pencil that supports the weight.

They can have a weight hanging from a loop of string, have that string supported by a pencil that is shoved through a hole in their device, and slide the pencil out of the hole to release the string and drop the weight, if that's what you mean. But 5d says that they can only touch the pencil, so they need to be careful not to apply counterpressure to the device while they're pulling the pencil out.

If you mean "can they have a string as a pull-cord to release the weight, and use the pencil as a handle for that cord", then again they have to ensure that they touch only the pencil but not the string, which might be a little difficult (the normal configuration would have the string tied round the middle of the pencil, and then you'd grasp the pencil in your hand with the string emerging between your fingers. This is almost guaranteed to involve incidental contact between string and fingers.) And as Krish2007 notes, they must take care not to move any part of the string outside the launch box.

[creativecurio]

Thank you! Yes, we saw at several invitationals that students tied a string around the pencil and held the pencil with string attached to the clasp that held the weight and students definitely touched the string, not just the pencil. I think more event supervisors need to be aware of this detail. I appreciate your response!

[knightmoves]

Thank you! Yes, we saw at several invitationals that students tied a string around the pencil and held the pencil with string attached to the clasp that held the weight and students definitely touched the string, not just the pencil. I think more event supervisors need to be aware of this detail. I appreciate your response!

The nice thing about the Air Trajectory rules is that there's a relatively modest penalty for this sort of technical violation: you get your score multiplied by 0.9, which is enough of a penalty to say "you should fix this", without completely destroying the score for a build someone has worked hard on for a very minor issue. I can understand the ES that don't want to tier or DQ someone for a minor technical fault, but a 10% penalty is mild enough that ES shouldn't be afraid to apply it.