Postby Balsa Man » October 30th, 2013, 4:37 pm
You raise some good questions and observations.
Clearly, as rule 3.f. reads, it is saying that NOTHING (“no part”) may extend beyond the front of the dowel. That clearly covers a/any part used to hold/secure the base of the dowel if it wraps around, and hence extends beyond, the front surface of the dowel.
Yes, by saying the vehicle must have the dowel attached to it, the student must bring it; it must be part of the vehicle. If your solution is to permanently attach it, say by gluing on the front (being careful the glue does not extend to/past the front edge), it would be very clumsy to transport- as well as being a real pain to work with in testing and competition (dowel breaking off, having to re-glue, repeat ad nauseum…. If it falls off on a competitive run, construction violation).
Yes, the rules as written do create a “unique challenge.” While the purpose and use (tripping timing gates) is exactly the same as the vertical dowels called for in both Scrambler and MagLev (and used previously in Mousetrap Vehicle), only Wheeled Vehicle has this significant, additional engineering challenge. On both Scrambler and MagLev, you can use a ‘holder’ configuration- a hole the dowel slides down into, or a tube it slides down into- a solid, reliable, easy to construct attachment, where the dowel can be removed for transport, and easily replaced. If, for instance, the rules said, “must be placed within 1cm of the foremost part of the vehicle…”, a) it would not make a measureable difference in timing, and b) it would make using a reliable holder easy.
It makes sense to think then, given the timing dowel rules for Scrambler and MagLev, that the Wheeled Vehicle rules were intentionally written differently; were written with the intent of making it significantly more difficult for this event; of creating this unique challenge. That may well be the case here. We have no way of knowing, unless someone involved in the rule making were to shed some light. With all due respect to the people who volunteer their time to put together the rules, there have been instances over the years when significant consequences were unintended; where the implications of particular wording just didn’t get completely thought through, and the result was ‘oh, we weren’t trying to do that…’
Regardless, there are a couple things to think about is mastering the challenge. First, you want the dowel as light as possible. Given how high it has to stick up, and the acceleration/deceleration the vehicle will experience, every little bit of weight off will make a major difference in the strength needed at the attachment point. Second, by working to close tolerances, one could get pretty close to a “holder”- play around with drilling a ¼” hole in a nice solid piece of…..something, then slice off (saw, file, etc.) a side of that piece until the edge of the hole just emerges- that way you have a hole almost all the way around the dowel…..
Len Joeris
Fort Collins, CO
