Wait the sandgags power the catapult? That will get you DQ'd in a hurry, go with the bungee cords if that's the case. It's ok to use the sandbags to hold your device down to keep it from moving, but you can't use it to launch the projectile.Help! I have an urgent question before regionals this weekend. I'm a coach for a B-division team, and we are having a rules question. We have essentially built a trebuchet, but are wondering about this:
"3a) The launching force must be supplied by non-metallic elastic solids such as rubber, wood, plastic, rubber bands, bungee cords, rubber tubing, etc."
How does this affect us? The devices we saw at an invitational seemed to be similar and use concrete as weights.
If we have a metal lever arm and our weight is supplied by sand in bags, is this in violation of that rule? Should we find a way to use bungee cords instead?
It depends on your point of view. If you don't actually use the graphs, because your calibration data is in a tabular format or an equation, then the only purpose of the graphs is to maximize your graph score. If you don't have compete tabular data for every possible distance and elevation then the graph can be very useful for quickly determining the setting for your trajectory device. Without the graphs, and assuming you don't have every possible elevation and distance in a tabular format (you would need 1680 distances and elevations for C division or 660 for B to cover every possible combination at Nationals), you are going to have to interpolate or extrapolate to get the correct setting for your device. You can also use the graphs to give you an idea of how much correction to apply after your first shot. For example, if your first shot goes 12cm too far then you need to be able to see how much of a change of setting is required to decrease the range by 12 cm. With you graphs that should hopefully be relatively easy to do. At regionals the graphs may actually be more important to many teams because the only possible ranges are 2,3,4,5,6,7,8 (9,10 for C), so you could quite reasonably go to competion with only 60 total data points. If your first shot misses by the same 12 cm I mentioned above then you would have to interpolate between two widely spaced data points, whereas hopefully your graphs would give a reasonable approximation of the required adjustment.What's the point of four graphs?
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