sonac36 wrote:Hey guys. Thanks for all the quick responses! When I mentioned the 2 wheeled vehicle I thought of having some sort of frame with a wingnut braking system that would attach to the axles and hold some sort of weight on it. The reason for the 2 wheel idea was that I was thinking about ways to keep the center of gravity of the vehicle as high as possible. One thing in the rules that I am concerned about, however, is rule 3f: "The vehicle must have... a Measurement point on either side of the vehicle between the front and rear axles." Although the rules never say you have to have a front and rear axle specifically, it is implied that every vehicle will have a front and rear axle in 3f. Any ideas? Thanks again so much.
That's a really good observation. As usual, this isn't the place for official clarifications, but I think the wording does require 2 axles. Of course you could potentially make the device 2 wheeled like a bicycle (as opposed to a segway)
Sonac, it sounds like, but I can't tell for sure, you're thinking bicycle-arrangemend ("...the axles..."); if so, that's clearly consistent with the rules, no measurement point issues. If you're thinking single axle-segway arrangement, it does sound like a clarification would be needed to clear that. A challenge with that arrangement is going to be getting it to run a consistent path - precise alignment and release. Then once its rolling, it's going to be much more sensitive to imperfections in the floor than a 4, or 3-wheeler; one of the wheels getting deflected will turn the direction of motion. With 3 or 4, the contact of other wheels will act to keep it rolling on the path it's on. Something to think about.
Having the center of gravity/mass as high as possible at the start is, indeed important. As discussed earlier in this thread, the basic physics at work are:
Mass (M) x gravitational acceleration(g) x height (h) = potential energy at the top = kinetic energy at the bottom = 1/2 M x velocity (v)squared
Mass cancels out, so the final velocity would be the square root of (h x g)
So, getting as much of the mass as high as possible is the first part of the challenge of getting as much velocity off the ramp as possible. The second is maximizing how far the (center of) mass falls - maximizing h.
If you have a "high" center of gravity/mass (CM), when it rolls off the ramp at the bottom, you have effectively given up the potential energy from the height of the CM above the floor down to the floor. To maximize h, you need to somehow start the CM as high
as you can, and
have it come off the ramp as low
down as you can. Figuring out the various possiblities and tradeoffs to do this is a key part of the design challlenge on this event.