I put almost all of my research and development into the bot I called Tank. Successfully resisting the urge to add tons of complexity, I kept the design simple: bumpers front and rear that dragged on the ground, high traction tires, and fully sloped armor. I went with the tried-and-true one-motor-powers-one-side approach to give me skid steering.

I was very proud of the bumper system. The front and rear bumpers dragged on the ground, but were mounted on a lever system that allowed them to pivot up. This was just in case I went up against a lifter - even if it got under my bumpers, my drive wheels would remain contact with the ground.

I played around with many other advancements in my prototype units, but none of them made it into the production unit (other than the bumper system). Car-type four-wheel-drive systems and automatic transmissions were both abandoned because of the added weight and complexity.

The other bot was named Rampy, for obvious reasons. I just threw it together in an evening; there wasn't a whole lot of thought in its design.

I don't remember exactly how the bots finished, but I think Tank was #6 and Rampy was #9 out of 14 bots. Rampy did better than I had expected; Tank did worse. Tank had no major flaws, but a lot of minor issues that led to problems when faced with the most successful bots. Having to drag the bumpers reduced the traction by reducing the weight on each drive wheel; other bots still managed to get under the bumpers (although I did usually keep all four wheels on the ground); I tried to compromise on a good balance of speed and power, while most other contenders went purely for one or the other; and, while I thought I had done a lot in the weight limit, other bots showed me (once again) that I had a massively overbuilt frame. I should have traded some of my frame and armor for two additional motors.

The program was very simple (both bots ran the same code). The drove in one direction until a light sensor detected the white edge; they then turned slightly and reversed until they hit the other edge.

This shows the overall shape of the bot..
The RCX has been removed, and you can see most of the drivetrain.
A view from the bottom, showing the drivetrain. I would have liked to move the motors into the middle, rather than hanging them off the ends, but there wasn't enough space. The light sensor mounts were relatively weak, but were well protected behind the bumpers.

This image shows the top of the bot. It has a flat top and a ramp on each side.
Another picture of the top, this time with the access panels off. To start a bout, I'd have to take the large panel off, use the remote to start the bot, and then get press the plate back on during the five-second countdown.
A view from the bottom, showing the very simple gearing. You can also see all of the smaller wheels, used to balance the bot and prevent the ramps from dragging on the ground.

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