R/C Tank Combat

Rocket Launcher #RL001

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After this I soldered a pair of wires to the marker's trigger switch contacts and ran them out a small gap cut into the grip cover plate.

This is the base of the assembly. In the first battle I decided it needs to be wider than the top (so plants don't obstruct the rotation) and it needs some easy way to level it (I used small rocks, but something like the Navarone Gun's feet would be better). I drilled a hole in the ball-bearing turntable (lower right corner here) to allow me to screw the upper plate to the box from below. The gray sheet is a piece of shower pan liner and provides good traction for a small wheel (see below) that protrudes through the bottom of the box. I used GOOP on the rubber sheet but it didn't work very well; I think staples might have helped keep the edges from curling up.

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This is my quick-and-dirty solution for turning the box. The ridged black wheel is the cap from a sherry bottle cork. I drilled a hole in it for the rear of the servo wheel's spline and used Super Glue to bond them. The black part is not quite centered but it works fine. A cheap servo hacked for continuous rotation and mounted in the floor of the box drives the wheel which rotates the box at a reasonable rate. This isn't a great solution but with what I had on hand I'm happy with it for now.

The box top has a cutout for the vertical copper pipe and the whole top can be lifted slightly and rotated to allow access to the inside. A cheap servo is mounted under the middle of the top and its arm protrudes through a slot. Fishing line attached to the servo arm and the pipe/barrel joint adjusts the elevation. When the joint was new it was stiff enough to hold the barrel horizontal, but after flexing a few times it softened up. I attached some thin elastic cord to the front edge of the box and passed it around his neck to keep him forward and the servo pulls him back. In the battle for A Bridge Too Far I realized it would be handy to be able to depress the barrel so the next version will have a different mechanism.

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Joe took half a dozen direct hits defending A Bridge Too Far, but came through unscathed. His helmet went flying with the first hit and I found it 3 feet away after the battle. That dislocated knee doesn't look good but the joint is only fabric so the corpsman popped it back in place with no need for morphine. The Agent Orange used by the evil Tiger commander wiped off easily and Joe was ready to fight another day.

For British Invasion Joe's Bazooka has a trigger/grip, front and rear cones, and matt camo paint. His new helmet is a better match for his dark uniform.

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Internally the servo now drives a pushrod giving much better fore-and-aft stability.

The marker and servo are screwed down into wooden blocks, making the mechanism quite rigid.

The rotation mechanism has a commercial continuous-rotation servo (a Hitec HSR-1425CR) driving an 18-tooth 0.250"-pitch sprocket.

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The base was replaced with one much wider than the rotating platform, to keep flora from affecting rotation. The new base is covered with stone-patterned floor tiles. These are surprisingly slippery so I used coarse sandpaper to roughen up a track for the rotation sprocket. It was still slipping a lot so I spread a layer of clear silicone sealant over it and it works like a dream.

For Zombie War Bazooka Joe had a major re-build.

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