A radio controlled, heavier-than-air blimp,
also known as
an ...
R/C Submarine
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click any image for a larger view
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Yes, this sub actually works!8 1/2" inches long, 3 channel control, runs on 600AE ni-cads. Steered by differential thrust; like a tank except wetter. The three motors run just fine in fresh water, but salt water = death, don't even try it. Dives and surfaces with the help of the fan in the middle. Here are some notes on its construction in case you want to build one. This is a fairly advanced project. We will be adding some much simpler, fun projects over the next few weeks. Come back and see us then. :
Body: The round things are 80 mm split, hollow balls from a crafts shop. Long piece in the middle is a 2-piece candy cane from the same source, with the ends cut off. Orange piece is cut out from plastic sheet. Fan is from a cooling fan salvaged from some discarded electronic thing, with a servo motor attached. Batteries are in the yellow thing at the bottom and are encased in a 1/16" thick acrylic tube. The ends of the tube are capped with solid acrylic hemispheres, called "cabs". The motors and batteries are attached to the flat piece above the yellow tube. You could also attach these directly to the bottom of the clear balls to eliminate this piece. Electronics: A 3-ch Novak Polaris receiver fits and works very well. Speed controls for the three motors are the amplifier boards from old servos. Potentiometers are mounted under the black cap so motors can be easily trimmed. (See article about modifying servos for more information about how to do this stuff.) The speed controls are in the rear ball and their leads pass through the top tube. The Deans 2-piece base-loaded antenna is very good. Drive motors are from Edmund Scientific; dive motor came from an old servo. Operation: The sub's thrust line is below its center of mass which causes it to pitch up and rise slowly when going forward at full speed. Raise the motors to trim this out, but this setup makes it less likely to drive into the bottom of a lake. For maneuvrability in cookie jars, bathtubs, etc there is no vertical stabilizing fin, but this makes it steer tricky. A removable fin would help. The sub has to be ballasted to float almost neutrally, with just a bit of positive buoyancy so it will rise up in case of trouble, or if you run down the batteries. On this one, the "waterline" is just above the top of the tube, with the dog sticking out above the water.
The dog:
If you are not a huge fan of really bad puns, you can leave out the dog.
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