H-Bridge

The demultiplexer, made of two OR gates, worked perfectly.

Fire Control

Ignition

Tried a few times to get reliable ignition from a hot wire. Making the wire thick takes too much current; a thin wire is at the mercy of wind. Nichrome expands and gets soft, making it hard to use. Tungsten burns-up a little too fast. Then we saw this http://hackaday.com/2013/03/25/giving-an-electric-rc-plane-an-afterburner/ where they use an $8 stun-gun. Lucky for us the politicians have not outlawed these in Vermont! The device draws about 2 Amps at 5V and the output current is high enough that moisture on the wires doesn't affect the spark. Emissions?---we will see. We will probably use a CM choke and some capacitors. It will be fired along with the fuel, I think.

Fuel

It takes about 30 N to fully push the butane valve on. We want it to be able to turn itself off if power is lost so this will use a $5 linear actuator and not a servo. Most of the brackets are ready, just need a few screws.

The copper butane evaporator coil seems OK. There is a bit of residual flame but it's mot too bad. The mouth is aluminum so it's safe enough.

Head

The neck is a curved length sch. 20 PVC. The head is aluminum (for fire) and ABS. It looks OK but we need a plan for the float drop. Champ needs to fully submerge before the drop. Maybe we can allow the float to float while submerged? Then ignite the target, and then drop the float. This is a rough sequence.

Journal CW34