it's time to build ducks and chew bubblegum

And as our hero Duke so pathetically complained, I am all out of gum.

Here we have our duck this year.  Although really I should say 'one of' our ducks.  Last year was a fairly simple bolt-on affair, but this year we realised we were going to need to do major surgery on the body in order to get this duck down the line.  Four ducks were purchased, with the intention of possibly destroying them in the prototyping process.  A lot more cutting was going to be necessary.

I guess the first place to start is the plan - I've been holding off on this for a while for two reasons.

1. To stop people from copying it until it was too late, and,

2. To be intentionally obtuse.

This was the first step.

Any guesses?  Glue these two halves together.  But that looks like a water tube.. Oh screwit, here's the drivetrain when assembled.

What that is, ladies and gentlefolk, is a Graupner G2340 Jet Propulsion system.  This jet-pump is usually installed in high-speed dragsters and racing boats, and is prized for quick acceleration and maneuverability.  Sounds insane?  It is, but that's just the start.  The engine, a 9.6v Speed700 Race motor, is capable of putting out just over 400w.  If the duck weighs 2kg when it's finished, that'll be a power to weight ratio of 200kw/tonne.  Two hundred.  That's more than my car, and that does 0 - 100km/h in 5 seconds.

So not only do we have an absolute buttload of power, we've got an efficient, low-resistance mechanism of putting it down without raising the centre of gravity.

Back from last year's design, we also have a wireless camera system which we'll hook up to a laptop for remote piloting capabilities.

Unfortunately, it hasn't all gone to plan at time of writing.  One very important part that we'd ordered was missing - the main drive belt.  I tried going to Hobby Engineering Supplies but the only belt they had that would fit was too big, and it turned out it didn't even fit.  I had planned to make up a custom mounting bracket but the belt itself couldn't sustain the bend radius of the drive cog.

Sadface.  Today I'm on the hunt for something else I can use to connect the drivetrain and the motor.  I can't mount them end-to-end because it would be too long to fit in the duck, and because the high-revving motor is more efficient at high revs - this gearbox lets it spin freely up to its high RPM goal, providing more torque, better acceleration, and lower current draw.

For more photos, hit up the Flickr photostream.  Stay tuned for the answer to the drivetrain problem.