The driving force

After a few design meetings and some basic agreements on what we wanted to do, we've decided a few things:

1. Buying an RC boat and gluing the duck to it is cheating.  If we were going to go that route, we may as well have just hired a Jet-ski and sat the duck on it.  We need to use the duck as the centre of the design and build out from there.

2. Dual-drive is not the way to go.  Last year's attempt showed us a few things about dual-drive propulsion systems in water and the main ones were that it was only a balanced system when both motors were at full power.  Many problems came from the fact that if one motor had more power than the other, there was no hull buoyancy to resist it, causing rolling.  If you intend to have multiple motors, they need to be INSIDE the extents of the hull.  It made for a servo-less steering system, but the complications of then having frame-mounted motors meant having wings, further destabilising an already unstable system.

3. Keep everything internal.  Everything that sits outside the duck is moving the median distance from centre of gravity, making it easier to tip.  In addition to that, everything that sits outside the duck needs its own waterproofing, making things fiddly and difficult.  This also created a higher CoG, destabilising even more.  Can you tell stability was a problem?

4. Drive angle.  Last year we angled props into the water from a frame, which caused an opposing force angling out of the water.  This caused the duck to rotate around its CoG, angling the nose down and lifting the engines out of the water.  We countered this with skids, but that's not an effective solution as it just caused us to waste energy opposing force that could have been used for acceleration.

So, with all those things in mind, we've placed an order for the drivetrain and the motor.  Once those things have arrived, we'll start figuring out how to control them, what we need to do in order to get them in the duck, and how it's going to move once it's all in there.  We're going to be a little light on the details until we have something to show you, so it'll be more impressive when we do, but the goal here is to stay one development cycle ahead of the competition - by the time we show what we're working on, it will be too late to replicate it.

We looked at our solution briefly last year, but never investigated it to the depth that would have revealed that it was an excellent idea.

Stay tuned..