I'll admit to enjoying both fast electric and warship models, so something based on torpedo boats is an obvious thing to build. My first attempt, based on the 80 foot Elco PT boats ( Model Boats Nov 99) showed that speed, duration and handling were fine if the model weight was kept under control. A second attempt, based on the smaller "Miami" rescue boats built in the USA, had to be constructed to about half the weight of the PT boat, resulting in the change from a 545 motor on six sub-C cells to a 400 motor on six AA cells. The result was the same good performance and handling as before and this one was published in the June 06 issue.
A year later and another fast scale type of model was built. Sticking with 1:32 scale and a more ambitious project was started using the "Hellcat" prototype PT boat made by Higgins. This was smaller than the Elco model but I wanted it to be fast so a racing 500 motor and six sub-C cells were squeezed into the hull. The result was rather faster than expected, infact it was suggested I ought to enter races with it, but the handling still safe and predictable. To calm things down a little, the motor was replaced with a standard 540, it's still fast but I can enter steering events with more chance of sailing through obstacles rather than over them.
On the basis of these three models I've learnt that fast scale models are practical if the weight is controlled. The Elco is about 1.5 kg and the Hellcat around 1 kg. These are reasonable targets using balsa for the hull structure plus a little plywood, plastic but the minimum of metal. A single motor driving a large propeller via a gear reduction seems to be the way to go for speed and duration. I've had success using a 2:1 reduction and "X45" props with the 500 motors. A single rudder with sufficient area to keep the model on the right heading is also essential.
With luck the editor of Model Boats will publish this plan so I might get the chance to indulge in some fast scale racing?
GlynnG