[Ecurie Martini]

John and Chris:


Thanks for your comments – food for thought and a little more discussion:

I think there is just enough width considering the narrow wheels and tires to be fitted to accommodate an FF 050 motor. The 030 could be a fallback – my reservation is some reports I’ve read suggesting that reliability could be an issue.

Certainly in the days of the open motors with alnico magnets, the idea of soldering to the motor would never have occurred. I’m not certain how current ceramic magnets react to heat. I know that soldering in is a routine method of motor installation in some of the hot “thingy” classes often with motors costing 10 to 20 times will we pay for our little Chinese cans. I have used this approach in a couple of chassis. A pre-and post installation check a few simple parameters, current draw, unloaded speed and speed with a fixed load (a small propeller) has not revealed any differences. I use a large iron, a low melting solder (TI X) and an in and out very quickly. I hold the motor down on the soldering pad with a bare finger without discomfort.

On gears – a couple of points and a question: for planning purposes I looked only at conventional 64, 72 and 80 DP gears. My prejudices that a better mesh, i.e. smoother, quieter and lower energy loss can be obtained with these gear sets then with gears such as Slot It that use a modified tooth shape to achieve an approximate diametrical pitch in gears with a constant diameter and varying tooth count. Here is a chart that I drew up listing a theoretical diametrical pitch for a range of Slot It gears. My observation is that reasonably good performance is obtained with gears sets where the calculated number for each gear is close. As the spread becomes wider, noise, a good surrogate for poor mesh and power loss, increases. Looking at the website, I assume that the Mossetti gear sets are similar in design to the Slot It gears. Chris: what has been your experience with their performance?

The “regular” pinions are available in a wide range of tooth number. Bore size is not important. I’ve had good success with using metric tubing to bring the motor shafts of slimline motors up to 2 mm.

I will typically try to use gears with the highest tooth count possible. I believe they run smoother (after all, a 4 tooth pinion would be essentially square)The downside is of course that as the DP increases, the teeth are more fragile and mesh more critical.

Back to the sketchpad and drawing board.

Al