Caldercraft Clyde Puffer Motor and Prop - Help Needed
Looks like a standard 385 - its high torque - slow motor with 5 poles - just what you need for the slow scale speed of a puffer. Low current draw too - gives nice long run time. Prop normally 3 or 4 blade . Try starting with 35mm Graupner plastic - check motor for heating after a few minutes - gives you a bit of a pointer - you will have to experiment as Glynn Guest suggests - take a handful of props with you to the pond. Anywhere from 30 to 45 with different pitches. Could use a test tank outside otherwise - even a slow running motor pushes a large volume of water - the indoor test tank would tend to empty quite quickly. Better halves seem to get a bit twitchy about that.
You can attach a fishing scale or similar and tether boat via it to any convenient tree etc. That will give a good indication of thrust produced - and you can quickly find out what the motor does heatwise.
You can attach a fishing scale or similar and tether boat via it to any convenient tree etc. That will give a good indication of thrust produced - and you can quickly find out what the motor does heatwise.