German S-100 Class Schnellboot (Fast Boat)



The SBoot Motors and Drive system

I have bought three Cobra 4130/12 motors as the Turnigy motors that I purchased are not really suitable for the type of mounts that I have. The Cobra Motors are nearly 50mm (2") diameter and 61mm long.

I have also bought three 50mm props and three 120Amp brushless speed controllers and I have three 5000mAH 14.4Volt Lithium batteries for this beast!

The Specifications - 4 Cell Lipo battery at around 14.8 Volts should produce about 1000 watts for each motor, that should be enough!

Cobra 4130/12 Motor Specifications
 Stator Diameter  41.0 mm (1.614 in)
 Stator Thickness  30.0 mm (1.181 in)
 Number of Stator Slots  12
 Number of Magnet Poles  14
 Motor Wind  12 Turn Delta
 Motor Kv Value  540 RPM per Volt
 No Load Current (Io)  1.85 Amps @ 20 Volts
 Motor Resistance (Rm) per Phase  0.029 Ohms
 Motor Resistance (Rm) Phase to Phase  0.019 Ohms
 Maximum Continuous Current  65 Amps
 Max Continuous Power (5-cell Li-Po)  1200 Watts
 Max Continuous Power (6-cell Li-Po)  1440 Watts
 Max Continuous Power (8-cell Li-Po)  1920 Watts
 Motor Weight  398 grams (14.04 oz.)
 Outside Diameter  49.8 mm (1.961 in.)
 Shaft Diameter  6.00 mm (0.236 in.)
 Motor Body Length  61.8 mm (2.433 in.)
 Overall Shaft Length  84.5 mm (3.327 in.)
 Motor Timing  5-10 degrees
 PWM Frequency  8 KHz


I bought these 1/35th scale cast propellers from G-Factor (E-Bay) the top three are for a 35th scale S-Boot and the bottom three are for the 35th scale Elco. note that the Schnellboot outside props are counter rotating and the middle one has no spike because it sits in front of the main rudder support.

The Elco props are all the same.

These are all solid cast brass, the quality looks really good - I need some 20th scale versions!


2021, I have finally designed some 20th scale Schnellboot propellers that I am happy with, see the sbootshaft page, I had three attempts with designs, all made by Shapeways in brass and the latest ones I have had made are also available in Nylon with a natural finish (and a chemically polished finish, which is not bad but takes off a bit of material). I have three of the nylon props to try on the boat as I think they will be great, they seem tough enough and they are really inexpensive compared to the brass or bronze option, 3D printing seems to give a much better result than trying to cast propellers, much more accurate. I am very happy with these!


(C) Copyright 2014 - 2021  - John Drain