The rules for brushless stock motors for BRCA (based on EFRA and adopted by many international organisations);
10.3 The Stack/Stator: Slot-less stators are not allowed. The stator must be
continuous laminations having the same overall shape, being one after the other
without anything in between. The laminations must be of one homogeneous material
without cut-outs, holes or hollow sections other than for the three slots of copper coil
wires and the three grooves for the screws used to hold the entire assembly together.
Stator minimum length 19.3mm, maximum 21.0mm. The thickness of the stator
laminations is 0.35 +/- 0.05mm. The Inside diameter of the stator must accept a ‘plug
gauge’ of 14.50mm +0/-.005 diameter, clearing the stator, plus its windings and the
electrical collection ring at any end of the stator.
10.4 The Winding: Only three slot (phase) “Y” (star) wound stators are allowed. No
delta wound stators allowed. Only circular (round) pure copper wire permitted. The
three slotted stator must be wound with: -
21.5T Class:- 21.5 turns of 2 x 21 awg. (or 0.724mm) max. wire dia.
17.5T Class:- 17.5 turns of 2 x 20 awg. (or 0.813 mm) max. wire dia.
13.5T Class: - 13.5 turns of 2 x 21 awg. (or 0.724 mm) max. wire dia.
and 2 x 23 awg. (or 0.574 mm) max. wire dia.
10.5T Class: - 10.5 turns of 2 x 20 awg. (or 0.813 mm)
and 2 x 22 awg. (or 0.643 mm) max. wire dia.
Dimensions are before lacquer coating
10.5 The Rotor: Shaft diameter must be 3.175mm where the pinion gear locates.
Only one piece, two pole Neodymium bonded or sintered, or Ferrite (ceramic)
magnetic rotors are permitted. Magnet length will be 25.00 +/- 1.00mm, not including
any non-magnetic balancing aids. Magnet outside diameter will be 12.20/12.51mm
(min./max. with no further tolerance) for the entire length of the magnet. The shaft
outside diameter where the magnet is mounted will be 7.25mm +/- 0.15mm, with this
diameter extending beyond the magnet to facilitate measurement.
10.6 All motors must have the original manufacturer’s logo or name
moulded/engraved by the manufacturer into the end bell/plate. A unique marking or
feature that is difficult to remove must be incorporated into the assembled motor to
identify the motor is either a 21.5T, 17.5T, 13.5T or 10.5T Spec. class motor. Spec.
motors introduced from 2011 onwards must have; the 'wind' # etched/engraved onto
the outer surface of the motor on a part of the motor that cannot easily be separated
from the stator windings. They must also be identified as Spec. class motors.
NOTE: The above rules form the basis for Brushless Spec. motors. If it is found that
variations of these motors from different manufacturers give large differences in
performance, then electrical tests may be adopted.
ROARS Motor rules;
]8.4.2 Specifications and Dimensions:
126.96.36.199 Only industry standard “05” size motors may be used.
188.8.131.52 All motors must have the original manufacturer's logo or name molded or
etched into the end bell.
184.108.40.206 Can must have the original manufacturer’s logo, name or mark.
220.127.116.11 Overall maximum diameter: 36.02mm measured at whatever point yields the
18.104.22.168 Maximum length: 53mm measured from the mounting face of the motor to the
furthest most point of the end bell, not including solder tabs or lead wires.
22.214.171.124 Shaft diameter: 0.125”.
126.96.36.199 Motor mounting holes must be on 1.00” centers.
188.8.131.52 Maximum Armature stack length: 22.6mm
184.108.40.206 Maximum Armature stack diameter: 23.2mm.
220.127.116.11 Only three pole armatures are permitted.
18.104.22.168 Magnets: Only ceramic, Neodymium, or Ferrite magnets are permitted. Cobalt
and other rare earth magnets are specifically prohibited.
I wonder why there are so many differences?