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Brother Hobby Sphinx FS2405 2425kv
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A wide stator motor made for ZDrone by BrotherHobby.

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Summary

Published: Apr 18, 2018

Brother Hobby Sphinx FS2405 2425kv<br />

Tested KV:2410kv
Weight:30.1g
Stator W:24mm
Stator H:5mm
The debate of width over height for stator size has raged in the hobby for years, with firm adherents to both taller and wider stators.  Recently the 2405 stator size has become popular, and this motor is an entry into that market. It has all the bells and whistles of the Returner line, but with a wider stator and a customized bell design. This version sports the usual 16x16 open-bottom design, thick single-wire windings, very tight air-gap, strong arc magnets, and hollow titanium machined 4mm internal single piece shaft with 9x4x4 EZO bearings and screw retainer,  The build quality is up to the usual excellence of BrotherHobby, with beautiful fit and finish.  The motor comes in at only just over 30g, which is quite impressive for a motor with this stator volume. Really nice work here from ZDrone and Brother Hobby.

Results

The results here are extremely interesting given the stator size and design of this motor. It very much backs up my previous experience with wide vs tall stators.  This motor has plenty of low end response, the RPMS jump up pretty quickly in the low throttle and the number down low are on par or a little ahead of the 2206 motors of similar Kv and design from Brother Hobby, but as the throttle increases the torque drops off. One thing of particular resistance is that the coils in the 2405 seem to be a good bit higher resistance than in the 2206, creating a larger voltage drop as current increases, which seems to be contributing to the torque losses as the RPMs increase. The rate of change of RPMs, especially on the heavier props, was also slightly slower than it's 2206 equivalent. This is particularly interesting as the overall stator volume of the 2405 is about 4% larger than the 2206. This backs up the theory that wider stator motors give better low throttle handling at the expense of top end speed, though more testing definitely needs to be done.  Don't let this discussion of the minutiae distract you though, this motor still does extremely well, and I was struck by how smooth the acceleration was on the stand. The throttle curve is likely to be ideal for some pilots looking for the specific type of control this motor offers, the smoothness of the acceleration will appeal to certain flying styles, and the thrust numbers are still on par with other motors in their weight class, all in a very attractive and well produced package.