Greg Covey

Hi,

I am working with my first Razor brushless motor from Bishop Power Products. It is the RZ-400 model.

Additional information comes from the Razor Web site.

First, let's compare the size and weight of my RZ-400 to some popular brushed motors that it can replace.

• Speed 400 motor = 2.6oz
• Speed 300 motor = 1.7oz
• Speed 280 motor = 1.4oz
• Razor Motor = 1.0oz

Greg Covey

My application uses a Potensky Eagle with a GWS EPS-300C (CS) 5.33:1 geared Speed 300 motor and a GWS 11x8 prop on a 3-cell Lithium pack. After burning out several 6v Speed 300 motors, I switched to a 280BB motor that provides even more power and can handle the abuse of hovering. However, to keep the current draw at about 10amps maximum, I switched to an 10x8 prop. The down side of my Speed 280BB setup is that it is current "hungrey".

The pinion gear pressed onto the motor shaft. Alternatively, you can lightly tap it onto the shaft using a hammer and adjustable wrench opened just wide enough for the motor shaft. It is always best to support the opposite end of the shaft on a metal surface to absorb the taps.

The Razor motor simply fit in the same holes with the screws that came with the motor. It doesn't fit in the plastic housing of the gearbox but it is not needed.

Mike Ledbetter

So the holes for the mounting screws line up with the holes on a speed 400 motor?

Also, I see you have a threaded prop shaft. What adapter would you use in order to use an APC or Graupner prop and where are they available?

Thanks and regards.

Greg Covey

Hi Mike,

Yes, Speed 300 and Speed 400 motors have the same mounting hole distance. Speed 280 motors have a shorter distance.

I'm sure that either AeroMicro or Balsa Products sells the GWS drive shaft to APC prop adapters. I know that I've run across them somewhere.

The RZ-400 can draw up to about 10amps. Here is a shot of it mounted on my Eagle. It can hover at half throttle now which is about 5-6amps. It seems a perfect fit for my 3-cell, Kokam 1200HC packs.

Regards.

Mike Ledbetter

Thanks. I better call them to make sure I get the right one I guess. 2.3 mm, 3 mm whatever is the diameter of a wattage or gws threaded gearbox.

I am building a Cobra next, kit just arrived. Attached is a picture of my Wattage Tangent awaiting takeoff.

Regards.

MHawker

My Feedback: (16)

Hi Greg,

I did a similar conversion on my Foamtana. I had a GWS "D" gearbox and motor and put a RZ300 into it. I just installed a 3 cell Etech pack this weekend. GREAT power.

Be sure you put something to take up the space between the motor and gearbox. Some people use o-rings. I used a piece of RX foam.

Greg Covey

Mike,

You may want to try some plywood spacers wedged into 4 courners between the motor and the mount. The first 3/4 of the motor by the output shaft end gets the hottest and it would help cooling to keep it open to air flow.

A cooler motor lasts longer.

Regards.

MHawker

My Feedback: (16)

Great idea! Now you've got me thinking......

Dr Kiwi

Hi Guys,
I think you are trying to reinvent the wheel -hop over to the R-C Groups discussion forum and you'll find a lengthy discussion on this 'mounting' problem and our collective answer to it: here is the link to one of my own contributions, with photos -

http://www.rcgroups.com/forums/showt...r&pagenumber=4

Hope this helps, Cheers, Phil

Greg Covey

Phil,

You may be missing the whole point of R/C yourself by following what others have done too closely.

One of the biggest joys in this hobby is tinkering and self discovery...even if you arn't the first to do so.

Thanks for the link.

Regards.

cork

My Feedback: (1)

Speed 300 and speed 400 motors do NOT have the same mounting hole dimensions.

Since the copper runs the entire length of the motor, what is the rationale for the first 1/3 of motor getting hotter than the rest of it?

Greg Covey

cork,

The 1/3 was a typo and should have been 3/4. I've corrected it up above. The heat comes from the lost power in the windings. (I^2 * R(winding))

As for the motors, the distance between the holes is the same. Even the Razor motor has a different screw size and case diameter than the Speed 300 motor.

Regards.

cork

My Feedback: (1)

Unless they've changed recently.....

sp300s have 17mm between the mounting holes.

sp400s have 16mm between the mounting holes.

http://www.mabuchi-motor.co.jp/cgi-b...AT_ID=rs_380sh

http://www.mabuchi-motor.co.jp/cgi-b...AT_ID=rk_370sd

Greg Covey

True, but with the slop on the GWS EPS-300C or 400C gearboxes doesn't matter for 1mm. The context of the query was wheather or not a Razor motor could be mounted to it.