AstroFlight 4535, their largest motor yet, 15-kW / 20-HP

October 8, 2013

AstroFlight is a maker of high-end RC motors and components for RC-helicopters and model planes. Their headquarters are located in Irvine, Southern California. This month they have announced the release of their largest motor yet, the 4535. But before you start considering some project to fit this large RC motor to, be aware that getting this level of quality…and this much power…in this small of a package…will cost you $3,000 for the motor alone!

So…what are some of the reasons anyone would pay extra for this motor? The magnets are made from Samarium-Cobalt (SmCo), so they retain their full magnetic flux even when they are subjected to unusually high temperatures of up to 200C / 390F. Also, the stator laminations are made from a very pure and high-grade silicon-steel, and are also unusually thin, to allow for very high RPMs without significant eddy-current waste-heat losses.

This motor is not only built to survive extreme heat, it comes with a built-in temperature sensor, and a centrifugal fan to pull air through the center and fling it outwards.

The motor tips the scales at 12-lbs (5.4-kg), and the outer case is 4.5 inches in diameter by 7-inches long (114mm X 177mm). That is only one inch longer than a dollar bill! It comes with a standard shaft diameter of 1/2-inch (12.7mm), but a 12mm shaft is available upon request. The shaft is hardened stainless steel.


from the other end, you can see the integrated centrifugal air-fan.

From the other end, you can see the integrated centrifugal air-fan.


Once you get past the shock of the motor price, it is no small consideration that you should not power-up this motor with just any controller. AstroFlight of course provides a perfect controller for this beast, and it can be had in four different versions.

The Electronic-Speed-Controller (ESC) can be purchased as an:

80V-max by 75-amp max =  6,000W / 8-HP for $1,200or…up to:

100V max by 150-amp max = 15,000W / 20-HP for $1,500, and there are two other versions inbetween these two extremes.


The ESC-2413 controller from AstroFlight.

The ESC-2413 controller from AstroFlight.


You can get the same power for less, but it will probably not be with a motor and controller this small. All of AstroFlights motors are hand-assembled in the US, and they are dyno-tested after final assembly to ensure the quality of every product they make.

The Astro motor nomenclature refers to the diameter of the motor-case and length of the stator (both in inches), which defines its size and amp-capability. The 3220 is 3.2-inches in diameter, with a stator that is 2.0-inches long. In keeping with their established pattern, the 4535 is 4.5-inches in diameter with a stator that is 3.5-inches long.


Here are AstroFlights three most popular motors, the ones that built their reputation.

Here are AstroFlight’s three most popular motors, the ones that built their reputation.


Matt Shumaker is well-known on as a builder of high-end E-bikes. Below are two examples of the type of high-quality work he does. These reductions lower the high-RPMs of these Astro motors down to a usable wheel-speed.


The DaVinci drive and the V4 drive.

The DaVinci drive and the V4 drive.


You can read about Matts insane Astro-powered hot-rod yellow trike here.


Matt Shumakers Astro-powered yellow Trike.

Matt Shumakers Astro-powered yellow Trike.



Written by Ron/Spinningmagnets, October 2013

Grew up in Los Angeles California, US Navy submarine mechanic from 1977-81/SanDiego. Hydraulic mechanic in the 1980's/Los Angeles. Heavy equipment operator in the 1990's/traveled to various locations. Dump truck driver in the 2000's/SW Utah. Currently a water plant operator since 2010/NW Kansas


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