EPS-STD	EPS-DX	EPS-100C	EPS-300C
EPS-400C	IPS	LPS	IPSD

There is a bewildering range of GWS drive units consisting of several sizes of motor, each of which can be used for direct drive or with reduction gearing (above are only a few). Several gear ratios are available for each motor and there is a vast range of propellers to suit (actually, from 2.5" x 0.8" to 15" x 10"!). The most recent introduction features two motors geared to a single propeller. The GWS website has full details of the complete range.

However, while the motor packaging includes a chart of suitable propeller sizes for each ratio, this information is not on their website (the tables are there, but the cells are blank). Here is the information from the single motor IPS unit packaging:

And here is the information from the dual motor IPSD unit packaging:

The motor supplied in both of these units is only rated for 5 or 6 cells (to confuse things further, the motor is also available with a winding suitable for 4 cells maximum). More cells than this should only be used for the higher ratios and will shorten the motor life dramatically.

Note that the propeller sizes are easy to decipher. The unit numbered 9070 is a 9" x 7", the 8043 is an 8" x 4.3", and so on.

The GWS site contains details of nominal current consumption on 5 & 6 cells for each motor on suitable prop sizes, but no details of RPM to be expected. I have produced my own figures for those units that I have tried, in some cases on a greater range of prop sizes. These will be added to when possible.

7:1 ratio single motor

Prop Cells Current (Amps) RPM Comment 7 x 6 Gunther 6 1.17 3200 7 1.38 3500 7 x 6 GWS 6 1.11 3200 7 1.28 3500 8 x 4.3 GWS 6 1.09 3200 7 1.25 3500 Cut down 9 x 7 GWS 6 1.32 3100 7" dia 9 x 7 GWS 6 1.72 2700 7 1.90 2800 10 x 4.7 GWS 6 1.80 2600 7 1.90 2700 10 x 8 GWS 6 2.50 2300 7 2.60 2300

Weight: 30g (1.06oz)

6 cells = 6 x 300 mAh NiMH
7 cells = 7 x 750 mAh NiMH

3.5:1 Single motor

Prop Cells Current (Amps) RPM Comment 7 x 6 Gunther 6 2.80 3800 7 x 6 GWS 6 2.40 4200 8 x 4.3 GWS 6 2.13 4200 7 x ? Modela 6 2.90 2900 CO2 prop Cut down Modela 6 2.70 4000 6" dia 7.5 x 5 Wattage 6 3.10 4000 7 3.20 4100

Weight: 30g (1.06oz) With optional heatsink: 32g (1.12oz)

4.1:1 dual motor

Prop Cells Current (Amps) RPM Comment 7 x 6 GWS 6 3.30 4700 8 x 4.3 GWS 6 3.35 4400 2 x 640 Kokam 2.6 4900 8 x 6 GWS 6 2.90 4100 2 x 640 Kokam 3.40 4350 9 x 4.7 GWS 6 3.20 4000 2 x 640 Kokam 3.40 4100 9 x 7 GWS 6 4.60 3400 2 x 640 Kokam 4.20 3800 Cut down 9 x 7 GWS 6 3.90 4250 7" dia 10 x 4.7 GWS 6 4.90 3300 2 x 640 Kokam 4.50 3650 10 x 8 GWS 6 5.70 2800

Weight: 42.5g (1.50oz)

280 motor direct drive

Prop Cells Current (Amps) RPM Comment 5 x 3 GWS 6 3.15 10500 5 x 3 Cox 6 3.50 8400 Adaptor needed 5 x 4.5 Gunther 6 4.60 8300

Weight: 43g (1.50oz)

EDP10 motor direct drive

Prop Cells Current (Amps) RPM Comment 2.5 x 0.8 GWS 6 0.32 19200 3 x 2 Union (U80) 6 0.63 7000 2.5 x 0.8 GWS 2 x 340mAh Li-Poly 0.305 19000

Weight: 5g (0.18oz)

EDP20 motor direct drive

Prop Cells Current (Amps) RPM Comment 2.5 x 0.8 GWS 6 0.75 32000 2.5 x 0.8 GWS 2 x 340mAh Li-Poly 0.80 34000

Weight: 7g (0.25oz)

EDP50 motor direct drive

Prop Cells Current (Amps) RPM Comment 3 x 2 GWS 6 2.30 16300 7 3.10 18600 2 x Li-Ion 2.20 15800 3 x 2 Union (U80) 6 2.30 16600 7 3.10 18800 2 x Li-Ion 2.20 16200

Weight: 15g (0.53oz)

6 cells = 6 x 300 mAh NiMH
7 cells = 7 x 750 mAh NiMH
2 x Li-Ion = 2 x 700 mAh Lithium-Ion

Suppression

All of these motors are supplied with a single capacitor across the motor terminals to suppress RF interference. This is barely adequate and it is highly recommended that that two more capacitors be fitted, one from each motor terminal to the case. Value can be 0.1 or 0.05 microfarads. The optional heatsink available for the IPS series is also recommended.

Standard.

Additional suppression.

Lubrication

It is fairly obvious that all of these motors need to be lubricated. I use small amounts of 'Tri-Flow' oil which contains PTFE (Teflon). Don't overdo this at the brush end of the motor! Too much can get on the brushes and there is no way to remove it.

The motor used in the various IPS units has a bronze bush buried in the plastic end plate at the brush end. If the motor gets hot, this bush can easily melt it's way out through the plastic. Both the shaft alignment and the motor are ruined. Unfortunately, as supplied, there is no way to lubricate this. The solution is to use a sharp-pointed scalpel blade to dig away the center of the plastic end to expose the end of the shaft. Don't overdo this, as some of the plastic is needed to stop the bush from escaping.