Popular Power Systems:
I cannot stress enough that the GWS Beaver flies wonderfully on the stock brushed motor and prop with a 2 cell Lipo battery and any old 5-10 amp speed control. The stock power plant has even been used to fly the GWS Beaver on floats from water so dont let the information below lead you to think you need to upgrade or go brushless because in all honesty it is absolutely uneccessary.
There are nearly as many power systems are there are GWS Beavers! Here are Just a few that have been successfully used by the members of RC Groups:
My setup (bob_suruncle):
-Motor: Artech 3700 KV Brushless in runner but have also had success with an E-Flite park 370 brushess in-runner as well
-Speed control: Castle creations pixie 20
-Battery: Thunder Power 3S 1320 LiPo or Artech 3s 1800
-Gearing: 5.33:1 or GWS "C" Gearing
Prop: GWS 9070 3 blade originally but now using either a Master Airscrew 8x6 3 or 2 blade prop
-EST Flight times: 15 minutes / charge on the 1320 and 20+ on the 1800
(NOTE: Old #1 still flies reliably on is brushed "C" gearing power system and a 2S Lipo)
-Motor: Stock GWS 350.
-Speed control: GWS 100ESC (5amp continuous, its a bit minimal but seems happy).
-Battery: Kokam 1250 20C 2cell.
-Gearing: Stock Gearbox "C" gear 5.33:1 (slightly bent shaft)
-Prop: GWS 10X80 2 blade.
-EST Flight times: 15-20 minutes.
-Motor: Stock brushed 350
-Speed control: Castle Creations Pixie 20p
-Battery: Inexpensive 8 cell nimh, 700mAh.
-Prop: 9x7 GWS.
.-EST Flight times: 12-13 minutes
-Motor: Himax 2808-980 outrunner
-Speed control: CC Thunderbird 18 esc
-Battery: 2s and 3s Kokam 20C 740 lipos
-Prop: 9-7 gws prop
-EST Flight times: up to 16 minutes
-Motor: Stock 300 motor.
-Speed control: Castle Creation Pixie 20P.
-Battery: Thunder Power 2100 2 cell.
-Gearing: stock "C" gear ratio 5.33/1
-Prop: APC 10x4.7
-EST Flight times: Over 45 min; and I still had batt to spare.
Tracon's (The man the legend) setup:
-Motor: Himaxx 2015-5400
-Speed Control: Castle Creations Phoenix 25 ESC
-Battery: 3s Thunder Power 1320 11.1v
-Gearing:Stock GWS "C" Gear Ratio 5.33/1.
-Prop: GWS 8X6 Prop
AUW with floats 21 1/2 oz. (Aluminium Float Struts)
EST Flight times: 35-40 Min Flights at 1/3 Throttle
-Motor: GWS 350C C gearing
-Speed Control: GWS ICS400E
-Battery: Home built (from tab batteries) 8*AAA 950mAh with Deans plug
-Prop GWS 1047SF
-EST Flight times: 7 to 8 minutes.
Motor: GWS 350C
-Speed Control: GWS ICS 300
-Gearing: Stock GWS gearbox with "C" gearing
-Battery:- 7 and 8 cell niMh's...all are 750 mAh
-Prop: GWS 10X4.7's
-EST Flight times: with throttle management 12-17 minutes
Art Schmitz (creator of Art's Struts):
Land Beaver: BP21 motor with BP18a speed control, 8060DD prop, 2s 1250 Thunderpower lipos.
Float Beaver: E-Flite Park 370 Outrunner motor, E-Flite Park 20a speed control, APC 9x6E prop, 2s 1250 T.P.lipos
there are many more posted through out the Canada's Latest Beaver Thread and also in the GWS Power Systems thread.