I second the Big Stick's. Great all around performance. Very durable. Engine is installed upright and out in the open allowing easy access for tuning, fueling, maintenance, etc. I recommend NOT overpowering them ie; 40 range engine for 40 size stick, 60 range engine for 60 size stick, etc. The added weight gain from overpowering alters key areas of flight, one of which is landing speed.

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