t-turley
05-30-2001, 06:20 PM
A friend whipped up some simple gearboxes for a DM20BB, and gave me one. It is simply sheet metal, drilled and bent at strategic places. I made up basswood beam mounts, and used little plastic "L" clips to mount it in place. I added two 3mm ball bearings, and a gear adapter used for the MP gearboxes. Total weight of the whole mess is 2 1/2 ounces.
I rigged a test stand this afternoon, and tried several different props. First, I tried an APC 9x3.8 SF prop on 7 300 NiCd, the current draw was roughly 3A. Then I tried an APC 10X4.7 on the same pack, and the current jumped to 4A. Wrong direction.
So, I trimmed 1/2" from each tip of the 9x3.8, rebalanced it, and tried it again on the 7C 300. Current draw was down to 2A. That's better. THEN I tried the cut down prop on 8 270 NiMH. Current was back up to just under 3A, and the prop was really whizzing. Zowwee!! If the weather holds, I'm going to try this combo in my full fuselage Pico Cub some time in the next couple of days. Here's a photo comparing the DM20BB setup to the GWS unit from the Cub:
http://www.rcmicroflight.com/upload/motors.jpg
Tony Turley
I rigged a test stand this afternoon, and tried several different props. First, I tried an APC 9x3.8 SF prop on 7 300 NiCd, the current draw was roughly 3A. Then I tried an APC 10X4.7 on the same pack, and the current jumped to 4A. Wrong direction.
So, I trimmed 1/2" from each tip of the 9x3.8, rebalanced it, and tried it again on the 7C 300. Current draw was down to 2A. That's better. THEN I tried the cut down prop on 8 270 NiMH. Current was back up to just under 3A, and the prop was really whizzing. Zowwee!! If the weather holds, I'm going to try this combo in my full fuselage Pico Cub some time in the next couple of days. Here's a photo comparing the DM20BB setup to the GWS unit from the Cub:
http://www.rcmicroflight.com/upload/motors.jpg
Tony Turley