Carl Goldberg Jr. Tiger – Electric Conversion

I went to a swap meet Saturday. There were LOTS of airplanes in many forms and states of repair and disrepair. This Jr. Tiger caught my eye.

Goldberg made this airplane for .15 – .25 glow power back in the 70s and 80s. It’s still available in the .40 size and the .60 size today.  Eddie Taylor of Lazer-Works.com cut this plane as a parts package. He removed some of the ply from the fuselage and added cutouts in a few locations on the fuse to save weight. He built this plane himself and I have to give it to him. This plane is built beautifully. Everything fits well.

I’m running a Great Planes Rimfire 35-30-1450kv motor (also bought at the swap meet) with a 3s 2600mah lipo and a 60 amp ESC and an APC 9-6E prop. The motor is only rated at 30 amps, but I had the 60 amp ESC so it goes on. It is my understanding that going up a little is not a problem in ESCs.



I found an amazing ESC, motor, battery, prop calculator. This takes some of the guesswork out of pairing components for electric RC.

This plane balances just a little back of where I like a plane to balance. Determining the CG for this plane is fairly simple because it has a constant wing cord. It should balance about 25% back, usually just on or barely in front of the main spar. This one seems to be at about 30%. I’m going to fly it once before I add weight. There is nothing I can do to shift existing weight forward. I haven’t checked yet, but I’m probably an ounce to an ounce and a half of nose weight from being just where I like to be.



She weighs 3 lb. 4 oz. ready-to-fly, with the 3s 2600mah battery. The rule of thumb of having 100 watts of motor output for each pound of airplane is in play here. 100 watts per pound of plane is plenty of power for aerobatic performance, but not 3D.  With a draw of 30 amps on the 11.1V 3s battery, output watts are 333 (11.1 x 30). A ratio of 100 watts per pound would be 325, so it is perfectly in the correct power/weight range.

All in, including the obligatory trip to the hobby shop for spinner, a random servo and a few EC3 connectors, this plane came in right around $190 and it’s a quality plane.

I’ll post an update after I fly it. It should be a gentle flyer with plenty of power. I hate underpowered airplanes 😉

8/9/17

Maiden flight required two clicks of aileron and three clicks of elevator trim. As expected, very predictable and easy airplane to fly. This plane is so much fun to land. I’ll mostly shoot landings with it. Had a 15 mph direct crosswind today. No problems really. I won’t fly it in much more wind that that. It’s light.

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