Electrified Goldberg Cub
05-24-2016, 09:03 PM
#1
Fullscale JetMech
Thread Starter
Join Date: May 2016
Location: Baja Arizona
Posts: 4
Electrified Goldberg Cub
Kit built 23 year old Goldberg Anniversary Cub brought back into flying condition. The original build on this airframe included wing beef up mods in the center section allowing it to fly without wing struts and pull many Gs with no risk of failure. Old nitro burner K&B .61 was removed and clean electric conversion performed. Installed Exceed RC Monster Power .46 brushless outrunner with 5S lipo battery turning a 13 x 6.5E APC. All up weight with 3600 mAh pack comes in at 8 lbs. Metallic Plum Monokote with metallic green and chrome striping. Battle Troll for scale pilot effect. (Insult to Trolls everywhere)! New windshield from Fiberglass Specialties installed. Converted the original custom balsa cowling from gas to electric and recovered. Calculated 6 lbs. static thrust with this prop and almost 7 lbs. thrust with 13x8E here at 2600' elevation. Construction of the motor mount conversion as follows: #10 steel screws with nylon locking nuts. Stainless washers stacked with aluminum spacer tubing. Can change washer stacking to adjust the thrust angle of the prop. The mount ended up very rigid, even more than expected. No problem with a little extra weight in front and needed to move the motor 3 inches out from the firewall for weight and balance purposes. Have the heavy 3600 5S lipo as close to the firewall as possible in the cabin as well. 80A ESC handles an average 40A motor draw at full power with BEC supplying the receiver power. Used a 13x6.5E APC prop which should be drawing close to 35A given the average altitude and temps here in S. AZ. Have a 13x8E to install if needed which will push the amperage a little over 40 and add a lot of total thrust. It was at least 15 years since my last flight and more than that for the Cub, but still a pretty comfortable test flight. Very little initial trim needed for level flight at about half power lever angle. Was a "calm" wind day but still had unpredictable gusts to about 5-7 knots. Did several passes with touch and goes and 2 full stops. The last one with a quartering tailwind gust that left me stalled a little sooner than predicted. Resulted in a little wingtip rash on the RH side. Flying rouge off of a deserted dead end blacktop road, that tarmac was pretty unforgiving on the Monokote. Wingtips beefed up and protected with some 3M propeller erosion tape. Ready for some more flying, and the next conversion project.
Last edited by Wrenchbody; 05-26-2016 at 08:56 AM.
