Ancient Goldberg Cub conversion to electric - RC Groups
Thread Tools
Mar 20, 2016, 05:51 AM
Fullscale Jetmech
Wrenchbody's Avatar
Discussion

Ancient Goldberg Cub conversion to electric


23 year old Goldberg Anniversary Cub brought back into flying condition. Old nitro burner with K&B .61 removed and clean electric conversion performed. Installed .46 brushless outrunner with 5S lipo battery turning a 13 x 6.5E APC. Weight with 3600 mAH pack 8 lbs. Metallic Plum Monokote with Metallic green and chrome striping. New windshield from Fiberglass Specialties. 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. First flight in 18 years upcoming soon.
Sign up now
to remove ads between posts
Mar 20, 2016, 06:54 AM
aka eyesoar
Arecer's Avatar
Wow...does that bring back memories!

Remember this plane when it was glow powered, a lot of water has gone under the bridge since then!

Good luck with the re-maiden WB...and go easy on the elevator travel (as I recall, you always liked lots of it) **smile**

BTW, nice job on the cowling!
Mar 20, 2016, 09:28 AM
Kimbers Keeper.
BHOFM's Avatar
Looks good, but the long motor mounts make me nervous. I like something a bit more stable.

Mar 20, 2016, 05:42 PM
Cajun-American
Boogie_'s Avatar
Nice work on the cowl.

The long bolts are fine.
Most of my motors are mounted the same way.
Big props, 4s - 6s power systems, 1000w - 1500w with no problems after years of flying.

Heck, I don't even use spacers.
Just jam nuts with a spot of thread locker.
Mar 20, 2016, 06:40 PM
Fullscale Jetmech
Wrenchbody's Avatar
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 a heavy 3600 5S lipo as close to the firewall as possible in the cabin. 80A ESC handles an average 40A motor draw at full power. Will post flight findings as soon as I find the time to fly. Just got my "drone" license for it and need to start using it!
Mar 20, 2016, 07:59 PM
Registered User
Quote:
Originally Posted by wrenchbody
23 year old goldberg anniversary cub brought back into flying condition. Old nitro burner with k&b .61 removed and clean electric conversion performed. Installed .46 brushless outrunner with 5s lipo battery turning a 13 x 6.5e apc. Weight with 3600 mah pack 8 lbs. Metallic plum monokote with metallic green and chrome striping. New windshield from fiberglass specialties. 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. First flight in 18 years upcoming soon.
nice job!!
Apr 02, 2016, 11:06 PM
Fullscale Jetmech
Wrenchbody's Avatar

First flight electric


Finally! Got the Cub out for its first flight electric powered and first flight in about 19 years. Powered with the Exceed RC Monster Power 46 it was quite a performer. Unlimited vertical climb with the left stick pushed north. This bird is heavy at 8 total pounds. Used a 13x6.5E APC prop which should be drawing close to 35A given the pressure altitude here in Tucson today. Have a 13x8E to install if needed which will push the amperage a little over 40 and add a lot of total thrust. Man, I was rusty on the sticks, at least 15 years since my last flight, 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. Pictures attached and simple repair in work. Now to find a good powerplant to spark up my Kaos 40, something with a little more RPM per volt.
Last edited by Wrenchbody; Apr 03, 2016 at 10:38 PM. Reason: typo
Apr 02, 2016, 11:19 PM
Fullscale Jetmech
Wrenchbody's Avatar
OK Eyesoar, of course you are correct. Even with my "low dual rate" setting on the pitch control for the Cub, it was still too much! First loop with full up elevator input resulted in a Roop. Brought back to say about half pitch lever input it did a fantastic loop, power off coming over the top and still has enough throttle off velocity for an aileron roll at the bottom. Now I am going to get the Kaos sparked up. Stay tuned!
Apr 03, 2016, 07:19 AM
Cajun-American
Boogie_'s Avatar
Good job


Thread Tools