Keefer

My Feedback: (2)

I'm looking for ideas or suggestions as to how I might power a conversion of a Goldberg Jr. Skylark to twin electrics? The kit is a recreation by Early RC Models, LLC.

The plane was originally designed for single .049 or twin .020 engines. I was planning on building it with twin Cox TD .020s on throttle sleeves, but I don't have any confidence that I could get two TD .020s to run together consistently. I DO believe I could easily do this with e-power.

It's a 37.5" span plane.

What would be a good motor setup for this? Brushless have the higher power/weight ratio, right?

Matt Kirsch

My Feedback: (21)

On a plane that small, brushless probably wouldn't be necessary. I'm thinking that a 2-cell LiPoly and a pair of GWS IPS drives would probably be more than enough.

Keefer

My Feedback: (2)

This plane will way up towards 20 oz. Are there different sizes of GWS, or is that a standard motor? How does a "GWS" compare to a "speed 400" or "020".

jonathanbachman

I'm thinking of converting a Great Planes EasySport with three inexpensive brushed motors - the GWS 400 series is one candidate.
The goal being to avoid paying $250.00 for large single brushless. Not sure if I'm going to be successful ... but he project is a long term one.
Look at Ford Trimotor (close) and Partenavia twin (closer) as models. The challenges I expect to face are ESC choice, batter choice.
Anyone willing to give some recommendations for this crazy project?

mtacoustic

I adapted an old original Goldberg kit for two Graupner speed 400s. The motors are set for reverse rotation using stock nylon .049 props. The motors are a simple matter to mount- just roll up some paper tubes to fit the motor diameter & glue to the plywood firewalls. On an 8-cell NiMh pack it flies up a storm & is very stable. I use strip ailerons rather than rudder control. I had photos published in a British RC mag "Quiet Electric Flight International" awhile back. I'd post photos, but can't figure out how to attach them here. I'd be happy to e-mail them. Cheers! Stan

d_bodary

My Feedback: (85)

I will be building a Jr. Skylark twin. Scratch built of course. I ordered to 400 size outrunners for it from Hobby Lobby they were on sale for 24.99 each. I also saw and had a chance to fly one of the original twin skylarks. It had two speed 400's from a zagi guessing a 55 inch wingspan. Using stock zagi props. It flew pretty well I think it was nimh batteries. it was not lithium. Seemed like it could have used a little more power but it flew pretty nice.

Dennis

mtacoustic

Good luck with your Skylark Jr! It is a sweet little airplane. If I was to build a second plane, I would recommend altering the inner wings to carry the flat Li batteries. You could even use cooling slots like those on a DH Mosquito, with a battery on each side. With couter-rotating props the rudder is unneccessary; but with large propped bushless motors turning the same way, the rudder will be needed. I have photos posted for my model under "twins" --Happy flying! --SJ

d_bodary

My Feedback: (85)

Thanks for the info on modifying the inner wings. I think i may have to include the modification.

Dennis