What electric power unit for .049 powered gliders? - RC Groups
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Aug 30, 2004, 10:27 AM
North East England

What electric power unit for .049 powered gliders?

Hi all

Can anyone give me a bit of advice regarding powered gliders; I have several plans for Cox .049 / 1cc diesel powered gliders which I built and flew in my 'messy fuel' days and I'd like to know what equivalent electric power units I could use. For example, one plan is for a simple 60" span all balsa built-up glider, flying weight about 16ozs or thereabouts - what electric motor/gearbox/prop would I need to fly it?

I have a few GWS EPS 300 motors with the 3.22 gearing - would this (or any of the GWS motors) be suitable, as I'm trying to keep costs down? As long as it could take the glider up to a decent height I'd be happy - I'm not looking for mega performance, I just want to get a glider up there!

Any advice and suggestions would be greatly appreciated.

Steve, North East England
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Aug 30, 2004, 11:04 AM
Dragons, WindMills, all Same
jcstalls's Avatar

If you can keep the AUW under 18ozs, at about a 60" span, a SP400 direct with 6x3 folder will work well, with say a Kan 950ma pack, or similar. Any heavier, or larger span, than a geared sp400 with about a 11x8 folder may be needed.

A properly setup and flown sp400 direct system with atain just about the same altitude as a geared system, and cover nearly three times the air. Instead of climbing on the prop, direct systems require you to maintain speed and climb up on the wing.

I have never tried using the 300 geared motors, although if funds are tight, it may be worth a try. As well as using a light battery pack and components.Go with what you have and try and keep everything as light as you can. And you are right, just enough power to get her up, can be a lot of fun.

Aug 30, 2004, 11:47 AM
outrageously large member
xtc's Avatar
a proven system http://www.hobby-lobby.com/skimmer400.htm
Aug 30, 2004, 12:13 PM
RPV builder & operator
Pierre Audette's Avatar
Since it's mainly a glider, you would typically be looking for max thrust for the best climbing, so a geared setup with a big folding prop works best. An 8x4.5 folder on 7-8 cells would work great on your SP300 gearbox.
Aug 30, 2004, 12:37 PM
Registered User
16 oz plane at 50 watts per lb = 50 watts OUTPUT motor. This is accomplished easily with a speed 400 on 7 cells. 10 amps X 8 volts times 60% efficiency is 48 watts OUTPUT, close enough. These motors cost 10-20 over here. They get less efficient as they wear out.

A 6-3 folder would be decent. I think your 300 motor geared will be a little wimpy.
Aug 31, 2004, 10:48 PM
Registered User
Andy W's Avatar
When quoting watts per pound, usually we just consider input watts. That's why brushless is so impressive - the efficiency of these motors makes a big difference in performance.
Sep 24, 2004, 12:14 PM
Registered User
robbie's Avatar
what did you decide to use?
Oct 06, 2004, 06:59 AM
North East England
Robbie - haven't used anything yet, as I put the whole 'powered glider' thing on the back burner and concentrated on a couple of sports models! I appreciate all the info though and I'll probably go for the direct drive s400 option when I eventually get round to building the glider.

Oct 06, 2004, 07:11 PM
Registered User
You should look at the Skimmer 400 as a kit. It flies well. They have a low wing version too. I have one. I sheeted a bit of the wing with 1/32 and capstrips and have flown it on anything from a long-can 400 to a mega 16-25 3 on 11 1700AUP sanyos. It pulled the firewall right off and was probably twice as much power as it ever could use, I think the weight was around 2-2 1/2 lbs depending on batteries. These "fully" 480n motors are pretty good for a brushed set-up. I would run a 6-3 folder and 8 or 9 1100 GP nimh

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