I have two gliders that I would like to convert to electric as I don't like messing with those little Cox engines. Anyways, I am asking all here on the forum to help me find a setup that I could easily switch between the two planes. I already have a transmitter and receiver and you can tell by their looks, I have flown them quite a bit. The larger one, Goldberg Gentle Lady, is in the process of being recovered and I may recover the smaller, Begin-Aire, although it is still in great shape, albeit a little dirty.

I don't know what all I need and am relying on those here on the forum to help me. Think of it as a little contest (with no reward, as I have no means to have one) who can come up with a decent setup that is easy on the wallet. If at all possible, if those that post a reply with a setup provide links to the parts. Since I am completely new to electric, full names of items would be appreciated (engine size, type of battery, etc.).

Please help me out cause summer is coming fast and I want to get my step-son out and fly!

How much will you sell the engines for?

NorfolkSouthern

haha... they are gummed up as all get out cause I haven't flown these for several years. I never really thought about it. I suppose that if someone really wanted them, they could have them for the cost of shipping them.

Do both of them still have the glow heads? I notice the one on the left doesn't seem to have one. I may be interested.

NorfolkSouthern

No, the one doesn't have a glow head.

I know I saw this cheaper just yesterday, but I can't seem to find it now. I was looking to do the same thing with my Spirit 2M

http://www3.towerhobbies.com/cgi-bin...?&I=LXZ904&P=0

I think you could design a receiver for the gearbox/motor so that it's easily removable to install on your other glider. Maybe a plywood rail?

It looks like a good unit. You could use a small, like 700mA two cell LiPo and a ESC. You would probably have to keep your RX battery though or get a ESC with a programmable BEC and set it's cutoff HIGH so you have enough RX battery to fly for an hour. In that case I'd go with a 1500mA 2C LiPo. Just thinking it out here for my benefit too. You really only need about 5min of run time to gain altitude, so I think the small LiPo with your RX battery for the radio gear would work and keep cost down. I'll bet it won't weigh any more than the little glow motor, tank, fuel and throttle servo (if you run a servo)

If you are new to electric flight, you might find this useful:

Everything you wanted to know about electric flight
http://www.rcuniverse.com/forum/m_7100376/tm.htm

You might get more responses in the Electric Aircraft forum or the glider forum. This forum is primarily for glow pilots which is why you are getting interest in your motors, but no real useful answers to your question. Let me see if I can help.

I would need to know their current all up weight, but I will take some guesses.

A Gentle Lady is typically between 25 an 28 ounces, all up flying weight without a motor. Let's target 32 ounces, 2 pounds, with a moto. When sizing electric power systems we usually use watts/pound to size the systems.

I am going to suggest you use a brushless outrunner type motor since it looks like you would just bolt it to the pylon, or attach it to the nose and get rid of the pylon.

Not sure what kind of rate of climb you want but I am going to suggest about 60 to 80 watts per pound. That should get you to about 600 feet in about 20 seconds. So that would translate to about a a 120 to 160 watt motor, more or less.

If you are going to put it on the pylon, I need to know the clearence. Gliders like big, slower turning props that fold. Would shoot for an 8 to 10 inch folding prop for that plane using a brushless outrunner of about 800 to 1000 KV rating. I would want the ESC to have a brake to stop the prop from spinning.

If you can provide the info I requested, maybe I can help.

As a first cut, this combination looks reasonable - I would put this on the nose and replace the fixed prop included with a folding prop.
http://www.maxxprod.com/mpi/pdf/combo-061-10-15.pdf

I love this lipo charger because it is so simple and so safe to use.
http://www.fmadirect.com/detail.htm?item=2218§ion=45

This pack would work
http://www.fmadirect.com/detail.htm?item=2269§ion=69

Now, this is a first cut which which needs to be tuned based on information from you. But it is a first blush. There are cheaper parts, chargers and batteries, but these are good quality parts that should serve you well. And the charger is a very popular charger among electric flyers. I have one.

If you put the motor on the nose, you can remove lead used to balance the plane and maybe come out the same or lighter overall.

We would have to judege if the battery would fit in the fuselage. Packs come in various shapes.

If you have battery packs you want to use, you did not mention it.

Feedback needed and more info please.

Ed:

I just wanted to let you know that I went to your "everything you wanted to know about electric flight" thread.

Outstanding job. Thanks for taking the time and putting in the effort necessary to put this together. It's very informative.

I've often used the "water" analogy to try to explain electric flow, current, voltage, and resistance (or impedance as applicable) so when I started reading your post, well, I had to smile.

I book-marked it so I can go back to it and read on.

As I am primarilly a glow guy, this electric flight is often confusing because there is no real correlation between glow engines and electric motor power. What I mean is what electric motor is comparable to a .46 glow engine? The current draw, ie. batteries and ESC's.. is pretty much self explanatory... as long as things match... as defined as: if you need 30 amps then it behooves you to get at least a 30 amp ESC and a battery pack. Match components that are capable of providing the necessary constant and burst current to run this motor also at the right voltage. (see below)

There seems to be more information coming out on the web from various locations about this correlation but it still needs work. At least it did the last time I tried to find out some specific information on what I was building and how to power it. It seems that everybody (meaning suppliers and manufacturers) has a different methodology and terminology for determining what to use.

I learned the hard way with my Bug ( The Bug www.lightflite.com ). I used the provided 2 cell LiPo pack and it flew great. Then I thought, well, if two cells works, the added voltage of the three pack of approximately the same capacity should work better, right? Ok.. we live and learn. The KV of the motor was fine with the 2 cell, but when I hit it with the 3 cell, well, things happened, and happened very quickly. Needless to say that I threw that motor out (an inexpensive, throw away CDRom motor ) and learned something about electric powered flight.. The components must match!!! As soon as I hit the throttle, the engine mount was not strong enough for the increased torque. This twisted in the mount and wrapped the wires around the mounting post. On top of that, it seems that the windings in the motor were not necessarily appropriate for the increased heat caused by the increased current draw and voltage (Ohm's law.. If resistance remains the same, increasing the voltage will increase the current). Soooo...

Anyway, I could go on, but you get the idea.

So, thanks for your work and for putting that where we can find it. It is really useful.

CGr.