one successful Electric control line formula - RC Groups
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May 31, 2001, 05:19 AM
Registered User

one successful Electric control line formula

I took a 1.2 metre cabin model I had on hand. This had a low camber wing about 10% thick ( intended for electric r/c powered by a 150 watt motor) and rebuilt the wing with zero dihedral. I added a control horn and elevator linkage and gave the rudder some right turn by holding it in position with a pin. I did all the recommended things for control line such as outer wing tip weight,raking the control wires and a little more wing on the control line side.
I then placed a plain bearing speed 700 in the plane in direct drive and propped it for around 22amps current draw.
It was fed by 10 cells (Sanyo 1400mAh SCR) and I used a switch for motor control and added a 30A fuse in case of early arrival.
I had misgivings about the weight but I suddenly had a rock solid model flying on 15 metre (45 feet) lines. Not fully aerobatic but capable of flying in strong wind and doing mild wing overs in my hands.
In the hands of someone who could actually fly control line it did loops without problem.
It is obvious that given a purpose designed model and an efficient power system that an aerobatic model is possible. No mess or noise and I guess around 5 minute flights.
The subtle advantages are, as I see it - these
The speed 700 has a strong shaft that can survive the odd nose over and is cheap and robust.
The size of model this set up can fly does not require a model that has been built down to a weight that few can accomplish.
The model can have wheels large enough to take off in rough paddocks instead of bowling green type circles.
It can use regular control lines.
I hope this is of use to someone.
My next fiddle with c/l is a speed 400 model which I suspect will not be as easy a project as this one was. I admire Mike Gretz's model but I fear it would not take off on my fields with that small wheel.

[This message has been edited by robertc (edited 09-05-2001).]
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Jun 02, 2001, 11:20 AM
Registered User

Thanks for posting your results and congratulations on a successful ecl flight. Any information I can get on 'what works' is a big help to me as I slowly plod ahead with my own ECL project. My airplane will be a little smaller than yours and use a speed 600 with fewer batteries, and so I am encouraged by your results. It's always nice when actual real-world results match up with "that ought to work, don't you think."

BTW, you mentioned propping for 22 amps. What prop did you actually use, and did you pick 22 amps based on projected motor longevity, operating temperature, or?
Jun 03, 2001, 03:42 AM
Registered User
Im only glad to put something back into the knowledge pool.
I chose to prop close to 20 amps because I felt that around 200 watts input would be sufficient to start with and the motor would be running reasonably efficiently once in the air. I think I used a modified propellor (because it was what I had at the time) so that is why my notes from that time dont mention the prop. I would like to hear your specs for the one you are building. I am making a speed 400 one at the moment. It flew today for two laps before the rubber banded battery decided to come off. My stupid mistake. Have since modified for more secure attachment to plane. ROG with 30 foot rather draggy lines of 25 thou fishing leader for my remote motor control.