Power over lines

[Berentsen]

Hi everybody!
Has anyone of you ever tried to bring
the power over the lines from
the handheld to the plane ?

Martin

[steve lewin]

Sure, it was discussed quite a lot ages ago in this forum.

The general view was that it can work for very small trainers on short lines, S400 or less, but not for anything requiring real power.

I've tried it but you lose so much power in the lines that it's really not worth the effort.

Steve

[Berentsen]

It's just for a park trainer. I'll
try it with a speed 280 motor,
7,5 m lines (0.25mm square) and
a 160g and 800mm span model. The power
loss is very high, but no problem, because the batery is not on board. My problem is the line itself. These 7,5 m (2x) have a weight of 66g, and that's really heavy.

Martin

[steve lewin]

Yes you're right the lines are the problem. You need to use copper to avoid too much power loss and copper is heavy. Because they must also have insulation it's also quick thick.

It was mainly the drag I noticed on the lines. Because of that and the weight you seem to need more that twice the power at the motor of an equivalent size RC plane. With a 12V battery I couldn't get my S400 trainer to fly on longer than about 20ft (6m) lines.

Good luck - Steve

[Berentsen]

Buzzflight did it with a S400 and
6m lines. But I've never seen
it flying. They use a 12V + 6V battery.

My S280 needs 11-12 cells NC to run with long lines.

Martin

[AIR MOVER]

use 22g magnet wire. with hot wound brushless cd rom motor control throttle with a hip mounted tx..

[clipclop]

If being able to control the motor is the reason for putting the power through the lines , Why not put the battery onboard and use a 3rd line to work a resistive speed contol?
Stewart

[steve lewin]

I think the main point of using external power is to precisely to avoid having to carry all that battery weight onboard. But if you do want throttle control 3 lines are likely to create at least as much drag as a pair of insulated lines.

If you're going to use an onboard battery it's probably easier to use a conventional speed controller and run that either from a servo tester type circuit at the handle or infra-red (as made by Ztron). Unfortunately resistive control is mainly a way of wasting a lot of your battery power as heat.

Steve