CL power setup?

[ETKing]

Hi all;

I'm new to e-flight, and have an idea/question.

Why couldn't you use insulated wires and send the power down the lines instead of carrying the battery on the plane? I realize there would be resistive losses, but you could use as high a voltage supply as you wanted to. Anyone tried this?

I've got a Banshee and a VooDoo in the rafters, maybe I should give em a try again!

[steve lewin]

Hi Eric

Plenty of people have talked about this but I'm not aware of anyone actually trying it. The difficulty is finding lines that are strong enough but sufficiently conductive that they will work at the sort of currents we need without adding an awful lot of extra drag and weight (probably more than an onboard battery).

The idea has been discussed here a few times but those threads seem to have gone in the latest clearout. Perhaps this will get it going again. I'd love to hear of someone trying it out but I don't have the nerve to do it myself. For power down the wires indoor RTP (Round the Pole) is as far as I go. If you do decide to try it please let us know how you get on.

Steve

[philc]

Please talk to an electrical engineer before trying this. Some simple calculations show that for any readily available lines you will need pretty high voltage, at least 50-60 volts. That is enough to be lethal. Some folks talked about putting 110v. on the lines. Just imagine what would happen WHEN, not IF the insulation broke and they short circuited! That kind of experimenting is just plain foolish.

[Ray Lowinski]

philc is very correct. The power companies do the hi V thing because of distances losses. I just heard of CL flyers trying 3 and 4 packs just to get the voltage needed for 1 pack at the plane. This was passed on by a friend who is very active in PAMPA. Somewhere I have the resistance specs for steel braided wire and will do the math unless someone else has it right at hand.

Another thing to consider if this is for stunt is that the coated fishing line does not slide on itself very well. After a loop or 2 you might not have the control needed to get back to level flight. They work for scale where great stunts are not required.

Keep 'em hummin'

Ray

[ETKing]

Well, it's never easy. I hadn't thought about line to line friction with insulation. That could be a problem. Apropriate inslulation and protection (fusing) should keep you from getting fried. Definitely would require more thought than I've done so far!

That gummed up old Fox 35 is sounding good right about now!

Thanks for the great input everyone.

[Ray Lowinski]

I would think that if RC planes like Shaw's (in the latest MA) and others can do very nice airbatics then the addition of a control line can't hurt that much. Yeah, yeah I realize the extra drag is not good.

Can motors just don't seem the way to go. Cobalts may be OK but for the price why not just go brushless for a little more? The Hacker looks good and of course Aveox is the old standby. Even .61's are not turning 14K rpm in the circle. About 10.5K to 11K I believe with a 12.5X4 or so prop. Might be a balancing act with power vs. thrust but isn't it always that way?

I'm still looking at some way to go with 10 to 14 cells in something around 650 to 720 sqin.

Keep 'em hummin'

Ray

[philc]

Line drag is soaks up about 2/3 of the power of a CL plane. Bill Netzeband published all the info to do calculations back in the mid 60's in American Modeler. Excellent series of articles. I haven't done a set of calculations lately, but if I remember right, the drag on a combat plane was about 2/3 lines, 1/3 plane. Stunt speeds would be less, maybe 50:50.

A Stunt 35 is putting out about .4 hp. to fly a Nobler. That means you would need about 350-400 watts to the motor.

Looking into some of the motor suggestions, it looks like with the right motor, prop, and 7-10 NiMh cells 2-3 minutes of decent performance is now possible. Question is, do I want to spend $400 to find out.(motor, gearbox, batteries, charger, controller, etc.)

[DrDiode]

There was a steel cable that was quite small that we used to fly these things on.If we could get good electrical connections to these they would be
sufficient to fly small stuff ,under slower flight speeds.The smaller lines the less drag they're gonna be.

The biggest problem we have is the insulation of the wires.

Running 280 motors and such up to about 5 amps should work on these...I'm expecting to see about a volt drop on the lines maybe 2. If that's true then run another cell.

...and by the way I'm an Electrical Engineer

[ETKing]

Getting the connections shouldn't be a problem, just solder the battery connector of your choice directly to steel lines.

What is "coated fishing line"? I've only used steel lines.

I was thinking more like S400 at least.

On the insulation and drag issues. You really only need to insulate one line! That helps a little.

[Bare]

That ole gummed up Fox 35 is looking good??
Mebe, but the plane it came out of surely is.
An average sized stunter has a decent chance of flying reasonably with electric, cuz you can use a motor with enough power to actually fly the thing and it's big enough so that it can passably carry all the cells requiredto achieve that goal.. duration will be the major issue, not power
In my couple of attempts with s400 CL (cuz some claimed they made it work!) were total failures... barely enough power to keep it in the air (ever see a Carrier event?) let alone fly interestingly.
Power thru the wires is a long held fantasy.. try it .. don't just guess about it....
Mebe you'll be the very first one to make it work;-)

[robertc]

Fishing line trace is steel wire with plastic covering for use close to the hook to prevent the fish from cutting the line. Available most fishing shops that cater for salt water fishing I would think.
Bare ,how about telling us what you built in the way of an S400 c/l model that did not work. Might be a lesson for us there. Mine works as I described it.
Regards
Bob

[lensrc]

If you used 10-12 volts A/C through the lines,then rectify to D/C in the plane it might work.power edison lost the electricity battle with GE because he used D/C. A/C travels farther with less loss than D/C......just my two cents............

[lensrc]

If you used 10-12 volts A/C through the lines,then rectify to D/C in the plane it might work.power edison lost the electricity battle with GE because he used D/C. A/C travels farther with less loss than D/C......just my two cents............

[Mark E]

In the May 2002 Model Aviation, there's an article about the Hillsdale Flyers (in New jersey) who are trying electric C/L to cut down on noise.

They describe a model that flies on power through the lines, and they've apparently built a few of thiem. They are using Speed 400 motors with a 12 Volt, 2.2AH belt mounted battery. Power goes through 20ft 22 gauge insulated wires.

So I guess it's possible!

[meed7]

Hi Folks - I know nothing about model airplanes; I just surfed in here looking to educate myself. I'd like to do a little electirc control line flying with my son, who's not ready for full R/C quite yet.

However I do know a bit about motors and electricity, and it looks to me like it's not out of the question to power a C/L plane thru the wires. It looks to me like the advantages would be easy throttle control of the model (i.e. from where the pilot is standing), no battery weight in the plane (I assume some ballast would be needed instead), and use of non-exotic/non-lightweight batteries (i.e. non-expensive), like car or motorcycle batteries.

First off, forget about steel wires and especially *stainless* steel wires... terrible conductors. The nichrome heating wires in your toaster are a distant relative of stainless steel.

I would suggest that insulated solid copper magnet wire is the stuff to look at. Hard-drawn copper is not half bad from a strength standpoint... 50,000 psi or so. Nobody will ever mistake it for steel music wire (300,000 psi), but it is roughly comparable to nylon monofilament. At least on a strength basis! Flex life is also an issue, and you are probably going to want a foot or two of stranded wire at both the airplane (bellcrank) and control handle end of the system... however for the straight run I would think that with care you could get several days of flying out of one set of wires. The wire's cheap enough (a penny or two per foot) that it can be considered quasi-expendable.

Anyway, just to choose some round numbers to play with, how about a 20 foot control line, which means a 40 foot round trip for the electrons. 40 feet of #24 magnet wire is going to have a resistance of about 1 ohm. If we are powering a 10 volt, 10 amp motor (100 watts, which I understand is the ballpark power of a .049 glow engine), then we'll loose 10 volts running that 10 amps thru the 1 ohm wire. To get 10 volts at the motor, we'll need 10 + 10 = 20 volts at the power source. A couple of 12V motorcycle batteries (or riding mower batteries) in series would be 24V, which would give you some headroom to play with.

The #24 magnet wire is about 1/50th of an inch in diameter (.021" with "single build" insulation) and has a tensile strength of about 16 pounds. I don't know what kind of strength is normally used for .049 C/L models, but this seems adequate to me... aren't we talking a model that weighs a pound or two? The 40 feet of wire will weigh about a half an ounce. I'll leave it to an experienced pilot to comment on the drag penalty of .020" control lines (That's about the size of 20 pound test nylon monofilament).

A couple of safety cautions, if anybody tries this! First, use a fuse between the battery and everything else! Get a simple inline fuseholder at a carparts store or Radio Shack, and a fuse rated for 1.5-2X normal motor current. Batteries can put out a lot of juice into a short circuit... we're talking skin-searing, metal-melting, fire-starting amounts of juice here... and sooner or later the control lines ARE going to short out. Second, half the power in the example above is dissipated in the wire (a 50% efficient system)... that's about 2.5 watts per foot of wire. The wire is going to get warm, but in free air it should be OK. DON'T run the wire inside of things and don't run the motor with the wire coiled up. Third, if you fly a plane with wire control lines into a powerline, you will die. Don't operate ANYWHERE near power lines... just don't do it. Similarly, don't fly in thunderstorm conditions.

Final comment, this was just a back-of-the-envelope excercise. The efficiency of power transmission goes up with the square of the voltage (hence the 200-500 kilovolt transmission lines bringing us our power), so anything to increase the motor voltage and decrease the motor current will pay big dividends. DON'T go over 48 volts, the commonly accepted upper end of "safe low voltage" (and be careful in wet weather even below that voltage), but there is obviously some room to experiement and optimize with this system.

I would welcome comments from experienced modellers on the flight-related aspects of this; I am just at the beginning of the learning curve. (From a safety standpoint, I would especially feel good if someone told me that gas C/L models routinely fly with metal control lines, without anybody getting killed or doing the Ben Franklin thing.)

Ed M

[Neil McGrath]

You could try these people. They have been producing RTP products for years. It might give you a few ideas!

http://www.housecodex.freeserve.co.uk/rtp/rtp.htm