Originally Posted by aeajr

Hey, wait. We had the innovative idea of using this motor to build a winch. Has that now been dismissed?

Neil, are you going to build it? Oh, please, say you will. I want to see it work.

Thank for the encouragement, but we will be moving house soon and I won't have any time this summer. Also unfortunately my imagination is better than my engineering abilities.

I can accept that a small lipo powered geared winch may never be equivalent to a larger direct drive unit, but it could be much lighter, more convenient to use, and good enough for most non-competition use. Is there any need to have a turn around pulley, or could we use a 2.4GHz link to the winch, which is pegged where the turn around is normally situated? I can imagine a launch mode where my throttle stick controls the winch motor directly, no foot switch required.

Neil.

Originally Posted by Neil Stainton

Is there any need to have a turn around pulley, or could we use a 2.4GHz link to the winch, which is pegged where the turn around is normally situated? I can imagine a launch mode where my throttle stick controls the winch motor directly, no foot switch required.

What happens when you have to disconnect the battery in an emergency situation?

Found this article I got from somewhere- I can't remember where but it goes to show how simple it can be. Obviously this one is not good enough for anything larger than a handlaunch but interesting all the same.

"What happens when you have to disconnect the battery in an emergency situation? "

At least you'll be on the other side of the field when it blows up.



As to putting the entire winch on the far side of the field, you'll have a major problem with the line winding on one side of the drum unless you can fly straight as an arrow keeping the line perpendicular to the drum. Good luck with that.

If the line spills over the end of the drum, it'll jam. That'll ruin your launch, your line, and possibly your plane, since the line won't go slack like it needs to do to come off the hook.

You could put a turnaround in front of the winch, but it would have to be far enough away to make the line wind level on the drum. If the TA is on the far side of the winch, the line will probably snag on the winch often enough to make you go back to whatever you were doing before.

Having the winch off to one side of the TA seems like the best approach, but that leaves you with a TA, which is what you were trying to eliminate by having the winch over there in the first place.

Originally Posted by Wazmo

What happens when you have to disconnect the battery in an emergency situation?

I have yet to see an emergency shut off for an electric airplane ,maybe it's because they don't need them?

The only way a transmitter is going to control a winch is through an ESC. Solenoids get stuck from high current. ESC's just burn themselves up and fail to control the motor as in it stops running.

But yes safety is important even with a small motor! I know! I tried to see how much a small motor would "pull" a line by wrapping a line around the shaft and touching the wires to a battery with one hand and hold the line with the other. I came out the loser 135 pound nylon line burns big nasty cuts that take a long time to heal

Blue Skies....................Tim

I think a double solenoid setup would protect the winch. You could set up a circuit so that if one solenoid stuck, it wouldn't run at all. And maybe a third channel with a safety switch? A jam could be dealt with by guillotine. Full scale guys have winches without turnarounds. It might pay to study just how they do it.

Don't know if anyone else here is ancient enough to have been there, but I was at the 1981 F3B WC held in Sacramento. The Canadian team arrived with the winch which started all of the modern winch limitation rules.

I'm not sure of the motor used on this monstrosity. It had a drum of around 1 m in diameter and was powered by 36V of large lead-acid batteries. During use no one got within a hundred feet of this monster. This was in the days of the single lap F3B speed run. While everyone else was trying to get high launches and dive through the course, the Canucks launched their 5kg lead sleds directly onto the course at very low altitude. I don't know for sure that anyone got an accurate speed for the planes, but there was talk of coming off the end of the tow at 200 mph. Oh yeah, they exploded a couple of planes on launch, but it was sure cool to watch.

I always listen to the winch when I'm launching to judge how hard it's working and how much stress it's putting on the plane. I realize that's not a factor with the moldies, but I wouldn't feel comfortable launching when I couldn't hear the winch on the far side of the field.

Originally Posted by lincoln

I think a double solenoid setup would protect the winch. You could set up a circuit so that if one solenoid stuck, it wouldn't run at all. And maybe a third channel with a safety switch? A jam could be dealt with by guillotine. Full scale guys have winches without turnarounds. It might pay to study just how they do it.

Check this out - The Skynch: a one-man winch for paragliders and hang gliders - http://www.skynch.com/wordpress/

...

That's a slacker compared to this one, but mine's not as old.




They must have gotten some terrific line speed toward the end of the launch with that narrow drum.

Several months ago I started working on building a winch. Since I do not have access to a metal lathe or mill I decided to use wood. After searching and finding several articles where others have built winchs using wood I was able to find a starting point. This is not a modern winch but it is a cost effective one so far. It is not finished yet but is getting close.

Alan

Hey, ummmm... I have experience with wood drums. You won't be happy with that one. The line wraps around the drum core with incredible tension and it will pop the ends off your drum. Bust the plywood right off.

Multiply # of wraps X line tension = you get my drift...

Backing up with steel or alum plate might help.

Allen,
My first winch had a wooden drum just like yours. i did well over 1000 launches and had no problems what so ever with it.


JINKS D.

Seems like wood winch frames are lighter than the usual metal ones. I know mine is, and it was easy to make. I suspect the ends of that wood drum need a bit of reinforcement. Would not be too hard to do with fiberglass or something. Or maybe just thicker wood on the ends.