Not a new concept but well executed. Nice work. I’ve always thought that a second RX, toggled from the tx could be more interesting than a foot pedal, and should do away with the return pulley.

I'm pretty sure that some searches would turn up at least one similar project from a few years ago. And as I recall they had a similar issue with the drum size not being big enough to get the line to come in fast enough for flying.

It might be better if a different tool than a hand drill were to be used. Perhaps an angle grinder? on my 18v hand drill the max RPM is 1600. The same brand 18v angle grinder spins at 6500.

The downside is that it's full on or full off. But that just means that one needs to pulse the switch like we did in the past. Or perhaps it could be wired into a speed control from a hand drill or one of the online PWM DC motor speed controls.

Another option might be a circular saw with the base removed and a drum taking the place of the blade. The guard would need to be modified as well. Again it's a purely on-off switch so either pulse the power or fit a speed control as with the angle grinder option. So some permanent modification needed to either tool.

Why not use a large diameter, low KV brushless motor direct drive to the drum as a winch?

Yup. There are simple plans and threads going about for exactly that. A decent esc, lipo and second rx.

That's not a bad idea either. I'm seeing motors and 60 amp ESC's out there which even paired with a spare receiver and separate BEC (depending on input voltage) would come in at the same or less cost of a power tool.

I'm a bit puzzled over the favoring of a smaller winch vs a suitable hi start though. A hi start avoids the need for a turn around pulley and at the same time the drag of the line in often times damp grass. And anyone that has pulled back winch lines knows that the wet grass drag is not to be sneezed at. A high start doesn't need batteries and is less bulky than even a compact winch with turn around pulley.

So other than perhaps less tension during the walk back for the next launch what's the attraction?

With a small winch driven by a rx, there’s no need for a turn around. It’s infinitely more portable as a result of that. It’s basically a bungee equivalent without the rubber I guess. If the wind changes, which is pretty much a promise as soon as you roll out a bungee or winch, you can relocate it easily.

A two or three position switch on tx for preset motor speed, and a push n hold like DLG launch mode to turn motor on. Should work fine. Either a direct drive or a pulley and small belt will work ok as a drive structure. Think along the lines of the old belts on rc nitro boats that sat around the shaft.

Oh geez... serious face palm on my part aimed at myself Of course it doesn't need to be at the pilot's location.

Just make sure it's spiked down heavy enough that someone doesn't try to walk away with it.

I was still thinking about the hand drill or other power tool option with the trigger switch run by the flyer's foot like a typical standard winch and local switch.

Of course being at the other side of the field some extra efforts at avoiding line snags at the drum would be needed. Slow start feature? Never mind that! We would want a slow STOP feature!

Hmmm... Just occurred as I hit the post button. A servo running off the winch channel that when the winch shuts off it moves the servo to apply a soft sort of brake to the line. Something like a block of foam rubber? Just to stop the otherwise far too common drum snarls.

Most esc’s can have both soft start, soft stop and various brake functions...

It’s ok. I’ve been thinking about this concept for a while. My next step would be to manufacture a drum and make a base to mount it on. Motor mount one fixed hole, other in a radiused slot to allow tensioning of belt. I envisage a narrowish drum maybe 4-6” on the spool although I had another random though.
looking at some larger fishing reels a spool from one of those may suit. Bonus is you may be able to direct drive the reel and utilise the gearing maybe. Although the gearing is probably the wrong way. The spool turns 5 or so times faster than the crank handle/ motor. Hmmmm. There’s a bunch of options I guess

I like your idea of a belt... or perhaps a slight gear reduction drive? The other option might be a direct drive but with a precisely located support bearing for the drum. Or a drum with shaft in two bearings and the motor driving the drum directly through a universal joint of some sort. Like get it really close so there's not a lot of frictional loses but using the joint that does not require super precision accuracy on the build and setup.

I'd be very interested to know if anyone has ever tested how much winch power is saved by eliminating a turnaround. The turnaround pulley and line drag on the ground probably take up quite a bit of the power, leading to the possibility of a smaller motor and battery. Speed control on the motor would also enable adjustment for differing plane weights/spans and to individual launch preferences. Just eliminating an automotive 12V battery would be a significant saving in cost and portability.

A good electric sailplane launch requires ~275W/kg and I would have thought propeller inefficiency must absorb a good part of that. So this gives an approximate starting point for power requirements.

Am I misunderstanding post #s 2 & 5? A 2nd Rx on the Tx?

Andy, the setups I've flown with at the clubs all used ground level turnarounds so the line from winch to turnaround always ran in the grass. But a lot of setups I've seen in pictures use turnarounds up on a post with serious cable braces to screw in big dog tie downs.

Thinking a bit more on this I'd suggest that speed isn't the proper control. Torque control is the real issue. Torque control would give us the same effect as being able to control the cross section of the rubber on the fly in a high start. And with torque control the motor would then speed up or slow down as needed while maintaining the line tension. I'd even suggest that if we're making a bespoke brushless motor based mini winch that a special controller be built where the pedal controls the torque from zero up to the pre-set limit to suit the model.

The controller would also need to be able to deal with the motor being spun backwards at the same time that power is re-applied. Brushed motors don't care other than they'll pull a lot of extra current. I'm not sure how most regular brushless ESC's would handle that.

Bruce, yes torque control would probably work better.

To summarize all this, if someone designs a compact low weight more portable winch with power capable of launching up to a typical 3-4m plane, with control on the power, then I think they will have a winner. I would love to have a go at it, but just too many projects either on the bench, drawing board or mind's eye.

Originally Posted by Andy Meysner

Bruce, yes torque control would probably work better.

To summarize all this, if someone designs a compact low weight more portable winch with power capable of launching up to a typical 3-4m plane, with control on the power, then I think they will have a winner. I would love to have a go at it, but just too many projects either on the bench, drawing board or mind's eye.

Here is a compact variable speed winch I built recently. Scooter motors are available in higher wattages and could easily launch a 4M sailplane. We are able to launch anything from a small free flight towline glider to a heavy Aegea Mantis on a 300 watt motor with the PWM speed controller. I have incorporated it into a retriever but you do not need to do that. Allen Moore on YouTube did a great job in explaining how he designed his winch and clearly shows all the calculations that went into his design - DIY RC Glider winch - https://youtu.be/1_ViD_TcJ8o"]https://youtu.be/1_ViD_TcJ8o

Unfortunately the art of winching a sailplane is a dying art. The small amount of information that is available is typically contest winching which is not applicable to scale or general 2M woody type of flying. You do not need a big starter motor to have high-start type launches for sport flying.

https://www.rcgroups.com/forums/show...-and-retriever

Originally Posted by BMatthews

Thinking a bit more on this I'd suggest that speed isn't the proper control. Torque control is the real issue. Torque control would give us the same effect as being able to control the cross section of the rubber on the fly in a high start. And with torque control the motor would then speed up or slow down as needed while maintaining the line tension.

For what it's worth, with electric motors, current is directly and linearly related to torque, and is much easier to measure. The hard part is avoiding feedback loops due to latency between measurement and control. Smoothing by averaging helps, but increases latency.