Sailplane winch speed control

[Big 'n Dangerous]

I am looking for any information about speed control of glider winches rather than just on off foot control.... I drive like that not sure that I should get into winching like that! :D

[Gary Warner]

I am looking for any information about speed control of glider winches rather than just on off foot control.... I drive like that not sure that I should get into winching like that! :D

Modified golf-cart ECS?

Taping the foot on/off switch might be better in the long run. I don't know about you, but I can loose a bit of my balance as I follow the plane on launch. I think trying to keep my foot at "X" position without over throttling would be hard to do all the time. I'd say get used to an on/off switch. (oops... sorry, you didn't ask for my opinion - my bad :o , I don't like it when it's done to me :p )

Gary
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[Comatose]

How much current does your winch pull? Possibly what you'd want is a microcontroller with some sort of velocity profile programmed into it, that would then output to an ESC or motor driver via serial or R/C pulse or analog.

[Mr.RC-CAM]

How about a high current R/C ESC connected to a servo tester (servo pulse generator)? The servo tester board, or just its pot, could be built into the winch pedal. Heck, you could control the entire affair using a spare channel (throttle?) of the Tx if you stuck a R/C Rx in the winch control box.

I'm not a winch user, so I just don't know what is best for the app. So, please be kind to my suggestions. :)

[Terry S]

You can fix the speed control pot to a spring loaded arm on the winch cable and you will be able to just set the amount of pull you need. It will auto adjust to the wind for a perfect pull. We used simular for winching hang gliders.

Terry

[jbeanelliott]

You might consider the following 2 electronic speed controllers that could be adpated for use with a winch:

AXE-2444, 12-24v, 400A for 2 minutes, 200A for 1hr
http://www.alltraxinc.com/old/prod01.htm

MC1-HV $375.00 400 amp continuous (700 amp surge) speed controller with PWM input
http://robot-solutions.com/RS1/

-John Elliott

[deh6]

I've given a lot of thought to a controller, thinking along the lines of controlling the tension on the winch line. In the end I think that what would be gained is small compared to the added complexity. Dealing with the high currents and transients from inductance makes it a non-trivial undertaking.
.

[Terry S]

Thats a fair comment but with the Power FETs we have these days I think its workable. For a winch there is no restriction on weight so a big heat sink is a good option. As Comatose asked what current/volts are we talking about ?

Terry

[Windrider53]

I have a winch built from plans from RCM several years ago. It is quite simple in that there are no electronics, but the torque, thus line tension is easily controlled. Very simply, the winch motor is supported by the shaft on one end and a pivot on the other so it is allowed to rotate. The positive battery wire is not connected directly to the terminal, instead it connects to a high current contact (out of a car started solenoid) that is fixed to the frame of the winch. The other contact is mounted on a small bracket on the motor terminal such that any tension on the line wants to pull the two contacts apart. An "accelerator" pedal is then attached to the motor body with a spring such that it pulls the contacts together. When you step on the pedal it closes the contacts until the line tension overcomes the spring tension which opens them. The motor rocks back and forth on its pivots slightly as the contacts open and close. The tension is adjusted by how hard you press on the pedal and/or by changing the spring. I have lunched everything from small hand lunched gliders to large, very heavy scale gliders with this winch with no troubles.

I think I still have the article, so I could scan it (legal issues here?) or I could draw up a CAD drawing of what worked for me if anyone is interested.

[jbeanelliott]

You might get a ballpark idea of the maximum amps to expect by looking at the FAI Sporting Code for F3B at the following webpage.
http://www.ctie.monash.edu.au/hargrave/sc4-f3bj.04.pdf

Excerpt from page 10 of above document says:
"The complete winch equipment (battery, cables, switch and motor) must have a total resistance of at least 23,0 milliohms."

So using I=V/R and depending on how much the voltage of the battery drops under load we are looking at around 400 amps maximum for an F3B-legal winch. A USA-style Ford starter motor winch might well draw more amps.

I believe the F3B-legal European winches typically use a motor rated at about 1.5 killowatts.

I believe the USA-style Ford starter motor winches typically use a motor rated at about 4 killowatts.

-John Elliott

[vintage1]

If we are up around 400A - and from memory a SMALL starter motor pulls over 200 on startup, then a standard switching ESC wth outboard FETS should do the job.

Instead of a single FET you want about ten or so on a fat heatsink.

Simply take a small ESC - say a decent 5A one, and use it as a driver for the 10 MOSFETS

Then get a servo tester, and get an accelartor mechanism from a wracked drive-by-wire car..or a guitar volume pedal..mate that lot up and it should work.

I have a mate who used to build extremely high current pulsed power supplies for electroplating...its really mostly brute force and ignorance..just amke sure you have low value resitirs in series with the FET gates to prevent oscillation, paralell them up and drive them from the ESC..and a pull down resistor (or is it a pull up?) of about 100 ohms to simulate motor impedance..