Size of spool/amount of line /effect on launch

[ClayH]

If you have two winches with @ the same motor power, what are the effects throughout the stages of the launch of having a larger diameter spool full of line versus a smaller spool with minimum line. We had two winches out today and noticed that the larger spool full of line had the most powerup the line and on the zoom. The other winch had a smaller spool and the power was more manageble.

Is there any easy way to check RPM to see how close the motors are in speed ?

Both motors appear to be Ford Longshaft or Injoy types.

Thanks,

Clay

[Mark Miller]

All else being equal the winch with the larger diameter spool will have more speed and the one with the smaller spool has more power (torque). I usuallt try and put enough line on my spool so that there is only a layer or two on the spool when the winch and turn around are set up.

Mark Miller

[tewatson]

This is the reason that FAI winches are limited to a minimum drum width of 200mm, and there are usually just a few wraps of line on the drum when ready to launch. Minimal increase in line speed as the launch progresses.

Tom

[mlee8249]

Hi Clay,

I used to have the standard winch drum that was about 3-inch diameter, but I noted that I didn't need speed as much as I needed torque. So, I dropped down to the 2 inch drum diameter and got two things....I got torque like crazy and I got longer lasting winch motors. I was going through a motor about every 18 months. (of course, my winch was the "club" winch). With the smaller drum, it is less load on the motor. We did a measurement of amp draw one time, and the gauge could read up to 600-amps. At the moment of launch and through rotation, the meter could not read the draw...it was above the 600-amp mark!

I now run the 2-inch diameter drum with an Injoy motor, and I get torque and very good speed from my winch. Now, if you want some real ping at the top, just lace about 200-ft of monofilament on the winch line! I place about 400-ft on mine to simulate an F3J launch.

Thanks!

[rogerflies]

That's why it's so important to set the winch up so the line winds level back-and-forth across the drum. Letting it pile up on one side puts a real strain on the motor and hurts the launch.

Getting the right amount of line on the winch can be a problem for people who fly on fields where they can't always put out all the line. I once built a divided drum just for that situation. The larger part close to the motor was the working part, the small section at the outer end was a storage area for unused line. A groove machined in the side of the divider allowed the line to cross over without getting rubbed.

The result was almost-optimum winch performance regardless of the amount of line laid out. The downside was that the working part was slightly narrower, and it filled up a little faster as the launch progressed.

Roger

[jbrandon]

If you have two winches with @ the same motor power, what are the effects throughout the stages of the launch of having a larger diameter spool full of line versus a smaller spool with minimum line. We had two winches out today and noticed that the larger spool full of line had the most powerup the line and on the zoom. The other winch had a smaller spool and the power was more manageble.

Is there any easy way to check RPM to see how close the motors are in speed ?

Both motors appear to be Ford Longshaft or Injoy types.

Thanks,

Clay
I believe you are comparing a FLS 3110 to the new motors I am using on my winches – I think the winch in question is a Winch2048. The RPM of both motors is very similar, horse power from the 3110 is probably about 3.5-3.8 and from the other motor is 4.8HP. The motor in the Winch2048 is not from Injoy but is very similar in design and specifications. I also believe Mark has some Dacron line on his “Black Widow” winch which is not stretchy as the Nylon #36 (330#) used on the Winch2048.

The whole setup between drum core, line and the motor power is a balancing act. As one in is creased another will decrease. In the end it is subjective to the person launching. I personally like the smaller diameter core with the smoother application of power during the entire launch. I prefer the stretchiness of Nylon to the jerkiness of the Dacron line.

When I first started with these new motors I did extensive static testing with varying loads and not much documentation. One of the things I noticed first off was when the motor had power applied with no load it would spin up to about 2600-2700RMP fast then slowly build to a maximum of about 3000RPM. I used an optical RPM meter, not necessarily the best or most accurate. Free run current is about 65A. Field testing proved a different story. I did a much better job of documenting the results. The only thing I a sorry for is I did not have a recording amp meter so all I could get was general average or peak readings. Peak I would see as high as 480A, average during the whole launch ran around 180A. This was using the meters average and peak reading capabilities.

I do believe the apparent power from the larger diameter core and the Dacron line is what you are experiencing at the expense of battery life and stress on the motor and aircraft.

A few years ago I did some testing with drum core diameters ranging from 2” though 3”. I was more interested in current draw than anything else at the time and I did not check RPM other than applying the same load on the motor and had no way of measuring torque. The drums were identical (as far as width and flange diameter only the core changed.

I used a strap wrapped around the drum to provide resistance and with each drum core size and force was applied to get the motor to 1000 RPM and a current reading was taken. Motor used was a Lester 3110 with ball bearing endplates and timed to produce the best speed with minimum current draw at free run. Free run current was 85A. Meter used was a Fluke with a 600DCA clamp.

2” = 180A
2 1/4" = 194A
2 1/2” = 205A
2 3/4" = 245A
3” = 295A

Launching experience was subjective and as you stated with the smaller diameter the power/torque is more even and easier to manage. I never launched from anything bigger than the 2 1/2" core. During this test the line used was braided Nylon #24 with a 250# breaking strength.

Jim Brandon

[jrerickson]

Clay,

A really easy way to think about it is to compare it to a 10 speed bike (I'm dating myself right now, modern bikes are more like 27 speed). When you want to go up a hill on your bike the arrangement is small chainwheel in front, big sprocket in back. When you want to go fast it's big chainwheel in front and small sprocket in back.

So small diameter spool equals more torque, larger diameter equals higher speed. The stretch and weight of the line are just as important, as Mike said.

I would think that you could use a timing light to check RPM, but it's tricky as the RPM changes during the course of a launch.

John

[tewatson]

I would think that you could use a timing light...

Now you're really dating yourself!

Tom

[ClayH]

Jim,

Thanks for the detailed reply. We are really enjoying using your 2048 winch. It gives very clean pulls, is very predictable and I've had some excellent launches from it. It is especially efficient. My Optima was still reading 12.5 volts at the end of the day after doing probably 40 launches amongst our group.

We put enough line on for a 500 foot turn around so the amount of line is minimal. And with the 300lb test the spool gets smaller in a hurry as the thick line comes off. I like the setup and plan on many years of great launches with it!

Clay