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Author Topic: Walking in while winding  (Read 825 times)
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DavidOWade
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« on: September 05, 2018, 07:57:17 PM »

Is there a preferred or scientific methodology how to walk in while winding the rubber? I mean like stay out for the first half of the winds, or wait until 75% of desired torque before moving in, or whatever. I figure there is more to than just "golly that's pulling a lot, I should get closer". Ideas? Data?
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atesus
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« Reply #1 on: September 06, 2018, 12:45:56 AM »

Your examples are fairly close to what I do in practice. When I wind for turns, I wind 50% then start to walk. When I wind for torque, it's more like 60% before I start to walk.

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--atesus
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Red Buzzard
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« Reply #2 on: September 25, 2018, 11:18:23 PM »

Hi Dave,

I'm a little more anal than some and actually measure out from my stooge to 4x the motor length - that is the made-up motor length not the hook to peg distance or the length of a braided motor. Then I put in 60% of my winds at that distance. Then I walk in progressively as the turns build, hoping to be about a foot out from the model as the torque builds. If you count turns you should hit the nose at your number. If you do torque you might be a bit over because your torque will go down a bit as you place your nose block. I have also found that if you stop too far from the nose you may wind up with a clumsy glob of turns right at the Crockett hook which can make a mess of the nose unless you take the time to try to massage the knots back into the fuselage. Coming in smoothly and consistently really takes concentration and quick mental work to gauge your distance vs. the number of turns left.

And I am conservative at a 4x stretch before winding. I usually get two flights per motor.

Bill
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riversidedan
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« Reply #3 on: November 20, 2018, 11:47:22 PM »

long time "all phase modeler here and been flying OT rubber jobs for prolly 8-9  months  and have learned a lot, but still more trails and experimenting to do......models are cananda sr.....korda victory .......commercial.....comet cloud buster and the wonderful forgiving tuff "pacific ace 30 that has held up for many crash/burn flights! all models are P30

anyway take for instance ive been using 8 strands 1/8 22 in. long for the korda V and getting around 200 turns stretch winding which is nowhere enuff!
itll do about 4-5 laps but know its capable of more.......am aware the model needs atleast 12 strands but working with 8 for now.

so even with 8 strands 22in. long Ill feel it getting tight and back off at 200 turns. the rubber is SST FAI from a known source. question is why cant I get more winds??  
« Last Edit: November 21, 2018, 12:27:52 AM by riversidedan » Logged
vintagemike
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« Reply #4 on: November 21, 2018, 03:54:23 AM »

Pete Giggle used to have a string marked out with distances which he laid out on the floor when winding. He would start winding at the furthest mark, when he reached half turns he started walking in, at 75% turns he would be level with the next mark, basically he would be able to wind the same every time. He did win one or two comps as well!. The only thing was you didn't want to be around when he wanted to wind, he didn't use a stooge!!!! the rear peg was a piece of dural that only just poked out of the side of the fuselage _ nothing to hold on to!!! He also used to tell you off about taking the strain on the front of the model as well. By the time he had stretched the motor out to 5 times its length, wound (slowly, you cant stress the rubber) and then re-attached the nose block you had lost all feeling in both hands and arms!! I tried to make sure I was retrieving when he was winding!!!! RIP Peter.
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flydean1
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« Reply #5 on: November 21, 2018, 07:22:14 AM »

Dan, you need a torque meter.  Quit counting turns.  Easy to make.  Herb Kothe style plan is on this forum somewhere.  Do a search.  That way, you don't need to guess by "feel". 

Don't use the excuse "I am not a contest flyer, I don't need one of those."  Casual sport flyers need it, and a winding tube as well to protect your fuselage from needless destruction.

Search for torque meters by Herb Kothe.  Very simple and easy to make.  You can do it in an evening.
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calgoddard
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« Reply #6 on: November 21, 2018, 08:56:25 AM »

Dan -

Flydean1 is right.  You need to wind with a torque meter.  The hysteresis of the rubber we fly with varies from batch to batch.  It also varies in terms of the energy it can store based on temperature, how much it has previously been wound, how many times it has been wound, etc. I think both TAN II rubber and Tan Super Sport (TSS) rubber are made from proprietary formulas that include natural rubber (latex) and synthetic rubber.

With a given optimum trim, a model will perform consistently well if you wind a given motor size to a particular optimum launch torque.  Too little torque and the model will not climb as much as it could.  Too much torque and it will behave badly, such as going into a power stall and/or crashing.

By way of example, a first 8 x 1/8 inch rubber motor wound to 800 turns might yield 4 inch-ounces of torque.  A second 8 x 1/8 inch rubber motor made of a different batch of rubber wound to 800 turns might yield 5 inch-ounces of torque.  Don't rely on these figures. They are just ballpark numbers.  I would have to look at my flight notebook to get accurate data.  But the significant difference in torque for the same number of winds in my example is not unrealistic.

I use an estimated number of max turns I want to put into my motor as a gauge for winding.  For sport flying, winding to about 85% of the estimated breaking turns is a good target for me. After installing a blast tube I try to stretch the rubber motor 7 - 8 times its un-stretched length.  Then I put in half the estimated number of turns.  Next, I keep winding and gradually step in, hoping to get to the estimated max number of turns when the hook on my winder is near the forward end of the blast tube.  I watch my torque meter and wind more or less until I get to the optimum launch torque for the model I am winding, which I have recorded in my flight notebook.

Don DeLoach's spread sheet says that 85% of breaking turns for an 8 x 1/8 22 inch TSS rubber motor is 1,000.

BTW I love your selection of models.

If you live in Riverside, California, be sure to fly at Taibi field in Perris, which as you know is only about 7 - 10 miles south.  There are plenty of expert rubber fliers there on Wednesdays and Saturdays. There are contests throughout the year on Sundays.  Contact the SCAMPS, San Diego Orbiteers and/or the Scale Staffel free flight clubs.

If you are skittish about building your own torque meter, BMJR Models sells a torque meter for P-30 size models for around $20.  It is an excellent value. It should work for the size of rubber motors you are winding.


« Last Edit: November 21, 2018, 09:08:03 AM by calgoddard » Logged
tom arnold
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« Reply #7 on: November 21, 2018, 11:33:21 AM »

I can agree with Mike wholeheartedly about the BMJR torque meter and the ease and accuracy of using such a device. My only suggestion for it would be to cement on a white paper face of the readings as that classy black and gold face is really hard to read in the sunlight. Oh, and avoid continually stepping on it in the grass.....it really is disheartening. Fortunately, a little soldering will fix it up.

I am basically lazy and have a hard time thinking of 2 things at once so I have dispensed completely with counting turns and took the turn counter off my winder and wind only to torque. In winding I stretch the motor out to 4-6 times the slack length and to measure, drop a rag in the grass to mark the spot. Knowing what torque I want to fly at, say 6 inch/oz, I wind up to 5.5 in oz and then slowly walk in keeping the torque at that point as closely as I can and at the last foot, top it off to the 6 mark. My tortured logic says that will give the max number of turns for that torque. What that number of winds is, I could care less as that is all that is going in. I can't get in any more and I don't win by posting the number of winds but on the results of the flight. Hence, I pitched my turn counter.

There is a lot of scientific holes in my method, I am sure, but it gives me flights I am happy with and I feel I have a lot more control and understanding of my power package than just counting winds. As can be seen above, other excellent modelers do things differently and they certainly win more than me.
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calgoddard
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« Reply #8 on: November 21, 2018, 02:58:38 PM »

Dan -

Screw a cuphook to a 2 x 4 piece of lumber. Clamp the piece of lumber to a workbench or other suitable support.  Make sure the clamp is tight and secure.

Lube your 8 x 1/8 22-inch rubber with a suitable silicone lube like DOW CORNING 33. Hook one end of the rubber motor to the cup hook.  Hook your winder to the other end of the rubber motor.  Put on safety glasses. Stretch your rubber motor out at least 4 - 6 times its un-stretched length.  Start winding.  Wind to 500 turns. Then keep winding and gradually walk in. If you can't get at least 800 turns into your rubber motor without it breaking your rubber is probably no good.

If it does not break at 800 turns keep winding until it does break.  That is your actual max turns number.  In the future, don't wind past 85% of that number for a similar size rubber motor made from the same batch of rubber.

Good luck.
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riversidedan
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« Reply #9 on: November 21, 2018, 08:30:11 PM »

500 -800 turns?? yikes  Shocked!!!!!!!! Ive never gotten more than 250 on the size you mentioned and that was stretch wound, so if that's the case I can start blaming the rubber source Ive been buying from, just kiddin    so what I'm getting out of all this is " not to count turns but use a torque meter? if so how do I know how many turns ive put in the motor??   incorporate a turn counter? or just go by the torque meter? just bare with me this is a new phase for me to this rubber bizz

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riversidedan
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« Reply #10 on: November 22, 2018, 03:13:56 PM »

...btw thanx for the cup hook suggestion  will put that to good use

[/quote]
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Red Buzzard
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« Reply #11 on: December 03, 2018, 07:13:34 PM »

Hi Tom,

With reference to your reply #7 above, first thanks and what a slap on the forehead! BUT do you know if your method proves useful on larger motors? When winding my 16 strand 45 gram motors I walk out 4X the made-up length (12 feet), wind up to 60% of my estimated (from tables) maximum winds, then start to come in at a pace that puts me at the model's nose when the torque gets up to my target number (38 - 40 inch ounces). With your method, I would not start to come in until I saw something like 25 - 30 inch ounces. For an 85 gram motor at 28 strands x 40" long, I would likewise not come in until I got up to say 45 inch ounces if I wanted to launch at 50 inch ounces.

If you haven't used your method on larger motors, perhaps someone can comment. Along with a reply perhaps they can recommend a consistent "stretch" that works well - besides my 4X.

Many thanks to all,

Bill
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flydean1
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« Reply #12 on: December 03, 2018, 08:39:57 PM »

Large motors or small torque works every time.  You NEVER EVER, NEVER EVER, NEVER EVER, NEVER EVER, need to count turns.  If you are using a torque meter, number of turns is unimportant.

I don't mean any disrespect, I counted turns and used tables for years.  When I went to torque, LIFE got simpler. 

Yes, you should stretch at least 4X slack length, many say 6X is better for the very stretchy Tan Super Sport.  You will get more turns packed in using this technique, but actually you don't need to know  how many, just accept it on faith.
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Red Buzzard
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« Reply #13 on: December 03, 2018, 09:13:30 PM »

Hi Fly,

No disrespect taken and I get torque. My question actually had more to do with the point on the torque curve at which you take your first steps toward the model. Do you wind it all the way up to desired torque then come in? Do you have a percentage of max torque that you use? I think Tom's technique of hanging back as torque builds is an excellent suggestion. If it works consistently on big motors, I'm a happy camper.

Bill
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tom arnold
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« Reply #14 on: December 03, 2018, 10:20:29 PM »

Bill, I understand your question and I honestly admit that I don't know. The thought of winding motors to 50 in-oz sends me screaming into the night so I am a bad person to comment. My motors are  6 strands of 1/8th and I get terrified at 7 in-oz. Having said that though, my purpose of the slow walk-in is to have the motor knot all  along its length evenly. Otherwise you get that big tennis ball of a knot at the front that you struggle to shoehorn in the nose opening. Notice that my reasoning does not take into account the rubber hysteresis curve. It is all about an evenly knotted motor when I hook on the prop assembly. The second part of my reasoning is that my late walk-in is putting in the max winds at the max torque.

I also think that the larger motors may not work the same. I called friend Herb Kothe and discussed this question and he felt that a larger motor would burst if it was wound to flying torque while in the stretch. Herb has flown heavy duty rubber competition since the mid 40s and I place great value on his opinions. However, he and you fly with a LOT bigger motors than I do and things maybe different at that level. About the only way to find out is to try an experiment using a torque meter and a wind counter at the same time in your garage. You don't have to wind the motors to destruction, just pick a torque you want and try the two different walk-in methods and compare the winds finally put in. If you do, please share the results as it would be very interesting.
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flydean1
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« Reply #15 on: December 03, 2018, 10:37:55 PM »

OK Bill.  Me personally, I test a short section of motor made up to the same loops and width of the final motor.  Determine the breaking torque.  Then I pick a torque figure that is 85% of that.  Lets say my two loop motor breaks at 8 on my scale.   I will wind it to about 6.5 -6.8 and no more.  In the model, with a full length motor, same width and strands, I will stretch between 5X an 6X slack length and wind it to 5 at that point.  Then work my way in winding up at the nose with torque at the 6.5-6.8 figure.  Pull the winding tube (you DO have one of course), hang the prop on and launch.

Now I'm going to contradict myself.  On a test motor, outside the airplane, I will experiment with various winding techniques, with a (gosh I hate to say it) TURN COUNTER (man that hurt!) to see which stretch and wind technique will give you the most turns at launch torque.  Tom goes nearly all the way, I go 75%, I know some that win who go to 50% torque.  Your mileage will probably vary.

Once done, I don't ever count turns again, only torque.

Another advantage of torque meters comes in testing new designs.  Look at the thread of the Weddell-Williams racer.  He is constantly noting torque in his testing.  He would increase in steps.  Unfortunately, he wound up to more that his test level in competition and paid the price.

Here is an example.  I used to fly my Gollywock on 12 strands of 1/8.  It would go to nearly 30 ounce-inches on my scale.  For testing, I made up a motor of old black Champion rubber of twice the cross section--12 strands of 1/4.  It would "torque up" rather quickly, getting to 30 on about a quarter of the turns.  I had to ballast the model a bit to have the CG the same as the 1/8 strand motor.  I could actually test the model to slightly over 30 oz-in, say 35 to see if it was a safe launch torque.  I had much fewer turns so apart from the nearly vertical climb it wouldn't go very high, and the extra weight of the rubber and ballast kept it from gliding away.  I  was able to use a fairly small field for testing, but knew the model would be OK using the flying motor.

This is a real advantage on scale models which can be rather sensitive to torque.  You can find the max "safe" torque, then downsize the motor to get max performance.

Hope this helps.
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Red Buzzard
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« Reply #16 on: December 03, 2018, 11:12:28 PM »

Tom and Fly,

Thanks to you both. I do quite a bit of breaking of "experienced" motors and still have the remains of an 80 gram motor (24 x 40 1/8) that went all the way to 81 in./ozs. and caused quite a commotion when it blew up, broke loose from my test stand, and caromed around the garage. I am sure gossie has even more gory details. I am acquainted with Herb Kothe, too. But, Tom, I too have been plagued with the phenomenon of getting to the nose of the model too soon and paying later with a bunch at the rear or a jammed Crocket hook at the front from the uneven distribution of knots. I think the remedy may be found in staying out longer, letting more torque and winds build up before coming in. Hence my questions. Maybe gossie has ideas.

At the moment I am out of experienced motors, having broken 12 at a contest in Lost Hills. Usually if they survive two windings they count as experienced. Alas.

Bill
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flydean1
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« Reply #17 on: December 04, 2018, 09:58:13 AM »

When winding hard I assume my motors are good for only one flight.  If they survive, I use them for relatively low torque testing or sport flying.
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DerekMc
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« Reply #18 on: December 04, 2018, 12:26:34 PM »

Bill, with 28 strands you can wind it like a Wakefield motor. Stretch it as far as it will go using your full body weight. Start winding and at some point it will start pulling you in. Go with it and let the motor pull you into the plane. You want to be pretty close to full turns when you get to the plane.  With 28 strands of Tan 2 Super Sport you could hit 120+ inch ounces without to much trouble. And yes it will be good for one flight.  Frankly that's a waste of rubber in nostalgia classes.  A couple of lights at 80-90 in. oz. sounds pretty good Smiley  Just walk in a bit faster but still start with the full body weight stretch.
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Derek
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« Reply #19 on: December 04, 2018, 06:57:26 PM »

Thanks Derek,

When I pre-stretch 28 strands at 4.5X the length it does take a pretty good tug. Everyone laughs when I put down my stretch marker at contests, like Tom's rag, but it serves as a reminder when it feels like the motor is really fighting back. I've never leaned back with all my weight as I begin to think about a stooge-collapse that also happened to me destroying my best Lanzo Duplex.

We can compare notes next August. And, you're right, one does not have to go totally nuts when flying nostalgia...unless someone like you is sneaking up on me!

Bill
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