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Author Topic: Best winding practises?  (Read 2470 times)
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spr
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« on: September 20, 2017, 04:42:06 PM »

Please share your winding methods - how to pack in a F1D/F1M rubber the huge amount of turns that appear in plans specs?

I end up several hundred winds short of those numbers before breaking the motor (OK, I have just SS rubber, but still)

 I usually stretch the rubber to 5-6x length and wind about 50-60% before coming slowly in. Apparently should do somehow differently - but how? 

I'm also interested in different break-in techniques: winding, stretching, etc?

- Simo
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piecost
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« Reply #1 on: September 20, 2017, 05:05:40 PM »

I would also really appreciate any advice. I recently undertook comparative testing of different batches. I found that the turns at which the torque increased varied between winds of the same batch. I attributed this to bunching. The rubber in the bunch not taking subsequent turns causing the effective length. Of the moror to reduce. This causes a premature rise in torque. This effect was geeater than the differences between batches. I concluded that my winding lacked finesse. I think that i come in from stretching too soon with too little concern for even distribution of knots and prevention of bunches. I stretch to fives times and reach half target torque before coming in.
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jakepF1D
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« Reply #2 on: September 20, 2017, 06:25:28 PM »

The numbers will vary greatly by batch.  A tan SS motor might take a couple hundred fewer turns than a 5/99 motor of the same size and length.  It will also hold significantly more peak torque than 5/99.  They really are apples and oranges.
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piecost
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« Reply #3 on: September 20, 2017, 06:46:16 PM »

I was comparing batches but also getting large differences between tests of the same batch. This was of similar orders of magnitude.
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Flyguy
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« Reply #4 on: September 20, 2017, 08:00:00 PM »

I'm not an expert on this, but will simply make a quick comment based on my experience as someone who wants to get the maximum winds - if you're only pulling to 5 or 6 times the resting length, that's the problem - when I did that you really can't get much more than about 85% winds. Now I pull to about 8-9 times the resting length. One thing I noticed by the way is that if you pull it as far as you can and put in a few winds, you can then pull it a little further. Coupe motors are a good example - when I was pulling them to about 6 times, I got in maybe 400-450 winds, now that I'm pulling them closer to 8-9 times, I'm getting in about 480-500+ winds. Same with P30 (before- about 1000, now - about 1150). So it's important to pull it as hard as you can.
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Flyguy
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« Reply #5 on: September 20, 2017, 09:05:28 PM »

Dammit, I'm so sorry, I didn't notice this was the indoor forum, I kind of saw that as F1B, F1G,..., need some rest. In any case, I guess even on indoor it doesn't hurt to pull it harder!
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dslusarc
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« Reply #6 on: September 20, 2017, 09:16:36 PM »

On the TSS, specifically the 6/16 batch the stretch ratio is less than batches like 5/99 but total energy is nearly the same. In general what you want to do is make a loop of TSS that is about 10% longer than 5/99 but still the same weight. This will get more turns in it. I know Jeff Annis did some testing like this and I think he came up with 12% longer for his batch of 6/16 and 5/99 to get equal turns and torque curve. If you make a loop the same length and weight as 5/99 it will take less turns and have higher torque. So the longer loop drops the torque and gives more turns. I know John Kagan told me he did a 27-or 28 minute flight messing around at Lakehurst on 6/16 TSS and I asked him how much longer the loop was compared to his 5/99 and he said about 10% so it correlated. Jeff has done flights in other events and correlated with similar results to his 5/99 flights. So its a good starting point.   

Don   
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Hepcat
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« Reply #7 on: September 21, 2017, 09:15:40 AM »

First: 'Flyguy' you have nothing to apologize for;we did wonder a few years ago who was this unusual man who flew duration models amongst the skscrapers but we know you better now, not only as a talented modeller but also as a man who is meticulous about every aspect of the hobby.  Your videos on making up and braiding motors are well known and if you tell us you stretch your motors eight or nine times and get more turns then that is reiable information for us all.

Second: I got a distict impression after the last couple of world championships for F1D that best performances were being achieved by previously used motors that had taken a permanent set.  That is on the same lines that Don is talking about for TSS.  I guess that achieving a thinner motor by stretching instead by cutting to the narrower width may reduce the peak torque and perhaps give a more reliable motor.
John
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« Reply #8 on: September 21, 2017, 10:28:44 AM »

I was comparing batches but also getting large differences between tests of the same batch. This was of similar orders of magnitude.

I try to test all of my motors before using them in a contest and I always get significant differences between motors. It's expected to see differences between motors that come from different original boxes but I also see differences between motors cut from the same length of rubber. A lot of people have said that the difference is due to faulty testing on my part. They may or may not be correct but I still do the testing and I still go by the results of the testing.
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jakepF1D
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« Reply #9 on: September 21, 2017, 01:52:44 PM »

I've watched the torque on a freshly wound motor drop substantially as it cools off and the rubber relaxes.  I don't think this can be accounted for properly in testing.  Even a minor change in the speed you wind will change the temperature of the rubber.  I also see wildly different turns numbers depending on how hard the previous wind was on that motor. 

All of that is to say that I've used rubber sourced from 3 different people, and all of it is good enough that I no longer test it.  I already cringe at the thought of preparing 30-40 motors before a major contest.  Testing all of those motors would make me go insane.
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piecost
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« Reply #10 on: September 21, 2017, 02:16:57 PM »

Bill, i was testing 61mm loop length with 1.28g/m with a mass of 0.163g. Within each batch i was getting consistent cruise torque but differences of multiples of 160 turns to the kink in the torque curve and to peak torque. Different batches displayed similar characteristics. I found the anticipated differences between batches. In my testing i think that i was getting one or two bunches with each worth a reduction of 160 turns. This is worth about 5 percent on specfic energy (for the torque i wind to).

Supprisingly i achieved very similar cruise torque for a batch of rubber obtained from a top uk flyer, sugesting that our torque meters were calibrated consistently, but took had less turns to reach peak torque. I concluded that winding technique really matters and that i am not getting the most out of my rubber.

Jake, that is a daunting amount of preparation. How many winds do you typically get from a motor?
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jakepF1D
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« Reply #11 on: September 21, 2017, 03:15:26 PM »

I should note that number includes partial motors.  I typically make about the same number of full and half motors, so 15-20 of each for a major multi-day contest.

The number of winds I get really depends on my goals.  For starters I do at least 3 break in winds on every motor.  That includes 2 light break in winds, and 1 fairly hard wind.  On the 4th wind I sometimes get enough turns into a motor to make a good flight, but if I don't reach my turns goal I might wait until the 5th wind to use the motor.  If I'm winding really hard that might be all I get.  If I'm winding a little easier I might get a good 6th wind meaning I could conceivably make up to 3 official flights on the same motor (4th, 5th, and 6th winds overall).  I almost never get a 7th wind as the motor usually has substantial nicks by that point and almost always breaks if I try to wind it again.  Of course some motors break before I ever use them, so it probably averages out to 1 flight per motor if I'm pushing hard for official flights, and 2-3 flights per motor if I'm just testing.
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jakepF1D
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« Reply #12 on: September 21, 2017, 03:57:02 PM »

As a point of reference, both my official flights at West Baden last year were made on the same motor.  The motor was 32.9mg/in and processed at 399mg.

The 4th wind on that motor yielded 1197 turns at 0.46in/oz of torque, and the flight was 26:02.  The model used 1134 turns
The 5th wind on that motor yielded 1209 turns at 0.46in/oz of torque, and the flight was 26:06.  The model used 1144 turns.

These flights were made back to back with only enough time to process the motor and re-wind it in between.
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spr
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« Reply #13 on: September 21, 2017, 04:16:22 PM »

Interesting discussion with many valuable tips, thank you!

I'd still like to get practical info on the winding techniques you guys are using when winding really hard:  stretch? when do you start coming in? winding speed?  how many turns do you wind when already in motorstick length? massaging rubber?several stretches during a wind?  etc. Bill, Don, Jake - let us know!
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Olbill
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« Reply #14 on: September 21, 2017, 10:05:09 PM »

Disclaimer - I have no idea if my method is the best or even close to the best. Also, since I'm winding long motors and because I use a digital meter, I can't read my torque meter when the motor is stretched out. So:

I pull the motor to 6 times the original length. for a 24" motor this is 12 feet from the torque meter to the winder. Then I wind in 60% of the calculated maximum turns while the motor is stretched this much. Then I wind in the remaining turns as I move in, trying to reach maximum turns when the winder is ready to dock. I don't generally put in more turns at this point.

I'm using a 20:1 winder and probably wind too fast. I think the slower you can force yourself to go the more heat the rubber can get rid of during the process. Rubber shortens when heated so heat is a bad thing if you are going for max turns..

The F1D guys have developed winding techniques that are much more advanced than what I do. You asked - I answered.
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Tapio Linkosalo
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« Reply #15 on: September 22, 2017, 02:27:55 AM »


One thing that I started to wonder about is the effect of lube to the maximum turns and torque that you can achieve.

Two weeks ago I had quite bad experience when trying to figure out suitable motor size for a coming contest. I cut some half-motors from 99/7 batch (aiming for 300mm long full motor for F1M), but did not manage to put in too many flights as I broke many motors in row. My target torque was not too high, even, just 60 g*cm (0.67 oz in I think), but many motors broke before that. Or when putting to the model. Or just after I had managed to insert them, but before launch. No good.

When making F1B motors, I use rather thick (14,000 CTS) silicone to lube them. But I have noticed, that this lube is too thick, if I lube the knots with that, they start to slip when stretching the motors for break-in and test. So my procedure is to lube the ends that I knot with thinner (500 to 1000 CTS) silicone, tie the knot and then lube the rest of the motor with thicker silicone. The thin stuff gives enough slip so that the knot can be tightened without nicking the rubber strip, bet when pulled all in the knot still grabs and stops slipping.

For the session two weeks ago I thought of making sure that the knot keep and used the thin silicone for lubing. Maybe that is not sufficient for a tightly wound motor, but my constant failures were due to insufficient lubing? I will try tomorrow again with motors that are this time lubed with the thicker silicone. Had to revert to a not-so-tidy knot that holds better on more slippery strip. But then again, I do not stretch indoor motors as heavily as F1B motors are stretched in the pull-test.

 
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Olbill
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« Reply #16 on: September 22, 2017, 08:33:37 AM »

I pull the motor to 6 times the original length. for a 24" motor this is 12 feet from the torque meter to the winder. Then I wind in 60% of the calculated maximum turns while the motor is stretched this much. Then I wind in the remaining turns as I move in, trying to reach maximum turns when the winder is ready to dock. I don't generally put in more turns at this point.

Initial stretch should be 7x instead of 6x in my description.
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cglynn
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« Reply #17 on: September 22, 2017, 02:23:22 PM »

[These flights were made back to back with only enough time to process the motor and re-wind it in between.
[/quote]

So that pretty much disproves the idea that one must let a motor rest between flights to fly a decent time.

Good to know. 
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« Reply #18 on: September 22, 2017, 03:32:04 PM »

During my official LPP flights at USIC I broke a lot of motors. Whenever I had to start over with a new motor I did a prewind to close to full torque, a full motor test flight and then an official flight. I don't think any of my motors survived long enough to make 2 official flights except maybe the first one. Motors broke at each stage of the process.

The reason for this procedure was to gradually increase ceiling hits without getting hung (my use of a ceiling scrubber was protested). The purpose of the test flight was to make sure that the new motor wouldn't put me into the ceiling too hard. I didn't get hung but I wound up being a little too conservative and lost in the end.
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jakepF1D
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« Reply #19 on: September 22, 2017, 03:36:18 PM »


So that pretty much disproves the idea that one must let a motor rest between flights to fly a decent time.

Good to know. 

I only have my own data, but I don't believe resting a motor is beneficial in any way.

I also hear people say that a motor is tired and they need a new one.  All this means is they're using a motor that's too thin, and they are trying to use it before it's fully broken in.  This guarantees that they'll never reach maximum turns, and as a result they'll never maximize the energy stored in that motor.
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Dave Jackson
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« Reply #20 on: September 27, 2017, 04:29:56 PM »

This is an extremely interesting topic.

It seems that braking in the motor is very important. I stretch mine to 6x length for 5 minutes before using.

What is the best way to break in a motor? And how can you tell it is fully broken in?

Dave

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« Reply #21 on: September 27, 2017, 07:22:58 PM »

Dave,
I think you may be drawing the wrong conclusions and I think that 'breaking in' motors never has had much benefit, particularly with the amount of pull and holding time that is often recommended. If rubber is pulled to a high load it will give a permanent 'set' where the rubber is a little bit thinner and a little shorter.  This means the motor will take a few more turns and not reach such a high torque when fully wound.  How much you want to set the rubber depends on the type of flying you want to do.  I remember 15 or 20 years ago when I was flying a lot of Coupe there was a lot of talk about 'breaking in' but some of us realized it was better to use the rubber straight out of the box.  A coupe rubber motor is only 12.5% of the total weight of the model so the motor run is short but you want a fast climb to get amongst the thermals so you are better with an un-broken in motor giving high torque.
 
Indoor flying is the other end of the scale, a small percentage of the weight is rubber and you want a long, long motor run so a motor that has a 'set' giving less torque but more turns is the way to go. Now one way to do that would be to sit at home and have an evening stretching motors but I think that competition flyers do something a bit more clever.  Indoor competitions usually count the best two flights from five. I think what the top fliers are doing recently is to wind a motor, checking carefully on the turns and the torque and probably, more importantly the feel of experience and then then installing it on the model. And then if everthing looks good having a flight. The flight may be top class or it may hang up or get bad air. But whatever happens they have a 'known' motor which can be very useful on another flight.
John
   
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« Reply #22 on: September 27, 2017, 09:55:20 PM »

This is an extremely interesting topic.
It seems that braking in the motor is very important. I stretch mine to 6x length for 5 minutes before using.
What is the best way to break in a motor? And how can you tell it is fully broken in?
Dave

This is the way I do it and it works for me. I don't claim to do it right so I am just adding in another data set on how another person approaches it.

I break in by winding. Say I have a  loop that will take 2000 turns. My first wind on the freshly made motor will be around 1500 winds. Then I relube and wind again to around 1750-1800 turns. Then unwind again, relube then wind to around 1800-1850 turns. By now the rubber loop will have stretched in the realm of 8% or so in length. Then it is ready for competition flights. The next 1-4 winds near max will behave about the same but in some events I have noticed what some called getting "tired" . No cal is an event I fly frequently. My model does around 7 minutes. Scoring is 3 of 3 flights. The first two flights will be within a few seconds of each other. The third flight if I wind exactly the same turns and backoff will usually be a little less. So in that event on my third flight I usually back off less turns. Say 100 instead of 200 to get the same flight time. I think the tired phenomenon happens more on models with short flight times. An event like nocal you wind then fly 7 minutes, land, wind again , fly 7 minutes, land wind again for 7 minutes.

I think the winding to max repeatedly in a short time span has some effect. I do think repeated winding does do something to the motor that a recovery period does fix. I have had motors that were a little too "zingy" (meaning overpowered), and sometimes I will wind them a bunch of times to get rid of some of the climb. My dad and I call it "hammering the motor down a little". That is like the 5th-6th wind. We really noticed this at Johnson City flying heavy (6.2 gram nocal). That was scored best 1 of 5 and often you will see scores on flight #3 or 4 lower than 1 or 2. First official might be 7:00 for example, next flight a few extra winds and more height, 7:15 then third flight you get more winds and do 6:50. The model would not climb as high and land with more turns. Sometimes after waiting say an hour you take flight 4 and back to where you were on flight #2 then a real hard wind and either glory or the model sags and does less time. So we started going two routes, one was have a duplicate motor so after 3 winds or so you went to the duplicate. Or a heavier motor that after wound many times would act like the other motor when fresh. So I guess it is a matter or perspective. Some may say the initial motor was undersized, some may say the second motor was correct but had to be broken in properly. I am not sure exactly what is happening when it happens and it does not happen all the time. But it does more frequently happen when the motor is wound to near max turns and wound that way multiple times in a short time frame. I can usually tell when it happens when I suddenly get more turns in than expected. Now sometimes we have been surprised and the model will not climb as high but cruise longer and do more time!

Recently I started messing with stretching the motor for breaking in as a different method to try. Mainly as it is what is called out in the pull testing method I have been using recently. I have found though that I need to pull to about 7x to get the same relaxation I get doing my 3 wind method. Since I typically make motors at the contest, it is not practical for me to stand and hold the rubber stretched for 5 minutes. I just wind it instead.  

Don  
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« Reply #23 on: September 28, 2017, 10:51:58 AM »

Here's a question I hope some of the top F1D guys weigh in on:

So I make up a motor to 6" at 400mgs. After breaking it in, it becomes 6.5" let's say as a permanent set.

So what is it now? A 6" loop or a 6.5" loop?
With Fred Rash's spreadsheet, this is very different.

I guess I am asking Kang et al., when you put the grams/in on your plans, is this done before break-in rating or after break-in?

Regards.
Mike Kirda
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« Reply #24 on: September 28, 2017, 11:23:49 AM »

Here's a question I hope some of the top F1D guys weigh in on:

So I make up a motor to 6" at 400mgs. After breaking it in, it becomes 6.5" let's say as a permanent set.

So what is it now? A 6" loop or a 6.5" loop?
With Fred Rash's spreadsheet, this is very different.

I guess I am asking Kang et al., when you put the grams/in on your plans, is this done before break-in rating or after break-in?

Regards.
Mike Kirda

Everything we do is based on the length and weight of the fresh rubber.  It's impossible to make any reasonable comparison after a motor has been stretched or wound.  I'm also not measuring the length of the loop, but instead the length of the rubber before tying the knot.  This allows me to make my motors to exact weights, and it's the only way I know to get truly accurate numbers.  After all the measurements are done I use a method of knot tying that gives me zero waste.
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