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Author Topic: JUST BRAIDED A MOTOR  (Read 758 times)
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riversidedan
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« on: January 16, 2019, 08:31:35 PM »

finally decided to braid a motor and need someone who knows to comment and see if it was done right......….pic is attached,
 motor is 16 strands and both 8 strand parts were wound CW sepratley at first then joined and  unwound 5 turns CCW together creating the motor

sorry for the fuzzy pic
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JUST BRAIDED A MOTOR
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flydean1
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« Reply #1 on: January 16, 2019, 11:09:10 PM »

Looks fairly conventional.  I usually wind one half CW, and the other CCW.  Then hook up the winder with both halves together and wind CW like I will wind it in the airplane, then let the motor unwind.  Also, you need to lube it first.

I'm sure more than one technique will work.
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riversidedan
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« Reply #2 on: January 16, 2019, 11:14:49 PM »

yes its well lubed...…...will try it this way then your way and see what happens, braiding is all new to me but believe its more efficient.

another question, have a model called the PACIFIC ACE 40 and would like to use something braided, from rear peg to hook is 18in.
so staying with braided 16 strands, prop is 14x12 how long should the motor be??     thanx again
« Last Edit: January 16, 2019, 11:33:18 PM by riversidedan » Logged
Red Buzzard
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« Reply #3 on: January 17, 2019, 01:03:14 PM »

Hi Riverside,

Looks like the real deal to me. My standard practice is to have the knot, or knots depending on what you found while skeining the motor, wind up in the middle of the motor somewhere. Knots up against the Crockett or at the back by your bobbin can cause strange tangles when they encounter something hard like aluminum. Probably not worth undoing your braid, just something for next time.

For your PA, I'd suggest using your airframe weight as a guide rather than your hook-to-peg length. You probably already know but 16 strands of 1/8 by 36" long (made-up length not braided length) comes in at about 44 grams. I fly it in my Becker Unlimited small Nostalgia rubber model with an airframe weight of 84 grams and my Double Feature small fuselage OT model with an airframe weight of 114 grams (oink). Motor base on the Becker is 31" while the Double Feature is 27". Just grist for your mill but shortening and lightening will be in direct proportion.

If your PA is a sport model, a 16 strand motor shortened for your motor base will give you pretty good torque but not many winds. With a small prop you will buzz through them pretty fast.

Bill
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riversidedan
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« Reply #4 on: January 17, 2019, 04:02:21 PM »

great info thanx !  that motor you see was a 1st time experiment to see how it went together and am thinking it was fine. anyway I read what you said about rubber and model weight but didn't really get the Jest of it, am also new to weighing things but do have a nice Gram scale ,       that being will weigh the model and the braided motor you see and  get back to ya for more info...…...o Wink  
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Red Buzzard
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« Reply #5 on: January 17, 2019, 06:07:33 PM »

Hi Riverside,

I apologize for being a bit cryptic. Again, not knowing your purpose with the PA, I was only suggesting that the ratio of rubber weight to airframe weight is a pretty good indicator of what you can expect of performance. The Becker at 44g./84g. is a bit of a rocket with a 14" dia.x20" pitch folding prop. The Double Feature at 44g./114g. is less a rocket (big boxy fuselage, landing gear) but still climbs steeply on a 16" dia.x20" pitch folder. If you want a rocket/aggressive climber you can shoot for those ratios (roughly) but it will mean stuffing a motor that is 36" long into your 24" motor base.

If you are flying a sport model you can cut down you motor length and or strand count to lower your climb rate or dial in a longer motor run. Longer motors with fewer strands give you longer motor runs with less torque. Short, fat motors give you shorter runs and higher torque. Once you know your airframe weight you can take a guess at a reasonable ratio (rocket,sedate), weigh out your rubber, strand it, and see what it looks like.

Another, easier, thing to do would be to search on this forum (I'm sure I've seen this plane mentioned) and see what others have done with the same design. My guess is you will likely be happier with 12 strands for a sporter, especially with a smaller prop. Working up is a good idea as starting with too much power can get you in trouble pretty quickly. A twelve strand motor would braid just like the one you did already, to get this thread back on the braiding track.

Bill
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riversidedan
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« Reply #6 on: January 17, 2019, 07:20:08 PM »

thanx again, for learning purposes lets use an example the PA 40 version is 6.5 oz less motor ….. 16 strand braided motor 18in long - weight .098 oz or 2.79 G ..rough model weight RTF 7.5 oz.  14x12 balsa home brew prop.

what would your prediction be if this model flew??
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Red Buzzard
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« Reply #7 on: January 18, 2019, 01:06:18 AM »

Hi Riverside,

A little math would show you would need about 71g. of rubber to achieve the same ratio as my Double Feature. In other words the DF is 44g. of rubber/114g. of airframe which would be equal to your PA at 71g.of rubber/184g. of airframe. I believe you have a decimal point wandering around in the wrong place with your 16 strand x 18" motor. It is probably about 22 grams. So your ratio is 22 g. of rubber/184 g. of airframe.

And yes, it will fly. The motor run will be fairly short and the climb sedate. Probably not bad for testing. At that weight don't expect a floating glide, but I admit I don't know what the wing area of this craft is. My contest large Nostalgia rubber models will approach that total weight with 230 square inches of wing area and glide well. If you've got some wing area in the plane, it won't hurt to make that motor at least 24" long or more as your testing progresses. But again the trade off is torque (high strand count, short motor) or motor run (lower strand count, longer motor). Heavy bulky things need more torque.

Bill
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riversidedan
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« Reply #8 on: January 19, 2019, 01:10:20 AM »

just checked again ,air frame 187G   rubber 30G      wing area 210 sq.   for right now itll be a sport model in progress till I get things sorted out

so when you say I need a 24 in. motor  is that braided or straight strands?
« Last Edit: January 19, 2019, 01:22:23 AM by riversidedan » Logged
Red Buzzard
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« Reply #9 on: January 19, 2019, 01:14:28 PM »

Hi Riverside,

In general, motor length refers to what I call the "made-up length". That is before braiding. In discussions it helps standardize things because lots of people do not braid. As you will find your braided motors will vary in length, even if braided the same and made up to the same length. And I did say make your motors longer as your testing progresses.

Bill
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riversidedan
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« Reply #10 on: January 20, 2019, 03:31:36 AM »

still more questions>>>>>>>>>>>  Grin  certain models suggest different length motors,  does it matter if those are braided and non braided or are they the same length, get the picture??



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Red Buzzard
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« Reply #11 on: January 20, 2019, 02:54:14 PM »

Hi Riverside,

Just assume the plans, or what have you, are indicating made-up length. Once you know the rubber size, the number of strands and the made-up length, you have all you need. Then you decide if you want to braid it depending on the distance between your prop hook and rear peg, how you feel about braiding in general and your experience.

If the plans indicate a rubber size and weight in grams and the number of strands, then you weigh the rubber and make it up into the specified strands and away you go. Then you decide if you want to braid it or not.

If there is no strand count indicated, then you will have to get creative and make it up into some convenient strand count based on a need for torque (fat motor with more strands but shorter) or motor run (thinner, longer motor).

There is lots of room for experimentation. Read around in this forum, particularly in the scale section as there are lots of discussions about rubber size, torque and motor length. In fact take a look at many of the videos in the scale section as you can see various approaches in action.

Bill
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Maxout
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« Reply #12 on: January 24, 2019, 10:33:55 AM »

For what it's worth, here's my take on braiding:
https://www.youtube.com/watch?v=7r61CkY2aQM

That's the technique I've been using for almost 20 years now. It has not failed me.
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Red Buzzard
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« Reply #13 on: January 24, 2019, 12:33:09 PM »

Josh and Riverside,

Nicely done video Josh. I use the same method.

Riverside, there is info on the Pacific Ace in the Old Time Rubber section of the forum.

Bill
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