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Author Topic: Embryo Rubber Sizes  (Read 348 times)
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Thurman
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« on: February 08, 2020, 06:53:17 PM »

Hello Embreos,

Started my first Embreo but can't find how much rubber to use.  I have been told that many use one loop of 1/8 braided.  The only other references use odd sizes of rubber strip.  Is there a formula for rubber weight based on model weight?  My first attempt is an outdoor design with a weight of 18 grams (without rubber), 7 inch prop and a motor length of 15 inches.  Any guidance appreciated!

Thanks, Thurman
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lincoln
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« Reply #1 on: February 08, 2020, 11:47:07 PM »

I expect that's fairly close. You might need a little more.

Rubber that's a quarter of the weight of the rest of the model is a good starting point, though my guess is you could get away with more. However, the width of the rubber is important, too. You need enough torque to cope with the weight of the model and rubber. So a short loop can be thinner than a long loop.

I haven't specifically flown embryos, though I've flown other stick and tissue models.
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Thurman
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« Reply #2 on: February 09, 2020, 06:22:02 PM »

Thanks Lincolin,

I am going to try a loop of 1/8 and braid in a loop of 1/16 th.  Go from there.  The field at Palm bay will have experienced builders this coming Tuesday and will ask for help.

Thurman
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Bredehoft
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« Reply #3 on: February 09, 2020, 11:06:35 PM »

1/8+1/16 sounds good to me.  I was going to say a loop of 3/16 for a model of that size and weight with a 7" prop - which is what you've said.

--george
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Lee from Chitown
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« Reply #4 on: February 15, 2020, 01:18:16 PM »

Is there a noticeable difference between using a 3/16” strip versus strips of 1/8 and 1/16 of the same length together? Would having different lengths of 1/8 and 1/16 be of any benefit?
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ILM Tarheel
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« Reply #5 on: February 15, 2020, 01:37:03 PM »

Lee, Motors made from a strip of 3/16, or a strip of 1/8 + a strip of 1/16, or 3 strips of 1/16 all have the same rubber "cross section" and for all practical purposes are the same. I've always made all strips (loops) the same length.
Jimmy J
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Lee from Chitown
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« Reply #6 on: February 15, 2020, 04:31:18 PM »

Thanks, Tarheel. You saved me mixing potions.
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FLYACE1946
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« Reply #7 on: April 27, 2020, 10:38:43 PM »

Thurman do you have the name of the Embryo model you are trying to get to fly? Maybe if we knew what you are trying to fly we might be able to give specific information.
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