Rubber Length
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jjohanik
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Rubber Length
What is the ideal ratio between the length of the motor stick to the length of the un-stretched rubber motor?
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DoctaDave
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Re: Rubber Length
It won't be a very big difference. I think this year a reasonable hook to hook distance would be 10 - 15 inches.
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bjt4888
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Re: Rubber Length
jjohanik,
DoctaDave is guiding you correctly. The length of the motor stick relative to the rubber motor has no effect on performance. If you read last year's wiki threads, you will see discussion related to this question. If you are using the Ikara propeller you will discover that the motor length needed (depending upon propeller pitch and blade area) will range between 11.5" and 15.5" (corresponds to rubber thickness range from about 0.94" to 0.81" using plastic tubing cut o-rings). This information relates to the 7.0 gram airplane. It is possible that the ballasted airplane may require thicker rubber yet.
The Freedom Flight kit uses 11" hook-to-hook and my students are using a little less than this.
Build a proven design and spend the majority of your time testing various rubber thickness and propeller pitch and propeller types.
Good luck and congrats on getting an early start.
Brian T.
AMA since 1972 (off and on)
DoctaDave is guiding you correctly. The length of the motor stick relative to the rubber motor has no effect on performance. If you read last year's wiki threads, you will see discussion related to this question. If you are using the Ikara propeller you will discover that the motor length needed (depending upon propeller pitch and blade area) will range between 11.5" and 15.5" (corresponds to rubber thickness range from about 0.94" to 0.81" using plastic tubing cut o-rings). This information relates to the 7.0 gram airplane. It is possible that the ballasted airplane may require thicker rubber yet.
The Freedom Flight kit uses 11" hook-to-hook and my students are using a little less than this.
Build a proven design and spend the majority of your time testing various rubber thickness and propeller pitch and propeller types.
Good luck and congrats on getting an early start.
Brian T.
AMA since 1972 (off and on)