Props

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Lorant
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Props

Post by Lorant » February 11th, 2020, 6:35 pm

After watching the prop build tutorial posted by lechassin I remembered that many coaches on these forums mentioned that the most essential part of this year's plane will be finding the proper rubber and corresponding. Which props have all of you found to be most effective and how does one go about designing and building a custom prop?
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bjt4888
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Re: Props

Post by bjt4888 » February 11th, 2020, 8:19 pm

Lorant wrote:
February 11th, 2020, 6:35 pm
After watching the prop build tutorial posted by lechassin I remembered that many coaches on these forums mentioned that the most essential part of this year's plane will be finding the proper rubber and corresponding. Which props have all of you found to be most effective and how does one go about designing and building a custom prop?

Lorant,

Look at this thread and some others in Hip Pocket. Some of the info here is a good start.

https://www.hippocketaeronautics.com/hp ... ic=17412.0

My strategy when returning to indoor modeling about 10 years ago was to read all of INAV, all of Hip Pocket and all Scioly.org forum archives.

Hope your prop building goes well.

Brian T

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Lorant
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Re: Props

Post by Lorant » February 11th, 2020, 9:16 pm

Thank you for introducing me to this forum it is incredible the wealth of knowledge available. Besides that, I read that some teams are using 3 bladed props over the traditional 2 bladed design. From what I understand, 3 bladed props increase thrust but are less efficient than 2 blades, furthermore, increasing the pitch and chord of the prop increase thrust and drag. Where do I start in optimizing these parameters to create a proper prop and which factors (if any) are worth paying the most attention to? Also, I read through past posts and threads and have heard a lot about "flaring props." What are they, how do they affect the flight and how do I go about making a prop that can flare?

Side note: please correct me if anything I said is incorrect, I am still new to the intricacies of this event.
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Re: Props

Post by CrayolaCrayon » February 12th, 2020, 4:18 am

Lorant wrote:
February 11th, 2020, 9:16 pm
Where do I start in optimizing these parameters to create a proper prop and which factors (if any) are worth paying the most attention to??
By testing it
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Re: Props

Post by bjt4888 » February 12th, 2020, 5:03 am

Yes, I agree with Crayola. In our initial build in October, my teams built two propeller designs each in several different pitches. Since then, we have tested several other designs also in various pitches.

It only takes us about an hour or two to build a new propeller design, so easy to test lots of variations.

Brian T

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Re: Props

Post by coachchuckaahs » February 12th, 2020, 9:11 am

Agreed as well. We are on Prop S, so have built quite a few. Many did not work at all! We have tried a wide variety of pitches, planforms, pitch progressions, and flaring.

Flaring is simply a prop designed to flex so that it has greater pitch at higher torque, by having the bulk of the area ahead of the spar. With this year's small prop and high RPM, we have not had a lot of success with flaring. In fact, due to the high RPM, many "flaring" props actually flatten out at high torque, spinning even faster, which is the opposite of what you want.

In most years playing with the flexibility (flaring), pitch progression (helical or otherwise), and planform has eventually led to a high performing prop, usually only weeks before Nationals. This year the tiny prop certainly adds limitations that we have not seen in other years. Since there is little literature on such small props, you will have to get creative to come up with a best solution.

Coach Chuck
Coach, Albuquerque Area Home Schoolers Flying Events
Nationals Results:
2016 C WS 8th place
2018 B WS 2nd place
2018 C Heli Champion
2019 B ELG 3rd place
2019 C WS Champion
AMA Results: 3 AAHS members qualify for US Jr Team in F1D, 4 new youth senior records

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