Scioly.org

I need to correct the last sentence of my post on February 15, 2020 regarding Larrabee props.

My subsequent research confirmed that Professor Eugence Larrabee of MIT developed design theories for minimizing induced loss in a propeller to achieve maximum efficiency for a given power input. However, his theories produced the optimum blade planform, i.e. the outline of the blade, for a given P/D ratio and maximum chord, and not the distribution of the angle of the blade along the radius. I assume that maximum efficiency still requires a true helical blade shape.

Ikara has just come out with an 8 cm diameter prop supposedly designed for WS 2020. The new Ikara prop has two blades.

It has wide chord blades that are much sturdier than the thin plastic blades of the typical indoor Ikara prop.

The blades also appear to have a much higher pitch than the typical indoor Ikara prop.

See

https://www.wind-it-up.com/collections/ ... p-assembly

Hopefully it is not too late for some of you to experiment with this new WS 2020 prop from Ikara. It should yield higher times when compared to those achieved with a 6-inch indoor Ikara prop that has been cut down to meet the 8 cm maximum diameter rule. The new 8 cm Ikara prop should be less prone to breakage than the cut-down indoor Ikara prop.

Thanks for the update.

I am going to order now. Last year, no pitch adjustment needed for their new patch of props.

To my eye, the pitch just looks excessive to expect good thrust...

what pitch do you recommend for an ikara prop? Today I raised my pitch and my times improved by 20-30 seconds

jsegal wrote: ↑February 19th, 2020, 2:42 pm what pitch do you recommend for an ikara prop? Today I raised my pitch and my times improved by 20-30 seconds

My first inkling is to inquire what your base time was, but that aside, what's the new pitch? it seems like higher pitch may in fact be the way to go, but that seems counter-intuitive to me (assuming one isn't starting from such low pitch as to have an essentially flat prop)

I will get back to you on that tm when I measure the new pitch. I left my stuff at school and I forgot what I set it at.

lechassin wrote: ↑February 19th, 2020, 2:58 pm

jsegal wrote: ↑February 19th, 2020, 2:42 pm what pitch do you recommend for an ikara prop? Today I raised my pitch and my times improved by 20-30 seconds

My first inkling is to inquire what your base time was, but that aside, what's the new pitch? it seems like higher pitch may in fact be the way to go, but that seems counter-intuitive to me (assuming one isn't starting from such low pitch as to have an essentially flat prop)

how do you change pitch?

On an Ikara prop, you carefully twist the spar inboard of the blades. Best with two needle nose pliers.

However, if anything more than small changes, it will break after 2-3 adjustments. So pitch them initially to get them the same, and pitch them to a range of pitches (separate prop for each pitch) rather than plan on adjusting multiple times to find an optimum.

Coach Chuck

coachchuckaahs wrote: ↑February 19th, 2020, 6:07 pm On an Ikara prop, you carefully twist the spar inboard of the blades. Best with two needle nose pliers.

However, if anything more than small changes, it will break after 2-3 adjustments. So pitch them initially to get them the same, and pitch them to a range of pitches (separate prop for each pitch) rather than plan on adjusting multiple times to find an optimum.

Coach Chuck

what do you mean by twist? Are you rotating the spar along its own axis or bending it?