Prop model and length options?

[pschwenn]

I've ordered a propeller for the 912iS Sport I'm installing. Its an Helice E-Prop Durandel 100 (it would be a 155cm or 160cm Durandal 100 Model S on Sonex or Waiex (faster planes than my Xenos which will be a Model M 165cm [given slicker wheel pants a 2 inch taller tire will give you another 10cm prop diam without slowing you down]).

It's three blade solid composite ground-adjustable. The attraction of the Durandal propellers is that the shape, thickness and very short chord-length are such that is not (simplifying) near stall over a wider regime (climb, cruise, speed, altitude) than a conventional solid propeller. And since it is ground adjustable one starts out at your chosen regimes center point. For an Aerovee 80hp it would be a Durandal 80. The supporting documentation, test results and testimonials are more convincing and simpler than other wonder props and the concept is very simple.

Price is about $1600 against $4000 - $10000 for an in flight adjustable or constant-speed, and its weight is very low because it IS a solid composite prop (with inconel(?) )protection on the leading edge.

Matching carbon extensions and spinners are available.

I will report when I finish installation.

[Brett]

Has anyone flown behind the Sonex recommend prop for the Rotax 912 ?

From the website they recommend the WC64QR-81G

Thanks.....

[Brett]

Perhaps a better question would be is anyone considering using the recommended Rotax prop for the 912 in the future?

Or knows of anyone flying behind it?

[Concorde]

Perhaps a better question would be is anyone considering using the recommended Rotax prop for the 912 in the future?

Or knows of anyone flying behind it?

I bought the 64” prince p tip but haven’t install it yet . My 912 uls arrived before Christmas so I am trying to figure everything out . I have a tri gear Sonex and according to Sonex with standard tires I should have 6”of ground clearance. I am thinking about larger tires but I will wait and see.

[Zack]

Any updates?

[Murray Parr]

Does anyone have performance numbers (static rpm etc) for the early sensenich props sold by Sonex for the Rotax 912 100hp engines? The number was WC64QR-81G I believe. It would also be interesting to compare figures with the smaller diameter WC60QR-82G they sell now.

[Murray Parr]

I'll go first. Static runup for the early version Sensenich prop WC64QR-81G is 4900 RPM for my Rotax 912 ULS. Anyone else have any comparisons?

[GraemeSmith]

I'll go first. Static runup for the early version Sensenich prop WC64QR-81G is 4900 RPM for my Rotax 912 ULS. Anyone else have any comparisons?

Check my math.

4900rpm - Reduction gearbox 2.43:1 = 2,016.46090 rpm
x 60 = 120,987.654 rp HOUR

64" diameter propeller. Circumference = Pi * D = 201.0619 inches

Circumference x rpHour = 24,326,011 inches per hour

Which equals a blade tip speed of 774mph

Must have been INCREDIBLY noisy - as well as inefficient.

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With the 60 inch diameter prop we are in the realms of 726 mph

Still seems excessive.

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What did I miss?

[Area 51%]

I'm getting 384 mph tip speed with my math.

64" diameter X Pi = 201in. X 2016rpm = 405,216 inches per minute X 60 minutes = 24,312,960 inches per hour divided by 12 = 2,026,080 feet per hour divided by 5280 = 383.73mph.

[GraemeSmith]

I'm getting 384 mph tip speed with my math.

64" diameter X Pi = 201in. X 2016rpm = 405,216 inches per minute X 60 minutes = 24,312,960 inches per hour divided by 12 = 2,026,080 feet per hour divided by 5280 = 383.73mph.

And I agree!

For the life of me I can't see where I was out by a factor of 2. It's not like 2 is even a number in the calculation to be screwed up. And I did it twice coming at it from either end. We need emoticons on this site so I can post a :BLUSH: one.....