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garyb wrote:Hi
My Rotax powered Sonex has a 68 inch wooden GT propeller off a Tecnam P2008 .Static rpm is around 5100, Solo it climbs sea level at 1800 fpm at 70 kts, cruise 2500' 120 kts 5200 rpm and 5500 135 kts WOT it pulls to the red line 5800 rpm. The prop could probably do with a little more pitch.
Cheers

Sounds as close to perfect as you can expect, with a fixed pitch prop.

There is a French propeller maker E-Prop (https://www.e-props.fr/) that seems to have an enthusiastic following here in Australia. Claims of a new approach & great efficiency improvements.

garyb wrote:Hi
My Rotax powered Sonex has a 68 inch wooden GT propeller off a Tecnam P2008 .Static rpm is around 5100, Solo it climbs sea level at 1800 fpm at 70 kts, cruise 2500' 120 kts 5200 rpm and 5500 135 kts WOT it pulls to the red line 5800 rpm. The prop could probably do with a little more pitch.
Cheers

Gary!! Thats great info!!! Are you aware of the pitch of that propeller? If its not explicit in the model... Maybe we can decode it from your serial number. The other way is to measure the angle at 75% of the radius. But its a tricky task (much more tricky if installed on the plane!)

How fast is your level flight at 5800 WOT? And what fuel consumption are you seeign at your 120kt 5200rpm cruise?

PS: Those numbers are amazing... I think i went the right way with the 912...

Skippydiesel wrote:

garyb wrote:Hi
My Rotax powered Sonex has a 68 inch wooden GT propeller off a Tecnam P2008 .Static rpm is around 5100, Solo it climbs sea level at 1800 fpm at 70 kts, cruise 2500' 120 kts 5200 rpm and 5500 135 kts WOT it pulls to the red line 5800 rpm. The prop could probably do with a little more pitch.
Cheers

Sounds as close to perfect as you can expect, with a fixed pitch prop.

There is a French propeller maker E-Prop (https://www.e-props.fr/) that seems to have an enthusiastic following here in Australia. Claims of a new approach & great efficiency improvements.

Skippy... I live in Argentina, importing anything nowadays is almost impossible... Super restrictive laws and my country is ranked 3rd in the world for inflation... Im the representative in Argentina for AERO Propellers from Ukraine :( But theres no way to get anything from there because of the war. Im also a collaborative and im kinda sponsored by a local Custom propeller manufacturer thats been making great propellers im currently running in all my airplanes... (Outperforming in every case Every known brand of ground adjustable carbon fibre props)

A ground adjustable propeller has ONE sweet spot... where all the blade has the optimum angle of attack. When a custom propeller is made, the entire blade has the optimal angle of attack for a given airspeed and prop rpm... So when you aim for static thrust (stol applications) climb (maybe the allround everyone is using) or cruise (for cross country or high altitude performance applications) The whole blade is tuned for that specific mission.

It takes decision... Where you want your performance, calculations... and sometimes a couple trial and errors... But once youre done. Its cheap, light and a great performer.

Having a good solid starting point saves calculations, and lots of wood chips flying in vain.... So thanks a lot for giving me that information, for me its literally precious.

PS: Once the "purrrrfect" propeller is done, I could even ship wolrdwide :)

Xeriotti - sound like you are onto a winner. Have you looked at the E-Prop - also carbon fibre sculpture (there is even a CS version that weights a comparative nothing)

Im going for a wooden fixed pitch now.... If i really like the plane, i may end up with a constant speed in the future. But as i told you before those are not cheap or easy to get over here

I was looking at the Sensenich prop that Sonex sells for the 912ULS, and I can't find anything like it on the Sensenich site. Sensenich sells a 2 and 3 blade for the 912 series, but they're both ground adjustable. The 2 blade shows a diameter of 66-75 which is much larger than the 60" (presumed from the model number) prop on the Sonex page. Is this something Sonex has custom made? It's really hard to believe a 2-blade 60" prop is enough.

Rusty

13brv3 wrote:I was looking at the Sensenich prop that Sonex sells for the 912ULS, and I can't find anything like it on the Sensenich site. Sensenich sells a 2 and 3 blade for the 912 series, but they're both ground adjustable. The 2 blade shows a diameter of 66-75 which is much larger than the 60" (presumed from the model number) prop on the Sonex page. Is this something Sonex has custom made? It's really hard to believe a 2-blade 60" prop is enough.

Rusty

Not any written information... But Ive been investigating and watching lots of videos. Sonex Aircraft it self in some interviews talked about a 64X78 then more recent videos Ive heard 62X80 and the latest mention on propellers for a Rotax 100hp powered Sonex/Waiex came from the One Week Wonder build in Oshkosh22... Where someone mentions it spins a 60x82 propeller.

That may be the way the factory took to keep propeller clearance safe and to dont change the aesthetics of the plane too radically (I personally love how a long leeged sonex looks) ,
According to experience almost every Rotax powered Sonex/Waiex ive seen sports 2 and 3 bladed propeller between 64 and 69 inches with apparently good results.

In my experience, long propellers are always better. I dont mind lenghtening the landing gear legs, and switching to bigger tyres, i can create prop clearance. I would be aiming for best performance possible.

On my 912UL Onex, I'm running a 3 blade 60", because that still only gives me about 4" of prop clearance even with the larger tires. At only 80 HP, I'm still running a fairly high pitch. I've tried the square, and taper tip Warp Drive, and also a medium Ivo. So far, the tapered Warp Drive has been the best. I'm pretty happy with the performance for now, but I can certainly see a higher HP Rotax and better prop in my future.
Rusty

Here it is... at 6minutes 58 seconds....

https://youtu.be/OzNc-DfczJw

Thanks for the link. I don't see how that prop isn't stalled at lower speeds.
Rusty