Scimitar Propellers

[zadwit 105]

In the late 70s in Fairbanks, Doug Fowler built a KR-1 only he modified it a lot. LOnger wing, GA-W-1 Airfoil, different canopy , A-65 continental engine. He made his own wood prop. IT worked pretty well. He made several more props, each one a Scimitar prop and the last one he made was pretty radical Scimitar prop. He gained 15 mph in cruise with the last prop he made. Now the dangers of Scimitar dates back to WWI, the trailing edge of the blades is under a lot of tension and can crack. Doug made his prop out of thin laminations of wood, spruce I think and then after the blades were shaped, applied 8 to 12 layers of .8oz. fibreglass cloth, each later squeezed out to remove excess resin. He could make the blades thinner by l adding the fibreglas cloth.

The last prop was 68" I think and was a radical scimitar shape. It has a fair amout of pitch but when the engine rpm increased, the blade twisted towards a flatter pitch due to centrifugal twisting moment and centrifugal force. In WWI some of the early props flutters and self destructed so the amount of sweep was limited. Anyway as Dougs plane increase in speed, the airload on the prop decrease and he could reduce RPM and the blade naturally twisted in a coarse pitch direction...pretty neat. ALso the sweep of the blade delayed onset of mach compressible airflow so the blade had less drag at higher RPMs. Photos of these props are shown so you can get the idea of how it works...

[TJay 1041]

I got a 68 inch Luga sitting on the bench shaped just like that.  After Christmas I will be leaving Wisconsin and moving back home then we will see how they do on our early birds.

[FredStork 453]

Works well and looks great!

 

Edited 10 Dec 2018 by FredStork

[TJay 1041]

That was pretty good Fred I like that.

[sky4play 55]

Nice Fred...Short and SWEEET !!!  

[NorthIdahoAvidflyer 374]

I got a 68 inch Luga sitting on the bench shaped just like that.  After Christmas I will be leaving Wisconsin and moving back home then we will see how they do on our early birds.

Tjay, I would love to hear what you think about this propeller. Did you get a two or three blade.  I email them about getting one sent to the USA. Did you order from them direct or through a distributor?

[TJay 1041]

I got a 68 inch Luga sitting on the bench shaped just like that.  After Christmas I will be leaving Wisconsin and moving back home then we will see how they do on our early birds.

Tjay, I would love to hear what you think about this propeller. Did you get a two or three blade.  I email them about getting one sent to the USA. Did you order from them direct or through a distributor?

Im excited too and yes I bought directly from them Nice people to work with did everything I wanted got blue tips painted on and leading edge laid in the carbon fiber the prop is extremely nice looking. I got a 2 blade. took about 2 mounts to get but that is not a problem. I didn't care much for the western union money transfer. That cost me 35 dollars. But it did go smoothly. And I would buy another from them.

[Yamma-Fox 403]

My deal with Roman direct went well too.  Long wait but good deal.

Those props are a work of art.

And I shoulda hired Fred to come over to do my engine swap with the same method used in the video above.

[1avidflyer 1983]

 

And I shoulda hired Fred to come over to do my engine swap with the same method used in the video above.

I think Fred said something like abra-cadabra and snapped his fingers 3 times.  Maybe that will work for you.  JImChuk

PS  seriously though, it will be interesting to see how that prop performs on the Jabiru engine