One Bladed Props

[laminar]

I have seen pictures and heard rumours about guys running one bladed props on 150mph control line racers, something about the more blades means blades getting in each others prop wash, I understand it is done on wind turbines sometimes.

I am curious what people know about this.

[Stevo]

Re: One Bladed Props

In one of the aviation magazines a year or so back there was an article on a motor glider that used only one prop blade. Wish I could remember which magazine and/or the name of the plane

[King]

Re: One Bladed Props

Theoretically a one-bladed propeller is the most efficient prop.

Some studies have been done in years past, but the biggest problem that has to be overcome is balance, hence vibration.

[Stevo]

Re: One Bladed Props

Haven't been able to find anything on the motorglider, but I did find these...

http://www.hq.nasa.gov/office/pao/History/SP-445/ch4-5.htm

http://www.notplanejane.com/aeromatic.htm#everel1

[ramp mouse]

Re: One Bladed Props

Kit Planes magazine had an pirep article on a motorglider with 1 blade. It might work for low HP engines dont know about higher HP or RPM. I'll see if I can find the issue.

[Apteryx]

Re: One Bladed Props

...there was an article on a motor glider that used only one prop blade.

THIS ONE ?

Koyaanisqatsi

[First time Juke]

Re: One Bladed Props

I have seen pictures and heard rumours about guys running one bladed props on 150mph control line racers, something about the more blades means blades getting in each others prop wash, I understand it is done on wind turbines sometimes.

I am curious what people know about this.

I assume the one blade prop in CL planes is due to the high rpm and the short distance the prop tip travels per one round.

Real planes fly with greater velocity and travel lot longer distance in a given time.

Certainly a one blader is possible.....just like in this motorglider for space saving purpose.

[spacegrrrl]

Re: One Bladed Props

There was a fellow in the RC club I was in in the late 80's that was really a single bladed prop fan and made them in all sizes from two blade props. I saw him flying then on a regular basis. I can't say if there was much difference but in theory they are the most efficient. Now what I'd like to see is the APC props for the models made larger for F-1 racers!

Michele

[AirDOGGe]

Re: One Bladed Props

I have seen pictures and heard rumours about guys running one bladed props on 150mph control line racers,

This guy hit 208 mph with his.....one blade, one wing and one horizontal stabilizer... the website includes photos and a video of the record flight.

http://www.flyrc.org.uk/record/control_line.htm

.

[agerhart]

Re: One Bladed Props

One Bladed props are the most efficient mode, but present several problems:

1. The blade has to be bigger than multiple blade props to have the same area. Usually this means a larger diameter. Rare Bear would have to have REALLY long legs.

2. While you could work out the basic balance with a counter weight, what fast airplane wants to carry that much dead weight.

3. Loading. As the prop turns, the center of thrust moves with the rotation of the prop. Talk about P-Factor, it would apply all the thrust to the right side and in milliseconds, switch that thrust to the left side. The crankshaft and engine mount loads would be horendous. It would also shake the fuselage like a fish.

Al

[Chris300s]

Re: One Bladed Props

I've done single blades props for electric pylon racers in RC. Most of the props are wood with a lead counterbalance grafted on. The general rule (at these very low Reynolds numbers) is increase the diam. by 40%, leave the pitch and statically (cly?) balance the prop by shaving the counterbalance. We couldn't go much higher than a Cobalt 05 with out shedding the weight. I have no idea how the .40 CL guys do it at 26+k rpm with all of that vibration.

Chris

[Peashooter]

Re: One Bladed Props

Now what I'd like to see is the APC props for the models made larger for F-1 racers! Michele

Call Gary Hertzler...I did and I'm amazed! Wood core sheathed in carbon and glass.

[laminar]

Re: One Bladed Props

Does any one know anything about the construction of the one bladed props or how to overcome the asemetric loading, I am more interested in the RC application specifically size .61 OS motors. Are there manufacturers out there. Is there someone who I could pay to manufacture using their knowledge and expertise?

[AirDOGGe]

Re: One Bladed Props

This RC site has some mention of the brass/maple construction of his 1-blade prop, but no diagrams:

http://www.djaerotech.com/dj_askjd/dj_questions/onebladeprop.html

Interestingly, this site mentions that single blade props were used on free-flying models at least as far back as 1938!

http://www.theplanpage.com/Months/2302/berry.htm

As far as how to balance all of the forces, They address the weight/balance problem sufficiently, but I don't think anyone has ever solve the problem of asymmetrical aerodynamic loads.

I guess such loads are small on a little high-RPM model airplane engine with a light wood prop spinning a prop circle diameter measured in inches. That would explain why you only see them on small-scale models.

[Tin Man]

Re: One Bladed Props

Call Gary Hertzler...I did and I'm amazed! Wood core sheathed in carbon and glass.

What am I missing here? Pretty sure I see the othe half of the prop behind that funny looking spinner.
Tom