2 blade vs 3 blade....

[scottessex]

Anyone ever put a 2 blade prop on a dominator?
Just wondering, I have an IVO here, and I am sure I can remove a blade and make a 2 blade, just wonder if I might get better cruise.. (1 less blade-more pitch)

[jcarleto]

At one time I had a chart that showed the effectiveness of propeller blades relative to the amount of pitch. I can't find it. What I remember, in general, is too much or too little pitch is not a good thing. There is a range for each propeller blade...a sweet spot, if you will.

I'm sure IVO can tell you the range of angle that is in that area for your prop length. So, it's all down to horsepower and load. If you can keep the engine RPM in the acceptable range by adding pitch and not slip into the questionable range of the propeller, you win!

Two blades are always better than three IF you don't have to over-pitch. Fewer blades, less disruption of air for the coming blade, less drag, etc... When I rebuild (once again) the Bulldozer, I fully expect to put a 2-blade Tennessee prop on the new re-drive rather than to replace the 4 PowerFin blades. Tennessee Propellers can mitigate the need for excessive pitch with propeller blade width.

[phantom]

I am working on this now, I have almost finished my dominator and I am useing a 72 inch 2 blade warpdrive, I will post the results here when done .

[scottessex]

Thanks...I had the IVO 4 blade, and it worked great on the rotax 582, but not so well on the Arctic cat, (???) So I put the 3 blade warp drive back on, seems fine so far...But I still
have the IVO and can use it in 2 - 3 or 4 blade mode.

I also have to consider what prop I am going to use on the CAM100 2 place, but I am not there yet.

[WHY]

Just in case there are some "newbies" out there that are wondering about the question of blades, the reason has already been given, but a good example is the number of blades on WWII fighters. They went to more blades because they had so much HP that they could not make a two blade that would soak up all that Hp and still keep it short enought to fit on the plane, it would have looked like a heliocopter setting on its side.

Tony

[scottessex]

That is exactly what got me thinking that Tony, When I went back to the 3 blade it was because after getting the Arctic cat dialed in, it is less HP than the 582, (530cc)
so I was able to put more pitch in the prop and I can cruise at about 5500-5700 rpm.
That got me to thinking if the 2 blade might even be better with a little more pitch, then you lose takeoff and climb performance etc, I can do the testing with the IVO, from 2 blades, 3 blades or 4 all with 60" diameter, I just didn't want to start doing more R&D right now. :D

[WHY]

Hi Scott

The one factor that has not been mentioned that comes into play when you get down to the 2 blade application and using blade numbers for refference is-----blade profile, and blade width.

An rough overall comparision of blades efficiencs can be done with the same blades and various pitch settings but the final touch will involve blade profile (cord width and shape) combined with the other factors to get the max efficiency. This can usually be gotten from the manufacture if you give them the working parameters you are limited to like hp, rpm, length, "pusher/tractor" maybe even elevation.


Tony

[Rick Whittridge]

Scott, I believe the Carlinator uses a two blade prop? I`ve seen photos of it on the forum?

[WHY]

Making props is a science and a art and a good dose of witchcraft

Tony