I'm curious if anyone here has ever tried a 4 bladed prop on their aerobats.

I know Enge Modellbau has a CF 4 blader out in the 100-150 cc size range.

Any good? Any better than a 3 blader in noise or thrust, or just more expensive?

I saw one fly at a pattern contest. The extra blades greatly increase the "density" of the disc. The most noticeable effect was when the throttle was chopped, the plane slowed dramatically, almost like it had brakes. Made for good constant speen on down lines and halped bleed off airspeed on final.


Rob

They are extremely inefficient.....Even the 3 blades are less efficient than 2 bladers...



the reason more blades creating turbulence in the air that's being moved. Very few at the TOC this year used 3 blades. I personally like the looks but in the performance department its a loose loose situation.....the only gain is noise footprint.....


Yes brakes are also a benefit but on the big airplanes like the 33%+ they slow down very well anyway.

Now on pattern models flying at sea level with 2 stroke motors.....the results are better because at sea level the 2 strokes have the extra beans...plus have poor downline brakes compared to the 4 strokes....Therefore a 3 bladed prop can help you with the energy management.

For me the the new YS 140DZ solves the problem it has the same top end power of the 2 strokes and gives me the brakes of the 4 stroke....so the 3-4 bladers are not a real solution. I know many of the top flyers that have experimented with them on both 2 and 4 stroke pattern motors and the results seem to be overwhelming.....against them...There are just too many options with the 2 blade props in the 15-17" range...for pattern.


The big engines are more limited and the props are much more expensive.....Seems as though everybody uses about the same sizes for the displacement....a 100cc gets a 26-10 for the weaker ones and the 3W's and DA's get like 28-10's


With pattern props we have the choices of a 16.5-12 and a 16.5-12W and a 16-13 and a 16-13N and so on.......This really helps make the choices because they are like $12 each so you can try them....

On the bigger motors $40 is not as easy a test and for the big 3 bladers your looking $100-200 each......not experimental material for most people.


Just some thoughts on them


Troy Newman

Thanks guys.

I love the look of them and I would think they would load the engine up and cut way down on prop diameter which are both very conducive for low dB's

Now that I think about it, has anyone tried the newer NX props (that occasionaly run an add at this board)?

Well don't be discourage by those comment, while it's not as efficient I have run 4 blade for about two years when I was flying a older pattern models with little space for the 16 inch prop on the 140 L, I was running the 14.5x12 4 blade apc with very good success good pull good brake and bag of reserve power.

The top German guys were all running the APC 15.5x12 4 blade at the last world....very successful I might add.

Since moving to a newer airplane design I'm running OS 140 RX with the 16.5 x 12w on ES pipe and 25% cool power.

You do not need a 800.00 motor to be happy.

Daniel D.

I have a Hydeout with a Webra 1.45 that can be pretty "slippery" at times. Do you think I should try a 3-blade prop to help slow it down some, Troy since it is an older design? Thanks.

I would say your best bet would be to go down and buy a couple of props that look like they'll work well, and try 'em all!
It is expensive though!
Hope this helps!
Robert.