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  • Re: E-Props seem to be the new rage

    by » 7 months ago


    Its my understanding that the e-prop does not flex or deform to produce their "ESR" effect (extended speed range).  Instead they proport to use a narrow chord and special profiles to make this happen.  Other manufacturers also have fixed pitch propellers that are claimed to mimic a constant speed prop.  

    E-prop does mention flexing or deformation of the prop as one method to get the ESR effect, but then they go on to say that's "difficult to obtain". 

    I run a DUC Helices Flash prop, which has a similar claim.  Initially I was under the misconception that their prop used deformation to mimic a constant speed prop, but when talking with a factory rep I was told the prop does not flex at all, and instead relies on proprietary blade profiles to get that affect. 

     

    This is from the e-prop website. 

    From technical point of view, there are different solutions to obtain this ESR effect :
    - narrow chord with classic profiles
    - pitch reduction at low speed by blades deformation (difficult to obtain)
    narrow chord with special profiles, in order to avoid the stall of the blades => it is the case of the E-PROPS


  • Re: E-Props seem to be the new rage

    by » 7 months ago


    On the subject of 3-blade props reducing noise... A few years back, Aviation Consumer ran a test with two different airplanes, and two different prop manufacturers.  The "control" was using the same blade/hub manufacturer on the same airframe for the tests.  (They tested a  Bonanza, using two- and three-blade props from the same manufacturer for the tests.  Ditto for the other airplane - which I think was a 182, but can't really remember.)

    Anyway, they tried really hard to do a scientifically accurate, controlled test.  But they also had a good number of pilots participate in the review to obtain some "subjective" feedback.  The instrumented flight results were about what you'd expect:  2-blade props produced slightly faster cruise speeds, and 3-blade climbed slightly faster.  But the differences were pretty negligible – something like ± 100 fpm and maybe 2-3 KTAS.  And with both types dynamically balanced, the 3-blade props were slightly smoother in operation. (Keep in mind, this is with the same blade profile and construction - no "new tech here...)

    The "interesting" part of the results (to me anyway) was that 100% of the pilots reported that the 3-blade props were significantly less noisy, both when they're flying the airplane and when they were observing from the ground as the airplane flew a low pass.  The actual instrumented test results, however, showed that there was zero difference in the actual noise level as measured by a calibrated sound meter.  The only real differences was the "pitch" (frequency) of the noise.  Three-blade props produced their noise at a somewhat higher frequency than the 2-blade props.   That seems logical, with 3 blades turning at the same RPM), and the report concluded that this upward shift in frequency made the 3-blade prop "seem" less noisy to both pilots inside the airplane and to observers on the ground.  

    The other theory (which makes more sense to me, given some studies on helicopter tail rotor noise signatures I was involved with while in the Army) is that the 3-blade prop "sound waves" are at least partially disrupted by the wave produced by the next blade.  Obviously with 3 blades, there is a shorter interval between those sound waves.  It's similar to the principle behind active noise-reduction headsets.  Hughes Helicopter (now McDonnel-Douglas) was doing some R&D pursuing a "silent" tail rotor for the Army.  They found that just offsetting a 2nd pair of blades (at about a 30º angle from the first pair), the noise signature of the tail rotor was reduced by something like 60%.  It wasn't "silent" by any means, but it was far more "stealthy" than the original...  But to observers on the ground, it definitely seemed to be significantly more quiet than the standard rotor –far more so than the instrumented test results reflected.

    The other thing pretty much agreed upon by all participants (and even some casual observers who just happened to come by during the Aviation Consumer test) was that 3-blade props made the airplane look better – no contest whatsoever.  And as we all know, airplanes fly pretty much how they look...  (LOL)


  • Re: E-Props seem to be the new rage

    by » 3 months ago


    Brian FitzGerald wrote:

    I bought a 3 blade for my RANS S-12 with a 912UL. It arrived yesterday but I couldn’t get it mounted today and have house guests showing up tomorrow staying through the weekend. After that, it is job #1 and I’ll report my findings. I got it in hope of reducing prop noise but I would appreciate equal or better performance. We shall see.

    Brian,

    Did u ever get the e-props installed?

    Am very interested in ur review

     

     

     

     

     

     


  • Re: E-Props seem to be the new rage

    by » 3 months ago


    I’ve been doing some research since I personally don’t have first hand experience with EProp. I’ve heard and talked to many EProp owners now. Looks like sales are booming and everyone claims better results than their previous prop with climb and top speed. Sounds like a new and improved prop.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: E-Props seem to be the new rage

    by » one month ago


    I installed one in a Tecnam P2002. I have not observed any improvement in cruise speed, as expected because the pitch of original prop is already optimized for cruise, but definitely the take off run is shorter and climb performance is better now.


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