fbpx
Login

 

Jump to Forum..

3 blade versus 2 blades....

in General Tech Discussion 8 years ago
I have a 912 80 hp engine in my Merlin EZ. I've been running a 2 blade 72" IVO and it has always been vibrations. Carbs are balanced, prop is good etc. Anyone have any thoughts on me running a 3 blade with the same diameter. Will it be smoother and will it lower the speed of the plane. I'm doing 85-90 mph now at 5300 rpm. I would of course have to lean out the blades some. (ground adjust prop).

Andy C-IKEA
MerlinC-IKEA.jpg (You do not have access to download this file.)

  • Re: 3 blade versus 2 blades....

    by » 8 years ago

    Hi Andy,

    If you can only get 5300 rpm at WOT in level flight you are way over pitched. Shoot for something around 5600-5650 rpm.
    Your two blade prop may only need a dynamic balance.
    That said a three blade is usually smoother and I would personally drop in size down to a 68". There are several decent props out there, but I have gravitated towards Sensenich over the last few years.

    Bottom line it will boil down to a personal choice.

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

      
    Report

  • Re: 3 blade versus 2 blades....

    by » 8 years ago

    Remos Aircraft went to a 3 blade prop cut down on noise and vibration, I have flown the plane with both and there is a difference. Even the US Military is adding blades to reduce vibration related maintenance cost on various aircraft.
    Thank you said by: Andy Gustafsson
      
    Report

  • Re: 3 blade versus 2 blades....

    by » 8 years ago

    I was somewhat unclear in my question. 5300 is my cruise rpm. I can get it up to 5500 rpm no problem. If I put a third blade on my IVO (same diameter) I understand that I get rid of lots of vibrations but is the speed suffering from an added blade? (I have checked the balance and it is 1 gram difference between the blades.) I was thinking to keep the diameter of the prop. I don't know if me cutting the blades down to 68 in. will be advisable? Is the 80 hp 912 enough to spin a 72 in?

    Andy.
      
    Report

  • Re: 3 blade versus 2 blades....

    by » 8 years ago

    I think Sensenich or a company like them would be the one's to ask for those kind of details.
    Thank you said by: Andy Gustafsson
      
    Report

  • Re: 3 blade versus 2 blades....

    by » 8 years ago

    A 3 blade is much smoother.
    The IVO is a very heavy prop and if it is not dynamically balanced it can have a lot of vibration.
    The pilot will be amazed at the vibration/noise difference after a dynamic balance.
      
    Report
You do not have permissions to reply to this topic.
Related Topics
Title Category Replies
100LL-Avgas versus MoGas-Autogas General Tech Discussion 12
2 blade Warp Drive prop General Tech Discussion 1
Spinner for Sensenich 3-blade prop General Tech Discussion 1
What pitch to use on a 582 3 blade 68" Kiev 2.58 gearbox 2 Stroke Technical Questions 7
Copper versus Alumin radiator on 582 2 Stroke Technical Questions 5
Follow Us

Recent Videos

Safety First!

 

To receive critical-to-safety information on your ROTAX Engine, please subscribe to
ROTAX-OWNER.COM

ROTALK News



ROTALK NEWS Episode 5
Rotax-powered Sling aircraft from The Aircraft Factory, the AVMAP Navigation and engine monitoring system, and the Rotax powered Tucano Experimental and Light-Sport Aircraft.



ROTALK NEWS Episode 4
ROTAX's 915iS-powered Aquila A211 test aircraft, the Scheibe SF-25C Falke (first-ever 912-equipped aircraft!) and ROTAX factory in Gunskirchen, Austria.


ROTALK NEWS Episode 3
Michael Smith's Rotax-Powered Searey Circumnavigation, the amazing Rotax-Powered Lockwood Aircam and Anthony Caere's chimpanzee rescue operations.

Prize Giveaway!


SUBSCRIBE NOW
to automatically enter this years draw!

Login