I had an Ivoprop on a Wag-A-Bond with an EJ-22 Subaru engine withe 2.1:1 reduction unit. The prop performed well as far as power for takeoff and climb and cruise. That plane out climbed a brand new 3-bladed Super Decathalon. However, there were some drawbacks that made me decide to switch to a warp-drive prop. Problems included: -First of all, the brushes which transfer electric energy to the electric motor that change the pitch of the blades were very troublesome. Sometimes I would only get 20 hours out of a set of brushes. The most use I ever got from a set of brushes was about 60 hours from the new Ivo brush setup. -Secondly, the props including the actuator motor and prop adaptor are fairly heavy. I wouldn't consider one for a light plane like a KR for this fact alone. Also keep in mind that a heavy prop is not usually a good idea for a direct drive auto engine. Lots of broken cranks around from heavy props and auto conversion engines. -Thirdly, the basic premise on how these prop change pitch is through flexing via a torsion rod that runs through the middle of each blade. In theory this I great. It used to amaze people when I would cycle from fine pitch to course pitch on the ground. You could actually see each blade twist. It looked cool, but there was another heavy price for this. The blades had to be flexible. And a blade that flexes is less efficient than a good rigid prop because you lose energy to this flexing that should be used to push air. This flexing was evident in the air as a vibration. You could even see the blades flexing if you had just the right reflection from the sun while flying.
So, overall the prop performed well but was not very efficient, and had a vibration that was considered normal due to the inherent flexibility of the prop. I would not even consider one for any VW or Corvair direct drive engine. Plus the brush system was a real pain to keep maintained. If you have an engine that truly can handle a heavier prop I highly recommend the Warp Drive props. They are much more efficient and smooth. Plus they perform just as we'll as an inflight adjustable Ivo prop since they are more efficient. Hope this first hand account of these props was helpful. Cheers, Jeff Provenzano "Has anyone used or using an Ivoprop inflight adjustable prop." http://www.ivoprop.com/ Are they OK? Phil Matheson
