Without a method of converting the power produced by the engine into useful thrust an aircraft would just be sitting still and creating a lot of noise and not get anywhere. In the past, all kinds of different propeller designs were tried: sometimes flat wooden blades, from one bladed counterweighted to multiple blade models rotating at various speeds.
Variable pitch propellers have a distinct advantage compared to fixed pitch models. This translates into a more fuel efficient, higher performing aircraft with much improved rate of climb and shorter takeoffs for those tight places!
IVO prop is a small company based in Long Beach CA, US. The owner Ivo Zdarsky escaped from former communist Czechoslovakia in 1984 with his homemade trike aircraft (propeller too!) powered by a small two-stroke Trabant engine.
Since 1986 the company has sold more than 20000 propellers, mainly made from carbon graphite composites. These blades are know to flex visibly under load for maximum efficiency during operation.
One of the unique features of the IVOprop is the simple pitch change mechanism, see image. It uses a torsional rod embedded in each blade, which can be twisted by a cam in the propeller hub. Turning a screw adjuster in the center of the hub simultaneously sets the pitch of all blades without having to use protractors or torque wrenches to re-tighten hub bolts.
IVO also has a electric adjustable version, more appropriately called torsional twist, which can be adjusted in-flight by the pilot by operating a small switch. Another features is that with the three blade version, you can remove one blade and continue the flight with the remaining two...
With a separate electronic controller the in-flight adjustable IVOprop can be converted into a constant speed propeller.
The two bladed propellers weighs six pounds and the three blade version only eight pounds. The price is equally lightweight: $340 for the two blade and $460 for the three blade including the hub for both.
With propellers its important to stick to the correct installation and maintenance procedures. IVOprop has put out a detailed service bulletin explaining the proper procedure years ago.
The correct sequence necessary to torque the bolts is to install the propeller then run the engine, re-torque and check after the first 15 minute of flight. Knurling (i.e. teeth, like on the surface of a metal file) was added to the crush plate that sits against the base of the blades and the blades themselves are also strengthened. Metal tape is now used across the joint between blades so that any relative movement can be easily seen during preflight inspections.
You will see these propellers mostly on ultralight and trike aircraft.
The latest IVOprop development is a powered-parachute application using a tandem pair of two-blade propellers mounted in an X-configuration of 60/120 degrees rather than 90 degree right angles you normally see on a standard four-blade prop. The results in an accelerated air flow over the close following blade resulting in more thrust for the aircraft.
IVO Prop can be contacted at the following addresses:
|IVO PROP CORP.|
|2615 East 67th St. Unit E|
|Long Beach, CA 90805, USA|
|+1 562 602 1451|
Text and images used with permission of IVO PROP CORP.