The company is using Honda L15-series and Mitsubishi car engines for their conversion to an aircraft application. You may buy them new from Honda but most customers opt for used engines that have been used in cars for less than six months or 5000 miles. After they leave the Viking factory assembly line they can be considered as a rebuilt/new aircraft engine.
For almost perfect matching between engines, propellers and aircraft Viking manufactured in-house a variable propeller based on DUC blades and hub to install on their successful line of Honda / Mitsubishi converted car engines. On this page we elaborate a little about this latest development and its performance.
With a variable pitch propeller (either constant speed, ground adjustable or manually) the pilot is able to select certain power settings regarding efficiency and power, optimized for the current flight conditions. You will find more detailed information in our propeller section on site here.
With the forthcoming change in LSA rules regarding these aircraft and controllable propellers, Viking saw an opportunity to create a system which allows the pilot more flexibility with the Viking engines. For that they, being a DUC dealer, used the lightweight DUC propeller system which also has a constant speed controller.
DUC uses carbon fiber extensively in their products. The result is a very lightweight and strong hub and propeller blades. The hub (clamshell type and weighs 4,75 lbs) contains a spring, pushing the blades (Swirl-3, 2 lbs for one blade) in the fine pitch position. A rod runs through the hollow shaft in the gearbox and is moved by a small diameter electric actuator which, in turn, is operated by the C/S controller.
This system does not need an electric motor and slip rings in the spinner, reducing the rotating mass and complexity considerably. Also, and this is the big one: the variable valve timing and knock protection of the Viking 130 allow for an unprecedented efficiency by full throttle operation at all RPMs from 5400 all the way down to 3200 RPM. Which is something not normally done with comparable engines. Lastly, the price of the propeller, without the complex hub mounted parts will be less and the system will last much longer with the low 1.0 amp draw.
Best overall RPM to fly the variable pitch Viking propeller System installed on Dave Tillemas' CruZer is 4500 RPM. This represents up to a 380 mile increased range over factory published numbers. (His airplane can do 141 mph but these are the realistic and efficient cross country numbers.)
A detailed explanation by Jan Eggenfelner about the variable pitch propeller can be seen below:
Flight test video of the new propeller system:
For more information about this propeller see the website of Viking Aircraft Engines.
Video and images used with permission of Viking.