The EVIC Mk3 engine evolved out of the Mk2 engine starting in 2005. The initial objective was to design a stronger crankshaft to be housed in a larger crankcase to improve oil retention. Initially all the other parts came from the Mk2 engine. Once I had the engine running with the new crankcase I designed the Mk3 head with larger valves and a 3 solenoid configuration; 2 ganged exhaust valve solenoids and a single intake valve solenoid.
As I worked on this engine I began thinking about flying it in a radio controlled airplane. After my success with the Mk2 single and then the EVIC Twin in my radio controlled boat this seemed like a next "logical" challenge. I knew that to be successful I would have to increase the power to weight ratio of the Mk3 engine and to improve the engine's overall reliability. This led to a new cylinder and piston with the bore increased from 1", 2.54 cm, to 1 3/16", 3 cm, thus increasing the displacement from 12.5 to 17 cc. Although the 17 cc engine was running in November 2006 it took many months to sort out all the design issues that resulted.
By the spring of 2008 the engine was fitted with larger solenoids, 3:1 lever arms and stronger valve springs. The solenoid control voltage had increased to 42 volts. There were still problems with getting the exhaust valve to open reliably when the engine was accelerating. I added more accurate crankshaft positioning sensing using 9 magnets, one every 45 degrees plus a TDC indicator.
An exhaust valve open sensor was added to the exhaust valve 3:1 lever arm assembly. The control software was modified several times before I was satisfied that the engine was ready to fly. After a number of taxi runs and test hops the first real flight took place on September 29 followed by a much longer flight on October 7, 2008.
The valve lifts on this engine are 0.075", 1.9 mm. The controls are a Mk6 Electronics Package that uses a PIC16F628 main processor and 4 PIC12F629 processors with the exhaust valve open sensor added. Power output with a 14" x 7", 36 cm x 18 cm, model airplane propeller is approximately 0.85 hp at 8500 RPM.
After the October flight the plane was put to bed for the winter. Click here to see what I did to the engine over the winter.
