By STAN KASPRZYK

FlightLog Archive

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Aircraft Flown

Flying the Sinus - Sep 2012

The Pipistrel Sinus is a new motorglider that merges a well-designed sailplane wing with a Rotax powerplant for an impressive aircraft with a combination of good soaring capability along with very efficient cross country touring performance.

My friend Paul Kuntz had been constructing one of the first kit-based Sinus aircraft in the US, meticulously documenting his homebuilding progress. As Paul neared completion of his aircraft, we began discussing first flight preparations. I mentioned to Paul that experience in the same aircraft type would be invaluable for first flights in his personal Sinus. Paul was able to make contact with George Powers, builder of the first Pipistrel Sinus kit to fly in the US, and George offered both of us some flight time in his Sinus.

In late September, Paul and I flew to Reno, NV, then drove northwest into the California Sierras, staying the weekend in George's beautiful home outside of Clio, CA. We reviewed the Pipistrel Sinus flight characteristics and details over a delicious dinner, and then headed to the Nervino airport in nearby Beckwourth, CA the next morning.

Saturday morning was clear and crisp as we arrived at the 4900-foot elevation Nervino airport. George's Sinus was parked on the ramp right near the end of runway 8, so we untied and pre-flighted his bird in detail, removing the engine cowling to check oil levels and engine condition on the Rotax 912. Since I'm more comfortable with a stick in my right hand, I settled into the right seat, getting familiar with the cockpit layout and George's panel. Starting the Rotax was as easy as starting a car, and with a slight warm-up, we taxied the short distance to the active runway for takeoff. I applied power, and the Sinus quickly accelerated, allowing me to raise the tail, and with slight aft stick we seemed to levitate off the runway, climbing very well in the high altitude conditions. Pitch and roll sensitivity were pleasantly crisp, and George noted the surrounding lakes and rock outcroppings as we ventured around the high Sierra landscape. I especially enjoyed the great side visibility. We flew slow flight and a few stalls, with the Sinus just mushing along with little wing drop tendency, and simple recovery with forward stick pressure.

I flew three patterns and landings on the first flight, and quickly learned how sensitive the Sinus is if flown too fast on final. While not exactly skittish, the Sinus will respond to every slight gust, crosswind or pilot input, and provides a much better approach and landing platform if configured early and flown on speed. After a wheel landing on the second attempt, I finally slowed down enough to accomplish a passable three point landing on the third attempt.

Paul flew the Sinus next for his first flight, also working on patterns and landings as his priority. I was able to fly two more enjoyable flights on Saturday, bouncing a few landings in, and then finally putting things together for better landings on speed. George and I started finding bits of lift on the second flight, and shut down the engine, thermaled a bit, then easily restarted for the return to the airport. Even though landings can be made with the engine off, normal practice is to motor back to the runway, and then fly the pattern in idle power, modulating the descent rate with spoilers. On our third flight, I shut the engine down around 7000 feet (2000 feet AGL) and quickly thermaled to 10,000 feet under a sky filling with flat-bottomed cumulus clouds.

After three enjoyable hours in the air, plus two flights by Paul with George, we stopped at the Coyote Bar in Graeagle for a session to 're-hydrate'. George again provided an outstanding dinner, with more enjoyable flying discussions. On Sunday, I flew a final checkout and sightseeing session with George, exploring the Sierra Buttes up close, and then maneuvering through the ridges and canyons in the high Sierras. George then graciously allowed Paul and me to fly together, so I could assess Paul's progress and sign him off after a beautiful final approach and landing.

George, thanks for the outstanding hospitality and checkout in your amazing Sinus. Paul, I look forward to first flights in your newly completed Sinus in the coming months.