FLYING THE TAURUS G4
When Ordinary Becomes Extraordinary
BY DAVE MORSS
I WAS AT OSHKOSH 2009 demonstrating the Yuneec E430 electric
plane when I first heard about the GFC. After reviewing the requirements, I was baffled and amused and wrote it off as a pipe dream. I
had two years’ experience testing and flying electric planes. I just
couldn’t see how GFC thought its goal was possible. It was calling
for an average of better than 200 pmpg, for two hours, at more than
100 mph. Yeah, right. Electric planes were nowhere near being able
to meet those requirements.
But time moves on and engineers don’t sit still. About a year
before the challenge, I agreed to test for a different team, but as
time progressed, that team wasn’t able to meet deadlines and graciously released me to test for Pipistrel, which had teamed up with
Dr. Jack Langelaan’s Aerospace Engineering team from Penn State
for the contest.
I had met Pipistrel engineer Tine Tomazic at Oshkosh in 2009, so
last summer when the Penn State pilots were not allowed to do the
testing because of insurance issues, Tine called me. We met up again
at AirVenture Oshkosh 2011 and began an inspection of the G4,
which had just been issued its airworthiness certificate. We started
our testing there immediately after AirVenture ended.
The G4 was built specifically for an efficiency race. Most of its
substructures came from airplanes already in production at Pipistrel
and had good data, testing, and service time. The only new piece was
the center section and motor pod. Tine showed me extensive engineering and load test reports for these structures. Tine also had
talked to Scaled Composites pilots about off centerline aircraft, and
we felt we had a good handle on that aspect. For example, sitting off
center you descend for a right turn and climb for a left turn in relation to the center of the aircraft. And landing has its own issues.
Pipistrel R&D chief, Tine Tomazic, reviews data with pilot Dave
Morse after a test flight.
Tine had done high-speed taxi tests in
Slovenia and determined that more rudder
and elevator were needed. The bigger surfaces were already installed when I started
flight testing. But first I walked all the taxiways to make sure there was no signage
taller that my knee. The long wing tended to
hang out over the edges of most taxiways.
I started with slow taxiing and worked
my way up in speed and tasks slowly. During
the initial runs, the airplane still seemed a
little tail heavy. It took a little inboard flap to
help raise the tails at a reasonable speed.
The outer wings had full span flaperons and
the center wing had a large split flap. The
center flap was completely independent of
the flaperons. After several short hops, we
were ready for the first high flight.
Even though the plane weighs in at more
than 3,000 pounds, the acceleration at full
power is quite good. All went well until the
speed got to more than 80 knots, and then
stick forces became an issue. Having made
several landings in this configuration, I
decided not to try moving any flaps but just
guide it around and land. This was a very
low drag configuration so the pattern looked
very low, but crossing the numbers at two
feet, we went a thousand feet down the runway before I touched down. A few tweaks
and some fixed trim tabs, courtesy of our
friends at the EAA maintenance hangar, and
we were back in the air.