This is certainly the highest performance single-seater I’ve had the
pleasure to fly. I believe the flight tests would have been even more
impressive if the ambient temp hadn’t been so high (~42C). This
yielded a high density-altitude that prevented sustained operations at
the edge of the performance envelope. Nonetheless, a full test of all
flight regimes was attempted.
At 1300 hours, a thorough pre-flight inspection was performed along
with a very exacting weight & balance calculation. The designer and
several other test pilots had indicated that the CG range is very very
narrow. I can confirm that assessment! This also explains the lack of
a rear seat or baggage compartment. The test started off with several
aborted takeoff attempts. Due to the very course fixed-pitch prop a
long takeoff roll is needed. When I finally got airborne and got the
craft “cleaned up” I did the usual basic explorations of the craft’s
sensitivity to control inputs. Roll characteristics were benign and
the craft executes banked turns easily. Acceleration is smart
considering the pitch of the prop; probably due to the low
empty-weight for a craft of this speed. Next I tested approach
stalls, departure stalls and unusual attitudes. The craft accelerated
out of the stalls nicely if not a little too quickly. Finesse with
the throttle is a definite must. The unusual attitudes proved more
problematic and several UPDs were logged (all S-1s).
A short cross-country was flown to test comfort and to get in tune
with the cruise characteristics. This is definitely the perfect craft
for such operations! Pushing closer to the edge of the performance
envelope, several speed runs were made at military power settings.
The craft exhibited some moderate yaw instability in the form of
“fishtailing” much like that encountered on older V-tailed Bonanza’s.
Of course this is a much higher performance craft than a single-engine
Beech but the oscillations were similar.
On the return to the field, a final speed run was attempted at max
military power. As I was getting ready ease back on the power, the
overspeed light on the annunciator panel flashed brightly. I pulled
back the power a little too aggressively and the craft began pitching
forward along it’s lateral axis. I went immediately back to max power
but it was too little too late as the power-headroom had eroded to a
dangerous level. The craft continued to pitch over violently! I was
going to have to punch out to save myself. Unfortunately I was at a
very low altitude and the chance of a safe ejection was dubious.
Nevertheless, my reactions were automatic. I pulled my arms in to my
sides, reached down and yanked the red eject handle between my legs.
There was little time for my canopy to deploy before I hit the ground
at incredible speed. Looking back out of the corner of my eye, I
could see the craft coming down right behind me! I hit the ground
running, cleared my shrouds, and continued running as I heard the
craft pancake in right behind me. The craft was virtually undamaged
but I did have to log an S-2 UPD. Fortunately, no one on the ground
was injured. It could have easily been much worse but you know what
they say: “Any landing you run away from is a good one”!
Since then, a couple of modifications were made. The flanged
control-rods to the rudders were exchanged for straight ones in an
attempt to dampen the high-speed yaw oscillations. It remains to be
seen how effectual this change will be. Further flight testing in a
cooler climate will be needed. Also, some additional shimming in the
form of a tempered steel washer was added to the right engine mount to
fix some obvious asymmetry that could lead to metal fatigue and
eventual disastrous in-flight separation of the engine.
Respectfully,
Flight Leftenant Keith Williamson
Arizuni Squadron
“You build’m we fly’m”