Walking on the Edge
—the
challenges of data acquisition
 |
| Rudy Opitz just prior
to an inflight engine test that was nearly disastrous. Note the
camera used to record instrument readings at
intervals. |
On July 30, 1943, Rudy was test flying
the 163B with the new “hot” engine when violent thrust fluctuations took
place at 26,500 feet accompanied by a flashing fire-warning light. At
28,000 feet, he cut the rocket and brought the plane to a lower altitude,
but the engine would not restart. The aircraft was far too valuable to
lose, and he decided to risk landing the craft with volatile fuel on
board. Taking risks to preserve airplanes and data was characteristic of
Rudy throughout his test-pilot career. Nothing could be found to explain
the problems encountered, so the next day, Rudy made another test flight,
this time rigged for gathering of inflight data. Rudy recalls:
“Our
test program called for data acquisitionon ‘inflight engine operation and
performance’ and there was just not enough space available in the aircraft
to install the test and recording instrumentation. I decided to make room
for the test instrumentation by removing a big flight-attitude gyro and a
turn and bank indicator from the pilot’s panel and to do the data
recording with a small camera, equipped with an automatic film transport,
attached to a headband that I would wear on my forehead during the
flight.
“The day for the flight test was cloudless but
hazy, and the program called for takeoff to the northeast, establishing a
maximum power climb at 420mph indicated airspeed on a straight line out
over the Baltic Sea, taking panel pictures at 1,500-foot intervals up to
an altitude of 40,000 feet. It seemed to be simple enough. However, the
time schedule for taking the data was not easy to comply with when one
realizes that the aircraft needed only ten seconds to climb 1,500 feet
after reaching the desired airspeed and only six seconds were needed to
climb through 1,500 feet at higher altitudes.
“Take off, dropping
the dolly, retracting the skid, trimming and accelerating to airspeed for
best climb kept me very busy prior to recording my first checkpoint. The
eight to ten seconds available between each of the following checkpoints
were just enough to scan the instrument panel and to make necessary
control adjustments to hold the aircraft within the narrow operating
limits specified for the test. For a while, everything went fine, and I
met the recording points right on the dot.
“My airspeed, however,
started to increase during the climb toward the 15,000-foot checkpoint and
despite corrective action, I missed the airspeed requirement. I raised my
head to look outside for a quick check of aircraft attitude against the
neutral horizon only to find that it was not visible because I was
climbing in a heavy haze that blended perfectly with the sea below.
“The aircraft reached shock-wave-forming airspeeds within seconds,
causing it to pitch forward and forcing me to throttle the engine back to
idling speed. I then spotted a tiny island sliding by under my left
wingtip, giving me enough of a reference to establish my attitude as being
in a steep dive turning left. I started careful recovery and managed to
obtain level flight a scant few hundred feet above a perfectly smooth sea.
The engine had flamed out as a result of fuel-flow interruption caused by
negative acceleration during the flight at airspeeds above the critical
Mach number for the aircraft.
“Heading now for the coastline, which
loomed out of the haze in the distance, I restarted the engine
successfully and within minutes, appeared over the airfield for a safe
landing, much to the relief of our anxious crew, who had given up hopes
for my safe
 |
| Rudy Opitz, today,
describing the harrowing
flight. | return after observing the aircraft arcing to the
left during the steep climb and then suddenly heading down just as steeply
toward the sea and disappearing below the horizon from their point of
observation. Before landing, I noticed the craft would not slip.
“A
walk-around inspection of the Me 163 after the landing quickly revealed
signs attesting to the high speeds and stresses to which I had
unintentionally subjected the aircraft. The rudder had disintegrated
completely; only its spar was still attached to the vertical fin. Fairing
fasteners on the fuselage and wings had pulled out of their seatings. The
incident served as a stern reminder that enthusiasm can be dangerous if
it’s not coupled with the most careful planning, and the day was written
off as another experience of ‘learn and live.’ ”
—Jeff Ethell (“Komet, The Messershmitt
163”).
|
