Beech
Starship History Continued...
In
the final test a fuselage section dropped at 17 ft/s incurred
no damage, and the anthropomorphic dummies inside sustained
a spinal load of only 1000 pounds.
Sled testing, to 269 for crew seats and 219 for passenger
seats, has been done in keeping with the recently-established
standards of the General Aviation Safety Panel.
One of the greatest challenges to building and certifying
an all-composite airframe is lightning protection. Unprotected
composite material can be blown apart by a lightning strike.
This occurs because graphite epoxy is 1000 times more
resistant to current flow than aluminum, and the high
resistance converts the current flow to heat.
Lightning protection was the subject of intensive study
and testing; for instance a fuselage section absorbing
a 200 000 amp simulated lightning strike generated in
our test facility. Only 1 in 200 lightning strikes is
likely to contain that much current. By comparison, normal
US house current is only 20 amps.
We
had to be able to demonstrate compliance with the Federal
Aviation regulations concerning protection of structure
and fuel systems, as do all metal aircraft, but we also
had to show that Starship could sustain a lightning strike
without damage to avionics or other electrical components.
This
was accomplished by using a combination of fine wires
in the first layer of composite skin and a ground-plane
system to shield the electronics, allowing the lightning
current to flow through and out, leaving only minor surface
and cosmetic damage at the strike point.
There is an old saying that lightning will never strike
the same place twice, but the FAA does not believe it
for they were concerned about the ability to repair lightning
strike damage in a way that would continue to offer lightning
protection. To prove this, wires or thin aluminum sheets
were added at the time of repair.
Struck
lucky
During the course of final certification testing the number
two prototype, NC-2, sustained lightning strike. The lightning
attached itself to a test pod mounted on the aircraft,
one being recorded on videotape at the time. In
a remarkable piece of footage the strike was filmed
from inside the aircraft, showing the lightning striking
the front of the pod and exiting from the Starship's tip-sail
and rudder. The aircraft was unscathed.
The avionics system was developed specifically by Rockwell
Collins Avionics, and consists of a 16 tube EFIS panel
(Electronic Flight Information System). Basically, these
are TV tubes that display information on the lines of
a conventional T; the method is also known as the glass
cockpit.
The primary flight display shows aircraft attitude, as
well as the flight director commands, lateral deviation,
glide slope, radio altitude and marker beacon. The pilot
can select display of flight guidance modes, autopilot
status, airspeed deviation, decision height alert, altitude
alert, ILS deviation alert and minimum descent altitude
alert as desired. Our philosophy is to provide the pilot
with as much or as little information as desired to accomplish
the job.
The airspeed indicator provides the classical dial readout,
as well as outside air temperature and true air speed;
it also has a trend feature which will predict the aircraft's
speed in ten seconds at the current rate of acceleration
or deceleration.
Over on the right of the T we have a unique instrument
that combines the altimeter and vertical speed indicator
functions, as well as an altitude alert. It displays barometric
altitude, pre-selected altitude, barometric setting, and
a flight-level one-eight-zero alert.
During an instrument approach, either crew member can
set radio altitude decision height on their respective
altitude awareness panels and the readout will appear
on the primary flight display. Decision height and radio
altitude display appear automatically on the screen when
the radio altitude passes through 2500 ft descending.
Another key element of the T-display is navigation information,
where the display shows the aircraft's horizontal navigation
situation in a familiar manner, with heading, selected
heading, selected navigation source, selected
course and lateral deviation.
The primary navigation function can be displayed in any
of three modes -- the Horizontal Situation Indicator (HSI)
mode shows the full compass rose traditionally displayed
on conventional EFIS and electromechanical displays; the
are mode displays a 70" section of the compass, for a
closer look at a developing situation; and the map mode
adds a graphic representation of waypoints to the are
display.
Starship's radar display can be superimposed on the are
or map modes to assist in circumventing weather or turbulence.
The radar itself is a Collins TWR-850 unit which uses
Doppler technology to help predict where turbulence might
exist.
Avionics
enhance safety
Flight experience in the Starship prototypes has shown
that the unit is capable of accurately detecting and displaying
turbulence, sometimes in areas where conventional radar
sets showed only light rain. The avionics display offers
a conventional presentation, but one that is also enhanced
with capabilities not previously available to the general
aviation pilot. The design driver is function, with developed
features that reduce workload and provide real-world information
to increase the ease and safety of flight.
Engine instrumentation is also generated on video tubes,
in a display called EICAS (Engine Indication and
Crew Alerting System). The engine instruments are presented
in a traditional turbine display, but the pointers on
Starship's EICAS change color from green to yellow or
red to alert the crew to any abnormal condition.
Generally the philosophy in
EICAS has been that simpler is better, and the system
is designed to produce minimal or, in many cases, no display
when the aircraft is operating normally. When an abnormal
condition begins to occur, one of eighty color-coded caution,
status and advisory annunciations light to alert the pilot.
The system also records and stores the data, including
the time and date it occurred.
