TECHNICAL:
DEFENCE
Boeing reveals Condor details
T
hree
contenders
have
emerged for the Pentagon's
long-endurance unmanned air
vehicle programme, but only
one, Boeing Advanced Systems'
Condor, has so far flown, demonstrating an almost 30-hour flight
duration.
During five flights from
Boeing's test field at Moses Lake,
Washington State, Condor established new records for pistonpowered aircraft, which included
a maximum altitude of 66,980ft.
Boeing received funding for
the 50-hour Condor flight-test
programme from the US Defense
Advanced Research Projects
Agency.
Potential
missions
include reconnaissance, target
acquisition, search and rescue,
and communications relay. Civilian applications include drug
interdiction, meteorology and
mapping, or highway patrol.
PISTON POWER
Condor is powered by two 175
h.p. liquid-cooled piston engines
and has a 200ft wingspan, larger
than that of a Boeing 747. The
all-bonded structure is primarily
of an advanced carbonfibrereinforced epoxy composite, laid
over a lightweight Nomex honeycomb filler.
Fuel management within the
wing minimises peak shear and
bending loads at the wing root,
and a multitank arrangement
limits the hydraulic pressure
exerted by the fuel on tank sidewalls during wing bending. The
wingtip bends down 16ft when
static, and up 25ft under a 2g
load, giving a total range of 41ft
between the two limits.
To reduce weight, take-off is
accomplished from a dolly, with
the
wings
supported
by
outriggers which fall away as the
vehicle
becomes
airborne.
Condor lands on a skid main gear
and conventional nose gear.
On take-off, the onboard
mission computers command the
nosewheel to follow the microwave landing system (MLS)
azimuth
signal.
Maximum
centreline deviations ranged
from 4ft to 10ft during the test
programme, Boeing says. Once
Condor is airborne, the inertial
reference system navigates it
20
.on-powered aircraft
During tests, Boeing's Condor has tablished new endurance records for pist
The 200ft-span wing can bend up 25ftunder a 2g load. Shear and bending load
> are minimised by fuel management
through a programmed sequence
of waypoints, which may be
altered using a communications
link from the ground.
The two six-cylinder piston
engines have two stages of
turbocharging, and drive flexible,
large-diameter composite threeblade propellers through twospeed gearboxes. A full-authority
digital engine control system
includes fault detection and
accommodation logic to adapt
engine parameters to unusual
operational conditions.
The vehicle's drag is very low,
according to Boeing, with twothirds of the total generated by
the wing. The high-aspect-ratio
(36-6) wing has a high aft
camber, and has demonstrated
laminar flow to 50 per cent chord
on both upper and lower
surfaces. This gives Condor a
loiter efficiency comparable to
high-performance gliders.
On approach, the aircraft
intercepts MLS azimuth and
glideslope signals, tracking the 3°
glideslope to approximately 35ft
above ground level, where the
mission computers automatically
command a flare, using the signal
from the radio altimeter.
All five test flights were
successful, and verified pre-flight
predictions that "no single failure
of system design would result in
loss of the vehicle", Boeing says.
The flight control system demonstrated its ability to manage
system redundancy, including a
landing after a simulated rudder
failure, during which lateral
control was achieved through the
wing control surfaces.
Under Pentagon plans, endurance-vehicle demonstration/
validation will take place
between 1990 and 1992, with
development of the winning
vehicle beginning in 1993.
E-Systems will bid EVER
(Endurance Vehicle for Extended
Reconnaissance), a lOOft-span
air-refuellable craft which could
stay aloft for a week. EVER is
based on (and could be refuelled
by) E-Systems' Egrett 92ft-span
manned surveillance aircraft.
Leading Systems will offer
its high-wing, inverted-V-tail,
pusher-propeller Amber.
•
FLIGHT INTERNATIONAL 12 August 1989