UAVs have become so popular with the military that over 50 organizations
are flying, researching or developing such products - many by companies
not known for designing and producing aircraft. As expected, the
major aircraft companies are involved: Boeing, Lockheed and Northrop
Grumman. But, consider the following company names: Aurora Flight
Sciences, Chapy Corporation and Orion Aviation all working on such
products, and there are 20 to 30 more "unknowns".
In the past UAVs have been placed in five or more categories; however,
a more recent movement is to define them as Local, Regional and
Endurance. The size, weight and capability within these categories
vary widely from small, light
weight (a few pounds) to the 100,000 pound behemoths. Among past
efforts to develop types of UAVs, the Hiller Aviation Museum has
two examples on exhibit that span the range of size and endurance.
These are the spectacular Boeing Condor and the miniature MLB Trochoid.
The Condor with its 200-foot wingspan and the Trochoid with a blended
body about eight inches across are certainly the extremes in the
range for size. And for endurance, the spread is equally dramatic.
The Condor had a design goal of 150 hours and the Trochoid about
20 minutes. In weight the two are even further separated - 20,000
pounds for the Condor and only 12 ounces for the Trochoid.
The Boeing Condor is from the mid'80s, having first flown on October
9, 1988 for 1hr & 33 min. (the video at the Hiller Museum is
of this flight). It flew seven more times including the last flight
of 58:11. All flights originated and ended at Moses Lake, Washington,
using the 13,600 foot run way at Lawson Air Force Base. Boeing has
used this facility (now Moses Lake airport) for a wide variety of
test flights including the 747 airliner. Japan Air Lines used it
for pilot training.The Condor project is reported to have been initiated
by Boeing but was subsequently funded up to an estimated $300 million
by the Defence Advanced Research Projects Agency (DARPA). One estimate
places the aircraft cost at $40 million. The unique aircraft was
designed for electronic surveillance at high altitudes and extended
durations. However it is known that it only flew over Eastern Washington
State. Considering the location of all flights, it is unlikely the
electronics installed was used for anything other than evaluation.
Information is not available regarding which US Government agencies
participated in the testing activities other than DARPA.
DARPA provided the "payload" but it was classified so
it is not known what was included. Though the primary structural
parts of the Condor are a carbon fiber laminate, a few sections
are Kevlar to allow radio frequency signal penetration by the electronics.
Though the Condor has an ungainly appearance it did achieve some
measure of success by reaching a record altitude of 67,028 feet,
powered only by two 175-horsepower, six cylinder engines. The engines
were boosted with two stages of exhaust-driven superchargers.
To save weight, a "dolly" and two outrigger wing mounted
wheels were used for take off but remained on the ground. For landing,
there was a tandem positioned nose wheel and skid lowered from the
fuselage. In order to achieve the performance specifications the
aircraft had to be very, very light with very long, thin wings (even
an engine starter was eliminated).
To maintain structural integrity the fuel load was distributed
across the length of the wings. It was subsequently determined that
the wing design precluded air speed in excess of about 140 knots.
In fact, external weights we re added to the wing tips to reduce
torque and possible flutter. The engine choice required a special
propeller, which was very light Kevlar, 16 feet in diameter. Because
of the lightweight propeller, low horsepower engine and two-speed
gearbox, the engines had to be started using an external hydraulic
unit with a shaft inserted into the prop spinner.
This type of starting mechanism is called a "Hucks" starter
and was from the World War I era. Once started there was sufficient
momentum to continue. However, the engine/propeller combination
was sized for 60,000 foot operation; hence the drag on the blades
at sea level was too much for the engine. So, the two-speed gear
had to be shifted at 43,000 feet to reach maximum altitude. Flight
control was quite unique and different from many current UAVs. The
total flight mission was pre-programmed in an on-board computer
and was completed without any input from a ground station (the Global
Hawk is also pre-programmed).