NASA’s Dryden Flight Research Center, Edwards AFB, Calif., hosted A U.S.
Navy E-2C Hawkeye for structural loads tests. The tests for the carrier-based
electronics aircraft were conducted at the Dryden Flight Loads Laboratory.

The tests were done to determine if increasing the aircraft’s gross weight will
affect its performance. The Hawkeye, distinctive with its 24-foot diameter
rotating radome and quadruple vertical tails, is part of a fleet that has been
operational for more than 40 years. The Navy is planning upgrades that will add
weight to the aircraft, so officials asked Dryden to help formulate loads
equations to determine how the changes would affect the aircraft?s flight

“A loads calibration test is a primary part of the development of any new
aircraft,” explained Paul Lundstrom of Spiral Technology, Laguna Beach, Calif. He
was the lead test engineer on the project “It’s also an important step in
determining the flight envelope for any new configuration of an aircraft, because
you absolutely have to know what the structural loads are when it’s in flight.
The only good way to determine that is by doing a test of this nature.”

The tests applied force (loads) on the aircraft to develop equations, using a
data-recovery system connected to instrumentation on the airplane. The resulting
data allowed Navy flight test engineers to develop loads equations. Then they
estimated loads, while test-flying the airplane. “This allows them to know when
they?re approaching in-flight loads that are too high for the structural capacity
of the aircraft,” Lundstrom added. “A loads calibration allows us to define the
performance parameters of the aircraft while maintaining a safe structure.?

An unmodified E-2C weighs about 42,000 pounds empty. The plane tested at Dryden
had its weight beefed up with metal plates to simulate an empty weight of about
45,000 pounds, mimicking the latest configuration of the fleet’s upgraded E-2D
Advanced Hawkeye. Loads were applied to the aircraft?s wings and tail.

The E2-C has an 80-foot wingspan, is about 58 feet long and 18 feet tall.
Dryden’s Loads Laboratory accommodated the aircraft with room to spare for
equipment and fixtures necessary for the research. The E-2C research isn?t the
biggest project completed in the Loads Laboratory, but it is among the largest
and could lead to similar future work.

Lundstrom said the tests on the E-2C illustrate one of the core competencies of
the NASA Dryden Flight Loads Lab. “We’re one of the few locations in the nation
that can do this specific type of test,” he said.

The aircraft arrived at Dryden last fall from its base at the Naval Air Warfare
Center Aircraft Division (NAVAIR) at Naval Air Station Patuxent River, Md. The
work was completed in mid-March. “The Navy decided to use Dryden, because of the
unique facilities and experience that was hard to find elsewhere. I am pleased
with the support we received from Dryden,? said NAVAIR project engineer Jason

The E-2A Hawkeye first entered service in 1961. The E-2C was introduced in 1973.
Built by Northrop Grumman, the Hawkeye has extensive communication and long-range
radar capabilities. It is considered the eyes and ears of the carrier battle
group and manager of airborne operations. It can monitor six million cubic miles
of airspace and more than 150,000 square miles of ocean surface, while detecting
hundreds of ships, aircraft and missiles up to 200 miles away.

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