High-speed cameras
26 DECEMBER 2019 \\ AEROSPACETESTINGINTERNATIONAL.COM
PREPARING FOR A CRASH
After nearly a year of planning the crash
test of the Fokker F-28, the event at NASA’s
Langley Research Centre was a highly
orchestrated operation. Nothing was left
to chance – final preparations began three
days before the drop, explains NASA’s
Dr Justin Littell, who was lead researcher for
the test.
“Typically, a test will have an engineer, in
this case me – who provides a check-list of
how it is going to be performed,” says Littell.
This includes double-checking the data
systems and high-speed cameras are
working in a dry run.
An aspect the test engineer has limited
control over is the weather. “The Fokker
crash test was delayed by the weather,” says
Littell. “We had to stand down a day because
a thunderstorm came through, which are
relatively common in Virginia at that time
of year.”
As well as the test engineer the
pyrotechnic crew and safety personnel
are on hand during final preparations.
The pyrotechnic crew are responsible for
priming the pyrotechnic cutter, a guillotine
device that splices through the pull-back
cable used to hoist the plane in to place.
In the past the pull-back cable, like the
four cables that the aircraft swings down
on, was typically made from steel. But
many crash test facilities are now switching
to lighter weight cables made from a
high-density plastic which is called high
modulate polyethylene.
Once the check-list is complete the plane
is hoisted up. With everything ready the
countdown is initiated. Then, at the moment
of release, an electric current is supplied to
the pyrotechnic cutters, causing them to cut
the cable.
“After that it’s just pure gravity and the
pendulum equation,” says Littell.
1// Langley’s Landing
and Impact Research
Gantry in 1969, during
testing of the lunar module. 4
FAA, the Langley facility has made a
major contribution to aviation safety,
particularly in helping aircraft makers
understand how to manage the energy
that is transferred to the occupants
during a crash scenario.
While modern crash tests look similar
to those done in the 1970s, the use of
electronics and computer simulation has
made the set up and data collection
process vastly different.
STRUCTURAL PERFORMANCE
This summer’s crash worthiness test on
the Fokker F-28 – a regional jet used on
short to medium-haul flights – was
conducted to advance research on the
structural performance of this style and
size of aircraft.
The third test in a series, the tests
preceding it involved vertical drops of
F-28 fuselage sections. The full aircraft
test added the component of forward
velocity to the vertical drop.
It did this by suspending the aircraft
from cables set up in a pendulum
configuration, so that plane’s trajectory
The 150ft drop, on to a target of packed
earth, lasted four seconds. Those few
seconds were the result of nearly a
year of preparation, says Dr Justin
Littell, NASA’s lead researcher for the crash test.
“We started planning in July 2018 and we did the test
during June this year,” he says.
The 33,000 lbs Fokker is the largest airframe ever
dropped at Langley’s Landing and Impact Research
Facility, which is also known as the gantry. The 240ft
high steel structure has a pivotal place in the history of
aerospace testing.
Built in 1963, the gantry was originally called the
Lunar Landing Research Facility and was where the
Apollo astronauts trained to land on the moon. During
the 1970s the field of aviation crash testing was
pioneered here.
Research carried out at the Landing Research Facility,
which is now a US national historic monument,
contributed directly to the development of many aviation
safety standards, says Littell.
“One of the major developments that came out of here
was the dynamic seat test,” he says. “They carried out
several full-scale crash tests here and with that data
worked out the qualification standards for seats.”
The Fokker crash test was carried out by NASA and
the Federal Aviation Authority (FAA). According to the
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