C-5M #86-0013 flies near Edwards on an upgrade
test mission 2/16/2007.
Photo: USAF/Bobbi Zapka
7/30/2007 - EDWARDS AIR FORCE BASE, Calif. -- The
Combined Test Force for the C-5 modernization program
concluded a series of testing on July 23.
The CTF performed tests to determine the aircraft's
climb performance as part of the C-5M's Reliability
Enhancement and Re-engining Program.
The CTF consists of members with the 418th Flight
Test Squadron Detachment 4, a geographically separated
unit located at the Lockheed Martin plant in Marietta,
"We're roughly halfway through our test program,"
said Wade Smith, 418th FLTS, Det. 4 lead flight test
One of the types of testing the team performed is
called "sawtooth testing," said Tech. Sgt. Vernon
Lewis, lead electro-environmental test manager for the
"It's called 'sawtooth testing' because when you look
at a graph of the climbs and descents it looks like a
sawtooth," Sergeant Lewis said. "On one flight, the
testers were flying anywhere from 8,000 to 13,000
feet. We were gathering data on the thrust and drag
characteristics of the aircraft with the new engines."
The team conducted the first in-flight deployment of
the C-5M's thrust reversers in mid-July.
"Unlike commercial aircraft, which only use their
reversers on the ground, we use the two inboard thrust
reversers in flight as a high drag device if we need
to decelerate or descend quickly," Mr. Smith said.
The new engines have performed very well in tests,
Mr. Smith said.
"We have no problems with the engines," he said. "The
increased thrust has been very impressive. We operated
the C-5M at higher altitudes than the legacy C-5 could
The team recently used full thrust for the first time
during take-offs, Mr. Smith said.
"We consistently took off at approximately 810,000
pounds, which is more than the standard operating
weight of 769,000 pounds for the legacy C-5s in the
fleet," he said. "We've been taking off with no
problems at all. The legacy C-5 with the old engines
could not have taken off in these circumstances."
The replacement of the old engines with the new CF6
model has removed the distinctive sound of an
approaching C-5, Mr. Smith said.
"The C-5 is a notoriously loud airplane," Mr. Smith
said. "We have had problems with noise complaints. The
new engines will allow us to easily stay within
The CF6 engines enable the C-5M to take off and land
on shorter runways, which is important to the
warfighter, Sergeant Lewis said. These new engines
also save fuel. With more powerful engines and lower
fuel consumption, the C-5 can fly farther at heavier
weights into places it couldn't before.
"With this aircraft, there is a constant trade off
between cargo and fuel payload," Mr. Smith said. "Now,
we can carry cargo and put more fuel on the aircraft
and know that we have the performance to take off in
high-density, high-altitude conditions even if we lose
The C-5M should also provide better performance in
global air traffic management airspaces, Mr. Smith
said. A fully-loaded legacy C-5B has a difficult time
operating in certain GATM airspaces because the
aircraft can't climb quickly enough.
"One of our key performance parameters with the new
engines is to demonstrate the C-5M's ability to climb
into GATM airspace with a full combat load within a
certain amount of time," he said. "Our initial results
show we should be able to meet that requirement. That
testing will take place in the fall."
One more C-5 has been approved for low-rate initial
production to start the production line, Mr. Smith
said. However, the Air Mobility Command has not yet
decided on funding to convert the rest of the C-5
If funding is provided, the plan is to convert all 49
of the remaining C-5B models and the two C-5C models
that were modified for space cargo, he said. Whether
or not the remaining C-5A models will be modified is
still up in the air.
Edwards was the base chosen for the tests because of
its smooth air, good weather and long runway, Mr.
"The airspace here also allows us to do unrestricted
climbs, which is what we really need for this type of
testing," he said.
Another reason Edwards is a good test location is the
generally clear weather needed for the 23-foot long
orange nose boom the C-5M carries for tests, Mr. Smith
"The boom carries very precise air-data equipment for
measuring speed, altitude and temperature," he said.
"We need that data for all performance testing. We
can't fly through clouds or any visible moisture with
the test boom. If water gets in the boom, it can
freeze and damage the instrumentation in it."
Two C-5M's are scheduled to return to Edwards at the
end of August and stay through November, Mr. Smith
said. They will be used for conducting minimum control
ground speed and field performance data tests.
"The warfighter will get a lot more flexibility with
this aircraft," he said. "The main focus of the
program is reliability. If these modifications work
out the way they should, that will be the greatest
impact to the warfighter."
Source: USAF by Senior Airman Jason Hernandez