EDWARDS AIR FORCE BASE, Calif., - Engineers with the 418th Flight
Test Squadron are currently testing a C-130H3 cargo plane equipped with
Hamilton Sundstrand NP 2000 propellers.
The new eight-bladed composite propellers are shaped to provide additional
thrust in the takeoff and low airspeed range while using the current C-130
engines.
Regular C-130 "legacy" planes use four-blade propellers. With eight blades,
the NP 2000 props are designed to perform with more power and efficiency.
"A major limitation propellers have is the wave drag generated by shockwaves
when the propeller tips go supersonic," said Dustin Marschik, a 418th FTS
performance and flying qualities engineer. "Newer propeller designs aim to
reduce this wave drag, which improves efficiency and performance. The NP 2000
blade design incorporates a more efficient airfoil design, which
theoretically will lead to improved performance in the takeoff and climb out
phases of flight.
"The eight-bladed props are much more efficiently designed and utilize modern
design and manufacturing methods which aim to optimize twist and blade sweep
to improve performance," Mr. Marschik said.
Computer simulation and the composite materials that make up the blades help
engineers optimize the blade angle and twists to make the propeller faster
and better.
"It is designed specifically for the LC-130 mission in Antarctica," said Maj.
C.B. Cain, a C-130 flight commander. "Right now, they use these jet-assisted
takeoff bottles to help them takeoff to get to about a 60-knot takeoff range.
If this propeller does what it is supposed to do, then it would produce
additional thrust and reduce the need for those JATO bottles, or eliminate
them completely."
The 109th Airlift Wing of the New York Air National Guard is the only unit in
the Air Force that flies the LC-130.
Engineers have been conducting performance testing since May on the NP 2000
propeller to characterize how the propeller performs to produce a flight
manual for the LC-130, or any other C-130 that may be outfitted with the new
prop.
The 418th engineers just wrapped up flight tests involving velocity minimum
control airspeed Oct. 28, with Edward AFB's only C-130H3.
"This is where we shut down an engine on purpose and slow down to find the
point where we have neutral directional control," Cain said. "It involves the
pilot putting 180-pounds of rudder force in and then slowing, putting it in a
five-degree bank angle, and seeing where the directional control switches
back the other way."
"If you lose an engine, this is the slowest you ever want to get. Any slower
and you wouldn't have positive control of the heading of the aircraft."
In the previous week, squadron testers completed takeoff tests to see how the
cargo plane and its propellers perform on maximum-power takeoffs as well as
landing tests, which included free-roll landings to see how the plane stops
without using its brakes and using reverse thrust.
Cain said test data still needs to be analyzed, but preliminary testing has
shown that the eight-bladed NP 2000 propeller provides noticeable drag on the
free-roll landing tests and the C-130H3 seems to fly smoother.
He said with less vibration, there is less wear and tear on the propeller,
which can also be an added benefit.
"Instead of four similar airfoil blades pounding around up there, you have
these eight highly tuned blades that make it smoother with less vibration,"
Cain said. "From a maintainability standpoint, you can change one blade at a
time. On the legacy four-blade C-130, you have to change out the whole prop."
This flight testing is a continuation of a process to improve the capability
of the Air Force's workhorse C-130 fleet. The C-130J "Super" Hercules already
employs a six-bladed composite propeller.
"The NP 2000 has been optimized more and represents the next step in
propeller technology," said Cain.
In the coming months, the NP 2000 propellers will be replaced on the C-130H3
with legacy four-blade propellers to conduct flight tests to directly compare
the performance differences between new and old.
Additional testing will involve taking off with a maximum combat-load weight
and conducting takeoffs on three engines and malfunction simulations.
Cain said flight tests for the NP 2000 C-130H3 will likely go through January
2011.
Once all the data is assessed, and if Air Force officials see a solid benefit
of the NP 2000, certain C-130s may get a new and improved upgrade in the
future.