A400M Military airlifter
Barring poor weather or technical issues, Airbus Military officials late this week expect to complete a roughly 3-hr. flight from the company’s facility here to demonstrate the aircraft’s basic handling characteristics.
The event has been a long time coming, owing, in part, to development delays with the engine and subsystems that have set the program back several years. The event marks the official beginning of a flight-test program that calls for 4,370 hr., says Eric Isorce, chief flight test engineer. About 60% of the effort will focus on military certification, the balance will be dedicated to gaining European Aviation Safety Agency approval.
Six crew will be onboard, backed by 50 engineers at each of the two main telemetry stations in Seville and Toulouse.
The aircraft will initially be flown in direct law with some dampening. After takeoff—rotation speed is projected to be 120 kt.—the aircraft will climb to a medium altitude and the gear will be retracted. At 10,000 ft. some basic performance checks will occur, the aircraft will be taken close to its maximum speed of around Mach 0.72, and then to its minimum speed, says Ed Strongman, Airbus’s chief military test pilot who will be at the controls. Afterward, flight controls will be shifted to normal law and further segments of the flight envelope will be explored before returning to Seville.
The flight will likely be followed by two days of data evaluation and inspections. Strongman expects the pace of flight trials to pick up early next year.
Ground trials by the flight-test department have been underway since Nov. 12 and already a number of system refinements have been identified. Some are needed for first flight, others can wait until further in the development. Still, Strongman says, preparations are “ahead of my expectations.”
One problem is nacelle heating when the airlifter is on the ground. Heat buildup is higher than anticipated—something already seen on the C-130 flying testbed. As a fix, engineers have determined that they can take some air off the high-pressure compressor for a nacelle ejector system to provide better ventilation at low power. The switchover, only needed on the ground at low speed and low wind, is now activated manually, but an automatic function is to be developed.
The exhaust gases are also overheating aft parts of the nacelle in some conditions. As an interim step, insulation and metal plate protection is being added. A more permanent fix is planned for the third flight-test aircraft.
On the other hand, engineers are seeing less heat buildup at the auxiliary power unit exhaust on the wing than expected, potentially allowing the exhaust to be shortened to reduce drag.
Tweaks are also being made to the engine settings. For now, high reverse power is limited to inboard engines. The ground-idle position may change for a better neutral-thrust position, Strongman says, noting that the issue will not affect first-flight plans. Overall, engines have shown “good response.”
As expected, in ground reverse the pitot static tubes are exposed to airflow that is leading to anomalous air speed indications, which is causing the information to be rejected by the flight-control computer. Airbus officials anticipated the anomaly and are assessing where to apply the needed software filter.
Airbus also had to refine the software controlling the anti-skid braking system, which, early on, showed poor characteristics. Initial trials also encountered the loss of tachometer data from some of the wheels. This is being addressed in the near term by strengthening connectors.
“We are solving problems very quickly,” Strongman notes. In one case, the TP400D turboprop engines had start-up difficulties, but the Europrop International engine consortium was able to deliver a software fix to the full authority digital flight control system overnight.
Eventually, the flight-test program will comprise five aircraft. Program officials still have a bit of margin to handle any glitches, but are downplaying the chance of recovering some of the schedule lost.
From http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/A400MUPDATE120409.xml&headline=Airbus%20Military%20Poised%20For%20First%20Flight%20This%20Week
January 7th, 2010 at 7:46 pm
Hold yourself responsible for a higher standard than anyone else expects of you. Never excuse yourself. Thank You
January 10th, 2010 at 11:55 am
Amen