Come va il programma test dell'A380

[Oli]

http://www.flug-revue.rotor.com/FRHe...11/FR0511g.htm


By Sebastian Steinke

Fernando Alonso, vice president Flight Test division at Airbus and member of the crew who flew the A380 on its maiden flight, tells journalists gathered for a presentation in Toulouse that he is satisfied with progress to date on flight testing the A380. “As of 25 August, we have completed 72 flights with 247 flying hours. In the course of these flights 22 different test pilots have sat at the controls and personally landed the aircraft, among them two representatives of EASA. 31 flight test engineers have flown in the cabin, once again including two from EASA.”

Jacques Rosay, chief test pilot on the A380 programme, adds: “Of our own test pilots, only three or four quite junior pilots have not yet flown at the controls. But we want them all to get to know the A380. Up to now we have specifically needed test pilots, because not every flight condition has yet been certificated for non-test pilots. But from mid-September I expect the first training pilots from our customer airlines to be allowed at the controls. Provided that one of our B2 category test pilots flies as captain, a normal airline pilot could even serve as co-pilot. But to avoid falling behind in the test schedule, we would need a second aircraft to do that. At the moment the test flight plan is uppermost in our minds.”

Fernando Alonso: “Since the Paris Air Show, we have taken the aircraft up twice a day, once in the morning and once in the afternoon. A flying time of around three hours is normal. The longest flight so far lasted eight hours. It proves how reliable the A380 is. The whole infrastructure is right. Only in the 11th week of flying did we leave the A380 on the ground, otherwise all maintenance work has been carried out alongside.” The chief flight test engineer explains that engineers flew along during the flybys above Le Bourget, each lasting only six minutes and 40 seconds, analysing performance. “With such a crowded flight programme, the pilots are under a lot of stress. Watching them and all their actions during an air display under time pressure is particularly interesting for us, as it gives us a chance to eliminate any sources of error in the cockpit and controls.”

Alonso explains the test programme up to now. “In the first two to three weeks we addressed the envelope with two sets of control laws, “direct law” and “normal law”, and we kept widening the range of speeds. After that we were able to begin the testing proper. We are very pleased with the handling and aerodynamics. After just under one month, on the 17th flight, we were able to carry out the first automatic landing. After the first three to four flights we were already testing “engine relights”, that is, restarting engines that have been shut down in flight. We also extended the ram air turbine, which provides power in an emergency. We have already reached the stage of fine adjustment.”

Alonso adds that the high incidence protection and alpha-floor protection system, which automatically keeps the angle of attack within safe limits and even automatically produces thrust if there is a danger of the aircraft stalling in slow flight, had worked without any changes. Again, the “normal law” that will apply in future airline operations also functions well. Alonso continues, “Personally, I think we could get the flight control system certificated in its present state. That was a nice surprise, because otherwise it would have been expensive to make fundamental changes to the handling or aerodynamics at this point in time. Also it means that MSN004 does not require any fundamental changes compared with MSN001.” Despite this, MSN001 does differ on a few points from the next A380. “MSN001's engines do not yet comply with the standard and, as expected, we still have slightly higher drag on the fuselage and wings on MSN001.” On the engines, the engineers' main worry was excessive oil consumption early on, which is why the next A380's will have a slightly modified Trent design.

Test pilot Jacques Rosay goes on to talk about the area that he is currently focusing on in his test flights. “We are in the process of opening up the entire flight envelope at all speeds, altidudes and weights.” They had already flown high-speed flights at Mach 0.95 at the A380's operational ceiling, just below the red line at Mach 0.96, and had already reached the transonic regime, in the course of which areas of local supersonic flow form on the aircraft. The aircraft vibrates and jolts violently. Rosay reassures us by likening the experience to “being on a bumpy road. So far the flutter characteristics appear to be fine. We are watching how the wings behave. The buffeting built up quite gradually. At first a little, and then slowly increasing. That compares with other aircraft types, on which it starts quite suddenly.”

Nevertheless, one notices the respect that the professionals show before the maximum velocity. When this is reached, one has to be prepared for surprises and expect the aircraft structure to be loaded shortly before breaking point. Fernando Alonso: “The aircraft should be flown as seldom as possible at Mach 0.96. To get up to that speed, first of all you have to climb to 38,000 feet and then descend like crazy.”

For the purposes of certification, the A380 has to demonstrate at Mach 0.96 that it does not develop flutter oscillations or abnormally strong vibration. Naturally on these flights the crew always wear parachutes. The normal cruise speed of the A380 is Mach 0.85 to 0.87, well clear of this region. The first signs of “speed buffet”, that is, vibration and buffeting, occur at Mach 0.89.

Since the Paris Air Show, the landing flap settings and the leading edge slat positions have been optimised. In Position 1, the holding position, which is used for holding patterns, the leading-edge slats are extended to 20 degrees and the landing flaps are raised. Position 1+F corresponds to the combination of leading edge slats at 20 degrees with flaps at 8 degrees. Position 2, which is used on take-off, especially at high altitude airfields, combines leading-edge slats 20 degrees with flaps 17 degrees. For take-off and landing approaches on the other hand an extra new Position 3 of leading-edge slats 23 degrees and flaps 26 degrees has been introduced. Fernando Alonso explains, “We had not identified this setting beforehand in the wind tunnel.” Finally, the “Full Flaps” position combines leading-edge slats 23 degrees with flaps 32 degrees for the landing. At a velocity of only 138kt (256km/h) the reference velocity VRef is four knots (7.4km/h) less than expected. The A380 lands at a lower speed than an A340-600. Alonso is also very pleased with the A380's take-off performance. “We have even been able to take off with the maximum take-off weight of 569 tonnes without any problems.”

With regard to the take-off trials at minimum velocity in Istres (VMU tests), Jacques Rosay reports that on the first take-off the A380 had rotated further than expected and not just on the shock-mounted tail skid provided for this purpose, but had also unintentionally slid along the runway on the tail section behind it. Fortunately the tail had been protected at that point with a steel casing as a precaution, so that no damage occurred as a result of this tailstrike. But in this special case, the aircraft had behaved differently from what the simulator had led the team to expect.

Since then, according to Rosay, the test pilots have adopted a different rotation technique for VMU tests: they now raise the A380's nose from the runway in an accentuated way at a lower taxiing speed and then carefully reduce the distance between tail skid and runway with minimal elevator angles. The tail skid now only touches the ground very lightly and can withstand four VMU take-offs instead of the previous one before it has to be replaced.

Despite the slow pace, the landing gear was put under maximum load during some taxi tests on 25 June. This particular test included extremely tight turns on the apron, simulated push-backs and aircraft towing manoeuvres under a maximum weight of 546 tonnes and maximum steering angle of 60 degrees (the maximum permitted in operation) and even 72 degrees (technical maximum). The tyres on the two four-wheel wing landing gears ground especially during the push-back from the parked position with the steering twisted to 70 degrees, followed by a 90 degree curve, leaving thick, black swirl marks running almost sideways over the apron concrete. An extra hazard was posed by the fact that the rear axes of the two six-wheel fuselage landing gears, which are normally steerable, had been locked in position. Despite this, all the landing gear legs held up, all the maltreated tyres stayed on their wheel rims and the test was deemed to have been passed.

Finally, between May and August wake turbulence measurements had been carried out on the A380 in Toulouse (May to July) and Istres (July and August). For this purpose a container fitted with the LIDAR laser measurement system and the SODAR-RASS ultrasound measurement system from the German Aerospace Centre (DLR) in Oberpfaffenhofen was positioned, respectively, on the roof of a high-rise building in the landing corridor of Toulouse and in the presence of representatives of the American Federal Aviation Authority on the taxiway of Istres. As Alonso explains, “Now it is a matter of number crunching and processing.” In test operations from Toulouse, however, MSN001 is already flying with the regular wake turbulence distances for the “heavy” category between normal scheduled services.

One of the nerve-racking moments in the test programme to date was the first stall tests. Test pilot Rosay praises the way that the stall starts slowly on the wing root, with the control surfaces still working and a conventional downward pointing nose. But apparently the engineers performing the structural measurements registered alarmingly high bending moments on the horizontal stabiliser on coming out of the stall. Looking back on it, Rosay finds it amusing. “The ground station got really worked up on the radio, telling us that we must come back immediately.” After the landing, it turned out that the sensor concerned was producing measurements 40 percent higher than they should have been due to incorrect calibration. The structural load had actually remained within the safe limits at all times.

But there is one item that the engineers still want to change before the aerodynamic configuration is frozen: up to now spoilers 3, 4 and 5, when extended, have been generating air vortices that cause the elevator to vibrate strongly when they hit the horizontal stabiliser. For this reason, the first elevator rib is to be strengthened.

Charles Champion, Head of the A380 Programme and recently appointed Airbus Chief Operating Officer as well, sums up progress to date as follows. “We had feared some surprises that did not occur. There have not been any big problems, but many small ones, and there won't be any showstoppers. However, we did misjudge the amount of work involved on the wiring. The scale of individual customer special requirements surprised us. Now we are having to do the wiring with all the cable harnesses for many different customer versions in parallel. Emirates is even getting two variants. It affects not just the wires but also their fastenings, and hence the structure. Because of that, at the beginning we had sections in final assembly without the full system equipment for the cabin.”

To alleviate the wiring bottleneck, Champion has called in outside engineering services and hired several hundred extra staff. He expects to gradually make up the lost ground by employing extra teams in final assembly. Champion adds, “We will also ramp up production more steeply later on.” Although he calls the A380-800 the “top priority” at Airbus, he is not expecting production to normalise until between factory numbers 30 and 40, i.e. not before mid-2007, even though launch customer Singapore Airlines (SIA) is to take delivery of its first aircraft before the end of 2006.

Meanwhile the almost completed prototypes MSN004 (“performance aircraft”) and MSN002 are undergoing testing in the hangar, while MSN007 (the first one to the final production standard) has already been completed and final assembly of MSN009 (the first to be equipped with GP7200 engines) is just beginning. In the west wing of the final assembly hall, MSN003 and MSN005, the first aircraft earmarked for Singapore Airlines, are waiting for their engines.

At the beginning of October the second flying A380, MSN004, will be delivered to the Airbus flight testing organisation and a few weeks later take off on its first flight. This will be followed in mid-October by MSN002, which will fly straight to Hamburg to have its internal furnishings fitted and to be painted. MSN002 is the aircraft earmarked to undergo the notorious evacuation tests with the maximum number of seats fitted and 873 passengers on board in Hamburg at the beginning of 2006.

Before that, MSN001 will visit Sydney on 16 November as part of the celebrations to mark the 75th anniversary of Qantas, before setting down at the Dubai Air Show between 20 and 24 November. During the winter months, MSN004 will make its way to Australia for hot weather testing before commencing altitude trials in mid-January in La Paz.

From FLUG REVUE 11/2005, page 22

[marcogiov]

In Origine postato da Oli, scusate ma sono miope e in verde non vedo nulla. Altrimenti avrei cercato di fare il pilota!

http://www.flug-revue.rotor.com/FRHe...11/FR0511g.htm


By Sebastian Steinke

Fernando Alonso, vice president Flight Test division at Airbus and member of the crew who flew the A380 on its maiden flight, tells journalists gathered for a presentation in Toulouse that he is satisfied with progress to date on flight testing the A380. “As of 25 August, we have completed 72 flights with 247 flying hours. In the course of these flights 22 different test pilots have sat at the controls and personally landed the aircraft, among them two representatives of EASA. 31 flight test engineers have flown in the cabin, once again including two from EASA.”

Jacques Rosay, chief test pilot on the A380 programme, adds: “Of our own test pilots, only three or four quite junior pilots have not yet flown at the controls. But we want them all to get to know the A380. Up to now we have specifically needed test pilots, because not every flight condition has yet been certificated for non-test pilots. But from mid-September I expect the first training pilots from our customer airlines to be allowed at the controls. Provided that one of our B2 category test pilots flies as captain, a normal airline pilot could even serve as co-pilot. But to avoid falling behind in the test schedule, we would need a second aircraft to do that. At the moment the test flight plan is uppermost in our minds.”

Fernando Alonso: “Since the Paris Air Show, we have taken the aircraft up twice a day, once in the morning and once in the afternoon. A flying time of around three hours is normal. The longest flight so far lasted eight hours. It proves how reliable the A380 is. The whole infrastructure is right. Only in the 11th week of flying did we leave the A380 on the ground, otherwise all maintenance work has been carried out alongside.” The chief flight test engineer explains that engineers flew along during the flybys above Le Bourget, each lasting only six minutes and 40 seconds, analysing performance. “With such a crowded flight programme, the pilots are under a lot of stress. Watching them and all their actions during an air display under time pressure is particularly interesting for us, as it gives us a chance to eliminate any sources of error in the cockpit and controls.”

Alonso explains the test programme up to now. “In the first two to three weeks we addressed the envelope with two sets of control laws, “direct law” and “normal law”, and we kept widening the range of speeds. After that we were able to begin the testing proper. We are very pleased with the handling and aerodynamics. After just under one month, on the 17th flight, we were able to carry out the first automatic landing. After the first three to four flights we were already testing “engine relights”, that is, restarting engines that have been shut down in flight. We also extended the ram air turbine, which provides power in an emergency. We have already reached the stage of fine adjustment.”

Alonso adds that the high incidence protection and alpha-floor protection system, which automatically keeps the angle of attack within safe limits and even automatically produces thrust if there is a danger of the aircraft stalling in slow flight, had worked without any changes. Again, the “normal law” that will apply in future airline operations also functions well. Alonso continues, “Personally, I think we could get the flight control system certificated in its present state. That was a nice surprise, because otherwise it would have been expensive to make fundamental changes to the handling or aerodynamics at this point in time. Also it means that MSN004 does not require any fundamental changes compared with MSN001.” Despite this, MSN001 does differ on a few points from the next A380. “MSN001's engines do not yet comply with the standard and, as expected, we still have slightly higher drag on the fuselage and wings on MSN001.” On the engines, the engineers' main worry was excessive oil consumption early on, which is why the next A380's will have a slightly modified Trent design.

Test pilot Jacques Rosay goes on to talk about the area that he is currently focusing on in his test flights. “We are in the process of opening up the entire flight envelope at all speeds, altidudes and weights.” They had already flown high-speed flights at Mach 0.95 at the A380's operational ceiling, just below the red line at Mach 0.96, and had already reached the transonic regime, in the course of which areas of local supersonic flow form on the aircraft. The aircraft vibrates and jolts violently. Rosay reassures us by likening the experience to “being on a bumpy road. So far the flutter characteristics appear to be fine. We are watching how the wings behave. The buffeting built up quite gradually. At first a little, and then slowly increasing. That compares with other aircraft types, on which it starts quite suddenly.”

Nevertheless, one notices the respect that the professionals show before the maximum velocity. When this is reached, one has to be prepared for surprises and expect the aircraft structure to be loaded shortly before breaking point. Fernando Alonso: “The aircraft should be flown as seldom as possible at Mach 0.96. To get up to that speed, first of all you have to climb to 38,000 feet and then descend like crazy.”

For the purposes of certification, the A380 has to demonstrate at Mach 0.96 that it does not develop flutter oscillations or abnormally strong vibration. Naturally on these flights the crew always wear parachutes. The normal cruise speed of the A380 is Mach 0.85 to 0.87, well clear of this region. The first signs of “speed buffet”, that is, vibration and buffeting, occur at Mach 0.89.

Since the Paris Air Show, the landing flap settings and the leading edge slat positions have been optimised. In Position 1, the holding position, which is used for holding patterns, the leading-edge slats are extended to 20 degrees and the landing flaps are raised. Position 1+F corresponds to the combination of leading edge slats at 20 degrees with flaps at 8 degrees. Position 2, which is used on take-off, especially at high altitude airfields, combines leading-edge slats 20 degrees with flaps 17 degrees. For take-off and landing approaches on the other hand an extra new Position 3 of leading-edge slats 23 degrees and flaps 26 degrees has been introduced. Fernando Alonso explains, “We had not identified this setting beforehand in the wind tunnel.” Finally, the “Full Flaps” position combines leading-edge slats 23 degrees with flaps 32 degrees for the landing. At a velocity of only 138kt (256km/h) the reference velocity VRef is four knots (7.4km/h) less than expected. The A380 lands at a lower speed than an A340-600. Alonso is also very pleased with the A380's take-off performance. “We have even been able to take off with the maximum take-off weight of 569 tonnes without any problems.”

With regard to the take-off trials at minimum velocity in Istres (VMU tests), Jacques Rosay reports that on the first take-off the A380 had rotated further than expected and not just on the shock-mounted tail skid provided for this purpose, but had also unintentionally slid along the runway on the tail section behind it. Fortunately the tail had been protected at that point with a steel casing as a precaution, so that no damage occurred as a result of this tailstrike. But in this special case, the aircraft had behaved differently from what the simulator had led the team to expect.

Since then, according to Rosay, the test pilots have adopted a different rotation technique for VMU tests: they now raise the A380's nose from the runway in an accentuated way at a lower taxiing speed and then carefully reduce the distance between tail skid and runway with minimal elevator angles. The tail skid now only touches the ground very lightly and can withstand four VMU take-offs instead of the previous one before it has to be replaced.

Despite the slow pace, the landing gear was put under maximum load during some taxi tests on 25 June. This particular test included extremely tight turns on the apron, simulated push-backs and aircraft towing manoeuvres under a maximum weight of 546 tonnes and maximum steering angle of 60 degrees (the maximum permitted in operation) and even 72 degrees (technical maximum). The tyres on the two four-wheel wing landing gears ground especially during the push-back from the parked position with the steering twisted to 70 degrees, followed by a 90 degree curve, leaving thick, black swirl marks running almost sideways over the apron concrete. An extra hazard was posed by the fact that the rear axes of the two six-wheel fuselage landing gears, which are normally steerable, had been locked in position. Despite this, all the landing gear legs held up, all the maltreated tyres stayed on their wheel rims and the test was deemed to have been passed.

Finally, between May and August wake turbulence measurements had been carried out on the A380 in Toulouse (May to July) and Istres (July and August). For this purpose a container fitted with the LIDAR laser measurement system and the SODAR-RASS ultrasound measurement system from the German Aerospace Centre (DLR) in Oberpfaffenhofen was positioned, respectively, on the roof of a high-rise building in the landing corridor of Toulouse and in the presence of representatives of the American Federal Aviation Authority on the taxiway of Istres. As Alonso explains, “Now it is a matter of number crunching and processing.” In test operations from Toulouse, however, MSN001 is already flying with the regular wake turbulence distances for the “heavy” category between normal scheduled services.

One of the nerve-racking moments in the test programme to date was the first stall tests. Test pilot Rosay praises the way that the stall starts slowly on the wing root, with the control surfaces still working and a conventional downward pointing nose. But apparently the engineers performing the structural measurements registered alarmingly high bending moments on the horizontal stabiliser on coming out of the stall. Looking back on it, Rosay finds it amusing. “The ground station got really worked up on the radio, telling us that we must come back immediately.” After the landing, it turned out that the sensor concerned was producing measurements 40 percent higher than they should have been due to incorrect calibration. The structural load had actually remained within the safe limits at all times.

But there is one item that the engineers still want to change before the aerodynamic configuration is frozen: up to now spoilers 3, 4 and 5, when extended, have been generating air vortices that cause the elevator to vibrate strongly when they hit the horizontal stabiliser. For this reason, the first elevator rib is to be strengthened.

Charles Champion, Head of the A380 Programme and recently appointed Airbus Chief Operating Officer as well, sums up progress to date as follows. “We had feared some surprises that did not occur. There have not been any big problems, but many small ones, and there won't be any showstoppers. However, we did misjudge the amount of work involved on the wiring. The scale of individual customer special requirements surprised us. Now we are having to do the wiring with all the cable harnesses for many different customer versions in parallel. Emirates is even getting two variants. It affects not just the wires but also their fastenings, and hence the structure. Because of that, at the beginning we had sections in final assembly without the full system equipment for the cabin.”

To alleviate the wiring bottleneck, Champion has called in outside engineering services and hired several hundred extra staff. He expects to gradually make up the lost ground by employing extra teams in final assembly. Champion adds, “We will also ramp up production more steeply later on.” Although he calls the A380-800 the “top priority” at Airbus, he is not expecting production to normalise until between factory numbers 30 and 40, i.e. not before mid-2007, even though launch customer Singapore Airlines (SIA) is to take delivery of its first aircraft before the end of 2006.

Meanwhile the almost completed prototypes MSN004 (“performance aircraft”) and MSN002 are undergoing testing in the hangar, while MSN007 (the first one to the final production standard) has already been completed and final assembly of MSN009 (the first to be equipped with GP7200 engines) is just beginning. In the west wing of the final assembly hall, MSN003 and MSN005, the first aircraft earmarked for Singapore Airlines, are waiting for their engines.

At the beginning of October the second flying A380, MSN004, will be delivered to the Airbus flight testing organisation and a few weeks later take off on its first flight. This will be followed in mid-October by MSN002, which will fly straight to Hamburg to have its internal furnishings fitted and to be painted. MSN002 is the aircraft earmarked to undergo the notorious evacuation tests with the maximum number of seats fitted and 873 passengers on board in Hamburg at the beginning of 2006.

Before that, MSN001 will visit Sydney on 16 November as part of the celebrations to mark the 75th anniversary of Qantas, before setting down at the Dubai Air Show between 20 and 24 November. During the winter months, MSN004 will make its way to Australia for hot weather testing before commencing altitude trials in mid-January in La Paz.

From FLUG REVUE 11/2005, page 22