Pilots who have been flying civil aviation for many years are extremely sensitive to the cost control of civil aviation, especially veteran pilots who have been flying for more than ten or twenty years. They are familiar with the entire period of rapid development of China's civil aviation after the reform and opening up, and the entire process up to now.
Everyone has personal experience. There are more and more airports, more routes, more flights, more planes, and the cost of airlines is getting higher and higher.
Take the Capital Airport as an example. If air traffic control orders a plane to roll out of the terminal, the plane will enter the queue for takeoff. From this time on, the plane's engine must always be running. However, during busy periods, some flights
Even if it can't take off for an hour, every additional minute of delay will cost the airline a huge amount of fuel consumption.
The same goes for landing. If you delay for more than 20 minutes, the fuel consumption cost will increase in units of 10,000 yuan. The high cost makes the cost per kilometer of civil aviation much higher than that of railways and highways, and the fuel surcharge and aircraft installation fees alone will
This has shut out a large number of potential users of civil aviation. Due to cost reasons, the competitiveness of civil aviation has been unable to be qualitatively improved.
However, the overall performance of DC11 is enough to reduce aviation costs by a large margin. If airlines adopt Dongchen's aero engines, the entire civil aviation field will usher in a rapid development.
The crew was extremely excited about the performance of this new engine. After 48 hours of non-stop operation, there were no abnormalities in the entire engine process, which also proved that this engine has reliable and powerful continuous flight capabilities.
Come. The aircraft availability will be higher.
After 48 hours of continuous non-stop operation, Zhang Wenhao called all the crew members together for the off-line test of the new engine. In addition to the strength test, swallowing test, and containment test, it must also meet three thousand hours of operation time.
The installation test can be approved. This process is too cumbersome for Zhang Wenhao, and the waiter knows all the parameters of this engine. He can conduct more than 10,000 hours of simulation experiments on all parameters in a few minutes, and the simulation experiments
The result was infinitely close to the actual test, so Zhang Wenhao was prepared to follow his own strategy. That is, skip the application for an airworthiness certificate and directly install the machine for testing.
Although this is a way to violate the rules, the rules are made by people. Zhang Wenhao uses future technology and combines it with Xiaoer, an extremely accurate supercomputer, to have extremely high performance and tolerance of any part of this engine.
Therefore, Zhang Wenhao decided to hang the engine on the aircraft first and directly enter the ground hanging test.
Since it needs to be hoisted onto the aircraft for ground testing, it must obtain the consent of the crew. Therefore, Zhang Wenhao summoned the crew to discuss whether they were willing to enter the hoisting stage in advance.
The crew had some concerns, but this concern was just an instinct against the existing rules. At first, everyone felt that this unconventional way of playing cards was dangerous, but everyone understood that,
Judging from the current performance of this engine, it is definitely a brand-new engine with epoch-making significance. Therefore, the existing rules are not necessarily suitable for this engine.
After negotiation, the crew agreed to conduct the hoisting test first. However, the crew's attitude was that there was no problem with the hoisting test, but the test flight should not be too hasty. They needed to be familiar with the ground performance of the engine before deciding when to actually conduct it.
Test flight.
Zhang Wenhao has no objection to this. Seeing that the engine has been offline for more than ten days and has passed all tests except the prescribed time, if the delay continues, I am afraid that it will have to wait until at least the second half of the year for this engine to really go to heaven.
The hoisting is carried out first, and after the crew is familiar and reassured, we can then talk about the test flight.
The four engines that were tested in the laboratory were transported to COMAC's test airport in the suburbs of Zhonghai. This test airport has a super-standard 4f runway, which is used not only by COMAC itself, but also by many large military transport aircraft.
Transfer to this runway for the first time to conduct acceleration and deceleration tests, take-off and landing tests and crosswind tests.
The standard of this runway is very high, with a length of 4,200 meters and a width of an astonishing 70 meters. Even the largest aircraft in the world, the former Soviet Union's An-225 giant transport aircraft, has taken off and landed here.
For the 737 and 320, two small mainline passenger aircraft, the take-off distance requirement is about 22,002,500 meters. On this runway, the 737, 320 and other aircraft can accelerate to the take-off speed without taking off, and the remaining distance is also fully sufficient for the aircraft.
The braking distance required from take-off speed to rest is an excellent place for ground testing.
The crew and Dongchen's technicians were stationed directly at the test airport. The technician team spent two days dismantling all the engines of the two aircraft Dongchen purchased from China Southern Airlines, and installed Dongchen's dc11 engine in place.
The crew rested for two days and immediately entered the further testing process of the DC11 after the hoisting was completed.
The first thing to be tested is the sensitivity of the four new engines on the aircraft with the aircraft control system, the response speed of the engine starting and stopping, the response speed and sensitivity of the throttle, etc. in the static state.
Although the dc11 is a newly designed engine, in terms of compatibility specifications, it is the same as all engines on the market and can be perfectly hung on all models of the 737 and 320 series.
After the two aircrafts completed the engine replacement, the crews boarded their respective aircrafts. The chief engineer of the test commanded the engines of the two aircrafts to start at the same time. The engine turbofans responded very quickly, and the speed was quickly increased, and a sound was issued.
There was a roaring sound, and immediately, the two crews began to continuously increase the fuel supply to the engine, so that the engine quickly reached full operation, then immediately withdrew the fuel supply, and stalled the engine when it dropped to a low speed.
The whole process is very smooth, and the engine responds very sensitively to the crew's control. And due to the advanced design concept and high material strength, the dc11 is easier to enter the maximum thrust state in a short time than ordinary engines. This is true in actual use.
, which can relatively reduce the take-off distance of the aircraft.
The whole process of ignition, increasing fuel supply, reducing fuel supply, and stalling was repeated more than 60 times by the crew within one day. The engine remained extremely responsive without any accidents.
The next day, the crew got up at 5:30 and stayed until 10 o'clock at night, repeating the test process of the previous day 90 times. Still no abnormality occurred.
On the third day, 90 times, everything was normal.
Such a perfect and accurate response has greatly improved the crew's confidence in the DC11. For an ordinary engine, during more than two hundred consecutive starts and stops, it is inevitable that one or two startup failures will occur, or the startup response speed will be slow, but
, on dc11, every repeated test result is perfect.
The three days of testing made Dongchen's technicians and crew extremely excited. The COMAC employees and leaders at the test airport were also very interested in Dongchen's tests, because the production line used by Dongchen was transferred to COMAC.
Dongchen's, so these people also regard DC11 as half a COMAC product, and have been paying attention to Dongchen's testing of this engine.
On the fourth day, the crew was tired of repeating the start-stop test without any abnormality. They actively requested to stop the original five-day start-stop test in advance and enter the next step of dynamic test.
The so-called dynamic test is to completely remove the aircraft's braking system and ground fixation devices, and then allow the aircraft to propel normally on the ground at low speed. If the aircraft does not rely on a tractor to travel between airport runways, it needs to complete acceleration, deceleration, steering and other actions.
, and the aircraft needs to complete these actions in many states, such as queuing up to take off, turning to enter the runway, turning to leave the runway area after landing, etc. At this time, what is most needed is the accurate throttle control of the engines on both sides.
response.
If an aircraft turns on the ground, it depends mainly on the difference in thrust between the engines on both sides and the rotation of the front wheel guide wheels. Therefore, when the aircraft wants to turn, it will immediately change the thrust balance of the engines on both sides and increase the thrust on one side.
, or one side reduces the thrust, or both sides complete the increase and decrease of their respective thrusts at the same time. In this case, the sensitivity of the engine becomes extremely important.
In fact, all engines currently in service can meet the sensitivity requirements, not to mention the DC11. This test is just a routine test. If this test passes, then the next step can be to carry out the final test before the test flight.
Speeded up testing.
The dc11 has been subjected to more than two hundred start-stop tests in a state of exquisite testing, and each test includes a test of fuel supply sensitivity. The performance of the dc11 is very perfect. Therefore, in the dynamic test, various tests
They all passed easily. The whole process was very boring. It was to let the crew fly the aircraft, drive out of the parking space, enter the contact taxiway, then enter the beginning of the runway after turning, park at the beginning of the runway, and then turn back to the original route, with the engine running all the way.
Due to the low speed state, it gives the impression that it is powerful but cannot be used.
After two days of dynamic testing, the aircraft has completed various designed operating trajectories. This trajectory design is equivalent to various internal road test projects in driving schools. Even Poussin's performance can easily handle it. For dc11
, there is no more challenge.
The last step before the test flight is to actually test the aircraft's accelerated take-off performance. The aircraft starts the engine at the beginning of the runway. After the aircraft starts to move, continue to advance the throttle and let the aircraft begin to accelerate and sprint. When it reaches the take-off speed of the aircraft type, the crew
The personnel only need to lower the flaps and increase the elevation angle of the aircraft to complete the take-off process.
However, this acceleration test is not a test flight test. Therefore, after the aircraft accelerates to the take-off speed, the crew cannot lower the flaps. Instead, they must immediately reduce the fuel to allow the aircraft to rapidly decelerate at the critical speed for take-off.
Through this test, the approximate take-off distance of the aircraft can be tested, but it is only a rough estimate. If the wind direction and wind speed are different, the take-off distance of the aircraft will also be different.
However, at the commercial aviation test airport, when the two aircraft were subjected to acceleration tests, the take-off distance obtained was slightly shorter than that of ordinary aircraft of the same model by about 200,300 meters. Although this is an improvement, for civil aviation aircraft
It doesn't make much sense, because most airport runways are sufficient for aircraft to take off.
It is actually not troublesome to test the aircraft engine alone. The response speed of DC11 on these two aircraft is stronger than the previous original engine, and the thrust is sufficient. Therefore, after these days of hoisting tests, the crew and testers
Both believe that the two aircraft are ready for test flight. After all, the engine is just a source of power. The main body of the aircraft is in its golden period. Therefore, as long as the reliability and sensitivity of the engine are guaranteed, then these two aircraft will be qualified.
Test flight conditions.
The commander-in-chief led the testers to formulate five sets of test flight procedures. The first set of test flight plans was a simple take-off and landing test flight. After taking off from the airport, the aircraft flew ten kilometers along the runway, and then began to turn and perform five-sided maneuvers commonly used in civil aviation.
Approach method, turn back and drop the locomotive.
In the second test flight plan, the aircraft climbed to an altitude of 3,000 meters after takeoff. After reaching the altitude, it flew at the designated altitude for 50 kilometers, then turned back and performed a final approach and landing above the airport.
The third set of test flight plans. The aircraft needs to climb to an altitude of 7,000 meters.
For the fourth test flight plan, the aircraft needs to fly to an altitude of 10,000 meters to 11,000 meters.
The fifth set of test flight plans not only requires reaching the cruising altitude, but also requires the aircraft to perform a range test of 5,000 kilometers to 6,000 kilometers. The route of the range test must be very strictly formulated. Ensure that the entire route is completed every once in a while.
More than 300 kilometers away, there is an alternate airport so that if any abnormality occurs to the aircraft, the aircraft can land at the nearest alternate airport. If there are no problems throughout the entire journey, the aircraft can directly complete the entire route and return to the test airport.
All test flight procedures have been submitted to the air traffic control department for approval. Due to special care from the top management, air traffic control gave Dongchen test flight priority even more than the treatment of all civil aviation airliners. All procedures were quickly approved, and all
The alternate airport has also been notified and is ready to respond to Dongchen's test aircraft's alternate landing needs at any time.
For the first test flight, the two planes took off ten minutes apart. The first flight was the Boeing 737. Zhang Wenhao also boarded the plane in person and squeezed into the slightly narrow cab with several test engineers.
After receiving instructions from the tower and conducting routine inspections with the first officer, the captain started the aircraft's engine and slowly rolled out of the parking bay.
In the cabin, the roar of the engine was not too loud, and the captain also said very excitedly: "The noise at this low-speed propulsion state is much stronger than that of all medium and large passenger aircraft. The noise reduction of this engine
It is indeed a first-class level, and I believe the noise in the cabin will be much smaller.”
The tester nodded and said: "At low speeds, compared to engines of the same level, there is about a fifteen decibel reduction. If it is running at high speed, the noise reduction can reach nearly thirty decibels."
The captain smiled slightly and said: "Placing me in the first flight position today also makes me the first captain to fly dc11 into the sky. In the future, dc11 will definitely become a classic among classics in the field of civil aviation. For me,
It’s indeed a big honor for me.”
As he said that, the plane had entered the communication channel, which was connected to the runway at a 90-degree right angle. The captain gradually increased the thrust of the engine, causing the plane's taxiing speed to slowly increase. Soon, the plane had entered the final 90-degree angle.
degree turning angle.
Generally speaking, old pilots rarely stop the fuel before turning the corner, stop after the corner, align the runway, and then re-throttle the throttle to take off. For the sake of operational efficiency, the old captains basically start accelerating before entering the runway, and do not turn when turning.
Collect the fuel, and then accelerate to take off immediately after completing the turn. In this case, the aircraft will already have a certain speed when entering the runway without having to go through a long acceleration process, which can shorten the takeoff time of the aircraft faster.
The same was true for the captain. The plane accelerated, and then nimbly completed the turn at the turn. Without pausing after the turn, he and the co-pilot pushed the engine throttle at the same time. Then, the plane began to accelerate continuously. After reaching take-off speed, the captain
He smiled and said to himself: "Okay, it's time, let's get up."
Immediately, the nose of the plane began to rise and the plane took off smoothly.
As the aircraft lifted off the ground, the captain said: "I have to say that the performance of the dc11 is indeed excellent, not only its strong fuel economy and lower noise, but also its response speed and power feedback speed are faster than ordinary ones."
The engine is much more powerful. It can be expected that this engine will be the first to obtain China's airworthiness license. By that time, China's civil aviation companies should be the first customers to switch to DC11. If international peers know about this engine
Performance, I’m afraid I’ll be so jealous that I can’t sleep.”
The first officer on the side nodded and smiled: "That's right, the fuel cost alone has been reduced by nearly 40%. This is enough to make airlines around the world jealous."
When the aircraft engine is boosted to the maximum, the noise inside the aircraft is improved even more significantly. Zhang Wenhao himself can feel that the engine noise is much quieter than when he took the aircraft before, and he has also experienced the environment a few times in the first few times.
The worst economy class. He had sat in the economy class seat near the wing many times and knew that the noise there was the loudest. It was simply unbearable.
However, when Zhang Wenhao walked into the cabin, the noise level in the cabin was much quieter than every time he took it before. Even when he got to the seat next to the wing, he saw the engine running at full power under the window.
The noise is also within acceptable range.
The aircraft quickly began to turn and performed a routine final approach. The landing process was also very smooth. The engine did not show any abnormalities during this short test flight. Welcome to
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