Marseille, France, Dassault Flight Test Center.

A twin-engine fighter plane, quietly staying at one end of the runway, compared to the planes on the tarmac, although it looks similar in appearance, as if it is one size larger, however, there is a clear difference, that is, a pair of rotating canards are added to the front end.

Although in '79, the fighter began to fly test, but after talking with His Excellency Cusay, Marcel's horizons were broadened again, and he did not hesitate to waste any more time and redesigned the shape, the key is the movable canard.

How much vortex caused by the canard wing, how large the area should be, and how far away from the main wing is appropriate, all of these need to be blown through the wind tunnel to know.

And the DSI intake proposed by Lord Kusay, after passing through the wind tunnel, proved to be not very suitable, but this movable canard wing is something that can make the maneuver of the fighter have a radical change!

A very troublesome problem for the aircraft with delta wing layout is that the take-off and taxiing distance is too long, and the Mirage 3 needs a runway of more than 1,000 meters, which is also the reason why the later Phantom F1 adopts a conventional aerodynamic layout, but this layout does not bring much benefit to Dassault, because Dassault is best at tailless delta wing!

By adopting new technologies, high-thrust engines, fly-by-wire flight control, and relaxing static stabilization, the Mirage 4000 will be a leap forward from its predecessor.

Now the production version of the Mirage 2000C has begun to be produced, and it is expected to be delivered to the Air Force next year, Dassault's main technical force is also focused on the Mirage 4000, especially the addition of movable front canards, resulting in the flight control law of the fly-by-wire system needs to be redesigned, and the designers' understanding of the canards is not very good, so everything is in the process of exploration.

In this way, the test flight is even more fraught with risks.

The test pilot is also Dassault's most famous Bill, who is in the wide bubble cockpit, methodically preparing for the flight.

Since the Phantom 2000 and the Phantom 4000 have 80% of the common surname, the current cockpit is basically similar to the Phantom 2000, the same layout, there is only one screen under the front, and there are some instruments on both sides, but because the Phantom 4000 is larger, the nose has increased the radius, and even the cockpit appears wider.

Marcel stood on the runway, surging in his mood, this is the last project in his life's work, and he is already gray-haired, looking forward to the successful test flight of this heavy air superiority fighter.

The canopy slowly closes, and Bill sticks out his thumb in the cockpit to the distant crowd on the ground, and then, with the help of ground vehicles, starts the two engines.

After successful ignition, Bill checked the instruments in front, looked at the straight runway, and said calmly: "Tower, No. 1 requests to take off." ”

Marcel looked at the plane on the runway, the ground taxiing experiment had been completed, and this time, it was the real takeoff!

Getting a reply from the tower, Bill didn't turn on the afterburner, just turned the throttle to the maximum, released the brakes, and the huge Mirage 4000 began to slide on the runway.

Soon, the expected take-off speed was reached, and Bill pulled the boom back.

Suddenly, he felt a huge force coming, surging, under the thrust of the powerful engine, under the support of the lift generated by the huge wing, and under the pry of the duckling wing in front, the Mirage 4000 keenly raised the nose of the plane, and then, pointed straight to the blue sky!

At this time, the distance of the sliding run is only 500 meters, which is without afterburner!

Marcel looked at the eagle with expectant eyes.

Just at the moment of flying, the duck wing played a great role, its rotation provided the nose with a head-up torque, the tail fin in the rear of the aircraft to take off, is to pry the plane up, the torque required is very large, and this front canard wing layout, is to directly lift the aircraft to the nose, the effect of the two is of course not the same.

Bill was also very satisfied with the control just now, and the take-off process was enjoyable, this is a real fighter!

Since the other systems have already been verified on the prototype, it is not like the first prototype to take off without retracting the landing gear, and moreover, just go around the airport and return, after takeoff, it is time to verify the maneuverability of this fighter!

Bill retracted the landing gear, turned on the afterburner, and pulled the nose up.

Suddenly, the plane pointed straight into the sky and climbed rapidly.

This is also a very important indicator, climb rate, the aircraft has a lot of energy in the high altitude, but the fierce air battle will quickly consume these energy, so the shorter the time to climb back into the high altitude, it means that the aircraft can achieve more advantages in air combat.

In this regard, the advantage of twin-engine fighters is very obvious.

Coming to two thousand meters in the air, Bill flattened the plane and did a few very common actions, rolling, side sliding, figure 8 flight, the Mirage 4000 fly-by-wire system, showing excellent agility, fast response, coupled with the static and unstable design and the front canard, compared to the Mirage 2000, this fighter is the master of the future sky!

Bill pushed the throttle again, reducing the thrust and preparing to change out of the dive.

Suddenly, on the dashboard in front of him, two rows of red traffic lights were displayed.

It's actually the engine stop!

"Report, engine stopped." Bill shouted over the radio, and at the same time, the rescue operation began.

In the beginning of the test flight, Bill had already made these maneuvers on the prototype, and there was no engine shutdown, but now, there was a sudden accident, and moreover, both engines stopped at the same time!

When the engine stops, the power supply will be interrupted, and the backup power will need to be left to restart the engine.

So, according to the instructions on the radio, Bill began to switch to the alternate hydraulic mode, but this could not last long, because the hydraulic mode also required a higher oil pressure, and after he a few times, the oil pressure would decrease, and the plane would not be sensitive, and if he did it again, he would be completely unable to move.

This point is not as direct as the original steel cable drive system.

Bill switched to hydraulic mode, and suddenly, the lever was not as easy as it was just now, and he barely leveled the plane and aimed it in the direction of the airport.

Next, an order came from the tower to tell him to align with the airport and drive in the air.

Bill calmly made the air drive, toggling a few buttons, and then pressing a switch.

A loud roar came, and the engine behind it started again.

I don't know how many times this is the first time to rule out danger, as a test pilot, I will always be accompanied by death.

Bill didn't feel it just now, but now he realized that his entire back was soaked, and he switched back to fly-by-wire mode and began to return to the airport.

Damn the engine!

The crowd waiting at the airport had already received the news and were all eagerly awaiting it at the airport.

Finally, Marcel was relieved to see the plane again.

Although it is said that accidents are likely to occur during the test flight, it is not what any engineer wants to see, and falling off the plane can delay the progress at least and may lead to the death of the entire project.

The plane taxied back to the tarmac and was towed back to the hangar.

Bill got off the plane, and engineers had already begun to test the plane with various data, ready to find out what the problem was.

"Bill, tell me about the situation in heaven." Marcel asked.

"It was normal at the beginning, the aircraft was agile, and with the addition of front canards, the flight quality was much better than the prototype, but our engines stopped in the air." Bill said.

"What maneuvering maneuvers are you doing when the engine is stopped?" Marcel asked.

"I was in the middle of a dive, and I had an accident when I was about to change out, but luckily I was at enough height, otherwise I would have had to skydive." Bill said.

The dive, the change, the engine stopped, Marcel already had a rough inference about the reason this time, and it was the M53 engine that was to blame!

Although SNECMA has tried its best, the developed M53 engine has been completely finalized in 76 years, and it has been officially put into production in 79 years, but this single-rotor engine still has its inherent shortcomings: it is prone to surge!

One of the basic principles of an aerojet engine is that the front is a compressor, which compresses the oncoming air flow, and the middle is connected by a connecting rod to the turbine blades behind, and the air flow is compressed and enters the combustion chamber to combustion, generating high-temperature and high-pressure gas, pushing the turbine blades behind, and spraying backwards at the same time.

In order to improve efficiency, the compressor is multi-stage in series, the further back, the higher the pressure, the faster the speed should be, in order to adapt to this situation, the advanced engine is coated with two rotors, which are connected to the high-pressure compressor and the low-pressure compressor respectively, to adapt to different states. This is the twin-rotor engine. In addition, the middle is equipped with a deflation valve and the inlet blade can be adjusted, which can completely avoid this phenomenon.

However, M53 is still a single rotor, so that when the intake air changes sharply, such as pulling up from the overhead, the intake airflow seriously deviates from the design working state, and when the gas flows through, serious airflow separation occurs, and the strong vortex almost blocks the entire blade channel, and the airflow is intermittent, which will cause the compressor to enter a surge state.

It's like feeding a baby a big spoonful of food, and the child's mouth can't eat and then gets stuck, and the engine surge is actually caused by a mismatch between the compression capacity of the intake air intake and the compressor.

Why, then, did this problem not occur when the test flight began?

Because in the beginning, the Mirage 4000 was not so agile! The front movable canard wings allow the Mirage 4000 to raise its head more quickly, but it makes the engine unbearable.

At this time, the data analyzed by the engineer also came out, and it was exactly the same as Marcel had imagined!

With a more agile maneuver, the engine is not powerful!

(To be continued)