After the low-altitude and large-speed test flight, according to the opinion of the aviation doctor, considering Yang Luo's physical reasons, the test flight mission was not arranged on the second and third days, and he failed to fly a lap in the air.

It wasn't until the fourth day that a new test flight mission was ushered in.

Also at nine o'clock in the morning, after accepting the mission in the flight briefing room, I changed into the pilot's anti-load suit and went to the hangar.

This time it flew another J-10C, that is, the one with the call sign Raptor-11, and the previous one has not been repaired because of damage.

Today's mission is not very dangerous for Yang Luo, and it is a test flight with the minimum level flight speed.

The level flight velocity corresponding to the critical angle of attack is called the level minimum velocity. At this time, the stability and maneuverability of the aircraft are very poor, and the flight state is not easy to maintain, so it is generally not allowed to fly at this speed.

The significance of this speed is to give the pilot a quantitative concept, and when the flight speed is close to this speed, the push rod should be changed quickly.

The minimum level flight speed safety range of the J-10C is 200 kilometers per hour, the angle of attack at this time is 25 degrees, and the throttle has reached 93, while the critical angle of attack of the J-10 series fighters is 26 degrees.

There are also people who have flown at a lower speed, it is said to be 145 kilometers per hour, but it was not the test pilot who flew out, Yang Luo didn't know whether it was true or not, and today he just wanted to verify it.

After communicating with the tower and obtaining meteorological parameters and take-off permits, Yang Luo drove the plane into the blue sky.

Still in the desert a few days ago, after Yang Luo leveled out at 5,000 meters in the air, he called the tower and said, "Call the tower, the Raptors 11 has arrived over the designated area, and asked to start the minimum level flight speed test flight mission." ”

"The tower has received it, and you can start." In the monitoring room of the tower, Chief Engineer Wang gave an order.

Compared with the low-altitude and large-speed test flight a few days ago, it seems quite relaxed in the monitoring room today, first, I know that Yang Luo's flight skills are very high, and second, the danger of today's test flight is indeed not high.

The minimum level flight speed test flight, even if you don't master the stall, it will not crash all at once, there is still time to change it, and then take a step back, even if you can't change it, you can also parachute, at least the life of the test pilot is safe.

"Raptors 11 received, start executing."

Yang Luo responded, took a breath of airborne oxygen, slowly retracted the throttle valve, reduced the power output, and opened the speed brake and flaps to reduce the speed of the fighter.

The speed of the J-10C was extremely reduced, and soon dropped to 220 kilometers per hour, at this time, Yang Luo became dignified, and was already on the verge of stalling, and the speed brake had been retracted, and the angle of attack of the fighter must be changed to obtain greater lift.

The angle of attack can be changed in two ways.

The first is to disrupt the airflow through canards, flaps and horizontal tails, so as to achieve the effect of changing the angle of attack of the fighter.

The second is to change it by controlling the pitch of the fighter, but Yang Luo's task now is to test the minimum level flight speed and change the direction of flight, so it is not in level flight, and naturally it cannot be achieved by relying on nose pitch.

The biggest change in pitch in the nose is the angle of elevation, not the angle of attack, which is fundamentally different.

The elevation angle is the angle between the longitudinal axis of the aircraft and the horizontal line, which is related to the flight attitude of the aircraft, which is positive upward and negative downward.

The angle of attack is defined as the angle between the wingstring of an airplane wing and the opposing airflow, which is also positive upwards and is also known as the angle of attack.

There is no inevitable connection between the angle of attack and the angle of elevation, the large angle of elevation does not mean that the angle of attack is large, the same angle of elevation can have different angles of attack, because the angle of attack when the aircraft elevation angle is 70 ° is only about 10 degrees, the wing of the aircraft can still work very well, producing normal lift.

The angle of attack data during flight is given by the aircraft's atmospheric data computer, generally on the side of the fuselage, there will be an angle of attack detector, the principle is a bit like a weather vane.

What Yang Luo wants to use now is the first way to change the angle of attack of the J-10C, but the J-10C does not have a horizontal tail, so it can only be adjusted by canard wings and flaps.

At this time, it was at an altitude of 5,000 meters, so Yang Luo's eyes were focused on the dashboard, staring at the angle of attack table on the dashboard, stabilizing the attitude of the fighter with his right hand, maintaining level flight, and adjusting the position of the canard wings and flaps, so that the angle of attack of the fighter slowly increased and improved the lift of the fighter.

As the angle of attack increases, so does the lift of the fighter, but so does the corresponding drag.

Because both the lift coefficient and the drag coefficient are functions of the angle of attack, within a certain range, the larger the angle of attack, the greater the lift coefficient and the drag coefficient.

The speed is still decreasing.

210 km/h!

200 km/h!

At this time, the angle of attack gauge showed that the angle of attack had reached 25 degrees, but on the other side, Yang Luo was pushing the throttle valve, and the throttle had reached the 93 position.

Some people may be puzzled, why do you need to refuel when you are flying at the smallest possible flight speed, shouldn't you retract the throttle?

You must know that the lift of an airplane is only used to counteract the gravity of the aircraft, while the forward speed of the aircraft depends on the thrust of the engine.

Now that the angle of attack has increased, so does the corresponding drag, and to overcome the drag to fly, the engine must have sufficient thrust.

"Report tower, flight speed 200 kilometers per hour, angle of attack 25 degrees, throttle 93." Yang Luo reported.

"The tower receives it, and it stays flying for twenty seconds."

"Understood, after twenty seconds I tried to slow down again."

"Yes."

In the tower, everyone's eyes are focused on the monitoring screen, it is not surprising that this speed has been reached, the J-10 prototype has reached this speed when it is tested, and what they want to know is how low Yang Luo can do, whether it can reach the rumored speed of 145 kilometers.

After flying at 200 kilometers per hour for 20 seconds, Yang Luo adjusted the position of the canard and wing again, and the angle of attack increased again in an instant, reaching a critical value of 26 degrees.

If it increases again, exceeding the critical angle of attack, the lift and drag will not continue to increase, but will decrease, and the aircraft will stall.

With the increase of the angle of attack, the lift force is further improved, and the corresponding drag is also increasing year-on-year, and the speed of the fighter is decreasing sharply.

180 km/h!

160 km/h!

"Drop!"

A rapid alarm sounded in the cockpit, and the yellow warning light flashed, which was the buzz of the stall warning system, reminding Yang Luo that the fighter was about to stall.

When the actual angle of attack is close to the critical angle of attack and the aircraft is in danger of stalling, the stall warning system will send out various forms of warning signals.

Yang Luo ignored the buzzing alarm, continued to push the throttle valve with his left hand, increased the injection of aviation fuel, and stared at the various instruments on the instrument with his eyes intently, his face solemn and solemn.

"Boom!"

Aviation fuel enters the combustion chamber at maximum speed, burns wildly, and the aero engine runs at maximum power, roaring violently and bursting out with maximum thrust.

The final speed was fixed at 145 km/h, and there was no further decline, at which point the angle of attack had reached a critical angle of attack, and the thrust of the engine had reached its maximum.

Yang Luo's operation is actually very complicated, the position of the canard wings and flaps must be very precise, the slightest mistake, the angle of attack will change, and eventually stall.

"Report the tower, the speed is 145 kilometers per hour, the angle of attack is 26 degrees, the throttle valve has reached the end, the engine is at maximum thrust, and the flight is stable at the moment, there are no signs of stalling."

Yang Luo clenched the joystick with his right hand, stabilized the fighter's attitude, and calmly reported to the tower.

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