Then you can simply use a radio altimeter, why do you need a barometric altimeter?

Each has its own use.

At altitudes of less than 1000 meters, the accuracy of the radio altimeter is better than that of the barometric altimeter. Therefore, during the take-off and approach landing phases of the aircraft, most of them use radio altitude to measure the ground altitude of the aircraft.

However, in normal flight, everyone looks more at the barometric altimeter.

Because the radio altimeter indicates the distance between the plane and the objects directly below the plane, both land and mountainous, that is, on the plains, my height is three thousand, and on the high mountains, my height suddenly becomes a thousand, because this height is relative.

Of course, this is inconvenient, if you talk back to the tower, the height is several thousand, this height is for the sea level, or for the height of the airport.

This can only be solved by a barometric altimeter, otherwise you will have to carry a flight map with you and look at the altitude below superimposed.

Now, as the altitude dropped to less than a thousand meters, Qin Feng put his afterglow on the radio altimeter, and as he continued to fall, he gradually became serious.

Two hundred in height, flatten the plane!

At this time, there is already a flat river in front, which is a large enough Gobi desert, and there are no people coming and going in ordinary times, which is quite desolate.

Seeing that the horizon indicated that the fighter had flown flat, Qin Feng shouted on the radio: "006 has arrived in the designated airspace, request to start testing." ”

"Roger, you can go."

With the command, Qin Feng turned on the afterburner.

That's right, flying at low altitude and high speed, how can you do it without turning on afterburner?

A blazing flame erupted from the tail, and the J-8 fighter began to accelerate like a roaring bull with the afterburner turned on.

The speed started from 400 and kept increasing, 500, 600, at this time, Qin Feng had already felt that the nose of the plane was starting to rise.

This is the normal reaction of fighters.

The fighter plane is flying level in the air, that is because the lift and gravity of the wings are just balanced, and the lift of the aircraft is related to the speed, when the speed increases, the lift of the aircraft increases, and the nose of the aircraft naturally has to go up.

Qin Feng had already prepared, his hand began to push the operating lever forward, as long as he applied force to the tail rudder surface and let the nose of the aircraft lower again, wouldn't it?

As the speed increases, the amplitude of Qin Feng's hand putter is also getting bigger and bigger, and the speedometer continues to increase, 650,700...

When the pointer pointed to 700, suddenly, Qin Feng heard a "bang" sound.

With this sound, the plane also began to shake.

"006 reports that the fighter plane has an unexpected sound and begins to shake." Qin Feng said, "Request to return." ”

"006, please return immediately."

Qin Feng pulled the operating lever, for fear that the fighter would suffer some major damage, but now that he saw that the fighter plane was flying normally with his own pull, he was immediately relieved.

There was still a shaking of the plane, and it was not very violent, as if the skin of the plane had been torn open and then blown in the wind.

Qin Feng's heart was a little strange.

The low-altitude and large table speed, not to mention the measurement of 1,004, to say the least, you have to measure 1,002, right? What now? It's just seven hundred, and it's actually out of order?

If you can only fly to 700, then it is not a low-altitude and large watch speed, and even the medium watch speed is not enough!

The fighter plane flew normally in the sky, and saw the runway of the test flight institute from a distance, Qin Feng maintained a steady state of mind, opened the landing gear, and prepared to land.

"Bang." There was another soft thud.

Worst!

Qin Feng's heart sank suddenly, could it be that the landing gear was malfunctioning?

The fighters are all three-point landing gear, if a landing gear can't be put down, then landing is quite dangerous, now, hearing the sound when he put the landing gear, Qin Feng suddenly became worried.

At this moment, the voice of the tower came from inside the headphones: "006, the landing gear is normal." ”

A false alarm! As long as the landing gear is lowered normally, it's fine.

Qin Feng operated the fighter, stopped steadily, and when he released the parachute, he couldn't help but think of the brakes of the Mirage 2000 and landed directly, which was chic enough.

The fighter plane stopped steadily, the cockpit canopy opened, and a ground crew carried a ladder to let Qin Feng come down, just when Qin Feng was just about to climb down the ladder, the ground crew suddenly shouted: "The landing gear guard is gone!" ”

Several other ground crews also surrounded them one after another.

Fighters are retractable landing gear, when the landing gear is retracted, both sides enter the wing, the front enters the nose, of course, it also needs a guard plate to cover, otherwise it is exposed outside, and it cannot maintain air tightness.

Now, the guard plate on the right landing gear has been broken by half!

"The landing light glass is gone!" After a closer look, someone shouted again.

Qin Feng had already gotten down the ladder at this time, and looked down to see it, sure enough!

The "bang" sound came from here, when I was flying at a low altitude and a large speed, I just pulled it to seven hundred, and I couldn't stand it here, and the FRP guard plate was broken; The landing light glass flew off.

Where did the broken guard plate go?

Could it be that it fell at the time of his own test flight?

Qin Feng followed the position of this guard plate and continued to look forward, and saw the tail of the J-8, and gasped again!

I saw the front edge of the right flat tail, and at this time there was something about 50 cm in length!

It was the FRP guard that was knocked out!

If you hit the back and get stuck on the rudder, you will be in big trouble!

At this time, other people also followed, looking at the broken FRP guard, everyone immediately studied, what's going on?

It's good to fly at high altitudes, but it's not good at low altitudes?

"The culprit this time must be the guard plate of this landing gear." Qin Feng walked back and forth twice, and then looked at the other side, although the guard plate was not broken, it was already obviously deformed, and he already knew the reason.

"The landing gear FRP guard plate is not stiff enough, when flying at low altitude and high speed, it is elastically deformed by suction, and there is a gap on the surface of the wing, even if it is a slight small gap, it will break immediately under the action of high-speed airflow, this fragment hit the landing light, broke the landing light glass, flew to the rear, and hit the front edge of the right flat tail."

The analysis of this accident is not difficult to judge, everyone heard Qin Feng's words, and they all nodded, yes, Qin Feng's analysis is completely reasonable.

"So how do you solve it?"

"The solution is simple, let's increase the strength, in order to save costs, we used FRP, since this FRP is not good, let's change back to aluminum alloy." Qin Feng said: "Everyone has to check other openings again, whether the same situation has happened." ”