In the following period, with the help and guidance of Chang Haonan, the prediction results of the ice topography of the surface area of the main wing and tail of the Y-8 were quickly obtained.

In the cold wind of late November and early winter, in the assembly workshop of Factory 182, a group of people were surrounding the 8F that was dragged out as a research object.

Not far from the aircraft, there are two drawing boards, on which three views of the main wing and horizontal tail of the Y-8 are drawn.

If you look closely, you can see that there are several irregular lines outlined in different colors around the edge of the wing.

Due to the problem of wing icing involving flight safety, the work of the entire 182 factory has slowed down during this period of time, especially the test flight work of the Y-8J has been directly stalled because of the last second-class accident.

According to the schedule, the first two sets of Soshui-2000MS radars purchased from the UK will soon be shipped back to China.

Although in the preliminary preparation in the past few years, the radar part has been simulated with a counterweight model of equal weight to verify that the flight performance of the aircraft will not be too seriously degraded due to the installation of radar, but to install real electronic equipment on the aircraft, it is necessary to consider a series of problems such as energy consumption, vibration, working environment, electromagnetic compatibility, etc.

These are all things that have to go to heaven to test.

Therefore, if the test flight subjects cannot be restarted by the time the radar is returned to China, it will have a very negative impact on the time for the equipment to form combat effectiveness.

At one point, some people even thought that they should first build a simple multi-stage electric heating device according to the initial plan, and wait until the next model to slowly consider a more complete de-icing system.

In the end, it was Liang Shaoxiu who resisted the pressure and fully supported the basic research subjects of Chang Haonan and several people, which only saw the actual results today.

"Comrades, after nearly half a month of work, I and two professors, Lin Guofan and Zhu Lan, have completed the simulation and prediction of the growth of ice accumulation on the wings of the Y-8 aircraft, and also determined the corresponding heating and de-icing system load."

Chang Haonan's first sentence caused a round of applause in the huge assembly workshop.

No matter what kind of attitude the people standing here had towards this research before, since the results of the research have been available now that only half a month has passed, there is nothing to fight about.

If you're not worried about the project schedule, who wouldn't want a system that works better and improves flight performance?

"The red, orange, blue and green lines in these two pictures correspond to the growth of ice on the wing section of the aircraft after 120 seconds of passing through the ice area under different severe climatic conditions."

The conditions of the 182 factory are really limited, and there is no digital projector in the capital or Shengjing, if you use slides, on the one hand, the clarity is relatively low, on the other hand, there is no way to project such a large drawing, so I have to put it on the drawing board, so that everyone can look around.

"So in the worst climatic conditions, the ice is mainly distributed on the underside of the wings?"

Someone immediately saw the clue.

In the mid-90s, due to objective reasons such as insufficient performance of ice detectors, not to mention China, the world's research on ice damage during flight was still in a wild era.

Not to mention anything else, even the natural icing test, which has been very popular in later generations and has even become one of the standard procedures for the certification of airworthiness of civil aircraft, does not have a particularly unified and scientific standard.

Americans basically rely on the fact that the temperature in the Great Lakes region is low enough and the water vapor is abundant enough, so they find a similar cloud to fly in and around.

As for other countries, they are even more powerful.

Fortunately, most jet aircraft are already on the edge of the ice zone, so the number of ice-related air crashes in the civil aviation field is still within acceptable limits, and most of them are regional airliners such as ATR72 and smaller general aviation aircraft such as Cessna 172, and the impact is relatively limited.

So the results of this simulation are really counterintuitive for most people.

According to our research, in the case of an incoming velocity of more than 75m/s, supercooled water droplets will have a greater probability of impact retreat after hitting the wing surface, rather than the normal spreading stickiness, so the upper surface of the wing with faster airflow speed is relatively clean."

"In addition, even if the upper surface of the wing is frozen, because the faster incoming velocity corresponds to a smaller incoming flow angle, the ice shape is mainly frost ice without overflow process, the adhesion ability is very poor, and the ice surface shape is very close to the wing shape, and the hazard is much weaker than the life ice on the front edge and lower surface."

"If this is a slower aircraft, such as the Y-5, then the focus of the ice area will be the leading edge of the wing and the upper surface."

Chang Haonan's explanation was clear and clear, and it quickly made the engineers around understand it:

"So we, or almost all the large propeller planes in the past, have not grasped the point of de-icing according to experience?"

"Yes, a large part of the energy is wasted."

Chang Haonan nodded, then picked up the pen again and pointed to the horizontal tail part:

"Another point is that the degree of ice accumulation in the aircraft decreases with the increase in wing chord length, which means that the closer to the outside of the wing, the less likely it is to accumulate ice, which may also explain why the ice accumulation in the horizontal tail is often more severe than that in the main wing."

"According to our research, in a considerable part of the case, wing icing not only does not lead to a decrease in lift, but also provides an additional positive pressure area due to the strong vortex formed in the back area of the ice, which will be a strong head-down moment for a normally laid out aircraft, and the previous Yun-8J has an accident because of this."

“……”

After Chang Haonan, Lin Guofan, who introduced the influence of meteorological factors on the ice accumulation problem, and Zhu Lan, who designed the microstructure of the wing surface.

This small-scale seminar, which was held in the assembly hall, lasted until the evening, and even dinner was sent by the canteen.

As the explanations of the three people continued, a new set of ice accumulation theories was gradually laid out in front of all the participants......

"Then, as long as we give different de-icing designs in different areas of the wing according to different ice accumulation conditions, we can greatly improve the anti-icing capacity and improve the level of energy consumption."

"According to our calculations, after applying the columnar surface microstructure designed by Professor Zhu Lan on the leading edge of the wing with the most severe ice accumulation, the power requirements of the electrically heated de-icing system per meter of the wing corresponding to these four lines are 160W, 465W, 992W and 1430W, respectively, while the converted thermal power of the aerothermal de-icing system is 128W, 402W, 817W and 1265W, respectively."

"Even if a 50 percent safety margin is considered, it saves 65 percent of electricity and 85 percent of heat compared to the previous Soviet design."

"The latter, in particular, can directly increase the engine output by about 8% when the hot gas de-icing unit is turned on!"

Chang Haonan said this, and threw the pencil in his hand on the table in front of him:

"So, comrades, our next job is to design the corresponding two sets of de-icing devices according to the calculation results, and match them with the internal structure of the wing, so that the veteran of the Y-8 can be reborn!"

Note: The problem of the velocity on the upper and lower surfaces of the wing in this chapter is explained using Bernoulli's principle (high velocity brings low pressure) from secondary school textbooks. Strictly speaking, however, the question of why airplanes can fly is still not entirely clear, and there are several different schools of thought regarding the specific source of wing lift

(End of chapter)