Chapter 249 - 243 Test Flight_1

On September 13, the Aerospace Development Committee officially announced the launch schedule for the Ask Heaven and Dream Heaven experimental modules on September 19 and 20.

China’s space agency seemed to be influenced by the pace set by New Yuan, focusing more on time efficiency and opting for clustered launches even for important spacecraft like these.

Of course, the main reason was the plentiful supply of usable New Yuan-2 rockets, making it easy to allocate two for the mission.

The Ask Heaven and Dream Heaven experimental modules each weigh about 43 tons, and the mass of the Tiangong Space Station in orbit has been steadily increasing due to frequent resupply launches over the past year.

Once the two modules are launched, the Tiangong Space Station will overtake the Hila Space Station by a single-digit margin, weighing in at 230 tons to become the world’s second-largest man-made object in orbit.

The Hila Space Station, with a mass of 225 tons, ranks third, while the March spacecraft’s axial module is fourth at 220 tons.

It’s a pity that the March spacecraft’s axial module orbits higher and wasn’t designed to dock with space stations, otherwise it would have surpassed the ISS in an instant.

After the announcement by the Aerospace Development Committee, the comments section saw a rare appearance by Ma Yilong himself, to which the Committee replied with an invitation for him to watch the rocket launch in Qiongzhou.

Ma Yilong replied, "I will if I get the chance."

In what seemed like a simple online interaction, both parties subtly expressed their attitudes. And as for Ma himself?

At the time of sending the message, he had already confirmed that he would take a flight to Modu City on the 17th and hurry to China as soon as possible.

...

At the Desert Base, watched by Yang Wei and a group of base design personnel, a J-20 fighter jet, its surface a mottled grey resembling the discolored sheen of oxidized metal, was rolled out of the hangar.

A tractor towed the test aircraft, marked with the number 2201 on its new coating, to the end of the runway, where ground crew opened the canopy to conduct a final inspection. Nearby, a pilot clad in a gray flight suit waited for his turn to take to the skies.

Yang Wei glanced at the intense sunshine overhead and gave a thumbs up to the base research personnel beside him:

"To have developed the thermal-resistant stealth coating so quickly, that’s impressive."

"Not really, we actually had the technology from before, it just took some time to adjust the formula."

The Desert Base had been working on the Xuehu project for over half a year, and now they had finally completed the original design of the aircraft and were ready to move into the prototype and research stage.

An important technology for the Xuehu project was the thermal-resistant/stealth coating, capable of withstanding extremely high temperatures.

Although in reality, an aircraft traveling at 10 times the speed of sound generates friction with the atmosphere, causing surface temperatures to soar above 1600 degrees Celsius, with other parts reaching around 700 to 800 degrees Celsius.

In theory, such high temperatures could still be detected by infrared remote sensing satellites, but satellites also have blind spots, don’t they? Without accurate flight trajectories, it’s not that easy to detect, so stealth remains a priority consideration.

For instance, the SR-71 Blackbird reconnaissance aircraft reaches peak temperatures over 450 degrees Celsius when flying above Mach 3.2, with an average temperature exceeding 260 degrees Celsius, yet the radar cross-section is less than one square meter, making it a classic stealth aircraft.

The goal set by the Desert Base for Xuehu was to have a radar cross-section less than 0.15 square meters.

The radar cross-section of the J-20 is less than 0.05 square meters. Given Xuehu’s aerodynamic profile and size, 0.15 square meters is about right. With a cross-section under one square meter, few radars can detect it now.

Even if detected, at Xuehu’s flying speed, a slight acceleration would be enough to escape missile pursuit, and current means, excluding laser weapons, pose no effective threat to Xuehu.

But the J-20 was different. After acquiring the XW-9, Yang Wei designed the interceptor version, the J-20B.

Compared to the J-20, the J-20B’s fuselage was longer, its wingspan smaller, with an empty weight of 22 tons and a maximum takeoff mass exceeding 44 tons, embodying the typical heavy interceptor.

The J-20B sacrificed some maneuverability, but the two XW-9 engines it carried could bring it to a staggering optimized top speed of 3.5 times the speed of sound, with a maximum service ceiling of 33,500 meters. Thanks to the fuel-efficient characteristics of the XW-9 and the reduced drag resulting from the less maneuverable airframe, as well as an increased internal fuel load due to the added weight, the J-20B’s cruising radius was increased to 3,000 kilometers—an extraordinary feat.

Such a J-20B required a major overhaul of the skin of the aircraft while still ensuring minimal impact on stealth capabilities, maintaining the radar cross-section within 0.05 square meters.

After more than eight months of collaboration across four research institutes, the skin issue for the J-20B was resolved.

In contrast to the SR-71, which over fifty years ago required reserved gaps to control the expansion of skin at high temperatures, the J-20B used costly aerospace materials that would not leak oil, and the weight remained largely unchanged—even if the price was more than double.

Institute 611 built a prototype validator for the J-20B and then flew it quietly to Desert Base, where it was coated with a special paint developed for Xuehu.

The stealth/heat-insulating paint required by Xuehu needed to be reapplied after each flight. For the J-20B, the paint could last four to five flights before needing a fresh coat, with ground technicians simply making minor repairs at weak points before each flight.

The formula for this paint had been a closely guarded secret since the beginning of the last century’s space fighter program and saw significant breakthroughs during the Shenlong initiative, which was around seven or eight years ago.

As Dou Ping put it, this paint was the most advanced in the world, a full generation ahead of America, which is why its confidentiality was of the utmost importance. J-20B test flights had to be conducted at Desert Base.

Once applied, this new type of paint gave the skin a dirty metallic color. It was said to cost six figures per kilogram with extremely low production. The supply used for the J-20B had been accumulated over four months.

Of course, this was also because Xuehu was still only on paper, so production remained within the lab.

When the official version of the J-20B enters service, it definitely won’t use this type of paint but rather a downgraded version that reduces cost and simplifies the process.

Over half an hour later, the ground crew completed their check. A pilot, suited in astronaut attire, climbed into the cockpit and first ensured the ejection system was not jammed by any objects.

Because of the high temperatures, the J-20B lacked the elegant bubble canopy. The front half consisted of three pieces of thick flat glass, which looked somewhat like those on the J-8 F.

The cockpit area also looked slightly bulged on both sides because the J-20B was an unprecedented long-endurance interceptor, so it adopted a side-by-side dual-seat layout to reduce the strain on pilots, which was more comfortable than tandem seating.

"01, are you ready?"

After a second or two, the test pilot pulled down the mechanical valve of the face shield to secure it before replying through the built-in microphone:

"01 is in good condition, ready for a test flight!"

Due to the extreme heat generated during the high-speed flight of the J-20B and the limited size of the cooling equipment to reduce weight, the air conditioning couldn’t always be on. It could only be used when the two pilots needed to rest and switch shifts.

Normally, the cockpit temperature would exceed 39 degrees Celsius. Without wearing a suitably equipped spacesuit, one would be cooked dry.

Yang Wei commanded, "Begin the high-altitude, high-speed flight test of aircraft number 2201 immediately!"

The J-20B’s maiden flight had already taken place at Institute 611. At that time, it flew without stealth paint, its bare yellow skin not standing out among a host of validation aircraft, but it only conducted subsonic test flights.

After receiving the command, the test pilot pushed the throttle and took off. Due to the XW-9 engines and a smaller aspect ratio of the wings, the aircraft required a longer takeoff roll, pulling up only after 400 meters.