bonanza

Chapter 851 Spaceflight
"You mean to follow the technical route of General Electric's YF-120 or Pratt & Whitney's F-135?" Yang Dongsheng asked with a frown.

"En!" Vice President Wang nodded.

"The steps are too big!" Yang Dongsheng shook his head, "You should know that the variable cycle technology of YF-120 is too complicated and the response speed is slow, which directly caused YF-120 to be out of the bidding for F-22 engine!"

"According to the information we got, the U.S. has not actually given up on YF-120. People we poached from General Electric said that after General Electric failed to bid for the F-22 engine, the U.S. government continued to support General Electric to improve the technology of YF-120 , It is said that it is preparing to make a next-generation engine. If you want the fuel-saving capability of a turbofan and the high-altitude and high-speed performance of a turbojet, the variable cycle is the best choice!" Vice President Wang said.

"However, I don't know how long it will take for General Electric's variable-cycle technology to be perfected! We don't have any experience with variable-cycle engines. It's too risky to directly upgrade to variable-cycle engines!" Yang Dongsheng said.

In this era, the United States is counting on the F-22 to hang the world for 50 years.

All technologies related to F-22 are top-level technical secrets.

Even Israel was not allowed to buy F-22.

General Electric's YF-120 once participated in the F-22 project and is the next-generation engine of the United States.

The confidentiality level of this engine is definitely not comparable to the civilian gas turbines that have been sold all over the world, and the F-110 engine that has been in service for decades.

Even if there is an economic crisis next year, Yang Dongsheng is not sure that he can get the relevant team from General Electric.

What's more, I am afraid that General Electric itself has not solved the related technologies of variable cycle engines.

The development of our next-generation fighter jets is not waiting for anyone!

"As for the F-135 engine?" Yang Dongsheng scratched his chin, "According to the news I got recently, the maneuverability of the F-35 fighter jet is so poor that it can almost only be used as a ground attack aircraft. Satisfied! But they have F-22, F-35's poor air combat ability is not a problem! We don't have it!"

The F-35 fighter jet was finalized in December 2006, and its nickname is still "Lightning". Many problems have not yet been exposed.

"Then we can only compress the bypass ratio as much as possible!" Vice President Wang said.

The bypass ratio is the ratio of the air flow of the turbofan engine's external bypass to the internal channel air flow.

The larger the bypass ratio, the larger the fan at the front of the engine, the greater the thrust, and the higher the fuel efficiency.

Both transport aircraft and civil aviation airliners use turbofan engines with high bypass ratios.

The CFM-737 engine used by Boeing 320 and Airbus A56 has a bypass ratio of 6.

The GE-777 engine used by the Boeing 90 airliner has a bypass ratio of 9.

The large bypass ratio of the large fan at the front of the engine is beneficial to thrust and fuel efficiency, but it is also a huge air resistance.

And the larger the diameter of the fan, the lower the speed must be.

Once the speed of the fan blade tip exceeds the speed of sound, a shock wave is formed.

Shock waves can cause damage to the casing, adjacent blades, and affect air intake efficiency.

Therefore, the bypass ratio of turbofan engines used by fighter jets is less than 1.

The F-16 engine used by F-15 and F-110 fighter jets has a bypass ratio of 0.76.

In order to allow the F-22 to supersonic cruise, the bypass ratio of the F-119 engine is only 0.25.

By the time of the F-35, the F-135 engine bypass ratio was increased to 0.57.

The result is that although the F-135 engine uses more advanced single-crystal blades and the thrust has increased, the F-35 fighter basically loses its supersonic cruise capability.

"Is it technically difficult to derive a turbojet engine from a turbofan engine?" Yang Dongsheng asked.

"It's not that difficult!" Vice President Wang said in a daze. "The turbofan engine has a bypass ratio of 0, which means there is no external bypass. It is a turbojet engine. But the turbojet engine has high fuel consumption and poor economy. , the advantage is that the diameter is small, and the speed range that can be used is large. At present, it is basically only used in drones and cruise missiles, and there are still applications!"

At this time they had already walked out of the factory building, Yang Dongsheng looked up at the sky, "Old Wang, don't you think this kind of material is only considered to be used in aero-engines, isn't it too wasteful?"

"You mean..." Vice President Wang didn't understand what Yang Dongsheng meant for a while.

"How much do you know about scramjet engines and rotary detonation engines?" Yang Dongsheng asked.

Vice President Wang thought for a while and said, "I know a little about scramjet engines. Rotating detonation engines? I've only heard of the name before!"

Yang Dongsheng smiled, and asked again, "Where's the aerospace plane?"

Vice President Wang was taken aback, "Do you want to get involved in aerospace? But our country has not released this piece of private capital yet."

"The United States has already let go, and sooner or later we will let go!"

Yang Dongsheng's promise to Little Tiger to be an astronaut was not just talking.

Originally, he planned to learn from Musk and engage in rocketry, but now he has a better choice.

Satellite launches are expensive for a number of reasons.

First, the rocket takes off vertically.

The thrust-to-weight ratio of the rocket must be greater than 1 to fly, and once the launch fails, it can only do free landing movement, which is hopeless.

Extremely strict requirements on reliability!
In contrast, the thrust-to-weight ratio of civil aviation airliners is mostly only a little more than 0.2.

UAV thrust-to-weight ratio can be smaller.

Second, the rocket body is basically a disposable.

Musk's space exploration technology company's rocket recovery technology method requires a large amount of fuel to be reserved, the rocket body must be strengthened, and a recovery device must be installed.

After recycling, cumbersome inspections are also carried out.

Basically offsetting the profits of rocket recovery, in fact, the gimmicks outweigh the benefits.

Third, in rocket manufacturing at this time, a large number of parts are still inseparable from manual polishing.

The most important technology of Space Exploration Technology Corporation is the industrialized manufacturing of rocket engines.

Relying on the advancement of electronic technology, the control system is perfect.

No matter how heavy the rocket launch is, it only needs to stack the Merlin engine on top.

Make the rocket from a "handicraft" to an "industrial product".

If the Soviet Union's N-1 launch vehicle had this technology, it would not have failed.

This is also the route Yang Dongsheng originally wanted to take.

Fourth, the rocket must have its own oxidizer.

90% of the weight of a rocket is fuel, and more than three-quarters of the fuel is oxidizer.

Remove the weight of the rocket hull itself.

A rocket with a take-off weight of hundreds of tons can only achieve a payload of a few tons in the end.

It's no wonder that such a satellite launch is not expensive!
The aerospace plane is different, it takes off horizontally like a civil airliner.

Even if you fail, you can fly back by yourself.

The aerospace plane can be used repeatedly. First use the turbojet engine to accelerate to Mach 3, then start the scramjet engine, accelerate to Mach 10 or more, and finally start the rocket engine to enter space.

A large amount of oxidizing agent can be saved.

Or use a rotating detonation engine and accelerate directly from zero.

Until space elevator technology is available, it may be the cheapest way to fly into space.

In the previous life, countries did not develop aerospace aircraft. The main reason is that both the scramjet itself and the body of the aerospace aircraft need materials that can withstand high temperatures of [-] to [-] degrees.

(End of this chapter)