Yu Chengwu nodded with a smile and said, "It can also be said to be the beggar version, but the technical difficulty is not much lower. If it is really that simple, how could it be that there is no Rocket with this kind of technology yet?"

It's very difficult? Zhang Jun asked subconsciously.

Yu Chengwu nodded and replied: "In fact, the principle is very simple and technically not too complicated, but it is difficult in some core technologies and manufacturing processes.

First of all, the rocket's arrow body is very heavy, even the empty arrow body is very heavy. If parachute landing and recovery is adopted, it means a large set of parachutes.

But in this way, the weight of the umbrella bag will be greatly increased. As we all know, the load of the rocket is calculated in terms of rocket load. Suddenly adding such a large umbrella bag means that the rocket's carrying capacity will be greatly reduced.

This also raises another problem. If the carrying capacity of a rocket is weak, the weight of the satellites or other loads that can be carried is very limited.

This not only makes the Rockets use very limited, but also greatly increases the cost of the Rockets. This makes it not cost-effective even if it can be reused."

Speaking of this, Yu Chengwu paused for a moment, and then continued: "There is also the recycling technology. The parachute method is of course simpler than the reverse push-down landing of the Falcon Rockets of SPX, and the cost will be lower.

But it also has its difficulty and even its shortcomings. For example, the large umbrella bag and weight mentioned earlier, this is a problem.

Moreover, using this parachute landing and recycling method is easily affected by the air wind speed, thereby changing the landing location. This not only invisibly increases the risk of landing and recycling, but also increases the difficulty of recycling.

Finally, the most core and most troublesome technical problem is the rocket's engine. Unlike single-use rockets, this recyclable and repeated rocket has stricter requirements for the quality of the engine and various indicators.

At present, this type of recyclable rocket mainly recycles the first-stage rocket body. The second-stage is too difficult and generally not recycled. Boosters can also be recycled, but conventional launch missions generally do not require boosters to provide additional thrust.

Now SPX's Falcon Rockets have begun to explore recycling this fairing again, but we will not consider this at the moment.

We are mainly developing single-unit multi-combination launch vehicles, so taking this as an example, the working flight time of most rockets at the first stage is about 200 seconds, that is, more than three minutes.

Generally, rockets only need to consider these more than 200 seconds, even if they are rich, they will not be too much. Therefore, the entire rocket body structure, system, engine, and materials are designed and manufactured according to this standard.

But our retractable rocket body is not just about 200 seconds, but about thousands of seconds or even tens of thousands of seconds of working time. This has more stringent requirements for the entire rocket's body structure, system, engine, and materials.

Only in this way can we control the cost and enable it to achieve a cheaper launch and delivery price than a single-use rocket."

"Is it so difficult?" A entourage who came with Wu Hao and the others this time couldn't help but ask.

Yu Chengwu glanced at the man, then nodded and smiled bitterly: "It's several times or even dozens of times more difficult than you think.

I'll give you two simple examples, and you'll know after all.

First of all, in terms of structural design and material processing and manufacturing of rocket bodies, because repetitive use is considered, the structural strength of the arrow body must be strengthened.

This not only starts from structural design, but also from materials and processing and manufacturing. However, this invisibly increases the weight of the arrow body, which not only has a huge adverse impact on the rocket's carrying capacity, but also brings trouble to the rocket's recycling.

Increasing the weight of the arrow will affect the carrying capacity of the rocket, which will undoubtedly greatly increase the cost of a single launch, which is not conducive to market competition.

Similarly, increasing the weight of the arrow means that the difficulty will be mostly increased when landing and recovering. Not only will the parachute be larger, but the reverse thrust before landing will also be increased, which has brought about a series of problems.

But if the rocket's body is not strengthened, it will certainly solve many problems, but it will cause huge trouble in recycling. Even if the parachute and landing counter-pushing power aid technology are used, it will still cause irreversible damage to the fragile arrow body when landing, resulting in failure in recycling and losing the role of reuse.

The second is the Rocket's engine technology. During rocket launch, the engine has to withstand the high temperature and high pressure of thousands of degrees during fuel injection.

Traditional single-use rockets also have high requirements for this, but the requirements for such recyclable rockets are much lower. It only needs to consider two hundred seconds of working time, and nothing else needs to be considered.

Therefore, the overall structural design, materials and manufacturing technology of the engine are not so harsh. Recyclable rockets can be different because they need to be used multiple times, which means that the engine they use not only has a large structural strength, but also has higher requirements for the materials.

Currently, the countries and companies that master this rocket engine technology seem to be the only one with Laomi's SPX company's Falcon Rockets.

I heard that our National Aerospace Corporation has also been doing it in recent years, but the outside world still doesn’t know what the progress has been.

There are many other technologies like this, such as fuel formulation, rocket division control system, and the most important grid rudder technology for recycling rockets, etc..”

"Since that's the case, why don't we concentrate on developing easier disposable rockets? Why do we have to make such time-consuming and labor-intensive recyclable rockets that may not be successful?" Someone questioned the crowd present.

Haha, Yu Chengwu smiled and shook his head: "It is easy to disposable rockets, but they are already very common. Even if we create a more reliable and cheap integrated rocket, it is difficult to break through in this field.

In this field, our domestic aerospace groups have done a very good job, and it is difficult for us to compete with each other, let alone the other party is a national character.

Second, it seems that the rocket is difficult now and the R&D cost is relatively high. But once the R&D is successful, it will bring huge benefits.
Chapter completed!