Yu Chengwu smiled and nodded: "It can also be said to be a beggar's version, but the technical difficulty is not much lower. If it is really that simple, how could there be no rockets using this kind of technology yet?"
Is it difficult? Zhang Jun asked subconsciously.
Yu Chengwu nodded and responded: "Actually, the principle is very simple, and the technology is not too complicated, but it is difficult in some core technologies and manufacturing processes.
First of all, the rocket body is very heavy, even the empty rocket body without fuel is very heavy. If you use parachute landing and recovery, it means a set of very large parachutes.
But in this way, the weight of the parachute bag increases significantly. As we all know, the rocket's load capacity is calculated in grams. The sudden addition of such a large parachute package means that the rocket's carrying capacity will be significantly reduced.
And this creates another problem. If the rocket's carrying capacity is weak, the weight of satellites or other payloads that can be carried is very limited.
This will not only make the rocket's use very limited, but will also significantly increase the cost of the rocket, making it uneconomical even if it can be reused. "
At this point, Yu Chengwu paused, and then continued: "Then there is the recovery technology. Using a parachute is certainly simpler than the reverse thrust landing of SPX's Falcon rocket, and the cost will also be lower. .
But it also has its difficulties and its shortcomings. For example, the large parachute bag and weight mentioned earlier are a problem.
Moreover, this method of parachute landing and recovery is easily affected by wind speed in the air, thus changing the landing location. This not only increases the risk of landing and recovery, but also increases the difficulty of recovery.
Finally, the core and most troublesome technical problem lies in the rocket engine. Different from disposable rockets, this kind of recyclable rocket has more stringent requirements for the quality and various indicators of the engine.
At present, the main recovery of this type of recyclable rocket is actually only the first stage of the rocket. The second stage is too difficult and is generally not recycled. Boosters are also recyclable, but generally, boosters are not needed to provide additional thrust for conventional launch missions.
Now SPX's Falcon rocket has begun to explore the recovery of this fairing, but we are not considering this aspect at the moment.
We are currently mainly developing single-body multi-component launch vehicles, so taking this as an example, the working flight time of the first stage of most rockets is about 200 seconds, which is more than three minutes.
Generally, the Rockets only need to consider these more than 200 seconds. Even if they are rich, only more than ten seconds 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 considers not only the short period of more than 200 seconds, but thousands of seconds, or even tens of thousands of seconds of working time. This places more stringent requirements on the entire rocket body structure, system, engine, and materials.
Only in this way can we control the cost so that it can reach a launch price that is cheaper than a disposable rocket. "
"Is it so difficult?" A member of the entourage who came with Wu Hao and the others this time couldn't help but ask.
Yu Chengwu glanced at this person, then nodded and smiled bitterly: "It's several times or even dozens of times harder than you think.
I'll just give you two examples, and you'll know after you finish them.
First of all, in terms of the structural design and material processing and manufacturing of the rocket body, because reusability must be considered, the structural strength of the rocket body must be strengthened.
This is not only about structural design, but also about materials and processing and manufacturing. However, this will virtually increase the weight of the rocket body, which will not only have a huge adverse impact on the rocket's carrying capacity, but will also cause trouble in the recovery of the rocket.
Increasing the weight of the rocket body will affect the rocket's carrying capacity, which will undoubtedly significantly increase the cost of a single launch and is not conducive to market competition.
Similarly, increasing the weight of the rocket body means that the difficulty of landing and recovery will also be greatly increased. Not only does the parachute need to be larger, but the reverse thrust before landing also needs to be increased, which brings a series of problems.
But if the rocket body is not strengthened, this will solve many problems, but it will also cause huge trouble in recycling. Even if the parachute and anti-thrust assist technology are used, it will still cause irreversible damage to the fragile rocket body when landing, causing the recovery to fail and losing the role of reuse.
The second is the rocket engine technology. During rocket launch, the engine has to withstand the high temperature and pressure of thousands of degrees during fuel injection.
Traditional disposable rockets also have high requirements for this, but compared to this kind of recyclable rocket, the requirements are much lower. It only needs to consider the working time of two hundred seconds, and does not need to consider other things.
Therefore, the overall structural design, materials, and manufacturing technology of the engine do not need to be so demanding. Recoverable rockets are different because they need to be used multiple times, which means that the engine they use must not only have strong structural strength, but also have harder and more durable materials, and higher manufacturing technology requirements.
At present, the only country and company that has mastered this kind of rocket engine technology seems to be the Falcon rocket of Laomi's SPX company.
I heard that our National Aerospace Group has also been working on it in the past few years, but the outside world still doesn’t know the progress.
There are many technologies like this, such as fuel formula, rocket sub-control system, and the most important grid plate rudder technology of recovery rockets, etc. "
"In this case, why don't we focus on developing disposable rockets that are easier? Why do we have to develop such recyclable rockets that are time-consuming and laborious but may not be successful?" someone in the audience questioned.
Haha, Yu Chengwu smiled and shook his head: "Disposable rockets are easy, but they are already very common. Even if we come up with more reliable and cheaper integrated rockets, it will be difficult to make a breakthrough in this field.
In this field, our domestic aerospace group can be said to have done very well. It is difficult for us to compete with each other, not to mention that the other party is still prefixed with the prefix "国".
Second, it seems that retractable rockets are more difficult now, and the research and development costs are relatively high. But once the research and development is successful, it will bring huge benefits.
Moreover, we can apply this series of technologies to other space exploration missions in the future. For example, this reusable rocket engine technology can be applied to the space vehicles and spaceships we design and develop in the future. "
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