Vol 2 Chapter 455: Difficult retractable rocket

Yu Chengwu nodded with a smile: "It can also be said to be a beggar version, but the technical difficulty is not much lower. If it is really that simple, how could there be no rocket with this kind of technology?"
Difficult? Zhang Jun asked subconsciously.
Yu Chengwu nodded and said, "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 without fuel is very heavy. If the parachute is used for parachute recovery, it means a large set of parachutes.
However, the weight of the umbrella bag has increased significantly. Everyone knows that the rocket's load is all calculated. Suddenly adding such a large umbrella bag means that the rocket's carrying capacity will be greatly reduced.
This has created another problem. If the rocket's carrying capacity is weak, the weight of satellites or other loads that can be carried is very limited.
This will not only make the use of the rocket very limited, but also increase the cost of the rocket significantly, so that even if it can be reused, it will not be cost-effective. "
Speaking of this, Yu Chengwu paused and then said, "Then there is the recovery technology. Using a parachute is certainly easier than the reverse thrust landing of SPX's Falcon rocket, and the cost will be lower .
But it also has its difficulties, and it has its disadvantages. Such as the large umbrella bag and weight mentioned earlier, this is a problem.
And using this parachute landing recovery method, it is easy to be affected by the wind speed in the air, thus changing the landing place. This not only increases the risk of landing and recycling, but also increases the difficulty of recycling.
Finally, the core and most difficult technical problem is the rocket engine. Unlike disposable rockets, this recyclable rocket has more stringent requirements for engine quality and specifications.
At present, this type of recyclable rocket mainly recovers only the first-level arrow body of the rocket. The second-level difficulty is too great, and it is generally not recovered. Boosters are also recyclable, but conventional launch missions do not require a booster to provide additional thrust.
SPX's Falcon Rocket is now exploring the recovery of this fairing, but we do not consider this at this time.
We are currently developing a single multi-set launch vehicle, so taking this as an example, the current working flight time of most rockets is about 200 seconds, which is more than three minutes.
Generally, the rocket only needs to consider the time of more than 200 seconds, even if it is rich, it will not be too many more than ten seconds. Therefore, the entire rocket arrow body structure, system, engine, and materials are designed and manufactured according to this standard.
But our collapsible retractable rocket body does not just consider the short 200-odd seconds, but thousands of seconds, and even tens of thousands of seconds of working time. This has more stringent requirements for the rocket's arrow body structure, system, engine, and materials.
Only in this way can we control the cost so that it can reach the launch launch price cheaper than the one-time rocket. "
"Is it so difficult?" Asked an entourage who followed Wu Hao and they came this time.
Yu Chengwu glanced at the man, then nodded and smiled bitterly: "It is several times or even dozens of times harder than you think.
Let me just give two examples, and you will know when you are done.
First of all, in the structural design of the rocket arrow body and the material processing and manufacturing, because the reusable use must be considered, it is necessary to strengthen the structural strength of the arrow body.
This is not only from structural design, but also from materials and processing. But in this way, the weight of the arrow body is virtually increased, which not only has a huge adverse impact on the rocket's carrying capacity, but also brings trouble to the rocket's recovery.
Increasing the weight of the arrow body affects the rocket's carrying capacity, which will undoubtedly greatly increase the cost of a single launch and is not conducive to market competition.
Similarly, increasing the weight of the arrow body means that the difficulty will be mostly increased when landing and recovering. Not only is the parachute larger, but the anti-thrust force before landing is also increased, which brings a series of problems.
But if the rocket's arrow body is not strengthened, this will of course solve many problems, but it will cause huge troubles in recycling. Even if the parachute and anti-thrust technology are used, it will still cause irreversible damage to the fragile arrow body when landing, which will cause the recovery failure and lose the role of reuse.
The second is the rocket engine technology. In the rocket launch, the engine must withstand thousands of degrees of high temperature and pressure when fuel is injected.
The requirements of traditional disposable rockets are also very high, but the requirements for this kind of recyclable rocket are much reduced ~ EbookFREE.me ~ It only needs to consider the working time of two hundred seconds, and other need not consider.
Therefore, the overall structural design, materials, and manufacturing technology of the engine do not need to be so demanding. Recyclable rockets can be different because they are used many times, which means that the engines they use are not only strong in structure, harder and more durable, and have higher requirements for manufacturing technology.
At present, the countries and enterprises that have mastered this rocket engine technology seem to have only the old Falcon rockets of SPX.
I heard that in recent years our National Aerospace Group has also been working on it, but how the progress has progressed is unknown to the outside world.
There are many other similar technologies, such as fuel formulation, rocket sub-control system, and the most important grid plate rudder technology for recovered rockets. "
"That being the case, why don't we focus on developing easier one-off rockets, why do we have to build such recyclable rockets that are time-consuming, labor-intensive, and not necessarily successful?" Someone questioned the crowd.
Ha ha, Yu Chengwu shook his head with a smile: "Disposable rockets are easy, but they are very common. Even if we have a more reliable and cheap integrated rocket, it is difficult to make a breakthrough in this field.
In this field, our domestic aerospace group can say that it has done very well. It is difficult for us to compete with each other, not to mention that the other party still has the national prefix.
Second, the retractable rocket is now more difficult and the research and development costs are relatively high. But once the research and development is successful, it will bring huge benefits.
Moreover, in the future we can apply this series of technologies to other space exploration missions. For example, this reusable rocket engine technology can be applied to the spacecraft and spacecraft we design and develop in the future. "
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