Chapter 1241 The boost phase is extended
“New technology?”
Shapur Collinger frowned slightly:
“Tell me about it.”
< br>As an old-school engineer, although he does not reject various new technologies per se, he does not want to create branches beyond the original plan.
From an engineering perspective, every change in the R&D plan midway means the introduction of new uncontrollable risks. Even if additional time and funds are spent, it is difficult to ensure that the overall reliability performance returns to the original level.
If there are a few more accidents in the middle, it will not end at all.
Haste makes waste.
Once the delay is too long and the external environment changes, Party A will naturally give new demands, which in turn will force Party B to modify the R&D plan again, forming a vicious circle.
If things go back and forth, it is easy for the project to become an unfinished project with huge sunk costs.
Therefore, Collinger's original plan was to modify the aerodynamic shape of the X51A's waverider-like front section to reduce the resistance during the initial acceleration process, while optimizing the shell structure and reducing the overall weight of the aircraft.
In this way, without changing the core power system, the entire flying body can reach a speed of Mach 5.5 before being thrown away from the booster, ensuring the startup success rate of the SJX61-1 scramjet engine.
However, although this method has the least risk, it does not leave any room for opportunism.
Extensive numerical calculations and wind tunnel testing are required to ensure the aerodynamic and structural balance after modification.
The problem is that in NASA’s hypersonic wind tunnel, only the gas flow rate meets the requirements, and the total air flow temperature and duration of a single test are not enough to fully restore the actual hypersonic flight conditions.
Judging from the current situation, I am afraid that it will not be able to meet the new requirements imposed by the above.
Just listen to Charlie Brinker’s advice.
The other party is almost 20 years younger than Collinger and is a rising star who only entered the hypersonics project in 2001.
Similar to many researchers of the same age, there is still a gap between the basic skills and the older generation, but the advantage is that the thinking is more flexible.
The superiors originally appointed Brinker as Collinger's deputy, and they also had the idea of learning from each other's strengths and weaknesses.
The former was obviously well prepared, and replied almost without thinking:
“The time given above is very tight, and it will definitely be too late to temporarily modify the aerodynamic and structural design of the waverider-like body. And if the boost section is simply extended, , firstly, it will also increase the weight, which may not be able to obtain sufficient benefits. Secondly, it will also need to rewrite the flight control system, which is equivalent to dragging a It moves the whole body.”
“So, a simpler and more effective way is to directly modify the boost section to obtain stronger propulsion performance while maintaining the same volume and weight distribution to ensure that during the boost process. The speed at the end of the push phase can meet the starting requirements of the scramjet engine.”
This idea is indeed simple.
As the saying goes, bricks fly with great strength.
It is also very consistent with Boeing’s excellent tradition.
However, Collinger’s frown did not relax at all:
“According to my experience, simplicity in engineering usually means complexity in technology.”
He said in the tone of someone who has experienced it:
"Although the design indicators of the X51A are radical, most of the project's technologies have actually undergone different forms of technical verification in the past. What really determines success or failure is this power system composed of a solid rocket-scramjet engine. .”
"In order to meet the thrust and working time requirements under hypersonic conditions, SJX61-1 has been set to a very extreme working boundary. The reason why the power section of ATACM was selected as the booster was also out of prudent considerations. If it is rashly used now Improvement, that accumulation The risk of rising..."
In fact, in addition to the above concerns, Collinger has another reason that has not been stated clearly -
Like most colleagues engaged in aircraft design, he Research in the field of aerodynamics is not very deep.
The scramjet engine, including the X51A, is also developed and produced by Pratt & Whitney.
But this was decided upon when the project was first established. It is a single project contractor and has the same status as Boeing. The two parties are in a cooperative relationship recognized by Party A.
Because the boost section was borrowed, as an integral part of the aircraft, it was handed over to Collinger's technical team for integration.
It’s integration, not R&D.
Now that the project is halfway through, it is simply not feasible to overturn the contract and add another individual project contractor.
So if you want to make a fuss about solid rockets, you can only take the path of subcontracting layer by layer.
Ke Lin's style is old-school, and he really doesn't like the feeling of losing control at any time.
What's more important is that if something goes wrong with this kind of subcontracted work, he, the second party in the contract, will have to take the blame.
However, Brinker was very positive about this matter and was not discouraged at all by Collinger's hesitation:
"Mr. Supervisor, according to our previous test results on the boost section It seems that because the ATACM power section adopts a larger filling ratio, the actual effective working time can even be extended to more than 40 seconds.”
While talking, He even took out a printed test result from nowhere, obviously prepared: "It's just that at the end of the working period of the solid rocket motor, there will be strong and irregular phenomena in the combustion chamber. pressure oscillations, accompanied by an increase in average air pressure... In order to avoid this unstable working curve, we limited the working time of the boost phase to 29 seconds.”
This test was a task that Collinger personally assigned a few months ago, and he still has an impression of it, so he quickly caught the other person’s meaning:
“You mean to extend the working hours of the boost phase? ”
cloth Link nodded and was about to speak when he heard the other party change the topic again:
"No... no way." Collinger pointed to the pressure rise curve after 30 seconds on the picture:< br>
"After 30 seconds, although the boost stage still seems to be working normally, the coupling of the fluctuating heat release rate and pressure oscillation during propellant combustion may have a gain effect on the air pressure amplitude."
" Army Tactics I have seen the design of the missile. The structure is relatively simple and the skin is rough and fleshy. It is not sensitive to this kind of shock. However, the speed of the X51A is too fast and the structural redundancy is relatively small. It is very likely that the engine will deviate from the design state or even disintegrate... "
But Brink seized this opportunity and rarely jumped in directly:
"But supervisor, if there is a way to ensure that the solid rocket motor can be launched within 30-40 seconds, Continue to burn steadily...or should there be only a certain pressure oscillation without an increase in average air pressure?"
Collinger was not angry at being interrupted, but looked surprised:< br>
"Ah?"
Then he looked at the deputy with a suspicious look:
"I know that you conducted solid rocket-related research for a period of time before joining the company. , but the unstable combustion phenomenon of double-base propellants has not been solved for decades. To overcome all the problems, your words are just to extend the stable working time by one-third..."
He was still guessing in his mind just now, thinking that Brink might suggest that he add high-energy to the composite propellant. Oxidizers, such as RDX or Octogen, increase the energy of the propellant.
But I never expected that it would be this kind of plan.
Of course, having said that, extending the working time of the boost phase does have the least impact on the overall design of the X51A... It can even be said that there is almost no obvious impact.
The extra workload extended is just to modify a few small modules in the flight control involved in scramjet engine startup.
It can be done in a few dozen working hours at most.
Seeing that Collinger was still questioning his integrity but his attitude had obviously changed, Brink quickly gathered strength and took out a new page of charts:
Supervisor, please see, according to the current calculation results, the boost stage works for 29 seconds, which can already accelerate the flying body to Around Mach 4.9, then if we can extend it by another 10 seconds, we will definitely be able to reach the separation speed of Mach 5.4-5.5... And we don't even need to recalibrate this engine. We only need to set a trigger gate to detect that the speed exceeds Mach 5.5. Then automatically throw away the boost section! ”
Having said this, he flicked the edge of the paper in his hand and made a crisp "pop-" sound.
The former had no other options at the moment. His expression changed from gloomy to bright for a long time, and finally he gave in helplessly:
“What about the specific technical plan?”
It’s over. At this point, Brink knows that although the matter has not yet received final approval, it can be said to be a certainty.
“This technology was developed by Dr. Mellie Hurst of the Massachusetts Institute of Technology. You may need to contact the other party for specific circumstances.”
He replied:
“In general, it is to introduce metal into the traditional AP/HTPB dual-base solid propellant...or more specifically, an aluminum oxide nanoparticle catalyst to optimize both The combustion rate ratio between solid fuel particles is improved, and the linearization level of propellant surface thermal feedback and combustion rate is improved."
This explanation is quite reasonable and has eliminated Collinger's concerns. Seven or eight.
As for the more specific content, as Brink said just now, it must be discussed in detail with the technical personnel actually responsible for the research.
"Okay..."
Collinger finally relented:
"How should we contact Dr. Hester?"
"I have her business card here..."
Brink took out his wallet. He took out a beautifully printed small card from inside:
“But in the final analysis, they still take advantage of this kind of thing, so I will ask the other party to contact us proactively and send more detailed technical information at the same time. Come here.”
Similar to the situation in all other industries, subcontracting must be the grandson of the general contractor.
Ke Linjie doesn't like to engage in subcontracting, but that doesn't mean he doesn't understand the twists and turns involved, so he just casually took the business card and glanced at it:
"Ask them to do it as soon as possible, By the way, contact the legal department, regarding the subcontract..."
He originally wanted to try to share some risks through the subcontract.
If something happens, you can’t let yourself bear the blame alone.
But just in the middle of the sentence, he stared at the business card in his hand and froze.
After hesitating for a moment, he still expressed his thoughts:
"This Dr. Hester... seems to be much younger than I thought..."
Then he quickly added:
“Of course I’m not saying that a young lady cannot achieve outstanding research results, but she looks like she just graduated from a bachelor’s degree...”
Halfway through, Collinger raised his head and looked at Brink:
"I remember that all your degrees were completed at Cornell University. Why do you know someone from MIT who is not a very good person?" A famous doctor?"
The latter obviously did not expect to be asked this kind of question, and a look of confusion flashed on his face.
Logically speaking, this is a private topic and you don’t need to answer it at all.
But after all, it is related to the project, so I still explained:
"My supervisor during the doctoral stage later moved to MIT, so this... can be regarded as my junior sister to a certain extent. This research topic including this new composite propellant was also shared with me by my supervisor some time ago."
This explanation was reasonable and logical, and Collinger stopped dwelling on these details. He just put the business card in his pocket:
"I hope to meet with her within a week... preferably with your tutor. Some things are difficult to explain clearly through phone calls and emails."
"Okay, I'll contact you right away!"
(End of this chapter)