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Chapter 1823: Tell the truth

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    Laymen watch the excitement, while experts watch the way. When Qin Baoshan said this sentence, Cochrane was immediately surprised.  She never thought that Qin Baoshan would actually raise this question.  For this huge bomber, the problem of engine overheating has always existed.

    In order to achieve a take-off weight of more than 60 tons, the b-29 bomber deliberately uses four engines, and each engine is very powerful.  In fact, such an engine consists of two radial engines connected in series.  The front nine cylinders form a star shape, and the rear cylinder forms a star shape.  In this way, the two engines are combined to achieve a power output of more than 2,000 horsepower, but this also brings another problem.

    The engine has two ways of water cooling and air cooling.  This kind of radial engine is an air-cooled engine. When there were a row of cylinders in the past, there was no heat dissipation problem.  Because the oncoming airflow can directly cool down the engine, but now this kind of double-row star-shaped cylinders, the working environment of the rear row of engines is very harsh.  Not only can it not receive fresh air, but it is also affected by the heat of the front exhaust cylinder, so the temperature of the rear exhaust cylinder is higher.

    Throughout the b-29's service life, pilots have struggled with engine overheating.  It's not just overheating. Once the gasoline engine overheats, it will catch fire.  Due to the high altitude of the b-29 bomber, it is difficult to be intercepted and shot down by the enemy.  During its initial service life, pilots were not worried about interception by enemy fighter jets, but overheated engines.

    Of course, at the very beginning, the problem of engine overheating has been highlighted.  As a test pilot for the plane, Cochran even experienced it once.  It's just that she didn't expect that Qin Baoshan would reveal a defect of this aircraft engine with just one glance.

    Did he just say it casually, or did he have research on these?  Cochran couldn't help asking: "How can this kind of aircraft engine overheat? Its heat sink area is very large, which is enough to meet the needs. Have you seen other problems?"

    Whether the heat dissipation of an air-cooled engine is sufficient depends on how large its heat sink area is.  It's the same as looking at the size of the water tank for a water-cooled engine.  When this engine was designed, the possibility of overheating had been considered, and the area of ??the heat sink was deliberately increased.  Specifically, the total fin area for the 18 cylinders is 5,850 square feet, or 3,900 square inches per cylinder.  You know, in this day and age, the cooling fins per cylinder of an ordinary aircraft engine are only 3,100 square inches.

    The cooling area has been increased a lot, it should be enough.  But in fact, we still often face the problem of engine overheating, especially when the speed of the aircraft is not enough, that is to say, after taking off from the runway, during the process of slowly climbing to the sky, the problem of engine overheating will appear from time to time.

    Cochran's questioning was like Qin Baoshan's exam, and Qin Baoshan didn't think it was disobedient.  Now that it is here, and since I have met this big guy, I hope it can mature quickly. Only after it matures can it be used on the front line, especially if this thing is going to be used in the base of the Eighth Route Army.  Now Qin Baoshan looked at this big guy, and was already thinking about how to get this thing into his own hands.  Let it mature quickly, so Qin Baoshan doesn't need to hide it.

    So Qin Baoshan pointed to the exposed engine and said to Cochran: "It has two cylinders at the front and rear, so the heat dissipation of the rear cylinders must not be in place. Especially the front cylinders are exhausted forward. This way the exhaust pipe  You have to circle around to get to the back. This circle of exhaust pipes increases the heat inside the engine."

    How to arrange the exhaust pipe depends on the direction of the exhaust valve of the engine.  In terms of this design, the engine in front of me is a wonderful thing.  Its front cylinder exhaust valve is at the front, which means that the exhaust manifold has to be at the front, but the aircraft eventually ejects exhaust backwards.  In this way, the exhaust pipe has to go around in a circle, and then go around to the back.  Moreover, this engine needs to reduce the windward area as much as possible, so the exhaust pipe is tightly wound, and it is attached to the heat sink of the engine, so that the heat emitted by it simply adds heat to the entire engine compartment.  I really don't know what the famous engine designer Wright thinks, is it just to facilitate the arrangement of the exhaust collection pipe of the exhaust gas turbine?

    Qin Baoshan said seriously: "First of all, the exhaust valve must be changed. If it is changed to the back, the exhaust pipe does not need to go around like this."

    What Qin Baoshan said made Cochrane's eyes widen in disbelief.  Originally, Cochrane thought that Major Cromlin was exaggerating when he mentioned Qin Baoshan.  But now, after hearing Qin Baoshan's analysis, she was overwhelmed with admiration.

    The problem of engine overheating has always plagued Americans.  Designer Wright is not an idiot either.?? noticed this problem, so he has improved the exhaust pipe, which is improved in the way Qin Baoshan said, but the plane they are flying now has not been modified, and the old engine is still used.

    Cochrane opened his eyes wide, looked at Qin Baoshan adoringly, and said: "After this improvement, will the problem of engine overheating be solved?"

    Qin Baoshan shook his head: "Of course not, there are still many problems."

    Hearing him say this, Cochran was a little strange.  The designer Wright has designed an engine with the front exhaust cylinders exhausting backwards, and he is very satisfied with this, and feels that the problem has been solved perfectly.  But Qin Baoshan said that there are still many problems.

    "Any more questions?" Cochran asked.

    "Another problem is that there is also a problem with the intake manifold of the front and rear cylinders." Qin Baoshan pointed to the above structure and began to analyze it.

    The intake manifold is behind the impeller of the supercharger, so it is bent down, which leads to a new result: the intake air flow of the front cylinders is not smooth, so the air inhaled by the front cylinders is insufficient, and the front and rear  The rows are designed according to the same flow rate. Now the air sucked in is different, which will cause the engine to do different work, which will lead to overheating.

    During the intake stroke of the gasoline engine, the gas mixed with gasoline is already sucked in, which is also the basic principle of the gasoline engine.  So it is not easy to change this thing.

    Hearing Qin Baoshan's analysis, Cochran frowned, and solemnly said to Qin Baoshan: "Then how to solve this problem?"

    This is a problem with the pipeline design, but it is impossible to change the design, otherwise, it is nothing like redesigning an engine, the difference will affect the whole body.

    Hearing Cochrane's question, Qin Baoshan said: "It is very simple to solve it. Just change the fuel supply method from single-point injection to direct injection in the cylinder." (Remember the website website: www  .hlnovel.com
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