In this way, the development of the fuselage has reached a stalemate, but Hu Jun is going exceptionally smoothly. The pen "Fun" Pavilion www.biquge.info successfully built a new 9-cylinder engine, but Hu Jun also knew that the piston engine needed to rely on the compression of the cylinder to increase the pressure of the gas. There is no compression section before the air enters the cylinder to improve the intake air?? The pressure, so when the altitude of the aircraft increases, the pressure of the gas entering the cylinder?? The force will go down, and the compression ratio of the cylinder is constant, and the result is to provide combustion. The gas pressure will decrease, resulting in a decrease in combustion efficiency and horsepower output. Then it came down. Once at an altitude of 4,000 to 5,000 meters, what is the output of the engine? There will be a considerable drop.?? So Hu Jun came up with the idea of adding a supercharger to the engine, and with the help of teachers and students from Northeastern University, Hu Jun successfully added a supercharger to his engine. However, in order to save materials and facilitate processing, after repeated trade-offs, the turbocharging scheme that was popular in later generations was excluded for them. The turbocharging device is to introduce the exhaust gas of the piston engine up to 600-700 degrees Celsius into the turbine, and then there is a turbo drive compression device to compress the air, but the engine equipped with a turbocharger will rise a lot after compressing the air, so that the density of the air decreases, resulting in poor compression efficiency, so it is necessary to install a middle cooler between the turbocharger and the throttle valve to reduce the air temperature and prevent the compression efficiency from decreasing. The structure of the intercooler is similar to that of the radiator. The cooled air temperature decreases and the density increases, further improving the supercharger's supercharging effect. This mid-section cooler will increase the weight of the aircraft and the complexity of the engine, resulting in the improvement of the engine process requirements, which is not conducive to large-scale production, so they use the traditional mechanical supercharging device, increase the engine air intake and increase the engine power by using the engine spindle to drive the compressor blades, so that there is no need to add an additional turbine device, a set of blades can be saved, the technical threshold of this supercharging device is low, the structure is compact, although it is small at a certain height, the effect will become very unsatisfactory, But it is also enough for Jiang Tao's current needs.

"I said, we can spray a mixture of water and methanol into the engine, and this will increase the power of the engine immediately." A chemistry student suggested. Although the calorific value of methanol is only about 45% of that of gasoline, it has a high octane number and excellent anti-knock performance, which can win greater battlefield initiative at the moment of life and death.

However, after this set of devices and the engine, a huge problem was discovered. While methanol can increase engine power, it can also swell rubber and corrode it, undermining reliability in precision components. In addition to damage to rubber parts, methanol also has a corrosive effect on fuel tanks, lead-tin plating of oil circuits, and welded steel pipes, copper, zinc, aluminum, and alloys, which can lead to rapid damage to combat equipment.

After repeated discussions, this set of methanol afterburner devices was also shelved, and in Jiang Tao's eyes, it was a crime to hand over the aircraft that would have problems at any time to a pilot to use.

At this time, a mechanical student gave Jiang Tao a brilliant proposal - to adopt a variable pitch propeller. What was popular in this era was fixed-pitch propellers. This type of paddle is a bit simple, that is, it is easy to process, low cost and reliable. Generally speaking, fixed-pitch propellers are divided into two categories: climbing propellers and cruise propellers, and the climbing propellers have a small pitch (relatively flat), so the drag is less, the engine speed is higher and produces more thrust, so it is inevitable that the acceleration and climbing performance of the aircraft is better. The cruising propeller pitch is large and the resistance is large, but the speed is low and the power is small, which can save a lot of fuel in the cruise. However, the inability to change the pitch distance of the fixed pitch propeller is a flaw. Often, only aircraft with less engine power and those that are too old will be equipped with such paddles.

Now, the teachers and students of Tohoku University plan to combine the advantages of these two types of propellers and develop a propeller that can adjust the pitch. In the take-off and low-altitude and low-speed sections, the air density is large, and the blade inclination angle is small, which reduces the rotational resistance, and in the high-altitude section, the air density is small, and the blade angle becomes larger, providing sufficient power for the aircraft.

However, when the prototype of the aircraft was processed, everyone realized that theoretical things are always theoretical, and it was only when they were actually built that they found that this all-metal aircraft still had great shortcomings. Because the all-metal aircraft has greatly increased its weight, the power required is greater, and the engine transformed by Hu Jun has reached 800 horsepower, surpassing the R-1340 Wasp engine and R-1690 Hornet engine of the famous Pratt & Whitney Company in the United States (the current series, with greater horsepower in the later period), as well as the regular series of BMW 132 developed by the German BMW company. Arguably the best-performing 9-cylinder star engine at the moment. However, for an all-metal aircraft equipped with four 12.7 mm machine guns, this horsepower can only make his level flight speed fixed at about 430 kilometers per hour, which is somewhat insufficient for the Japanese Air Force, which has always advocated high speed, although the plane can maintain its speed at a higher altitude without dropping through the pressurization device, but the Japanese are not fools, knowing that their aircraft has superior performance at low altitudes, and will not attack the enemy's strengths with their own shortcomings.

It seems that the only way to reduce the weight of the aircraft is to know that the empty weight of this aircraft is more than two tons when it is not equipped with weapons, and the type of fighter used by Japan in World War II is only 1.5 tons in the air.

"Mr. Feng, you're right, we're still a little too fast to make all metals now." Jiang Tao bowed his head to Feng Jintang, but Feng Jintang shook his head, "No, you're wrong, our all-metal is feasible, the key is that we can adopt the idea of key protection, and reduce the armor of some non-critical parts, if you really want to pursue high speed, we can change the back half of the fuselage to wooden materials, and add metal protection, you must know that the advantage of metal is that the overload resistance of the fuselage is better at high speed, and our current speed is as long as the key components are made of metal." Feng Zhanhai dotted Jiang Tao.

"But isn't the protection of an all-metal aircraft better?" Jiang Tao was a little entangled, but he was still more concerned about the safety of the pilot.

Feng Jintang laughed when he heard this, "You expect that thin layer of metal to block bullets, we mainly rely on those additional armor to increase defense, you remove the armor, this defense is not much different from wood." ”

"You're please, let's just change some unimportant parts of the fuselage to wood."

"If you can figure it out, it's up to me."

Feng Jintang two weeks, Feng Jintang got the improved fuselage out, after some transformation, the weight of the fuselage dropped to less than two tons, Feng Jintang also improved the fairing, so that the drag of the fuselage became smaller, and finally let the speed of the aircraft under the condition of dive can reach 500 kilometers per hour. The 4-door 12.7mm on either side of the wing also provided the aircraft with indestructible firepower, and it can be said that it was about to be a nightmare for Japanese pilots. His code name is "Falcon".