I am an industrial worker during the War of Resistance

Chapter 84 A Simple but Practical Wind Tunnel

Everyone agrees on the specifications of this new cannon.

Master Zhang, who was in charge of smelting, casting, and forging, believed that there was no problem with the forging of the cannon barrel.

Forging a 75mm caliber gun barrel is well within the pressure range of a 500-ton forging press.

It can definitely forge through the core of the bar stock.

As for the aluminum-magnesium alloy rims and the casting of various aluminum alloy parts for the cannon.

For Master Zhang, an experienced foundry worker, this was even simpler.

Master Liu from the machinery factory gave an affirmative answer regarding the initial processing of the cannon barrel using a seamless steel pipe rolling mill, as well as the subsequent boring and pinning processes.

He also made a solemn pledge to produce the 75-caliber cannon barrel and the enlarged breech chamber structure.

Ensure that the processing task can be completed.

Master Wu from the precision parts factory also gave his assurance regarding the two core components of the cannon, the retraction piston, on the hydraulic air spring retraction and reset device.

The mechanical and optical sights on this gun were also guaranteed to be reliable.

They are able to meet the technical requirements on the technical drawings.

Director Zhao of the headquarters ordnance factory was in charge of processing the entire gun carriage.

They also consider the processing of high and low speed machines and steering machines to be entirely within their technical scope.

Because the main structure of this gun carriage is basically the same as the main structure of the gun carriage of the Type 1 infantry gun they are currently producing.

The only difference is that the board is thicker and heavier.

There are some differences in the details.

This cannon was designed to expand its firing arc to 15 degrees to the left and right.

Therefore, the single-leg structure of the Schneider M1923 mountain gun was abandoned, and an open double-leg structure was adopted instead.

So if we don't count some details...

The overall structure of this new mountain gun's carriage is basically the same as that of the infantry gun.

When faced with the shells for this new cannon, Director Liu of the ammunition factory sensed that it would be somewhat challenging.

However, he was still confident that he could overcome the manufacturing process of this shell.

As for the pair of three-chambered hollow tires on the cannon's wheels...

The tire manufacturer also believes there is no problem.

They don't need to change the molds; they can simply use the tires of a tricycle and manually glue three rubber partitions together.

As for the inner tube, it's simply made by creating three small air bladders using the same method as making a large inner tube.

This is a very simple thing.

Moreover, Chen Changzai considered the issue of versatility when designing the gun wheel.

Therefore, he chose the 660mm outer diameter rear tire of the tricycle.

They simply replaced its steel rims with aluminum alloy rims.

In this way, in addition to its versatility, the overall center of gravity of this cannon also becomes very suitable.

In addition, it also uses the Z-type adjustable crank arm shaft used on infantry guns.

This makes the cannon more stable when firing and more maneuverable when moving.

The reason these people are so confident is...

One reason is that Chen Changzai had already provided them with all the blueprints.

Chen Changzai also provided them with an outline of the manufacturing process for these items.

They themselves already had a certain foundation for what they needed to produce.

Therefore, this new cannon was not too difficult for them.

No matter how you look at it, it's just a small-caliber, short-barreled cannon.

In terms of manufacturing process and difficulty, it is still far from being as difficult as long-barreled, large-caliber artillery.

At this moment, the leaders of the headquarters' ordnance department, who had been sitting to the side without saying a word, saw the technical leaders or factory directors of the various factories.

They all expressed their opinion that the cannon was technically feasible and that they were fully capable of meeting its technical requirements.

Only then did a smile appear on the leader's face.

Just now, after Chen Changzai finished explaining the data of this cannon...

The two leaders of the headquarters' ordnance department were truly on tenterhooks.

Although they also have some knowledge of military technology.

But frankly, they themselves know that what they know is just the tip of the iceberg.

When facing these technicians in this workshop.

All they knew was that firing the cannon required pulling a fuse.

They truly don't know any more than that.

However, they felt that if this cannon were as powerful as Chen Changzai had described, it would be a disaster.

They were genuinely worried about the technological capabilities of these factories.

This is not to say that they lack ability, but rather that everyone has a different division of labor.

As the leader of the Ordnance Department.

Their main job is not to engage in frontline technical production.

Instead, it is able to fully coordinate the cooperation of various departments.

It is also necessary to ensure the supply of raw materials, personnel transportation, and other logistical support for these military factories.

The complexity of these issues is actually no simpler than the technical problems that frontline technicians face.

Sometimes it's actually more complicated.

They are naturally very pleased that this technical conference has achieved such a good result.

At this point, a leader said, "Since everyone has no objections to this cannon..."

Moreover, everyone is able to meet the technical requirements of this cannon.

So I think everyone should get moving as soon as possible.

We hope to see this cannon in front of us as soon as possible.

It can appear a day sooner.

Then we can use it to fight the Japanese sooner.

The sooner we eliminate the Japanese devils, the less our people will suffer from their ravages.

Therefore, we entrust the technical and production issues here to you all.

After the leader finished speaking, he gave everyone a military salute.

Everyone present returned the salute.

He shouted, "I guarantee I'll complete the mission!"

After lowering his arm, the leader said, "Okay, I believe you can definitely do it."

Director Chen, I have a question, but I'm not sure if I should ask it. Let me clarify first, I don't mean to put any pressure on you.

I just wanted to have a general idea in mind first.

Chen Changzai said with a smile, "Boss, please feel free to ask me any questions you may have."

Of course, we will speak frankly and openly about everything we know.

The leader of the Ordnance Department then said, "Director Chen, I would like to ask when the first prototype of this cannon will be ready."
If it goes into full production.

How many of these cannons can we produce?

Chen Changzai first looked at the people around him, then lowered his head and thought about it for a moment.

He asked everyone, "I think ten days should be enough time for this prototype cannon to be produced, right?"

The most difficult part here is the cannon barrel forging on your side, Master Zhang.

Aluminum-magnesium alloy: the aluminum plant has already produced quite a few aluminum alloy ingots.

Therefore, casting the wheel rim and other aluminum alloy parts on this cannon was not a very difficult task.

The tire factory was in a similar situation; the cannon used a tricycle rear tire, which they could easily modify manually. Master Liu's processing capabilities were also sufficient.

Whether it's the manufacturing of seamless steel pipes, or boring and rifling.

We have made preparations on this side as well.

I think the ordnance factory at headquarters should have no problem with the gun mount; it's basically an enlarged version of an infantry gun.

The precision parts factory also prepared mechanical sights, optical sights, and artillery sights.

The most difficult situation right now is probably with Director Liu of the ammunition factory.

Do you need our support over there?

"No need. Director Chen, those disciples of yours who learned ammunition from you are all carrying the heavy burden on our side."

You have now provided the drawings and production process.

We guarantee that we will be able to produce qualified shells within ten days.

Even if we make molds now, there definitely won't be enough time.

However, we can completely manufacture these shells using machine tools.

Within ten days, we will be able to process fifty of each of the two types of high-explosive shells and shrapnel shells you provided.

And it's delivered with guaranteed quality and quantity.

After listening to what Director Liu said, Chen Changzai said, "That's good, then let's set a time."

In ten days, we will fire this prototype cannon.

After five days of testing, we must find out the faults and shortcomings of this cannon.

If there are no major problems, then we should let this new cannon be temporarily finalized.

In these fifteen days, we must also prepare for the mass production of this new artillery.

Based on our current industrial capacity allocation.

We should be able to produce ten to twelve of these new artillery pieces per month.

What do you think?

These production technology managers and factory directors were all secretly calculating their current production task plans and the space for capacity allocation.

Finally, they all nodded and said, "Yes, that's fine. Our current production schedule is also very tight."

However, there is a 15-day grace period.

It can still be arranged and readjusted.

Now that the prototype production plan has been finalized, everything can proceed step by step according to the plan.

The two leaders from the headquarters' ordnance department also need to return to headquarters and give a detailed report on the situation here.

Before leaving, Zhao Laoge's two veteran gunners asked Chen Changzai if they could take the wooden model from the workshop back with them.

One reason is that it also lets the leaders see what this new cannon looks like.

Another benefit is that it allows the gunners who are testing the cannon, as well as the artillerymen who will be using it in the future, to become familiar with its operation as soon as possible.

Chen Changzai would certainly not object to this.

The first purpose of this wooden model is to allow everyone to see what the cannon looks like at a glance.

The second purpose is to allow the artillerymen who use this cannon to familiarize themselves with its operating procedures.

This model was actually originally prepared for them.

This 1:1 scale cannon model is identical to the real cannon in every way except that it is entirely made of wood.

The breechblock and elevation mechanism are all usable.

When everyone had left and started working on the new cannon.

Chen Changzai is about to start his new job.

This afternoon, he needs to work with Su Zhihong and their entire aviation team to conduct the first wind tunnel test on the wooden airplane model they have made.

The wind tunnel is a very simple and rudimentary low-speed wind tunnel.

It was actually just a long, arched structure built with red bricks and cement, with an inner diameter of 1.6 meters and a height of culvert inside.

At one end of this culvert, there is a large fan with a diameter of 1.5 meters, powered by an electric motor.

The electric motor, through the gearbox, allows this large fan to generate different wind speeds at different rotation speeds.

The wind it blows can simulate wind speeds of 260-280 kilometers per hour.

The model being tested is a biplane trainer with a speed of 180 to 200 kilometers per hour.

So this simple little wind tunnel is enough.

Because of the urgent need, and because this is the most basic level of trainer aircraft, it won't be able to perform any major maneuvers.

Therefore, this wind tunnel is just a straight-tube test section wind tunnel, and the entire wind tunnel is less than four meters long.

There are no contraction or diffusion sections, nothing like that.

The only part of this wind tunnel that looks somewhat decent.

That is, on both sides of the wind tunnel, there are two observation windows made of double-layered laminated tempered glass, and adjustable smoke pipes on both sides that send smoke into the wind tunnel.

Making tempered glass at home can be a bit difficult.

However, it is very simple to make this thing in a precision parts factory that can successfully fire optical lenses.

To put it simply, it involves heating ordinary float glass to 600 to 650 degrees Celsius.

To bring the glass close to its softening point without melting it.

Then blow cold air onto the glass surface to cool it down quickly.

This creates mutual pulling stress inside the glass.

If the glass is subjected to a heavy impact, the internal stress will cause the entire piece of glass to shatter into small pieces.

Adhesive is then sandwiched between the two layers of glass.

Even if the glass breaks, it will be held together by adhesive, reducing the possibility of it shattering and injuring people.

The reason why laminated tempered glass is used for this wind tunnel observation window is because the wind pressure inside the wind tunnel is quite high.

Although it doesn't sound like simulating a wind speed of 260 kilometers per hour is very high.

However, that is only relative to the wind speeds in wind tunnels at Mach 1 in later generations.

In fact, the wind speed in a simulated wind tunnel is very high, reaching 30-60 meters per second.

If we're driving on the highway at 100 kilometers per hour, and you roll down the window and reach out your hand...

You can feel the power of the wind, which is less than half the wind speed inside this low-speed wind tunnel.

Under such wind force, the wind pressure inside the wind tunnel is also very high, and ordinary glass cannot withstand this pressure.

Only this type of laminated tempered glass can be used.

And those two adjustable exhaust pipes that extend into the wind tunnel.

This is the most intuitive way to observe the model inside the wind tunnel.

When blowing the model in the wind tunnel, we want to observe the direction of the airflow on the aircraft model, as well as its effect and interference.

The part of the aircraft you want to see is where eddies are most likely to form.

Where will the wind pressure be high and where will the wind pressure be low? Will this cause turbulence?

Therefore, using the smoke flow method and the silk thread/silk cluster method are the most intuitive methods.

This is also the most commonly used and effective method for wind tunnels in later generations.

The smoke flow method involves heating mineral oil to produce thick white smoke, which is then sent to the front of the airplane model through an adjustable smoke pipe.

Then the strong wind from the fan blows the smoke onto the airplane model.

All that was left was for the staff to observe the flow of the smoke through the observation window.

The direction of these smoke streams is the airflow that the airplane faces during flight.

After the 10:1 scale model of the biplane, with a fuselage length of 0.85 meters, a wingspan of 1.15 meters, and a height of 0.35 meters, was fixed in the wind tunnel.

The wind tunnel experiment is about to begin.

(End of this chapter)