On March 6, after breakfast, a flight test of the <> was conducted using <>.

The remote pilot is Reiko. She was chosen for her reaction time.

The reason why it is not Hope is that the size of the control unit is rather suitable for Reiko.

The location is Tatsumi Bay in Horai Island.

The team is ready for anything.

Jin and Gou are present. Meltze had left Elsa and Amanda in Leuthart.

"Well, I'm off."

Reiko says no and starts the engines of the .

The tail jets spit out a powerful jet of flame.

Using the pier as a runway, the <> starts to run.

It picks up speed and glides about 30 meters before taking off.

"It's flying!

Rubina exclaims.

Reiko keeps the < at an angle of 45 degrees to the ground.

In no time at all, we can no longer follow it with the naked eye.

But don't worry.

There is a large magic screen inside the temporary hut as a temporary monitor.

The image that the old man followed with his "peepers" is being projected on the screen.

"The flight attitude is stable," he said.

"Yes, because it's the sixth delta wing."

Rubina says proudly.

This is the sixth delta wing aircraft that we have built in both model size and actual size.

It was an aircraft in which we had put all of our know-how.

"Yeah, that's what Rubina says," she said.

Right?

Reiko, it's time to test its mobility. ...... is good, right, Rubina?

Of course.　Of course!

Okay.

Reiko then performs the basics, three somersaults in a row, followed by three inverted somersaults in a row.

"That's good. There's not much of a slowdown."

Next, Immelmann turns and split S. < handled these with ease.

Next is an aileron roll from level flight. This was also very stable.

"You look good!"

Rubina looks happy.

"I can see that the top speed is over 400 kilometers per hour."

Considering that it is only one-tenth the speed of the real plane, this is more than enough.

After that, the roll while ascending vertically and the roll while descending vertically were performed without any problems, so Jin gave instructions to Reiko to land the <>.

"Oh, I see it."

The <> returns to Tatsumi Bay.

Reiko lands the Nile VI safely on the pier.

"Come on, let's check the aircraft. Be careful around the ...... engine, it's hot."

"Yes, sir!"

Gough, help him out.

"Yes, sir. ...... Rubina, I'll help you.

Thank you.

With Goh's help, Rubina proceeds with the check.

Jin had one point of concern, but he kept quiet to see if they would notice it.

"...... Rubina, here."

"Huh?"

Goh was the first to notice.

"This is the support rack of the Magi rocket engine, it is slightly weakened.

"What?　That's not ...... true.

"Why is that?"

"...... the only thing I can think of is heat."

Rubina was the first to guess the cause.

"Yes. This engine generates a lot of heat, so we have to consider the heat resistance of the surrounding materials."

Jin confirmed the guess.

"......Oh, my plane was set up based on a ."

"Good, you figured it out."

The light silver and 64LB that make up the fuselage have a very low thermal conductivity among metals. In other words, heat tends to be trapped.

Although 64LB has high heat resistance, when the heat buildup reaches nearly 600 degrees Celsius, <> occurs.

This causes the strength that should have been increased by work hardening to decrease.

To prevent this, either use an annealed material from the beginning, use a material with higher heat resistance, or cool the material so that it does not reach the annealing temperature.

There is more, but it is up to Gough and Rubina to find out.

"Well, Rubina, what would you do?　Goh, let's think about what you would do. You have five minutes."

"What?　Hmm. ......

"Yes, yes. ...... and ......."

The two think about it.

After 5 minutes, Jin asks each of them what they think.

"I'll use a material with high heat resistance. Like adamantite."

"Yeah. What about you, Goh?

"I'll use cooling."

They have different opinions.

Since there is no one right answer, Jin gives his opinion on each decision.

"First of all, Rubina, that method will increase the cost.

"That can't be helped.

Adamantite is generally very expensive. It can be used without concern on Horai Island and Onogoro Island.

"Goh's method makes the engine, and thus the aircraft, much larger."

"That can't be helped."

There are pros and cons, but neither of them is wrong.

By the way, Jin is more in favor of Rubina's way of thinking. He is in a position to use rare materials in abundance.

But of course, it is also possible to make them at <>.

In such a case, Jin says .......

"I would use annealed materials from the beginning.

"Why is that?"

"First of all, taking cost.64 light silver as an example, the strength loss due to annealing is about 40 percent. This means that we can make the support racks 70% stronger to achieve the expected strength even with a 40% reduction in strength. This would eliminate the need for cooling."

Cooling is necessary because it would make it unusable in environments ...... where cooling is not possible, such as when the aircraft has to fly in ...... high temperatures.

"Of course, you need to assume a maximum and minimum temperature in terms of the operating environment. In the case of my <, the operating environment would be from minus 80 degrees Celsius to plus 300 degrees Celsius."

"Where does that temperature come from?"

"Minus 80 degrees Celsius is based on the temperature of dry ice. 300 degrees Celsius is not so reliable.

"Hmmm... ......"

"By the way, the lowest temperature in the Nordic Union is about minus 50 degrees Celsius."

It's cold!

"Yeah, well, that means we should use materials that won't be annealed at 300 degrees Celsius."

"...... got it."

Rubina and Goh thus gained another experience.