"Hmm, I see what you mean."

The plane has just returned from a supersonic test in the stratosphere. Part of the canopy was altered by the heat.

"...... diamonds were vulnerable to heat, right?"

Diamonds, which are crystals of carbon, are said to transform at about 600 degrees Celsius and burn at about 800 degrees Celsius.

It was thought that the high temperature was probably caused by the adiabatic compression of air due to supersonic speed.

"...... to turn it into aluminum oxide?"

Mineral name is corundum, same as ruby and sapphire. With a Mohs hardness of 9, it is said to be the second hardest material after diamond, but in fact there are man-made materials that are a little harder.

Nevertheless, among the transparent materials available today, this is the best when it comes to hardness, heat resistance, and chemical stability.

Cubic zirconia is also hard, with a Mohs hardness of 8 to 8.5, but it is one step behind ruby. However, zirconia has a higher melting point and boiling point.

However. Corundum can be synthesized from aluminum oxide Al2O3, but cubic zirconia is made by adding yttrium, calcium, magnesium, hafnium, etc. to zirconia, Cubic zirconia is made by adding 4 to 15% of yttrium, calcium, magnesium, hafnium, etc. to zirconia, so it is very difficult to synthesize.

Therefore, the material imported from the is used.

"We should change the outer layer of the three layers to corundum."

Jin rushed to improve it.

And one more thing.

"Father, this is not a defect..."

Is there something wrong?

"Yes. Before we climbed into the stratosphere, there were clouds forming at both ends of the wings."

"What ......?"

Jin thought it might be a trailing vortex, or wingtip vortex.

It is a vortex created by the air that goes around from the lower surface of the wing to the upper surface.

(It's a plane that flies with a force field generator. ......)

(It is a plane that flies with a force generator. ) It is a plane that was built without any wind tunnel tests. It is not surprising that such a thing could happen.

Jin thought it would be better to keep it in mind, though it would not be an immediate problem since it does not rely on the lift force generated by the wings.

"Okay. Then please test me again."

"Yes, sir."

Jin looked over at the aircraft as it took off again,

"......700672... ...or maybe we should use corundum instead of diamonds for the dome..."

Leaving aside whether or not there is a concern about fire ......, now that we have noticed that it is not heat resistant, we feel bad about leaving it alone.

So, Jin had 50 craftsmen (Smith) help him to replace the material of the dome while Reiko and Hope were conducting the test flight.

In addition, the inside of the dome was coated with a subterranean spider resin (GSP) in case it cracked. This is a measure that even the had not taken.

"You are a worrier, Jin-dono," said .

The 700672 said to me,

"It is said that you should take care of yourself before you fall," he replied.

He replied,

"I see. So that's your belief, Jin-dono.

The laughed and agreed.

Meanwhile, Hope and Reiko had completed all the tests without any problems this time.

* * * * *

After the test flight by Hope and Reiko, it was time for Jin to get on board.

"Father, how would you like to name it?"

"Well, I don't know."

This was not Jin's favorite naming question.

After thinking about it for a while,

"Okay, let's name him Sparrow.

Jin decided to name him Sparrow because he was small.

Jin engraved the name <> on the dull silver-colored fuselage.

"That's it. Let's go!"

< in that order.

Hope is in the pilot's seat, first in line.

Jin and Reiko are in the back. The pilot's seat is about 30 centimeters higher than the cockpit, so visibility is good.

The lower part of the cockpit is also made of transparent material to ensure a clear view.

The rearward blind spots are projected on a special magic screen, so that even if Jin is a human being, Hope and Reiko can instantly see almost the whole area with their reaction speed.

"Now, let's go!"

Hope announces, and the VTOL < lifts off the ground.

Jin's new craft, <>, is now flying freely in the skies of Hale, with Hope at the controls.

"The new acceleration pressure absorber is working well, isn't it?"

Jin nodded in satisfaction.

This is a mechanism that synchronizes the <> and the > to generate gravity in the aircraft in the same direction as the acceleration, but in the opposite direction.

Thanks to this mechanism, the occupants do not feel anything even if they accelerate at 10G. In addition, normal gravity is applied to the cabin, so the passengers can spend a comfortable time.

...... and so far it has been used before. What Jin has introduced this time is an additional <-like device.

It absorbs acceleration pressures above 0.5G (the upper limit is adjustable between 0G and 1G).

Thanks to this device, Gs during ascent, descent, acceleration, deceleration, turn and roll can be sensed without any physical burden to the body.

Incidentally, the acceleration G of a passenger plane is said to be 0.2 to 0.3G.

A roller coaster ride is said to accelerate at 3G to 5G.

"Oh, I feel like I'm flying.

Jin had ridden roller coasters in modern Japan a few times. The roller coaster ride at that time would have taken about 3G, so 0.5G would not be a problem at all.

I was Jin, who gave instructions to Hope to fly in an acrobatic manner and enjoyed the ride.

"The maximum normal speed in the atmosphere is still Mach 3. ......"

The limit of the wind shield is at that level, so any higher speed would generate a shock wave and cause trouble to the surroundings.

"Well, considering the application, this is about right, isn't it?"

And Jin said,

"Okay, that's enough. Let's go back."

Jin gave the order to return.

* * * *

"You didn't think about the hangar at ......."

The VTOL aircraft can take off and land from anywhere, but the area around the <> has been groomed as a garden.

It was built in an underground workshop, which is now connected to the ground by a ramp.

"......700672... .......or if there is a rock wall like at 's place, it would have been cool to launch from there......."

Jin thinks to himself.

"I guess we should build a hangar ...... or garage on the ground and launch from there.

Jin decides to build a garage in the yard like a country house and launch the car from there.

As expected, he decided not to make it look like a <.

So Jin decides to build a garage-like structure.

Ten <> helped him and it was completed in an hour.

Walls made of concrete blocks, steel shutters, and a concrete roof.

The garage turned out exactly as Jin had envisioned.

Of course, the materials are not as they appear, but everything has been to increase strength and prevent deterioration due to ultraviolet rays and the like.

Yes, that's good.

The garage is wide enough to fit three cars. < is 5 meters.

The floor inside is an elevator that leads directly to the underground hangar and workshop.

"It looks like the <>'s house is almost ready, maybe we should invite Marikka and Zion."

Jin thinks about inviting some important people from the <> who have close ties to the planet Hale.

"In that case, why don't we invite Belialus ......?"

Jin was a little excited and a little worried about how Belialus would react to seeing his sister Archelle's rouge as it was in her youth, something he had thought about a little before.