5.

The control tower lobby was completely silent. Outside, however, the wind seemed to be picking up force.
Martine pointed at one of the screens on the console as a photo of the pilot came into focus.
In place of the name and badge number, though, was a single word in white lettering on a red background: CONFIDENTIAL.
"That's not going to help much," said the young woman.
"At least we know for sure he's a SAFRAN employee," Yann replied.
Calmotte folded his arms, saying: "I didn't think SAFRAN had its own pilots any more…"
Yann grabbed an armchair and started to roll it towards the door, signaling to his boss to get another one and follow him.
"Everything points to this being an experimental flight, so it's probably very recent. And very special too. It's got to be some kind of partnership, for a prototype."
Yann spoke as rolled the chair down a hallway that stretched a few dozen meters, followed by Franck Calmotte with a second chair, with Martine at his heels.
"A prototype of what?" Calmotte wanted to know. "I'm not an aviation expert, but even I know that the plane out there is a Falcon."
Yann shook his head: "It's not the plane, at least not the visible part. It's what's inside. I saw a lot of stuff in there made by SAFRAN and its subsidiaries. But what was most surprising—and I'm not saying I'm an expert or anything, but still—was the engine noise."
"The noise?", repeated Martine and Calmotte in unison.
"Didn't you notice how quiet the Falcon was for a plane with that much power?"
They continued down the hallway, passing offices where they could hear snippets of phone conversations or fingers clicking away on keyboards.
"Well I definitely noticed it. That jet whine you usually hear was a lot softer, not as piercing. And I think I know why…"
"So tell us, you know I don't like riddles!" Calmotte shot back.
"Thermostructural composites."
Martine and Franck Calmotte glanced at one another, somewhat reassured to see the same blank look on the other's face.
Calmotte made no effort to mask his irony: "You think you could explain a little for us non-Einsteins…?"
Yann stopped to open the door to the infirmary and rolled the two chairs inside.
"It means composite materials, with a matrix and a reinforcement, that stand up to high temperatures. In this case it means materials that react to heat. And here I think we're talking about self-healing ceramic matrices. So they're already in operation…" mused Yann, clearly fascinated.
Calmotte cut him short. "Come on Yann. Just tell us in simple terms what you're talking about."
"Right. You do know that they make the hot turbine sections of airplane engines out of metal alloys, right? But what they'd really like to use is ceramics. Metals are wonderful insofar as all the atoms share their electrons, which means that if there's too much local stress between any two given atoms at one point, the others share it to avoid any cracks. But metal is heavy, and only stands up to relatively low temperatures. Ceramics, on the other hand, are what is know as ‘refractory', meaning they can withstand much higher temperatures. Not to mention they're twice as light as alloys. But—and this is a very big ‘but'—they have a much more fragile microstructure, formed by the combination of electrons from only two atoms. So if the stress exceeds the strength of the iono-covalent bond, the structure breaks. No material on earth is absolutely perfect, everything's got cracks in it. In this case they're microcracks that spread until the ceramic breaks."
Yann lifted the pilot under the shoulders and Calmotte took his feet. Together they hoisted him on to one of the beds in the infirmary.
Yann continued: "The self-healing ceramic matrix solves this problem by producing a kind of glass when the temperature gets too high and risks expanding the microcracks. Thanks to the presence of boron in some of the matrix layers, this glass fills in the cracks to strengthen the structure. Result? You get a stronger component and a service life that's at least seven times longer."
"And what does all that mean?" asked Martine.
"Well, imagine an engine in which the metal alloys are replaced with this composite material. It could operate at higher temperatures, meaning greater efficiency and therefore better performance. The engine would be lighter so it would burn less fuel. It would also be more reliable, stronger and in general safer and more economical. In other words, it'd be a miracle!"
He had Calmotte's full attention now.
"And you think that's what the Falcon's engines are made of?"
"That would explain the lower noise, as well as why the plane didn't burn as much fuel as we thought. It would also explain the maneuvers out over the ocean. They were testing it, having a good time with their new toy!"
"But that would mean that this self-healing matrix already exists, wouldn't it?" said Calmotte, still a bit skeptical.
"SAFRAN has been a trailblazer in composites thanks to SPS 1 and its partners. And given the pace at which SAFRAN has been rolling out new technologies in recent years, I think it's entirely feasible that this miracle matrix really is being used today. It might even be what they call the ‘soft' version, a shape memory ceramic material that people were talking about a few years ago. The idea was to make the material soft to give it a predefined shape and let it automatically revert to the initial form if it moved."
Calmotte was fascinated, but noticeably disturbed. "So I just pulled a package of pure high technology down out of the sky?!"
"Looks like that's exactly what you did…"
Calmotte took a long, deep breath and raised his eyes to the ceiling.
They lifted the second man onto another bed while Martine turned to the pilot.
"I think he's starting to come around," she said.
All three moved to his bedside.
"I really want to know why they were both asleep," the director admitted.
The pilot's eyelids fluttered.
Martine filled a paper cup with water from the fountain in the hallway and placed it on the table next to him.
Calmotte spoke first: "How are you feeling?"
The man slowly sat up, took a sip of water and looked at the three people in front of him.
"What happened?" were his first words.
Yann opened his mouth to speak, but couldn't think of where to begin.
"You're a long way from your home base," Calmotte told him. "And I'm afraid it's all my fault."
The pilot raised his eyebrows.
"You…"
Before he could continue, frenetic footsteps rung out as someone ran down the hallway. A young computer operator rushed into the doorway.
"Mr. Calmotte," he blurted, out of breath.
"What is it?"
"Outside… You…you'd better come quickly. We have visitors…!"

1Snecma Propulsion Solide and the specialized LCTS thermostructural composites research lab.

***