Earth Afire (The First Formic War 2)

"What are they?" asked Patu.

"We call them self-propelled drill sledges, but they're tactical earth burrowers. Quite extraordinary, aren't they?"

That was putting it lightly, thought Mazer. The HERC might revolutionize flight, but the drill sledge revolutionized warfare, introducing an entirely new landscape to the battlefield. He immediately understood why the Chinese wanted the HERCs. The HERC could carry the sledges behind enemy lines, drop them off, and leave them to their digging. The two vehicles made the perfect assault team.

"What's their range?" asked Mazer.

"Only ten kilometers," said Shenzu. "But we're hoping to improve that."

Ten kilometers. That was more than Mazer would have suspected. "Are they weaponized?"

Shenzu laughed. "We'll have plenty of time for questions later. Come. I'd like you to see them up close."

They descended the valley and approached the nearest drill sledge. The entire cockpit was now encased in a thin layer of frost.

"It's cold," said Reinhardt, touching the surface.

"We keep the cockpit as cold as possible," said Shenzu. "We have to. Otherwise the pilot would be cremated, as in burned to ashes, bones and all."

There was a cracking sound as ice broke away from where the cockpit hatch sealed against the sledge's roof. The hatch opened, and a pilot climbed out and waved. He wore a helmet with a wide visor and lights on the top and sides. Mazer could see a hint of frost around the visor's edges as the pilot nimbly climbed down from the sledge. His thin body suit was lined with small coils that ran up and down his body and around his appendages like a continuous nest of very thin snakes. Every part of him, head to toe, wafted cool mist like a hunk of meat pulled straight from the freezer.

"It's called a 'cool-suit,'" said Shenzu. "The drill sledges work like an earthworm. Whatever it digs through in the front, be it clay or rock or whatever, is ejected out the back. The propulsion doesn't come from the biting action at the front. It actually comes from the backward ejection of the superheated debris."

Off to the side, a team of Chinese soldiers was putting out the fire on the felled tree and spraying the other mounds of spew with canisters of compressed chemicals, sending hissing clouds of steam into the air.

"When the sledge is moving fast through solid stone, it spews back lava," said Shenzu. "You don't want to follow one when that happens."

"How does it handle such lava-hot ejecta?" asked Mazer. "Seems like the spew would burn through any piping system."

"Very observant," said Shenzu. "That was one of the most difficult challenges. It's like the problem of the universal solvent: What do you store it in?" He pointed to the rear of the drill bit. "A series of internal tubes begins here at the nose and extends back to the spew end. The tubes are continuously water cooled. Each is wrapped in a network of thin water pipes that are pumped from a refrigeration unit at the rear of the sledge.

"But even with the cooling system, the entire cockpit is superheated when the sledge is chewing rock. That's why we have the cool-suits. We keep the cockpit as cold as possible because when you hit rock and go into hyperfast mode, the heat produced is incredible, well above boiling temperature. The suits kick in to cool the body and counter the heat. Then, when the sledge slows down, and the heat descends, the cockpit has excess cooling and the temperature drops to freezing. At that point the cool-suit reverses its process and channels warmth to the body."

"Sounds like a temperature roller coaster for the pilot," said Fatani.

"It takes some getting used to," admitted Shenzu. "Sweltering heat one moment, teeth-chattering cold the next."

"I've been doing this for months," said the pilot, "and I'm still n

ot used to it. But it's a such a ride, I'd dig all day if they'd let me."

"You said it had hyperfast mode?" asked Mazer.

"Speed is relative," said Shenzu. "We consider it fast for a drill sledge."

"How fast?" asked Mazer.

"We've topped them out at twenty-four kilometers per hour."

"Through rock?" Mazer was stunned.

"Oh yes. When it's gophering along, going normal speed, it runs about half that. But if you hit rock and punch it, if you go hot, she burns a hole through the ground."

"So rock is faster?" asked Patu.

"More propulsion," said Shenzu.

"What about communication?" asked Fatani. "Radio doesn't go through dirt."