The rotor growl faded back to an idling purr and the man in the pilot’s seat lifted a hand to open the sun visor of his flame-decorated helmet. Regarding Stone steadily, he turned the action into a flippant two-finger salute.
Another peculiarity: the pilot’s controls were in the forward cockpit, not in the rear as in a standard Cobra.
As the Marine hunched in under the machine’s whickering blades, the aircraft’s pilot swung back the side-opening canopy. Reaching down into the cockpit, he touched a control that popped open an access panel in the fuselage and Stone stuffed his sea bag into the empty magazine compartment of the internal cannon.
Swinging up onto a hard step on the fuselage, he leaned close to the aviator. “Okay,” he yelled over the rotors, “before I get in this thing, how about telling me what’s goin’ on?”
The aviator with CMDR ARKADY worked into the flames on his helmet’s visor shield looked at him through a penetrating set of blue eyes. “Captain Garrett sends her regards. How’s that suit?”
Quillain slapped the cockpit rail. Now it was all clear. “Ha! I’d say that suits just fine!”
The rear cockpit and the flight helmet waiting in the seat for him were both a tight squeeze, but Stone was willing to accept them.
Within minutes, they had lifted off from the ridgeline and were over the Timor Sea, streaking due west at a meager hundred-foot altitude and hugging the water in a radar-avoidance flight plan.
Quillain had flown aboard any number of aircraft in his life, both fixed and rotor-winged, but never in anything like this one.
For one, it was decidedly faster than any conventional helicopter he had ever seen. For another, it simply didn’t feel right. When they had first lifted off there had been the deep throbbing, all-inclusive vibration of a helicopter – but gradually, as their speed had increased, the vibration had faded. Now they were flying through the sky with the effortless smoothness of a commercial airliner.
“I gotta ask, Commander,” Quillain said into his lip mike finally, “just what the hell is this contraption?”
Arkady chuckled. “It’s a Bell/Piasecki AH/C-1A SPEED Cobra, a compound helicopter.” He twisted in the pilot’s seat and extended a hand back over his shoulder. “By the way, my name’s Vince Arkady.”
Stone reached forward and shook the offered hand. “Stone Quillain. I’ve heard Captain Garrett talk about you plenty.”
“The Lady’s been war dancing about you for the past few days as well. She seems to think
western civilization is doomed to certain extinction if we don’t bring a certain leatherneck into the package.”
Stone digested the statement. He was pleased that Amanda Garrett considered him indispensable, but for what? He decided to tackle things one question at a time.
“Okay, commander. What’s a compound helicopter?”
The aviator laughed again. “It’s the Holy Grail Piasecki Aircraft has been chasing ever since the 1960s.
Another name for the compound helicopter is a convertaplane. It’s a crossbreed of helicopter and airplane that can flip back and forth between
the two flight systems.”
“How d’you mean, sir?”
“As a Marine, you understand the concept of vertical envelopment and you must
know all about the advantages and limitations of helicopters. Right?”
“I know they’re damn handy because they can take off and land vertically,” Stone replied. “But they got issues with speed, survivability and range.”
“Exactly, mostly because of that speed limitation,” Arkady said. “You can’t shove a conventional helicopter through the air faster than about two hundred
miles per hour because of rotor stall.”
“I’ve heard helo drivers talk about that rotor stall business,” Quillain confessed, “but I didn’t know exactly what they were talking about.”
“It’s pretty simple, really,” Arkady replied. “A helicopter’s rotors are essentially its wings, only they generate lift independently of the aircraft’s airspeed by rotating around the transmission hub. Thus, a helo can hover, land and take off vertically and fly sideways and backwards.
“But the rotor blades also interact with the airflow around the helicopter. As
the helicopter accelerates in forward flight, each rotor blade loses a degree
of lift. As it swings aft toward the tail, the rotational velocity and the
airflow of the slipstream cancel each other out. But, as the blade swings
forward again, the rotor velocity and the slipstream enhance each other,
generating more lift. At a certain point, this imbalance becomes critical and
the aircraft pitches out of controlled flight. Generally, you hit the wall at
around two hundred miles per hour.”
Stone glanced out at the wavetops flickering below the SPEED Cobra. “We’re doing way better ’n that now, aren’t we?”
“Yeah, our airspeed is currently about two hundred and sixty and we have another
sixty in the can if we need it.”
“All right, I’ll bite, Commander. How are we doin’ it? What about that rotor stall thing?”
“We are doing it because …” The horizon tumbled as the gunship rotated through an effortless slow roll. “… at the moment, we’re an airplane.”
Quillain grunted and locked a death grip on his seat arms.
“Rotor stall doesn’t apply to us,” Arkady continued cheerfully. “Our rotors are completely unloaded.”
Stone loosened his death grip. “Unloaded?”
“Yeah. They aren’t producing appreciable lift. The cyclic and pitch of the rotors have been
zeroed and locked, and the blades are only rotating to maintain rigidity.”
The horizon pitched over a hundred and eighty degrees as the SPEED Cobra rolled
upside down and remained there. “See? Our wings are loaded now, generating the lift keeping us airborne. We’re controlling with our elevators, ailerons and rudder, and the drive propeller
is pushing us through the air.” The inverted sea and sky swayed as Arkady dipped the wings. “I say again, we’re an airplane.”
Hanging from his shoulder harness, Stone was certain his fingerprints were permanently stamped into the seat arms. “I’ll take your word for it, sir,” he said through gritted teeth.
The horizon snapped over again as they resumed a conventional flight attitude. “Where it gets fun is when we come down out of good cruise,” Arkady went on enthusiastically. “I’ll come back off on our throttle, or rather our ‘Velocity Controller.’”
The Cobra nosed up into a shallow climb. As the airspeed fell away, Stone didn’t detect any change in the sound of the power plant – but he did notice the growing return of a familiar vibration.
“As we fade back past the rotor stall limit, the fly-by-wire flight management system automatically diverts power from the drive propeller to the rotors and starts dialing in blade pitch. The rotors accept load and start to generate a growing percentage of our lift.
“As our speed continues to decrease, the control surfaces go to zero setting and
the rotor cyclic unlocks.” The compound helicopter began to weave sinuously through the air, this time in
response to the tilting of its rotor disk. “And finally a thrust deflector swings out in the propeller duct. It diverts the
blast of the airscrew laterally so it counters the main rotor torque like a
tail rotor. So now, bloop …” The aircraft came to a full hover and whipped around in a fast
three-hundred-and-sixty degree flat spin. “We’re a helicopter again.”
Stone swallowed mightily and straightened in his seat. “Beggin’ your pardon, Commander, but do you happen to know a lunatic helo pilot called
Cobra?”
Arkady looked around his seat back. “Captain Quillain, I personally taught Cobra Richardson everything he knows about insanity.”
