1. Fokker Eindecker

World War I began a little more than a decade after the Wright Brothers' first successful test flight at Kitty Hawk. Aircraft technology advanced at a rapid pace during the war, as engineers worked to build a durable and maneuverable plane, Air Force historian and author Walter Boyne tells PM. Improvements came so fast that no single aircraft could maintain dominance for very long. But for about eight months in late 1915, the German Fokker Eindecker ruled the skies over Europe, so much so that historians call this period the Fokker Scourge. "[The plane] was new and terrifying and caused all kinds of indignation in parliament," Boyne says.

The Eindecker's designer, Anthony Fokker, was Dutch. His technological leap was to synchronize the gears of the propeller and machine gun. Previously, most fighter planes possessed machine guns mounted to the side, so the guns didn't take out their own propeller or hull while firing. But the Fokker could fire right through its propellers, Boyne says, which shocked French and British pilots, who weren't accustomed to another plane attacking them head-on. Fokkers also instilled a psychological terror in ground troops--besides snipers, poison gas and artillery, they now had to worry about death from above.

Eventually, the British and French caught up to the Eindecker's monoplane design, and its reign ended in 1916. But, Boyne says, the Fokker aircraft changed the way military airplanes and their pilots were viewed. "It initiated the lethal aircraft," Boyne says.

2. A6M Zero

At the outset of World War II, Japan naval aviation outpaced that of the United States, according to Jon Parshall, co-author of Shattered Sword: The Untold Story of the Battle of Midway. The Japanese Imperial Navy could deploy devastating dive bomber and torpedo bomber attacks, destroying hopelessly overmatched Allied carriers within minutes, Parshall says. But the true class of the fleet was the Zero fighter, manufactured by Mitsubishi. Despite its reputation for early-war dominance that endures today, he says, the Zero might even be underrated. "You have to give it props, if nothing else, for the shock value that it induced in the Allies," Parshall says.

Put simply, the Zero could fly circles around anything the British or Americans could manufacture early on. Japanese manufacturers sacrificed everything--speed, self-sealing gas tanks and armor--to make the most maneuverable aircraft they possibly could. As a result, Parshall says, the Zero "was really good at dishing it out, but couldn't take a hit." That trade-off was acceptable during the early part of the war, he says, because it fit the offensive-oriented Japanese strategy: Japan had expert pilots who used the Zero's advantages to devastating effect. Allied pilots had to learn fast to avoid Zeroes in dogfights.

Unfortunately for the Japanese, Parshall says, the attrition of war eventually kills even the best pilots. Tactics also changed. Allied pilots learned to fight Zeros above 22,000 ft, where the Japanese plane's maneuverability waned and the superior horsepower of American planes took over. Americans not only created better planes as World War II progressed, they created more of them. Parshall says Japan didn't have the manufacturing capability to keep up. Because workers hand-built many of the Zero parts, assembly line mass production was impossible.

Parshall says that Japan continued to fly Zeroes until 1945, when they had become long outdated. Other World War II fighters deserve mention for their prowess, including British Spitfires and Hurricanes, German Fw-190s and Bf-109s, and American P-51s and P-38s. But in its heyday, Parshall says, nothing could touch the Zero.

3. B-29 Superfortress

World War I and early World War II fighters were fearsome in their day, Boyne says, but compared to what was to come, "all that stuff was just penny ante." The dawn of major destruction from the skies came with the wave of World War II-era bombers, including the German Ju-87s and Ju-88s; Britain's Avro Lancasters which ran nighttime bombing raids over Germany; and the American B-17s and B-24s that ran missions during the day. But none was a match for the B-29, America's first long-range bomber.

Boeing's B-29 entered World War II late. The aircraft began combat service in 1944 as part of Operation Matterhorn, in which B-29s bombed the Japanese mainland from forward bases in China. Each Superfortress could carry six tons of bombs, and scores of them flew together on missions to firebomb Japanese cities. In fact, the death toll from the B-29s' firebombing of cities like Tokyo and Yokohama far outstripped the deaths caused by the aircraft's delivery of atomic bombs to Hiroshima on Aug. 6, 1945, and to Nagasaki three days later. The planes had killed hundreds of thousands by the end of 1945.

B-29s went on to serve in the Korean War before being replaced by newer bombers; they were ultimately discontinued in 1960. But Boyne says the plane's ability to cover long distances--and to carry nuclear weapons--paved the way for those future Cold War bombers.

4. AC-130 Spectre/Spooky

Little more than a decade into the service life of the C-130 Hercules, Lockheed Martin's massive cargo plane, the U.S. Air Force made it into a warrior. During the Vietnam War, the Air Force needed major gunships to support troops on the ground, so it fitted C-130s with machine guns. The first squadron of these new AC-130 Spectres took flight in 1968.

In 1971, Pat Carpenter flew in AC-130s on nightly missions in Vietnam, where he served as gunner and anti-aircraft artillery spotter. He's now president of the Spectre Association, an organization of AC-130 veterans. In some ways, he says, it was an easy deployment--their airbase in Thailand was away from the fighting, and after flying night missions, the crew could go to the bar downtown. But that doesn't mean flying a Spectre was a picnic, Carpenter says. Despite unloading a barrage of 20 mm and 40 mm rounds every night, he says the massive firepower never made him feel safe during missions. "We didn't think about it that way," he says, "because most of the time they were shooting at us."

During the course of the Vietnam War, AC-130s were credited with destroying around 10,000 trucks. Carpenter says that after the aircraft's deployment, one of its main assignments was to find and destroy supplies flowing along the Ho Chi Minh Trail. During his year of service in 1971, his crew frequently flew two attacking missions per night, usually escorted by F-4 Phantoms. But, he says, the most gratifying missions were rescues, when the AC-130 could bring down a rain of cannon fire all around a group of stranded pilots or infantry. Once, he says, his plane--down one engine--flew above stranded soldiers until dawn, when helicopters could arrive. "As long as they could hear us," he says, "we were their comfort blanket."

The U.S. Air Force has upgraded AC-130s with bigger weapons and better sensors, and they are now used to support conventional and special operations forces units operating in Iraq and Afghanistan, making these lethal aircraft one of the longest-serving planes still in the skies.

5. A-10 Thunderbolt II

The A-10 is no glamour ride. When the design of this single-seat attack aircraft first appeared, the Air Force wasn't excited about bringing it into the arsenal, Boyne says--leaders preferred high-flying air support, not low-flying attack planes exposed to heavy enemy fire. And the Thunderbolt II's less-than-gorgeous appearance earned it the nickname "Warthog." But the A-10 is a hardy flier, armed to the teeth, and beloved among troops on the ground who benefit from the airplane's lethality. Designed initially for the purpose of destroying Soviet tanks and other ground-level armaments, A-10s carry a 30 mm Gatling gun in their noses that fires almost 4000 rounds per minute, as well as Maverick air-to-surface missiles or rockets on their wings. A-10s can attack at under 1000 ft, requiring redundant wing gas, self-sealing gas tanks and one-in.-thick titanium around the cockpit.

Warthogs found plenty of targets during the first Gulf War. According to Global Security, A-10s destroyed tanks, artillery pieces and trucks at a rate of about 1000 each during Operation Desert Storm. They also destroyed many other targets, such as radars, bunkers and Scud missile launchers. The aircraft flew attack missions in Kosovo in the 1990s, and they serve in the current Iraq and Afghanistan wars, where their ability to fly low has allowed them tosupport ground troops.

The U.S. continues to count on the Warthog for close air support, and will for some time--the aircraft is currently slated for retirement in 2028, according to Air Force Magazine. But the planes' heavy-duty use has left A-10s the worse for wear--one-third of the Air Force's A-10s are currently grounded because of cracks found in their wings.

6. AH-64 Apache

American aviation has enjoyed nearly total air superiority during recent conflicts, opening the door for low-flying aircraft such as helicopters to operate. In the world of attack helicopters, the AH-64 Apache stands out as a true killer. Boyne ranks the Apache, which was introduced in the 1980s and entered combat during the 1989 invasion of Panama, as the deadliest helicopter in the U.S. arsenal.

Jonathan Bernstein, author of the book AH-64 Apache Units of Operations Enduring Freedom & Iraqi Freedom, says the Apache's first major test in battle came in the Gulf War. As part of Task Force Normandy, he says, Apaches fired the first salvos of Desert Storm. Throughout the war, he says, they wiped out Iraqi tanks and infrastructure with such fury that "Iraqi soldiers on the ground were surrendering to Apaches." In Iraq and Afghanistan, Bernstein says, AH-64s moved from what the Army calls "deep attack," working behind enemy lines, to "close combat attack"--supporting troops on the ground. And, he says, Apaches have proven lethal at this task, too. Boeing told Bernstein that the helicopters accounted for 71 percent of all enemies killed in action in 2007 in Iraq.

Apaches are armed with 30 mm M230 machine guns; Bernstein says that you could fire "a 10-round burst in a 10-meter square and have every inch of that square covered." AH-64s can also carry up to three different kinds of rockets at once, including Hellfires.

Some experts, Boyne included, worry that the Army is overusing their Apaches, which have now been in service for nearly a quarter-century. But Bernstein says that the choppers have already received two serious upgrades, and they're scheduled for a third by 2011. The last upgrade, or "block two," provided full moving maps on the displays. "I love block-two birds," he says. "They're such an incredible machine." And last year, Apaches were equipped with MTADS, a new night vision and targeting system. More new designs may be coming down the pipe, he says, because the Army wants a faster chopper than the AH-64. But in all likelihood, Apaches will stay in service for another two decades.

DATE 2025

LOCATION Hangar 23, U.S. Forward Operating Base

AIRCRAFT MQ-Mb multirole fighter prepped for a precision strike mission	UNIT U.S. Air Force Expeditionary Fighter Squadron
POSSIBLE PAYLOAD Air-to-ground missiles, radio surveillance gear, high-definition video cameras, communications relays, nonlethal microwave-energy beams, 2000-pound precision bombs

LENGTH 45 feet	WINGSPAN 32 feet	PILOTS Zero
THE NEW AIR FORCE: PILOTS OPTIONAL The Air Force is planning to build a fleet of unmanned warplanes that will fly and fight without human guidance. The next-generation aircraft envisioned by the Air Force, and modeled in the illustration opposite, would be able to dodge enemy radar, swap payloads for multiple kinds of missions and use sophisticated onboard sensors to prevent collisions with other UAVs and manned airplanes.

Like its waterfowl namesake, the Heron unmanned aerial vehicle has the excellent vision of a hunter. Today, the 27-foot-long Israeli UAV is making a rare flight over the United States, using a high-definition video camera to track a speedboat buzzing across the Patuxent River in Maryland. The camera shares space with an infrared thermal imager and laser rangefinder inside a 17-inch sphere mounted under the aircraft's nose. The camera and the UAV both turn automatically to track the boat below, no satellite-linked joysticks required. On the Patuxent, a Coast Guard crew in a shallow-water patrol boat uses a real-time video feed from the Heron to locate the speedboat.

Less than 5 miles away, several hundred spectators watch the camera's feed on a massive color television monitor. The crowd of defense officials, defense industry wonks and military aviation buffs--many with bumper stickers on their cars that say "My other vehicle is unmanned"--is thick here at Webster Field, an auxiliary naval airfield in Maryland. The Heron is just one of about a dozen UAVs making flight demonstrations. As each one sweeps overhead, an announcer gushes over its abilities with the over-enthusiasm of a county fair emcee describing a prize sheep.

The crowd watches on the massive screen as the two boats converge and the Coast Guard crew completes the mock interception. The image of the river scene wheels as the Heron banks away from the boats and returns to the airfield. The UAV glides into a smooth, autonomous landing and as the Heron taxis, the goofball emcee coos over the PA speakers: "Aw, isn't that just pretty?"

The day is a spectacle of flying robots. A unit of Textron shows off an aircraft that it is pitching to the Marine Corps. It has a 12-foot wingspan and a pusher propeller mounted between its fuselage and inverted V-tail; it can be launched from a moving vehicle and is recovered by flying it into a net. The U.S. Army also has a marquee UAV to demo, the MQ-8B Fire Scout. The 3150-pound unmanned helicopter, the Army's first, may soon scan battlefields for chemical weapons, minefields and radio transmissions. And the showstopper, even while remaining earthbound, is the Navy's Joint Unmanned Combat Air System, a sleek, blended-wing aircraft with the maw of an air inlet placed almost mockingly where a cockpit would go. It sits like a resting bird, its 31-foot-long wings folded up for better storage on a warship. It is scheduled to perform an autonomous takeoff and landing from an aircraft carrier deck this year.

With all the hardware and enthusiastic attendees, it's easy to overlook a missing guest--the U.S. Air Force. Of all the advanced aircraft on the flight line, none is being developed for Air Force programs or is controlled by the service's airmen.

Unmanned aircraft are the biggest thing to happen in military aviation since stealth geometry, and the Air Force's leadership is dramatically increasing the UAV fleet this year. However, the service is still struggling over how the technology can be maximized in the future. "Today, the evolution of the machine is beginning to outpace the capability of the people we put in them," Air Force chief of staff Gen. Norton Schwartz said late last year in a speech to the Air Force Association. "We now must reconsider therelationship."

Under his direction, the Air Force is trying to become the Pentagon's leader of future UAV development. Schwartz's primary tool is the "Unmanned Aircraft Systems Flight Plan, 2009-2047," a comprehensive look at how the U.S. military can expand the use of UAVs over the next 38 years. The Air Force is proposing to use next-generation unmanned aircraft in a slate of new missions, including air strikes, aerial refueling, cargo transport and long-range bombing.

But how much freedom will the Air Force be willing to grant unmanned airplanes? Its airmen are only now coming to accept UAVs--they fly them every day over Iraq, Afghanistan, the Horn of Africa and other hot spots--but the service has articulated a way forward that not only marginalizes pilots, it also promises to replace many UAV ground-control crews with automation. Today's highly trained airmen may not embrace this vision of the future. One Air Force officer working with unmanned aircraft would only say he supports the report "because it's a plan. And having a plan is better than not having a plan."

Misfit Toys to Frontline Heroes

The Air Force squandered decades' worth of opportunities to lead U.S. military UAV development. In the 1970s, the service experimented with unmanned surveillance craft in Vietnam but dropped all funding after it decided the technology did not offer improvements over traditional airplanes. Continued advances of Soviet warplanes, such as the MiG fighter, kept a Cold War premium on air superiority won by high-performance, expertly piloted airplanes.

The idea of unmanned airplanes also runs contrary to the airman-centric ethos that has defined the Air Force since it became an independent military branch in 1947. Aviation Week and Space Technology magazine in 1973 quoted an Air Force official's disparaging verdict on remote-control warplanes: "How can you be a tiger sitting behind a console?" That attitude proved to be shortsighted. In 1982, Israel used UAVs to spoof Syrian radar in Lebanon, but the status quo in America continued for another decade. The Pentagon started UAV research in the mid-1990s, but even then the funding was tepid, in part because of Washington's bias toward large, job-generating manned airplane programs.

Guerrilla wars in Iraq and Afghanistan changed all that; the need for constant overhead video is driving a UAV spending spree. When facing insurgents who blend into a local population, good intelligence is worth more than even the smartest bomb. In 2010 the Defense Department will spend $5.4 billion on unmanned aircraft development, procurement and operations--about $2.5 billion more than the military spent on UAVs during the 1990s.

This boom is causing turf wars within the Pentagon. Military branches seldom develop weapons systems together, despite the potential savings of time and money if the services shared research costs and ordered hardware in bulk. The Air Force wants to coordinate UAV development within the Pentagon and drafted its ambitious Flight Plan to describe how the service would serve as the Pentagon's chief guide to unmanned airplane development, in concert with the Army, Navy and Marine Corps. "The Flight Plan is part of an Air Force effort to lay claim over everything that flies, whether it has a pilot or not," says military analyst and author Jim Dunnigan.

The Unmanned Aircraft Systems Task Force, which drafted the plan, is headquartered in a modest office that takes up a small fraction of one floor inside a banal building in Crystal City, Va. The full-time staff here tops out at a handful, but National Guard and Air Force Reserve temps fill out the administrative positions. Dozens of moonlighting planners from the Pentagon also volunteer for the task force, forgoing their free time for a chance to work on a project with high-ranking luminaries at Air Force headquarters who advise the task force.

The day-to-day work is supervised by the task force's director, Col. Eric Mathewson. The former F-15 pilot is a compact man with a soft, smooth voice that always sounds earnest. Mathewson often places a hand on his head when he speaks, as if his ideas could burst from his temple if he weren't holding them in. "It was clear we had been reactive, reactive, reactive," Mathewson says. "It was time to develop a vision."

That vision depends on developing smarter unmanned aircraft that can make life-and-death combat decisions on their own. According to the Flight Plan, UAVs will demonstrate "sense and avoid" collision-avoidance systems by the end of this year. Unmanned aircraft will be able to refuel each other by 2030. Global strike capability, perhaps even with nuclear weapons, is projected for 2047. "As technology advances, machines will automatically perform some repairs in flight," the Flight Plan reads. "Routine ground maintenance will be conducted by machines without human touch labor." The Air Force document not only discusses once-taboo subjects, such as automatic target engagement and autonomous UAVs flying in commercial airspace, it also includes short-term recommendations and goals to one day make them feasible.

Mathewson says that by 2020 just one control crew--airborne or ground-based--will be able to control multiple UAVs at once. Ground-control crews today, even when aided by advanced autopiloting, continuously monitor a single UAV. This level of direct control and supervision is referred to as man-in-the-loop. But a robotic system that only alerts humans when a critical decision needs to be made is called man-on-the-loop. A ground-control crew can opt to redirect the UAV or assume direct control until the key choice is made. "I don't think it's an overstatement that this is a revolution of military affairs," Mathewson says. "The revolution is the conscious application of automated technology."

Robot-Assisted Air Strike

Man-on-the-loop controls could make a battlefield look like this: An F-35A Lightning II fighter cuts through the night sky. The pilot's mission is simple--destroy an enemy bunker protected by a network of radar and antiaircraft missile batteries. His three wingmen--one flying scant feet away, another 150 miles ahead and the third preparing to cause a diversion far to the east--are following a meticulous battle plan meant to defeat these defenses. Of the four aircraft in the strike group, only the F-35A has a cockpit; the rest are semiautonomous UAVs that the pilot must trust with his life.

One of the most dangerous missions in military aviation is suppression of enemy air defenses, or SEAD. The lead UAV becomes bait as it flies into radar range of antiaircraft missile batteries. An icon on the F-35 pilot's virtual head-up display, projected onto the faceplate of his helmet, alerts him that the SEAD unmanned airplane has automatically identified the emissions of an enemy radar site. This is the first time in the mission that the SEAD airplane has communicated with any human.

Miles from the danger, the F-35A pilot coolly assesses the situation displayed on one of the screens in his cockpit, confirms the target is legitimate and authorizes the lead UAV to fire. The AGM-88 high-speed antiradiation missile follows the radar waves back to their source, obliterating the dish and its crew. There is now a gap in the enemy radar screen, and the pilot directs the UAV to return to base.

Meanwhile, another UAV east of the target, navigating by using a mix of GPS and accelerometer data, is busy scrambling other enemy radar installations by flooding the skies with emissions that share the radar's frequency. The jamming pods under the UAV's wings also disrupt radio transmissions from the air-defense network, covering up the sudden loss of contact with the radar sites protecting the bunker. Otherwise, an enemy commander could discover the location of the actual raid. After a preset amount of time spreading confusion, the UAV returns to base.

The F-35A pilot is closing in on the target fast and needs to carefully aim the F-35's electro-optical targeting system to release a bomb that will hit the structure at an angle calculated to collapse it without destroying nearby civilian buildings. He triggers the laser designator and authorizes the nearby unmanned airplane to drop a pair of bombs, which use fins to steer toward the laser-designated sweet spot. The pilot watches the twin, concurrent explosions, makes a quick battle-damage assessment and, satisfied, banks the airplane and heads back to base. His robotic wingman follows his lead, flying evenly at his side.

Skeptical Views From the Front

It can be hard to see the Flight Plan's vision of autonomous flying robots from the human-intensive work being done at Creech Air Force Base in Nevada. The desert base is in the midst of an unprecedented boom as it hosts the fast-growing 432nd Air Expeditionary Wing, the only one dedicated solely to flying unmanned aircraft. Every aircraft and satellite-linked ground-control station here is being used to fly missions in the Middle East, the Horn of Africa and points beyond. New buildings fill up with staff as soon as the construction dust settles. "Every time the fishbowl grows, the fish get too big for it," says Col. Pete Gersten, the 432nd's commander. Mathewson served at Creech as group commander before Gersten's arrival, but their jobs now are pointed in opposite directions. As Gersten wrestles with recruiting ground-control crews, Mathewson promotes ways to replace the airmen with artificial intelligence.

Every time an airman is replaced by a machine, the Air Force cuts the cost of health benefits, base upkeep and recruitment. Current unmanned systems require as many, if not more, people to fly missions than piloted airplanes do. For example, it takes a crew of three to operate a Reaper, even while it's on autopilot: one to fly, another to operate the sensor ball in its nose and a third to serve as military intelligence liaison. Another pair must deploy to the forward airfield to guide the UAV, using line-of-sight radio during takeoff and landing. By replacing these positions with automated functions, the cost of joystick operators could plummet.

But Gersten--who calls his unmanned airplanes remotely piloted vehicles to emphasize the crews operating them--does not give up human control over the aircraft unless it provides a clear war-fighting edge. For example, the Flight Plan pegs autonomous takeoff and landing for the Reaper by the end of 2010, but Gersten is not begging for that ability. In fact, when faced with a rash of accidents during landings, Gersten chose a solution to help, not replace, the joystick pilot.

The landing gear would collapse when Gersten's UAVs bounced down the runway. Operators have a tough time finding the correct pitch of the nose after a UAV's wheels bounce off the runway, causing oscillations that can destroy the aircraft on the third or fourth bounce. The seemingly obvious solution: Program the machines to take over and land automatically--something the Army's Sky Warrior, which is nearly identical to a Predator, already does. But Gersten opted for a simpler fix, adding a triangular carrot icon on the flight-control screen that sets the correct pitch to prevent the oscillation cycle from starting. This change will be made to ground-control stations this year, and he says "the cost is minuscule."

Gersten's reaction to the Flight Plan is coolly receptive. (He rolls his eyes at the report's language that suggests that UAVs one day could carry nuclear weapons.) The lower ranks on the base are more frankly skeptical of autonomy. Senior Airman Jessie Grace, a sensor-operator instructor at Creech, has spent wrist-aching hours keeping a UAV's camera trained on a target vehicle or locking his tired eyes on display screens to catch subtle signs of insurgent activity. While he does say that pilots could control more than one airplane at once, Grace sees things differently when it comes to his specialty. "I can't imagine a computer doing intelligence, surveillance and reconnaissance better than a person," he says.

Mathewson lists battlefield demands as the biggest hindrance to the Flight Plan, but he notes inflexible attitudes as another roadblock. "You see a cultural resistance," Mathewson says. "It's the same thing with the horse cavalry during the introduction of the tank."

Programmed Killer Instincts

Until the Flight Plan, it was nearly impossible to find officials who would even discuss the possibility of unmanned airplanes firing their weapons without human permission. But the report states that by 2030, flying robots could be programmed with "automatic target engagement" abilities. A UAV would open fire only after clearing a checklist of technical details from its sensors--its preset rules of engagement. Such a system would be an heir to ones currently used in Patriot antiaircraft batteries and some antimissile weapons on Navy ships. The legacy of the Patriot is mixed. During the second Gulf War, the system downed a pair of friendly airplanes, killing one American and two British pilots, after mistaking the planes for enemy missiles. Many military officials faulted an over-reliance on automation, but think-tank analysts noted that a lack of training caused the dependence and was the root cause of the tragedies.

Mathewson says that keeping people directly involved at the end of the kill chain is optional but preferred. "There are not that many cases where you'll have free fire, where you're going to have the system completely automated," he says. "If you look at the way we employ unmanned aircraft in the current fights, the rules of engagement require that someone [in charge at the rear] has to approve it, to say, `Yes, indeed, you're cleared hot' for every single case. And that would hold true."

While Gersten normally keeps any pride in check, the former F-16 pilot can be moralistic in arguing to have a man at the helm of a system that can bring death to its targets. "Warfare should be humanistic," he says. "Human value requires a human interface." It's his way of saying that even sworn enemies deserve to have an actual person, rather than an algorithm, make the decision to kill them.