Perhaps no field of technology is more directly tied to visions of the future than aerospace. Try to imagine a plausible world 50 years from now that is devoid of air and space vehicles. You can't. Flight almost defines the forward-looking genre of science fiction. Futuristic stories that set humans in worlds without air and space travel are in fact called "fantasy."

Aerospace has brought us the frequent flyer, barnstormer, astronaut and ace, mach number, jet lag, sound barrier, and bomb. Without it, there would be no moon shot, test pilot, airport, communications satellite, or stealth. The impact of aerospace technology on war, culture, language, knowledge, and the daily business of billions of people is immeasurable; its effect on the future, nearly incalculable.

Pretty heady stuff for a field of engineering that didn't exist until Orville Wright flew two feet off the ground for 12 seconds one day in 1903. Sixty-six years later, Apollo 11 rocketed to the moon. And through it all, experts and dreamers seemed always to spend more time thinking about the flying vehicles of tomorrow than they did of those today. So it came as no surprise when Design News asked 11 aerospace experts for their take on the future of air and space vehicles, they weren't shy.

"The technologies that are converging right now will change our life so completely in 15 or 20 years that it's nearly impossible to look out even 30 years," says Burt Rutan, president of Scaled Composites. But he and the other aerospace experts did just that--and more. We asked them to shuffle their mental tarot cards and envision the next 50 years of aerospace in fields ranging from commercial to military, general aviation to space travel. And here's what they see.

General aviation's golden years. Personal aircraft have really never lived up to their billing. Many people imagined that, by now, we'd all fly to and from work in George Jetson-like air scooters that collapse into a briefcase. And while such a vision will probably never come true, "I think that general aviation has a real possibility of becoming the dominant aviation theme in technology development in the 21^st century," says Steven Crow, professor of aerospace and mechanical engineering at the University of Arizona. He sees the production of consumer aircraft growing to 100,000 a year by about 2020. That's up from just 928 built two years ago.

Liability issues have driven much of the previous decline. But Jan Roskam, Ackers Distinguished Professor of aerospace engineering at the University of Kansas, sees something else. "We're still building very user-unfriendly aircraft aimed at pilots," he explains, "and most people are not pilots." To be successful, says Roskam, manufacturers will have to create airplanes that are so highly automated that someone who has only the skills to drive a car can fly them.

Such automation means computer power. And the focus of this power will be in the electronics, avionics, controls, and instruments. Physically, general aviation (GA) aircraft of the next 20 years should look little different from today's high-tech, composite, home-built planes. "Structure and configuration are not the big drivers in aircraft design, just like they are not the big difference between chimps and humans," says Crow. "The difference is the brain."

In the cockpit, engineers plan to pool this ever-growing computer brain power with GPS navigation and telecommunications breakthroughs to create airplanes that essentially fly themselves. "Planes will be 'magic carpets' with only the highest-level decisions made by the driver," envisions Crow.

Adds Rutan, "In 10 years, for a plane that is the size and price of a Bonanza, you will get a plane that is pressurized and flies coast to coast at 400 kts." Harbinger of such an aircraft is Rutan's personal plane, Boomerang, that can fly across the country at 260 kts. Unusual on the outside--it features two engines, one mounted at the nose of the main fuselage and a second one mounted like an outrigger in a nacelle on the left wing--the plane's real secret lies in the cockpit. There, Rutan replaced nearly all the instrument displays with an Apple Macintosh PowerBook computer.

The PowerBook runs a program called RAPMAS programmed by Rutan's son, Jeff. It communicates over RS-232 with a shielded, ruggedized data- acquisition system controlled by an embedded PC. Displays for such parameters as engine status, control-surface positions, landing gear, altitude, airspeed, fuel level, and--someday--GPS moving-map navigation all appear on the Mac's screen, updated at 3 Hz. "In a year, I can replace [the PowerBook] with one that has twice the capability and a lower cost," says Rutan of his cockpit's flexibility.

Revolutionary design. Members of the Kansas Joint Design Project took an even more radical approach for the control, display, navigation, and communication functions of their award-winning entry into NASA's 1995 General Aviation Design Competition. The team, consisting of faculty and students from the University of Kansas, Kansas State, and Wichita State, proposed Shrike, a futuristic family of three advanced single-engine airplanes (two-, four-, and six-passenger) all designed to be flown by relatively unskilled operators, not pilots.

The design's completely automated flight control system uses four GPS sensors--one on each wing, one in the fuselage nose, and one in the tail--to supply information about aircraft position and orientation. Combined with localized GPS marker beacons placed at airports, it permits fully automatic taxi, takeoff, and landing. The operator selects routes and conducts communication via two LCD touchscreens and 3-D auditory voice recognition and speech synthesis. Artificial intelligence and decision-aiding programming turn the pilot's job into that of a flight supervisor. A head-up display (HUD) projects in the operator's field of vision the image of an artificial "path-in-the-sky" that stretches out to infinity in front of the aircraft, and includes readouts for speed, altitude, and other critical parameters.

"In 10 years, there will be an elimination of the instrument panel as we know it," says Rutan. Instead of looking at hieroglyphics and motor-driven needles--or glass-cockpit representations of those needles--very-low-cost processing will enable a synthetic aperture radar view of the actual terrain that we now cannot see due to clouds.

Other offbeat but interesting ideas include:

- Starcar, a "transformer" vehicle conceived by Steven Crow. It consists of three modules--a passenger compartment, road module, and sky module--that combine into either a good car or a good airplane. Drivers can quickly change between the two, and advanced GPS navigation and computerized flight controls--similar to Shrike's--make it possible for the unskilled to fly even in limited visibility.

- The 3X Jet, a brainchild of former Lear Fan executive Richard Bacon. This aircraft carries two different engines--one sized and optimized for efficient cruise performance and another for takeoff-assist and emergencies. During most of the flight the plane flies on just the first engine, yielding a potential 20% savings in operating costs through reduced fuel consumption and maintenance.

Engines needed. Propulsion presents an area of general aviation that is ripe for innovation. "For Boomerang, I suffered through two Lycoming propeller installations," says Rutan. "I threw away the magnetos, vacuum pumps, the starter, and alternator, and put in things out of automobiles that are considerably better."

Some see in this frustration the opportunity for complete powerplants derived from automobile engines. Alternatives include: turbocharged rotary engines--such as that specified for the two smaller models of Shrike--or a small, cheap, gas turbine engine, should some engineer decide to design one.

Noise will also drive engine design. "Somebody in the 15- to 20-year range is going to solve the electric-power storage problem," Roskam believes, thus opening the possibility of electric power for light airplanes. Paul MacCready, CEO of AeroVironment, sees tremendous work occurring in noise reduction. Today, his engineers are working on a secret project to create a helicopter-like vehicle for the police--possibly an autogyro--that produces virtually no noise.

Future fighters. Ask Jerry Ennis, vice president of the prototype center for McDonnell Douglas' Phantom Works, where he sees the future of military aircraft, and he has a one-word answer: space. "It's the new military high ground," he says.

Space is the place where all critical tactical information is gathered, networked, and relayed. And from a vehicle standpoint, getting out of the atmosphere frees designers from limitations that have saddled them since the Wright brothers. Says Ennis, "It's pretty tough to go faster than Mach 2.5 in the atmosphere and do it affordability."

In the next decade or two, Ennis envisions a quick-reaction, deep-strike vehicle not, unsurprisingly, that different from McDonnell Douglas' vertical takeoff and landing prototype, the DC-X. It would be a single-stage-to-orbit (SSTO) vehicle and function much like a reusable ballis-tic missile, deploying kinetic weapons or other payloads from space. Using differential GPS, such a vehicle could fly over anyplace on the planet 40 minutes after launch, then touch down within a few feet of a desired landing site. "The DC-X has pretty much proven that you can go to war from a tennis court and return to a tennis court," Ennis says.

An interesting alternative takes the form Black Horse, a transatmospheric spaceplane concept proposed by USAF Capt. Mitchell Burnside Clapp. He suggests that a rocket-powered, fighter-size vehicle could be developed with current technology that takes off from a runway, refuels from a tanker in the air, and then blasts into space with a 5,000-lb payload. Fuel would consist of JP-5 (jet fuel) and 90%+ pure H₂O₂, neither of which need cryogenic storage. Mission turnaround would be less than one day, maybe a few hours. Adequately funded and started today, transatmospheric spaceplanes could be operating on a weekly basis in about 7-10 years.

Back on Earth, expect atmospheric fighter aircraft to steadily evolve into unmanned vehicles. Computer intelligence continues to increase, while the G limits of the human body remain unchanged. In addition, the cockpit and life-support systems account for much of the development cost in military aircraft. Roskam estimates that starting 15-20 years out, 50% of air combat will be done with unmanned machines.

Filling that 15-20 year void will be legacy aircraft (F-22 and F-18 E/F) as well as the Joint Strike Fighter (JSF). A multi-role fighter intended to replace the F-16, A-10, A-6, F-18 C/D, and F-14, the JSF may also be designed in a special Short Takeoff/Vertical Landing version to supplant the AV-8B. This November, two of the three teams--led by Boeing, Lockheed Martin, and McDonnell Douglas--will receive contracts to build competing prototypes of their designs.

JSF stresses affordability over extreme performance, and won't push the envelope except in areas like cockpit design, electronics, and systems integration. Pilots will probably wear a new super-helmet that combines a HUD with voice command.

Past 25 years out, unmanned fighters with neural-net computers will come into being. They might be hypersonic, and their neural nets will let them not only learn and adapt to various flight and environmental conditions, but also to dynamic battle scenarios. McDonnell Douglas has a 12- to 15-ft-long RPV currently under development called the Phantom X that is designed to test a neural-net flight control system.

Commercial transports. NASA estimates that by 2013, increases in commercial air travel will necessitate $1 trillion in new jet transports, and that by 2015, the supersonic aircraft marketplace could be worth $200 billion in sales.

One area of particular interest is the Super Jumbo jet or Very Large Aircraft (VLA). Targeted for market entry in five to seven years, a VLA would carry about 600-800 people, more than double that of a current MD-11. Some very viable concepts involve larger versions of Boeing's 747 that sport a full-length double deck and a larger wing. But technically more interesting is a blended-wing-body (BWB) concept developed by McDonnell Douglas.

The BWB looks much like a huge B-2 bomber. "It emerged from VLA studies that had wings of such a depth that a person could stand up inside them," says David Murphy, manager of advanced wide-body programs at McDonnell Douglas. Up to 800 passengers would ride in the center section of the wing. Murphy says that the BWB configuration improves lift-to-drag, and thus fuel burn, by one-third. The catch? Development cost would be $5-10 billion.

Supersonic and hypersonic vehicles face more formidable obstacles. They will require new variable-cycle engines that act like a turbofan at takeoff and then change more to a ram jet at cruise speed. Supersonic laminar flow wings--using suction perhaps--could cut direct operating costs (DOC) by 7-10%. The extensive use of lightweight composites could contribute another 20% cut in fuel burn. But to let this happen, Roskam of the University of Kansas says, composites must be substantially improved in the areas of hail and lightening-strike damage. A possible fix? Metal-matrix composites.

But huge barriers loom for widespread high-speed travel. How much will it cost? And how do engineers overcome the sonic boom problem and easily overlooked factors like maintaining acceptable acceleration and deceleration rates on the passengers for hypersonic flight? Rutan's solution: Forget super- and hypersonic flight, and go straight into space. "Burning fossil fuel to drag an airplane through the atmosphere for 4,000 miles will, in 10 years, be recognized as a thing of the past," he says.

Cockpits will become more and more automated until, about 25 years from now, there won't be any pilots on board, says Roskam. Fully automated takeoff, cruise, and landings will occur by leveraging GPS. The drivers are cost and ever-improving computers. Today, pilots account for about one-third of an airliner's DOC, and 20-25% of vehicle development cost goes into designing the cockpit. "The co-pilot will go in 10 years; then maybe we'll have just a 'systems monitor'; then 10 years later, nobody," Roskam says. Interim changes might include artificial vision that would allow the cockpit to be moved to anywhere in the vehicle.

Race into space. Better electronics, computers, and communication will have a big impact on launch vehicles. The use of GPS will improve orbital insertion accuracy from about 15 km today to 2-3 km accuracy in just a few years, says Antonio Elias, senior vice president of advanced projects at Orbital Sciences Corporation (OSC). "This might allow you to do away with the precision orbital maneuvering system for the satellite."

In the near term, hydrogen peroxide and kerosene (as proposed for the Black Horse spaceplane) may become the rocket fuel of choice. "These won't hold the world record for specific impulse, but they would be easily a factor of two or three cheaper," says Elias. Twenty-five years out he sees further improvements in chemistry leading to denser and more powerful fuels. And 50 years from now engineers may well have the ability to construct advanced materials at the molecular level. "These things are critical to the creation of a single-stage-to-orbit (SSTO), reusable space transportation system," Elias believes.

The future of reusable launch vehicles depends partly on the success of two joint NASA and industry programs, X-33 and X-34. Recently, OSC received a NASA contract to build the X-34, an air-launched, small reusable launch vehicle (RLV) intended to cut by a factor of three the cost of launchingsmallsatellites(&1,000 lbs) into low orbit and demonstrate key RLV technologies, such as extremely fast turnaround and advanced thermal protection systems.

And in July, NASA awarded Lockheed Martin Skunk Works the program to build the X-33. It's a 1/2-scale prototype of an SSTO designed to reduce the technical risks for private industry to enter the RLV business. A lifting-body vehicle, it uses innovative aerospike engines from Rocketdyne to power it to Mach 15, and then return to Earth and land on a runway.

Within 10-15 years, both X programs should yield follow-on, full-scale vehicles. X-34's successor will be used for the weekly (or more frequent) launching of small low-orbit payloads. The X-33 descendant will haul 25,000 lbs to the planned international space station.

Private industry isn't sitting idle. With the dream of commercial service to space as remote today as it was after Apollo, a group of influential aerospace experts and enthusiasts created the X Prize. Its intent: offer a $5 to $10 million prize to the organization that first builds and flies a re-usable vehicle that takes at least two passengers on a suborbital trip to an altitute of 100 km. "Flight out of the atmosphere is simple to do and should have been available to the public 20 years ago," says Rutan. "Ten years from now, we will have space tour-ism ... it will be the most exciting roller coaster ride you can buy."

Rutan thinks the X Prize could be won in as few as three years, with a regular business operating two years later. The vehicle wouldn't have to be high tech. Instead, it would be so robust "that you could re-enter the atmosphere in almost any orientation, it's just a wilder ride." Elias thinks 10 to 20 years is a more realistic goal, and he doesn't see orbital pleasure trips occurring for four or five decades.

Space propulsion. Exploratory space vehicles are being driven by the mantra, "do more, more often, for less money." An example is the New Millennium DS-1, scheduled for launch in 1998. It's headed out to visit an asteroid and a comet, but the vehicle's real goal is to demonstrate its ion en-gine--a spacecraft first. "Ion propulsion will change the way JPL flies planetary missions," says John Brophy, supervisor of advanced propulsion technology at the Jet Propulsion Laboratory.

Solar cells supply 2.5 kW of energy to the 7-kg engine that spits out just 90 mN (0.02 lbf) of thrust. The engine's advantage is its great efficiency (99%), and the fact that it can maintain full thrust for 8,000 hours with just 83 kg of xenon for fuel.

It works by stripping electrons off the heavy (131 amu) xenon atoms, and then accelerating the resulting ions to very high speed through a magnetic field. For comparison, the Shuttle's main engine exhaust exits at 4,500 m/sec, while the DS-1's ion engine blasts out at 33,000m/sec. "A main-belt asteroid mission would take six or seven years with chemical rockets," says Brophy. "Using ion propulsion, it would take less than three years."

Fifteen years from now, space vehicles might be driven by magnetoplasmadynamic thrusters. A prototype built for the JPL by the Moscow Aviation Institute uses lithium for the propellant and needs 100 kW of electrical power--with plans to scale it to 500 kW. "It's physically the same size as the New Millennium ion engine, but puts out 40 times the power," says Brophy.

In four or five decades, antimatter engines might take explorers to the planets and beyond. Just milligrams of antimatter--more than produced every year on Earth--would be required to power a piloted 100-day round trip to Mars, says Brophy. Researchers at Penn State University envision a hybrid engine in which antimatter triggers a fission reaction that triggers fusion reaction for thrust. Recently, they created a portable Penning Trap--a bottle to hold antiprotons--to carry antimatter from CERN in Switzerland to the U.S.

Other possible futures. Obviously, researching and presenting each of the possibly thousands of projects directed toward the future of aviation and space flight is impossible. Many of the ideas presented here may never come to pass. And others, not mentioned, might eventually play a tremendous role. The greatest technological impact 50 years from now will probably come from a sudden breakthrough--like the turbojet--that launches aerospace design in an unexpected direction. Such are the risks of forecasting.

Says MacCready, "Charles Lindbergh's flight across the Atlantic was one of the most important events of the 1920s, not because it was technologically a great airplane, but be-cause it got people thinking." We hope this article will do the same for its readers.

COMING ATTRACTIONS

- Single-stage-to-orbit reusable launch vehicle

- Pilotless aircraft

- Antimatter propulsion system

- Virtually noiseless helicopters

- Transatmospheric spaceplane

- Super jumbo jets

- Unmanned fighters

- Commercial service to space

"The co-pilot will go in 10 years; then maybe we'll have just a 'systems monitor,' then 10 years later, nobody."

--Jan Roskam, Ackers Distinguished Professor of aerospace engineering, University of Kansas

PREDICTIONS FROM THE PAST

"Heavier-than-air flying machines are impossible."

--Lord Kelvin, president of England's Royal Society, in 1895, eight years prior to the Wright Brothers' first flight

"Professor Goddard, with his 'chair' in Clark College and countenancing of the Smithsonian Institution, does not know the relation of action to re-action, and of the need to have something better than a vacuum against which to react ..."

--1920 New York Times editorial criticizing Robert Goddard's proposal to use rockets for space travel

"First Europe, and then the globe, will be linked by flight, and nations so knit together that they will grow to be next-door neighbors. This conquest of the air will prove, ultimately, to be man's greatest and most glorious triumph. What railways have done for nations, airways will do for the world."

--Claude Crahame-White, British Aviator, 1914

"Airplanes are interesting toys but of no military value."

--Ferdinand Foch, French marshal and commander in chief of Allied forcesduring World War I

"The way to fly is to go straight up ... Such a machine (the helicopter) will never compete with the aeroplane, though it will have specialized uses, and in these it will surpass the aeroplane. The fact that you can land at your front door is the reason you can't carry heavy loads efficiently."

--Emile Berliner, 1928

"Man will never reach the moon regardless of all future scientific advances."

--Dr. Lee De Forest, inventor of the electron tube and father of radio

"Don't tell me that man doesn't belong out there. Man belongs wherever he wants to go--and he'll do plenty well when he gets there."

--Wernher van Braun, rocket engineer, commenting on space flight in Time, February 17, 1958

BEARINGS HOLD KEY TO TOMORROW'S ENGINES

The future of jet engines turns on bearings. Requirements that they spin faster, run hotter, last longer, and weigh less are just some of the conflicting design criteria for the balls and rollers in next-generation turbines.

"So much is driven by weight," says Phil Parmenter, chief engineer at New Hampshire Ball Bearing (NHBB). "If we can get higher speeds out of a bearing and out of an engine, everything can come down in size." The ability to withstand higher temperatures serves the same master. More heat tolerance means less lubrication and smaller heat exchangers.

Achieving this means ever tighter bearing tolerance, says Parmenter. "It's what has let bearings progress from 1 million DN up to where they are today." Production bearings now achieve 2.2 million DN (rpm x bore in mm), and 3 million-DN bearings spin in test engines. "Ten years from now I can see 4 million DN coming online," he says. To get there, raceway finishes will have to be twice as good as today's.

Ceramic rolling elements will play a big role, too. Currently found in grinding machines, ceramic balls will be placed in jet engines as soon as engineers find reliable ways to inspect them. "[Bearing] life goes up exponentially with ceramic rolling elements," Parmenter adds. In 25 years, he sees ceramic rings being used as well, possibly reinforced with carbon fiber.

Someday, magnetic bearings may find their way into turbines. Currently heavy and complex, they offer the potential advantage of being able to adjust the centering of the turbine shaft to trim fan-blade tip clearance. Fifty years out, who knows? The concept behind the bearing of 2046 might not have been invented yet.

THE ENGINEER'S ROLE

Fifty years from now, engineers and not computers will still design aircraft and spacecraft. They will rely, however, on advanced expert systems to help conceive ideas, and lean heavily on CAE systems that fully integrate solid modeling with every aspect of analysis and manufacturing. The system will help engineers quickly iterate through a multitude of design possiblilites to find the optimum solution, says Jerry Ennis, vice president of the prototype center for McDonnell Douglas' Phantom Works.

Recently, Design Analysis and Research Corp. (DAR) of Lawrence, KS, introduced a precursor of such a system. Called G.A. CAD, it lets engineers rapidly evolve the preliminary configuration of a general-aviation aircraft, from weight sizing to detailed performance calculations.

Designers will more likely be generalists. "Each individual will be more aware of the total system and responsible for a bigger chunk," explains Antonio Elias, senior vice president of advanced projects at Orbital Sciences Corp. He sees the toughest challenge to be communicating from one generation of engineers to the next the ever-increasing accumulated technical knowledge. Computers will help here as well, serving as repositories and dispensers of vast historical information to help prevent designers from inventing the already invented.

TECHNICAL HURDLES

- Fully automated GPS-based navigation and flight-control systems

- Small, economical jet turbines

- Vastly improved internal-combustion engines for general aviation

- Inexpensive, easy-to-manufacturecomposite materials

- Affordable and practical supersoniclaminar flow techniques

- Ultra -high-temperature materials

- Reusable, cheap-to-operate rocket engines

- Improved human-to-computer interfaces

- Methods for sustainable antimatter-catalyzed fission and fusion

- Inflatable space structures for large deep-space arrays and antennas

COMPONENTS TO WATCH

- New-generation bearings

- More extensive use of lightweight, high-temperature composites

- Improved GPS systems to pinpoint orbital insertion accuracy

- Artifical vision systems that allow the cockpit to be moved to anywhere in the aircraft

- Ion and antimatter propulsion systems

- Magneto-
plasmadynamic thrusters