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The Future of Flight
Roland Piquepaille writes "With "High Times," the Economist delivers a very long and extremely well-documented article about the future of aviation during the next fifty years. It tells us about pilotless planes, with 32 countries currently developing more than 250 models of unmanned aerial vehicles (UAV), primarily for combat purposes. The article also looks at future civilian pilotless planes and at the future of personal aviation. But what captivated my attention in this article was the last part about future commercial supersonic and hypersonic (at least five times the speed of sound) planes. In particular, the Economist describes the HyperSoar. "The HyperSoar is a concept for a craft flying at ten times the speed of sound and able to reach any point on the globe within two hours." This overview contains more details and references about the HyperSoar which would fly from Los Angeles to New York in 35 minutes."
Eclipse Aviation of Albuquerque, New Mexico have produced a Air taxi capable of carring 5 people upto 1500 Km, but for this to be widely adopted 'free flight' must first exist. This allows piolts to plot there own jouneys, cutting distances and utlising more airspace. 'free flight' relies on each aircraft having it's own computer that allows aircraft to avoid each other. For more information see this weeks (13/12/03) New Scientist p28-33.
As an aerospace engineer, I'm always surprised about how many things we are supposed to achieve in the next so-many-years.
People, believe me: It is _not_ going to happen. Period.
Why not?
Well first of all, aerospace as an industry is extremely conservative. Despite it's high-tech image, the facts (and my experience) show differently. Look at the shape of aircrafts for example: Essentially unchanged since the 1930s. The fuselage-wing-tail concept is still the most popular, and all the research on blended wings, canards, double-fuselage, and other stuff people have made up, have not changed a thing (try to find the book by E. Torenbeek, you'll be amazed about how rich a phantasy some people have). That is because it simply is by far the most efficient concept: it's easy to stabilize, and you can put lots of people in it. Blended wings, for example, turn out to be too thin for people to fit in for, say, an aircraft for 100 people. Also, safety is easlier to achieve, and there's lots of room for cargo/luggage and fuel. Boeing's SST and Sonic Cruiser, and even the Concorde, did not fail without a reason. The A380, the "next generation aircraft", still has the same basic design as a DC-3 had 60 years ago. Another example is materials: Aluminum is still the primary construction material. It is _very_ slowly being replaced with composites and laminates (carbon, glass fibre/epoxy, GLARE). Aircraft manufactures can't sell an aircraft until it is absolutely proven that the new aircraft is safe and maintainable and has cheap Direct Operating Costs. So they all play safe and go with trusted concepts/materials. The A380 took about US$15_billion_ to develop. You don't go gable with such amounts. You play safe.
Then there's an economic reason. Profits for airliners are extremely low: 3-5% is not unusual. In fact, very few airlines have made a net profit over the past two decades. In the USA, airlines go bankrupt every 10 years, in Europe they would not survive without government support. Investing in airlines is high risk. This automatically means that investments in aircraft manufacturers is also quite risky. So actual research development of new technologies in the aerospace industry are very low, and usually government-sponsored, related to military applications, or conducted in universities or research institures. The "time to market" of any new technology in the aerospace industry has been estimated to be about 35 years.
This is already too long a story, I could go on for pages. But realy, this kind of views on the future just makes me laugh my pants off.
Airplanes are stable or unstable due to their roles.
Fighters are inherently unstable, to allow the radical combat sequences dictated by dogfighting. It's true some of the current fighters are unflyable without constant computer assisted tuning.
Large passenger jets ARE inherently stable. The use of computers to control the flight surfaces are dictated by demands for maximum fuel economy, which means constant re-adjustment of CG's, trim, and other parameters.
Nothing in their design prevents them from being flown on purely hydraulic controls in an emergency.