No traffic jams in the sky, for the moment
Where are the flying cars? It's a dream that has reduced many would-be inventors to despair as they grasped the immensity of the engineering and design challenges rooted in the widely divergent natures of airplanes and cars. Cars must provide occupants with comfort, decent handling and braking and protection in the event of an accident - while complying with government air-pollution and fuel-economy standards. Keeping weight to a minimum is important, but a few extra pounds here and there can be tolerated.
Airplanes are quite a different matter. Weight is everything in a flying machine; it determines the engine power and the wingspan required to get off the ground. Thus, aircraft make extensive use of lightweight materials that their designers fashion into the most efficient structures they can dream up.
Several small companies are working on flying car designs that they think will be the ones to finally crack the nut. One of these, Terrafugia of Massachussetts, has flown a prototype with self-folding wings and a pusher propeller nestled between two tail booms. The company is working on an advanced hybrid design capable of vertical takeoff and highway driving using electric motors powered by batteries, along with a piston engine turning a pusher propeller during forward flight.
A start-up in Bratislava, Slovakia, called Aeromobil has a prototype with a pusher propeller for flight and driveshafts turning the front wheels when driving. Its wings pivot backward parallel to the fuselage when the craft is used in automobile mode.
It helps to put on an imaginary engineer's hat when pondering the systems that would need to be on board a viable flying car. For starters, there must be an engine. And for weight and complexity reasons it would be ideal for a single engine to provide power for flying and driving. Therefore, some kind of transmission must be devised to send power either to a propeller or to the driving wheels.
Wings, and how to stow them for highway travel, are another big piece of the puzzle. "The heavier your vehicle is, the more wingspan will be needed to make the aerodynamic lift to fly it," Morgan said. The longer the wings become, the greater the challenge of getting them out of the way so the flying car will fit the width of a highway lane. Building hinges or pivoting mechanisms into the wings reduces their structural efficiency and adds weight.
Even a flying car's suspension system would require a fair amount of engineering. An automobile suspension is designed to withstand forces of about two gs as it smooths out the bumps in the road. Airplanes sometimes have bad landings, however, and their suspension systems must be built to tolerate four g forces.
A new aircraft must receive from the US Federal Aviation Administration what's known as a type certification, which approves the plane's design as safe and airworthy. Also mandatory is a production certification, which attests that the manufacturer has exacting quality standards in place and can build multiple airplanes identical to the approved prototype. "When the vehicle you're building is also a car, then you have to deal with the Department of Transportation and the National Highway Traffic Safety Administration," said Dick Knapinski of the Experimental Aircraft Association in Oshkosh, Wisconsin.
Enthusiasts have a think or two coming if they assume that one need only buy a flying car and point the nose skyward to soar above the dreary highways. Nobody gets off the ground without training and a pilot's licence, and no government agency will sign off on citizens' routinely taking off and landing on public roads. That's what airports are for.
A final impediment to swarms of flying cars filling the skies is the existing air traffic control system, which isn't set up to keep track of low-flying aircraft that don't have a flight plan and may impulsively change course. "If this situation became reality, how many of those people would live to see dinner?" Morgan asked.
Airplanes are quite a different matter. Weight is everything in a flying machine; it determines the engine power and the wingspan required to get off the ground. Thus, aircraft make extensive use of lightweight materials that their designers fashion into the most efficient structures they can dream up.
Several small companies are working on flying car designs that they think will be the ones to finally crack the nut. One of these, Terrafugia of Massachussetts, has flown a prototype with self-folding wings and a pusher propeller nestled between two tail booms. The company is working on an advanced hybrid design capable of vertical takeoff and highway driving using electric motors powered by batteries, along with a piston engine turning a pusher propeller during forward flight.
A start-up in Bratislava, Slovakia, called Aeromobil has a prototype with a pusher propeller for flight and driveshafts turning the front wheels when driving. Its wings pivot backward parallel to the fuselage when the craft is used in automobile mode.
It helps to put on an imaginary engineer's hat when pondering the systems that would need to be on board a viable flying car. For starters, there must be an engine. And for weight and complexity reasons it would be ideal for a single engine to provide power for flying and driving. Therefore, some kind of transmission must be devised to send power either to a propeller or to the driving wheels.
Wings, and how to stow them for highway travel, are another big piece of the puzzle. "The heavier your vehicle is, the more wingspan will be needed to make the aerodynamic lift to fly it," Morgan said. The longer the wings become, the greater the challenge of getting them out of the way so the flying car will fit the width of a highway lane. Building hinges or pivoting mechanisms into the wings reduces their structural efficiency and adds weight.
Even a flying car's suspension system would require a fair amount of engineering. An automobile suspension is designed to withstand forces of about two gs as it smooths out the bumps in the road. Airplanes sometimes have bad landings, however, and their suspension systems must be built to tolerate four g forces.
A new aircraft must receive from the US Federal Aviation Administration what's known as a type certification, which approves the plane's design as safe and airworthy. Also mandatory is a production certification, which attests that the manufacturer has exacting quality standards in place and can build multiple airplanes identical to the approved prototype. "When the vehicle you're building is also a car, then you have to deal with the Department of Transportation and the National Highway Traffic Safety Administration," said Dick Knapinski of the Experimental Aircraft Association in Oshkosh, Wisconsin.
Enthusiasts have a think or two coming if they assume that one need only buy a flying car and point the nose skyward to soar above the dreary highways. Nobody gets off the ground without training and a pilot's licence, and no government agency will sign off on citizens' routinely taking off and landing on public roads. That's what airports are for.
A final impediment to swarms of flying cars filling the skies is the existing air traffic control system, which isn't set up to keep track of low-flying aircraft that don't have a flight plan and may impulsively change course. "If this situation became reality, how many of those people would live to see dinner?" Morgan asked.
© 2014 The New York Times
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First Published: Aug 30 2014 | 12:03 AM IST