NASA’s X-plane program has, for the past 70 years, demonstrated some of the most exciting and innovative aircraft ever flown, including rockets and robots, scramjets and spacecraft (and lots more). It’s always worth paying attention when a new X-plane is announced, and NASA has just given us a hint of what the X-57 might be: LEAPTech, an experimental demonstratorthat replaces the single large motor on light aircraft with 18 (!) tiny ones, all mounted on an impossibly skinny little wing.
The specs on the LEAPTech X-plane are, for the most part, not anything to get super-excited about. With a top speed of 320 km/h and a 3567 meter (12,000 ft) ceiling, it’ll be able to carry four passengers 740 km on hybrid electric power. This is all about average for a light aircraft of this size. What’s unique are those 18 electric engines, and the wing, which has a total area of just over 5 square meters. In order to fly, a conventional airplane of this size needsthree times as much wing area at the expense of the huge amount of extra drag that comes with it.
LEAPTech’s big innovation is using 18 small engines to blow air directly across the wing, the part of the aircraft that generates the most lift. Traditionally, aircraft have a big engine or two that are used exclusively for forward propulsion, and lift is generated by the wing as a side-effect of that forward movement. As a result, wings have to be relatively large in order to provide sufficient lift at lower speeds (takeoffs and landings), and at higher cruising speeds, but all of that wing area just slows the aircraft down.
The LEAPTech X-plane tightly integrates engines with wings, so the engines all work together to maximize the amount of air moving directly over the lift surfaces. By doing this, the wing can be optimized for cruising speeds instead of takeoff speeds, drastically improving cruise efficiency. The only reason this concept works is that with electric motors, you can just slap 18 of ‘em on there, because of how well they scale in size, weight, and power.
So, we have stupid, inefficient airplanes wasting tremendous amounts of carbon-producing fossil fuels, but in the future we will (finally) have aircraft optimized for flying rather than taking off.
from Stowe Boyd http://stoweboyd.com/post/122791308567
