Boeing's BWB - a super-efficient bat jet Friday June 28, 1:02 PM EDT By Bradley Perrett, European aerospace & defence correspondent MUNICH, June 28 (Reuters) - Boeing Co (BA) engineers have designed a super-efficient aircraft that would look like a giant bat and slash the cost of air transport. The "Blended Wing Body" concept, outlined more than 10 years ago but now said to be almost perfected, would have no fuselage or tail. Rather, it would basically be a wing with a belly that would accommodate the passengers and freight. The secret to its design, described by project head Robert Liebeck this week, is that the whole structure of the aircraft would work to generate lift. The accommodation section in a normal plane, the tubular fuselage, is a burden that generates extra drag -- so the Blended Wing Body (BWB) does not have one. "Creation of the...BWB was motivated by a search for an airplane configuration that could offer improved efficiency over the classic tube and wing", the conventional configuration, Liebeck wrote in a paper presented to a seminar in Munich this week. The current standard airliner configuration, now more than 50 years old, comes from the B-47 bomber that Boeing built for the U.S. Air Force early in the Cold War. Among its advantages, the fuselage is fairly light, because its tubular shape is ideal for withstanding the pressurisation that passengers need when they fly at high altitudes. LESS FUEL, POLLUTION, NOISE The BWB's designers tried to find out what advantages they could get if they did without that tube and instead gave the wing a fat middle section for accommodation. The results were astonishing. Boeing calculates that a BWB seating 480 passengers would use 32 percent less fuel than the proposed A380-700 from Airbus, the main business unit of European aerospace group EADS (EAD) (EAD). The plane would weigh 19 percent less, suggesting that it would cost less to build. And it would need 19 percent less thrust, saving on engine manufacturing and maintenance costs. Needing less thrust, the aircraft would emit less pollution. And it would a lot be quieter, Boeing's research suggests. Its shape could also give it a little more speed than normal jet airliners have. A ROOM WITH NO VIEW So if the BWB is so good, why hasn't Boeing built it? One answer is that the company has been solving some of the problems that the new shape would present, such as how to evacuate it in an emergency. It also has one potentially serious drawback: almost no passenger would have a window. The accommodation section would be wide, rather than long, with passengers sitting in a series of side-by-side rooms largely sealed off from the outside. "The primary issue we really have to get comfortable with is the passenger-acceptance factor," Leibeck told the Munich-based Institute for Flight and Aerospace. The obvious answer is to fit big television screens showing what is going on outside, making every seat a window seat. Some engineers and industry analysts think even that would be unnecessary. Passengers sitting in the middle seats of current wide-body airliners already have little view of the outside, and few people complain when the cabin attendants close the window shutters at night. Roger EWROPS