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Posted on 04/18/2008 10:41:03 PM PDT by Paleo Conservative
Airbus has filed a patent application for a new commercial trijet, reviving interest in a powerplant configuration abandoned by airliner manufacturers for two decades,
The patent application, published by the US Patent and Trademark Office on 27 March, shows a new trijet design featuring a distinctive, noise-shielding tail structure.
But Airbus's North American division has downplayed the design's relevance to the airframer's future plans: "Airbus is regularly filing patent applications and this is normal business for a company that is a leader in innovation and technology," the company says. "That's not to say this is 'the' design we're looking at in the future - just one of a very many possibilities."
Two trijets - Lockheed's L1011 TriStar and the McDonnell Douglas DC-10 - led the long-haul widebody market in the 1970s, but the type's long-term popularity was limited by excess cabin and environmental noise created by the aft-mounted engine, as well as the extra fuel burn.
More powerful - and reliable - powerplant designs allowed airframers to safely shift to twin-engined types for long-haul flights, leaving four-engined aircraft as the only widebodies in production with more than two powerplants.
The Airbus patent filing, assigned to inventors Olivier Cazals, Jaime Genty De La Sagne and Denis Rittinghaus, argues that a new type of trijet can become viable again in the future. The twin-tail fin is reminiscent of the "butterfly tail" design proposed by Avro in the 1950s for its Avro 740 trijet narrowbody.
Twin-engined aircraft are burdened by turbofans with "ever-increasing mass and size, thereby making it necessary for the aircraft structure [fuselage, wings and landing gear, in particular] to be designed accordingly," says the patent application.
The Airbus inventors claim a trijet can compete against twinjets by using a tail-structure that doubles as a noise shield. Exhaust from the aft-mounted engine enters a channel framed by upwardly inclined horizontal stabilisers laid out in a "very open V" and the two fins.
This design "makes it possible to considerably reduce the previous acoustic problems, since the noise generated by the third engine of the fuselage is sucked up by the channel", the patent document says.
The tail structure and the third engine add weight and new structural complexity, but the Airbus inventors counter that the trijet can still beat a twin-engined type on fuel efficiency through offsetting improvements.
The added weight of the tail "is largely compensated for the by the drop in the mass of the landing gear, the reason being that the landing gear is dimensionally smaller and less voluminous given the smaller engines".
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They are adding a lot of weight at the rear. Given how far forward the wing is, and it appears the main gear as well, they might be able to get the nose gear off the ground while the plane is standing still.
I wonder if the real plan is to try to make it fly on center engine, and use the ones on the wing for take off and climb. That might save some gas.
And Boeing thinks they don’t have to do anything. The Air Force tanker business should be an entitlement they believe.
Their new Dreamliner may never get delivered. I guess that’s what happens when you have no competition.
No comprende, amigo.
Sorry.
Boeing thinks they’re entitled to the Air Force’s tanker contract without any competition. They lost it to Northrop Grumman - EADS and now they’re whining with every lame excuse in the book. This is after they were exposed for cheating the Air Force and the American taxpayer.
The management at Boeing should be looking for jobs.
Best ride was Virgin’s older 747-200 with the extra fuel tanks and a 12 seat/bed (only) first section up stairs.
Always had two stews up stairs. One would be a short, cute, very perky blonde who you knew had saved herself for you, and the other a tall brunette with long thick black hair, who obviously hadn’t saved herself for you, but seemed willing to correct her mistake the next evening.
They would open the door to the flight deck if you could show a pilot’s license. They would do it about dawn on the eastbound TA flights. Wonderful.
One flight MCO-LGW, the Captain was Nigel, Very much a Bomber Command man, complete with the proper mustache and attitide.
Co-pilot was Daphne. She was about 25, with about 5000 hours, movie star cute with a titled very rich father who had insisted she do something “worthwhile,” and then bought her a hew turbo Aztec so she could learn to fly.
FE was Frank, a 73 yr old retired American Airlines captain from Booston with 7500 PIC time in a 747, who now lived in the Cotswolds and flew a “half schedule” or more properly a “ha shed-u-al”, one trip a week to the US.
The good old, pre-9/11 days.
They’re gonna need tail attachments a hell of a lot stronger than on AA587.
Question..why couldn’t you have this configuration, but shut off the tail engine once cruising altitude is reached. It is also available in case of an failute of one of the other two.
The L-1011 wasn't the first to use it.
i guess sitting in the rear might not be the most survivable seating anymore...
Way, way back in the mists of time, I flew on one of these. I remember it was very noisy.
But probably lighter than the DC-10/MD-11 banjo fitting.
Assuming you can start it up quickly in an emergency.
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