Tri-jets anyone?

[GTX]

This is patent worthy???

Airbus files patent for new trijet design
By Stephen Trimble

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".

Regards,

Greg

[The Rat]

Well, I ain't a patent lawyer, so any thoughts of mine wouldn't matter. But I'm not sure that just shielding the rear engine would be enough to seriously reduce the noise footprint. But it's given me an idea...

If we want to reduce the noise a lot why not go with an updated version of the VFW-614, with the engines on top of the wing?



But it looks like the engine exhaust is still very close to the trailing edge, so let's try going further and adopt the look of the YC-14 or An-72:



You get a quieter aircraft, and by guiding the jet efflux over the flaps you have STOL abilities. I'm itching to try reconfiguring a Boeing 737. 

[John Howling Mouse]

You get a quieter aircraft, and by guiding the jet efflux over the flaps you have STOL abilities. I'm itching to try reconfiguring a Boeing 737. 

Playing with a 737 to emulate a YC-14?  Well, as long as the final product has a T-Tail, your model should be fantastic!   That much is obvious.

[Hawkeye]

Engines over the wing...check out Hondajet http://www.honda.com/hondajet/
No direct noise or vibration to the cabin. On the ground the engines weight is carried by the main gear not the fuselage...give more inside cabin space too.

Your Airbus Trijet will be a tail sitter...no way around that unless you stretch the fuselage forward of the wing a long ways!

[B777LR]

Maintaining the 2nd engine would be nasty. The MD-11 and DC-10 were a bi*ch i know, and they even had acces below the engine...

Nothing new though, i beleive Boeing has been patenting almost every design and configuration theyve come up with...