Why are there no Commercial or civil lifting body/blended wing aircraft?

[Kinglet]

I have noticed that there do not seem to be any active commercial or civil aircraft that have pure lifting body or blended wing fuselages. Why? A large number of aircraft has accidental lifting body fuselages, but still rely on their wings. Is there a reason why lifting body and blended wing designs are almost not used? Or are these aircraft designs used actively in civil and commercial aircraft?

Edited July 28, 2014 by Kinglet

[cpast]

Most sizeable blended wing designs I've seen have been extremely wide aircraft, which not only is less comfortable for passengers (less natural light), but poses serious problems for emergency evacuation, making them unsuitable for commercial passenger service. I'd assume another reason is that there has been a LOT of work done making conventional aircraft cheaper, driving the price to use normal planes low enough there's no benefit for freight operators doing something different.

[Kinglet]

Most sizeable blended wing designs I've seen have been extremely wide aircraft, which not only is less comfortable for passengers (less natural light), but poses serious problems for emergency evacuation, making them unsuitable for commercial passenger service. I'd assume another reason is that there has been a LOT of work done making conventional aircraft cheaper, driving the price to use normal planes low enough there's no benefit for freight operators doing something different.

But what about small civil lifting body aircraft that hold a few people?

[Traches]

Because a lifting body is optimized for supersonic flight. It's the opposite of a flying wing, which is best for subsonic flight, but is naturally unstable and presents its own design challenges.

[sgt_flyer]

one of the problems with BWB, is they have a drastically different flight model - no ones really knows what kind of flight characteristics to expect. (which is why Nasa and boeing are experimenting with the x-48 UAV to determine those flight characteristics).

you will also need to overcome serious structural problems - closed 'tube like' structures like most planes are, is a very good structure, very resistant to pressures, etc. BWB designs have - by design, large 'flat' surfaces - which can more easily be affected by pressure differences, etc - to devellop a support structure which will handle these kind of shapes lightweight enough to be used on a plane is going to be hard.

for all the research needed on those concepts, i don't see most manufacturers of civil aircrafts throwing money at such an heavy R&D process as the one of designing a radical design by themselves

(they have Boeing and Nasa doing the work for them )

Edited July 28, 2014 by sgt_flyer

[Kinglet]

one of the problems with BWB, is they have a drastically different flight model - no ones really knows what kind of flight characteristics to expect. (which is why Nasa and boeing are experimenting with the x-48 UAV to determine those flight characteristics).

you will also need to overcome serious structural problems - closed 'tube like' structures like most planes are, is a very good structure, very resistant to pressures, etc. BWB designs have - by design, large 'flat' surfaces - which can more easily be affected by pressure differences, etc - to devellop a support structure which will handle these kind of shapes lightweight enough to be used on a plane is going to be hard.

for all the research needed on those concepts, i don't see most manufacturers of civil aircrafts throwing money at such an heavy R&D process as the one of designing a radical design by themselves

(they have Boeing and Nasa doing the work for them )

In ten years:

Civil aircraft manufacturers: "Can we haz research data plz?"

NASA: "NO!"

Civil aircraft manufacturers: "Plzzzzz! We will pay!"

NASA: "Okay!"

[Idobox]

Flying wing designs are also notably harder to design, most importantly for stability issues.

Definitely feasible (it's been done several times for military aircraft), but a big risk for a civilian aircraft manufacturer in a very competitive market.

The first plane of this type flying will likely be developed by Airbus or Boeing, because fuel consumption is quickly becoming VERY important for airline companies, and they are big enough to absorb the risk to develop a small plane.

[shynung]

In ten years:

Civil aircraft manufacturers: "Can we haz research data plz?"

NASA: "NO!"

Civil aircraft manufacturers: "Plzzzzz! We will pay!"

NASA: "Okay!"

They won't even have to pay; NASA are generally open about the research data they have.

[PlonioFludrasco]

This is not lifting body, but the so called "best wing configuration", or more technically Prandtlplane configuration

An interesting design too, because is scalable to commercial aircrafts sizes.

Edited July 28, 2014 by PlonioFludrasco

[Kinglet]

This is not lifting body, but the so called "best wing configuration", or more technically Prandtlplane configuration

http://www.idintos.eu/wp-content/uploads/2011/09/idintos-ult-config.jpg

An interesting design too, because is scalable to commercial aircrafts sizes.

Isn't that also called boxwing configuration?

[PlonioFludrasco]

Isn't that also called boxwing configuration?

Yes, it's the same

[DaveofDefeat]

They won't even have to pay; NASA are generally open about the research data they have.

Nasa is actually required to give that kind of stuff away for free. Its the reason we have memory foam!

[Kerbart]

I have noticed that there do not seem to be any active commercial or civil aircraft that have pure lifting body or blended wing fuselages. Why? (...)

Aside from technical reasons mentioned, the aircraft industry believes (probably based on thorough research given the vast amounts of money involved) that many passengers will have a hard time flying in an airplane without a lot of windows, which is what pure lifting bodies are. For the same reason selling airliners with no windows (making the hull much stronger) is next to impossible.

[Red Iron Crown]

Nasa is actually required to give that kind of stuff away for free. Its the reason we have memory foam!

Only if it is released at all, some of their research is classified. Once published, though, it goes into the public domain, like all works of the US federal government.

[cpast]

Only if it is released at all, some of their research is classified. Once published, though, it goes into the public domain, like all works of the US federal government.

There are, however, plenty of things produced by the federal government that are unclassified yet not made available to the public for free (just because it's public domain, doesn't mean you can't charge for it or have to give it to anyone who asks; you just can't stop anyone who has it from doing with it what they please). For that, though, there's always FOIA.

[Sky_walker]

just because it's public domain, doesn't mean you can't charge for it

It actually does. What they charge you for are services around it or a specific implementation that isn't public domain.

[Seret]

(making the hull much stronger)

Hull? It's not a boat, it has a fuselage

Although I do admit that aviation nomenclature is a mishmash of nautical and obscure French, so it's a bit confusing. They may have bulkheads and use port/starboard, but they don't have portholes. Go figure.

[Red Iron Crown]

It actually does. What they charge you for are services around it or a specific implementation that isn't public domain.

That's not so. I can print copies of a public domain work and charge for them, or host those documents on a website and charge for access. The whole point of public domain is one can do what one likes with it; if I can convince someone to pay for PD content there is nothing stopping me. Cpast's correction of my post is accurate (thanks, cpast!). The only thing PD prevents is sale of intellectual property rights, so no patents, trademarks or copyrights.

[Sky_walker]

[softweir]

That's not so. I can print copies of a public domain work and charge for them, or host those documents on a website and charge for access. The whole point of public domain is one can do what one likes with it; if I can convince someone to pay for PD content there is nothing stopping me. Cpast's correction of my post is accurate (thanks, cpast!). The only thing PD prevents is sale of intellectual property rights, so no patents, trademarks or copyrights.

That depends on the licence of the individual PD document. Some forbid you to even charge for making copies! You need to read each licence to make sure you are complying with the wishes of the creator.

[Red Iron Crown]

That depends on the licence of the individual PD document. Some forbid you to even charge for making copies! You need to read each licence to make sure you are complying with the wishes of the creator.

It's public domain, there is no license. License implies that the copyright is still held by someone, public domain implies no copyright (either because it has expired or the copyright holder has relinquished those rights).

[mrfox]

Back on topic...

Some practical issues rgd BWB in commercial service I can think of are:

Wing fineness and aspect ratio - if your aircraft has a thick wing, its chord and span needs to be scaled up also, otherwise the wings performance will be sub-optimal. You end up with a massive design that does not fit any of the current runways and airport facilities avlb.

Loading, center of gravity, center of rotation issues - Most BWB designs lack a tail, which makes load balancing extremely critical. Same with lateral balance - You will need to load very symetrically and wont be able to tolerate much imbalance. In a passenger setting this means few to no movement can be tolerated in flight. There is also the issue of vertical accelerations experienced during roll manuevers by passengers on the outer extremes of the cabin. As they are so far out from the center of rotation, it will be quite the nauseating and uncomfortable ride - made worse by the lack of outside references - every turn will be a barf fest.

The lack of a tail also mean that the wing will not be able to take full advantage of the high lift devices typically used in most commercial aircraft for takeoff and landing - which means that its runway requirements, comparaed to an aircraft of similar performance, at anywhere near comparable weights, will be extraordinary (in a bad way).