Lifting body airliner model prototype flies.

[Corsairfoxfouruncle]

Came in my news feed tonight. 
 

https://www.cnn.com/travel/amp/flying-v-maiden-flight-intl-scli-grm/index.html

 

Dennis

Edited September 6, 2020 by Corsairfoxfouruncle

[noelh]

Interesting, calling it futuristic is a bit much. Flying wings are hardly new. But it would be nice to see a full  size version. 

Getting it into service is another thing. The traditional 'tube' airliner has the advantage of greater flexibility when it comes to differing versions and passenger capacity. Increasing capacity in this airliner would  mean new wings in effect.

 

But it's a great looking  design.

 

 

[Work In Progress]

Also inherent problems with emergency evacuation, and who wants to sit in the middle of a row of 30 seats?

[wellsprop]

On 9/6/2020 at 8:48 AM, Corsairfoxfouruncle said:

Came in my news feed tonight. 
 

https://www.cnn.com/travel/amp/flying-v-maiden-flight-intl-scli-grm/index.html

 

Dennis

 

On 9/8/2020 at 12:27 AM, noelh said:

Interesting, calling it futuristic is a bit much. Flying wings are hardly new. But it would be nice to see a full  size version. 

Getting it into service is another thing. The traditional 'tube' airliner has the advantage of greater flexibility when it comes to differing versions and passenger capacity. Increasing capacity in this airliner would  mean new wings in effect.

 

But it's a great looking  design.

 

 

It's definitely a much better design in terms of aerodynamics, hence why it's been investigated.

 

I'd go as far as suggesting the biggest difficulty is the huge investment cost needed to actually make a vastly different design. Not to mention the manufacturing issues and pressurisation issues.

 

I wonder if the engine position will create boundary layer ingestion issues too.

[Graham Boak]

Flying wing airliners have been the way of the future, according to their afficionados, from decades before I was born until now a decade after I retired.  Excuse me if I don't leap into the air with excitement at this latest turn of the wheel.  Granted the ability to rapidly micro-control small disturbances in the flightpath has been a giant leap in their credibility, but many other problems remain (as partially listed above), and this comes with a massive increase in software to be created, tested, and monitored.   Such is, admittedly, at least partially required by more conventional designs with reduced stability.  Nonetheless, it requires a considerable increase in design and testing costs which has to be balanced against the presumed promising economics for such designs .

 

 

[depressed lemur]

The other consideration here will be passenger comfort.  If any of you have experienced a lively landing in heavy winds it can be quite an experience even at the front and rear extremities.  How much will this be enjoyable sat halfway out on the wing is anybody's guess.

 

On the really negative side, those who pay for the window seat will get a really spectacular view if it goes down. If I recall, the crash of American Airlines  DC-10 flight 191 resulted in the removal of cameras from the nose gear showing live on the screen in the cabin for that reason as it was believed that the passengers could see the whole event.

[wellsprop]

1 hour ago, Graham Boak said:

Flying wing airliners have been the way of the future, according to their afficionados, from decades before I was born until now a decade after I retired.  Excuse me if I don't leap into the air with excitement at this latest turn of the wheel.  Granted the ability to rapidly micro-control small disturbances in the flightpath has been a giant leap in their credibility, but many other problems remain (as partially listed above), and this comes with a massive increase in software to be created, tested, and monitored.   Such is, admittedly, at least partially required by more conventional designs with reduced stability.  Nonetheless, it requires a considerable increase in design and testing costs which has to be balanced against the presumed promising economics for such designs .

 

 

Bang on. Modern, conventional airliners (A350, A320 NEO family, 787) are just so good now that there is no business case for putting up billions to design an aircraft that might be 20% more efficient (and don't get me wrong, given how efficient modern aircraft are, 20% is a huge improvement).

 

50 minutes ago, depressed lemur said:

On the really negative side, those who pay for the window seat will get a really spectacular view if it goes down. If I recall, the crash of American Airlines  DC-10 flight 191 resulted in the removal of cameras from the nose gear showing live on the screen in the cabin for that reason as it was believed that the passengers could see the whole event.

I've never come across that! Did some googling, in fact, it seems even worst, the camera was supposedly mounted in the cockpit! https://www.nytimes.com/1979/05/27/archives/dive-may-have-been-televised.html

 

That said, the new 777s and A350s (among others) have cameras for the passengers view.

[Mike]

That's a bit more fancy than your average tube

[mackem01]

Hmm, looks like a fixed wing version of Barnes Wallace's projected Swallow design.

[noelh]

I've long said, many others too, is that in technology we humans have reached  a point where can build just about anything we can think of. Supersonic airliners, been there done that. Rocket to moon, yes. A space shuttle that can fly back to Earth. A giant space station. Huge airliners. Fly to Mars. Yes it's doable. 

 

But the subsequent fate of many of the above tells us just because it's possible doesn't  mean it's needed or affordable or even useful. 

 

Depressed Lemur made a good point  about  passengers out on the wing tip. It would be quite the fair ground ride. Also if an aeroplane is maintaining a 1g turn at the centreline. What g force will the outer wings experience Greater than 1 or the same? My shakey aerodynamics has no answer. Then when rolling level will the upper wing  passengers float off their seats while the lower pax are crushed. What about  centrifugal and centripetal force? ???

 

 

So it may  just  be another paper aeroplane or is that digital these days?

 

Edited September 11, 2020 by noelh

[wellsprop]

1 hour ago, noelh said:

Depressed Lemur made a good point  about  passengers out on the wing tip. It would be quite the fair ground ride. Also if an aeroplane is maintaining a 1g turn at the centreline. What g force will the outer wings experience Greater than 1 or the same? My shakey aerodynamics has no answer. Then when rolling level will the upper wing  passengers float off their seats while the lower pax are crushed. What about  centrifugal and centripetal force? ???

 

1g

 

The load factor (g) experienced in a turn is equal to 1/*cos(alpha) where alpha is the bank angle.

 

The centripetal acceleration will be different from one wing to the other (but not noticeably so).

 

a=omega^2 * r, where omega is the angular velocity (rad s^-1) and r is the turn radius.

 

The difference in radius between the left and right wing is insignificant as, even with a wingspan in the 100m range, the turn radius for an airliner is huge. There is less difference in centrifugal acceleration as the bank angle increases.

 

At 90 degrees bank, the turn radius is the same across the aircraft as the aircraft is aligned to the vertical plane. Of course, at 90 degrees bank the load factor is infinite and if you're in an airliner at 90 degrees bank, you have more to worry about than centripetal acceleration. 

[Work In Progress]

The issue is not the G in the steady turn, but in the G variations experienced by outboard passengers when rolling in and out of the turn. These would be substantial effects, by the standards of what airline passengers expect and are capable of tolerating without becoming upset.

[Giorgio N]

This is sure interesting stuff and Delft is one of the best aerospace university in the world, so these guys sure know what they are doing.

At the same time there are so many problems with these configurations that I can't anything similar becoming reality before decades, if ever...

The configuration of an aircraft (or any other man made thing) in the end is the result of an evolutionary process that is similar to the one followed by living creatures and is driven by the same main factor: adapting to the "environment", where the term environment for an aircraft means the needs of the customer. With airliners the needs of the customer are very simple: minimising costs and maximising profit. With the added requirement of following regulations.

If today's airliners all look pretty much the same is simply because their configuration is the one that has proven to be the best to fulfil the typical requirements of an airline. All other configurations of the past have become "extinct" because they were not as suited to such needs. Reason why don't see anything like the Comet or the DC-9 and so on.

Apart from the problems with the passengers mentioned above (that in themselves are serious enough), I can see several other features of this design that would be bad for any ariline. Just to mention one, engines over the wing ? A maintenance nightmare that would force the use of dedicated access equipment. Equipment that is not necessarily expensive but would need to be procured and would have to be used for any engine check, so increasing the time between flights... and increase that time by 10 minutes only on average and the potential profit has decreased.

In the end an aircraft like this will only become interesting when its promised fuel saving capability will compensate by a good margin all the other extra costs involved with the operation of such a configuration. Personally I think will not happen quickly at all

[ckw]

50 minutes ago, Giorgio N said:

The configuration of an aircraft (or any other man made thing) in the end is the result of an evolutionary process that is similar to the one followed by living creatures and is driven by the same main factor: adapting to the "environment", where the term environment for an aircraft means the needs of the customer. With airliners the needs of the customer are very simple: minimising costs and maximising profit. With the added requirement of following regulations.

But sometimes you do get 'mutations' - the 747 is a good example ... when first proposed, there were no commercial airports that could handle it, but in this case the 'environment' was changed to suit.

 

Whether or not this design offers enough advantages to warrant such a radical change is another matter. I've followed the aviation industry long enough to know that theoretical performance improvements seldom survive in full into production models! But if there were a parallel technological development suited to this design (e.g. electric power/alternate fuel), then perhaps it could come to fruition quite quickly. A lot of current airliner design is predicated around the use of large turbofans (hence the problems with the 737MAX). Changes to the powerplant could result in radical changes to airframe design.

 

Cheers,

 

Colin

[Work In Progress]

You;re absolutely right that changes in power unit technology have been the main drivers of airframe design for airliners over the years, and that if we move to fundamentally different forms of power that will have wide-ranging impacts on airframe design again. But that has no bearing on this design because it is predicated on current engines.

[wellsprop]

On the engine side of things...

 

Turbofans need undisturbed freestream airflow, hence they are place beneath and we'll ahead of the leading edge of the wing, far from the fuselage. This also makes it easy to maintain the engines and mechanics have good access.

 

Putting the engines on top, at the back is a fairly bad idea. Particularly so on a large flying wing, are at high angles of attack, the airflow over the body will separate and become turbulent before entering the engines - bad news.

 

Conventional aircraft suffer from compressor stall at high power and high angle of attack (I.e. takeoff) anyway, I can only imagine this design will be even worst.

 

[Giorgio N]

10 minutes ago, wellsprop said:

On the engine side of things...

 

Turbofans need undisturbed freestream airflow, hence they are place beneath and we'll ahead of the leading edge of the wing, far from the fuselage. This also makes it easy to maintain the engines and mechanics have good access.

 

 

Another positive aspect of this configuration is the possibility of adding new powerplants to an existing design very easily. This is something that other engine configurations do not allow and is very important during the life of an airliner design (although not necessarily too important during the life of a single aircraft)

Edited September 15, 2020 by Giorgio N

[Giorgio N]

22 hours ago, ckw said:

But sometimes you do get 'mutations' - the 747 is a good example ... when first proposed, there were no commercial airports that could handle it, but in this case the 'environment' was changed to suit.

 

Whether or not this design offers enough advantages to warrant such a radical change is another matter. I've followed the aviation industry long enough to know that theoretical performance improvements seldom survive in full into production models! But if there were a parallel technological development suited to this design (e.g. electric power/alternate fuel), then perhaps it could come to fruition quite quickly. A lot of current airliner design is predicated around the use of large turbofans (hence the problems with the 737MAX). Changes to the powerplant could result in radical changes to airframe design.

 

Cheers,

 

Colin

 

You make a very interesting point, although I have a different view of the same events...

When I use the word "environment" in the parallel between things and creatures this includes all the factors that an object has to satisfy to "survive". These in the case of an airliner are mainly the customer needs and the regulations. During the '60s the size of existing airports was indeed seen as a potential obstacle to the use of jet liners over a certain size and some customers did take this into account when selecting their equipment. Not all companies however believed the same and as a consequence not all companies worried about this that much. For most airlines in the end the ultimate goal was and still is one: make money ! The 747 had to potential to generate better profits and this more than compensated the costs required to alter the existing airports.

Others saw the length of existing airports as a problem and followed different directions... and we all know the results. But then requirements were different and this led to different designs. And very different commercial success.

 

We can draw a parallel between the airport size debate of the '60s and other issues of today. For example this design aims at a strong fuel economy and this is undoubtedly a serious matter for the airline business. However this same design show critical points in other areas. Is the saving in fuel enough to compensate for the extra costs in these other areas ? If the answer is no then it will never happen. On the contrary, if someone came with a design that requires more fuel but for example allows a quicker turnaround, those companies whose business model relies heavily on fast turnarounds may well be interested. In the end the goal is always the same, generate profit. At least for private companies,

[wellsprop]

If anyone can't find anything better to do on this lovely September summer day, here's some "light" reading material

 

https://www.easa.europa.eu/sites/default/files/dfu/cs-25_amendment_25.pdf

 

EASA CS-25 is the Certification Specification to which all large aircraft must be designed, in order to get a type certificate in Europe.

 

https://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11

 

FAA 14 CFR 25 is the Standard Airworthiness Certification to which all transport aircraft must be designed in order to get a type certification in the USA.

 

I'd be very interested to find out how such an aircraft would behave in a ditching situation (land or sea). This forms part of certification, I honestly don't know if a flying wing would be better or worse. One one hand, a large flat plate (flying wing) might "skip" across the water better than a conventional airliner, but on the other hand, it may pitch nose in and make a mess.

 

What I'm mainly getting is, designing an aircraft in the virtual environment (and even making a large scale model) is only a small part of making an aircraft. Being compliant within the existing regulation framework is a massive challenge, when the framework is largely written around conventional aircraft.

 

Don't get me started on compliance reports...