yes, i informed about
https://en.wikipedia.org/wiki/Aurora_D8
but it dont looks having much sense


twin tail can be used as noise shield for unducted fun only,
so, it will be fun to imagine future planes in 3 different categories:

1) common planes with very big engines.

1a) will it be DC-9 style return?

(i dont hink V-tail useful for pax)
or
1b) just A380-style gull-shaped wing?
1c) up-on-wing variants

(blended wing not an option)
or something else?

2) unducted fun


current ideas is to use tail structure around fun as noise shield (Aurora D8 and other models (cant find now))

is there possible to invent well-CFRP unducted fun with low noise and no sonic boom?

3) unusual planes

this boeing picture looking for me as common biplane/strut monoplane with combination of disadvantages
but this backed to 2010
https://www.nasa.gov/topics/aeronautics ... lanes.html
and still here
https://www.airlineratings.com/news/boe ... ng-design/

joined wing seems no useful too.

i am personaly prefer triplane (avanty) layout with one big prop between tales plus one common jet engine for takeoff and backup

full or almost-full electro planes is too different on topic imho.

whats is top on the line now?

Armadillo1 wrote:

1) common planes with very big engines.

1a) will it be DC-9 style return?

(i dont hink V-tail useful for pax)
or
1b) just A380-style gull-shaped wing?
1c) up-on-wing variants

(blended wing not an option)
or something else?

Aviation Week has a slideshow with a bunch of concepts, mainly involving boundary layer ingestion.
https://aviationweek.com/future-aerospa ... es-1962838

Lightsaber mentioned that Airbus had a convincing presentation about a 250-seat blended wing body aircraft recently. I don't know if he has or is willing to spill the details, though. That would be great to see as a response to the Boeing MOM, though I think they're probably too conservative to do it. I wouldn't mind a windowless cabin as long as the seats and aisles are spacious. (How small can BWB scale down to efficiently, anyway?)

2) unducted fun


current ideas is to use tail structure around fun as noise shield (Aurora D8 and other models (cant find now))

is there possible to invent well-CFRP unducted fun with low noise and no sonic boom?

You've seen and responded to my thoughts on unducted fans/propfans in the Why didn't McDonnell-Douglas get bailed out? thread a few weeks ago. I'll also add that the low-noise, no sonic-boom UDF existed in the 1980s, and the technology was rejected for reliability and maintenance reasons, and not because of acoustic/speed performance. McDD took executives and media on test flights and got a favorable reaction. They also took it to Farnborough 1988 for daily flights. The company wouldn't be dumb enough to put on a thunder show in front of the public if it wanted to sell the MD-91/92 as a passenger airliner.

Douglas begins MD-90 hard sell (Flight International magazine, February 27, 1988)

This month Douglas stepped up its MD-90 sales campaign by flying executives from these and other airlines in its propfan-powered MD-80 ultra-high-bypass (UHB) demonstrator.

If these flights prove anything, it is that the engine's unusual configuration is not an issue. Airline executives were mainly interested in the engine's cost and its reliability and maintainability. Passenger acceptance seems certain, although Douglas and GE have still to achieve the promised "completely vibration-free cabin environment".
…
Douglas claims that the MD-90s will be the ' "quietest aircraft in the industry." Watching the demonstrator take-off with another load of airline executives aboard, just after a Boeing 727 and before an MD-80, one could see this prediction coming true—especially bearing in mind the continued development being applied to both airframe and engine.

3) unusual planes

this boeing picture looking for me as common biplane/strut monoplane with combination of disadvantages
but this backed to 2010
https://www.nasa.gov/topics/aeronautics ... lanes.html
and still here
https://www.airlineratings.com/news/boe ... ng-design/

joined wing seems no useful too.

i am personaly prefer triplane (avanty) layout with one big prop between tales plus one common jet engine for takeoff and backup

full or almost-full electro planes is too different on topic imho.

whats is top on the line now?

I like the truss-braced wing, but Boeing seems to be taking its sweet time in developing the plane. I bet we don't see much difference in airplane design in the 2030s -- maybe longer landing gear or gull wings to accommodate larger GTFs, and that's it. Especially if you leave things to the market and the current crop of airlines. It will take some sort of outside interference -- government emissions regulations, MHI/Japan building an unconventional new plane with support from their domestic airlines, or the same from China -- to end this caution (or cowardice, depending on your point of view).

I dont think any bwb useful for pax due deboarding sertification

Wow... what all is going on in that rendering?!?

1. BWB / "Flying Wing"- Okay, proven as a concept but not without serious challenges when one tries to adapt it to a passenger-carrying role.

2. Attaching a T-tail to a stubby BWB? Completely unnecessary because: A. BWBs are perfectly capable of controlling pitch without a separate tail plane, B. Because of its close proximity to that long (near the fuselage) chord BWB wing, a T-tail in that application would have almost no control authority at low speeds.

3. If you're going to have engines in that position, why not attach them to the fuselage rather than suspend them on struts attached to and behind the wing?

It is Lockheed proposal for galaxy replacement.
Wings unpressurised
Idea was to mount engines on wing which carry it and less structure to hold weight on tail

As i see even for military transport role you cant fit your load into bwb and still need a fuselage much longer than bwb chord. And idunno how bwb works with long fuselage

About md80 udf- it was geared or not?

Armadillo1 wrote:

It is Lockheed proposal for galaxy replacement.
Wings unpressurised
Idea was to mount engines on wing which carry it and less structure to hold weight on tail

Ah. Lockheed might want to consider this proposal as a better starting point, then-

Armadillo1 wrote:

About md80 udf- it was geared or not?

The General Electric GE36 UDF that flew on the Boeing 727 and the MD-80 was gearless. The lesser-known Pratt & Whitney/Allison 578-DX propfan was geared, and it flew briefly on the MD-80 after the UDF flight testing had completed.

First UDF flight footage on the 727 in 1986: https://www.youtube.com/watch?v=APzO7OVGakw
578-DX flight footage on the MD-80 in 1989 (go to 13:00): https://www.youtube.com/watch?v=W1y5c1lnDVs

Can some one explain the difference between an UnDucted Fan, and a Turboprop? Or between a Ducted fan and a Geared Turbofan?

To the lay person, those “technologies” are very similar, it almost seams like a way to make a turbo prop, without calling it a propeller airplane.

Web500sjc wrote:

Can some one explain the difference between an UnDucted Fan, and a Turboprop? Or between a Ducted fan and a Geared Turbofan?

To the lay person, those “technologies” are very similar, it almost seams like a way to make a turbo prop, without calling it a propeller airplane.

An unducted fan is like in between a turboprop and turbofan. In simple terms, it is like a turbofan but with no duct. It uses fan blades instead of propeller blades. Some people may say that it’s more efficient because of high bypass ratio.

A turboprop uses longer propellers (compared to a fan). At lower altitude and lower speed, turboprop could be considered more efficient than turbofan. However, because more efficient engines have long blades, the engine needs to be mounted high (like DHC-8 with the wing on top of fuselage).

A ducted fan is a term for any aircraft engine with the fan inside a air duct cowl. Most common is turbofan (turbine jet with bypass fan).

A geared turbofan is a turbofan engine with a gearbox for reducing fan rotation speed, which is more efficient for high bypass ratio.

Does it pw1100 turboprop? ))

but more funny to ask does it tu-95 using udf.

I thought term come to distinct high speed unducted fan, geared or not.
Tu-95 is turboprop flying faster than udf)

Web500sjc wrote:

Can some one explain the difference between an UnDucted Fan, and a Turboprop? Or between a Ducted fan and a Geared Turbofan?

To the lay person, those “technologies” are very similar, it almost seams like a way to make a turbo prop, without calling it a propeller airplane.

It's a matter of degree. If the rotation speed is high enough, and the number of blades is high enough, we call it an unducted fan. Otherwise we call it a turboprop. There is no commonly accepted legal border. It's like "when does a pile of sand become a heap of sand? Depends who's looking"

https://www.safran-group.com/media/safr ... e-20171003

Interesting is anywhere more info about this design

CowAnon wrote:

Armadillo1 wrote:

1) common planes with very big engines.

1a) will it be DC-9 style return?

(i dont hink V-tail useful for pax)
or
1b) just A380-style gull-shaped wing?
1c) up-on-wing variants

(blended wing not an option)
or something else?

Aviation Week has a slideshow with a bunch of concepts, mainly involving boundary layer ingestion.
https://aviationweek.com/future-aerospa ... es-1962838

Lightsaber mentioned that Airbus had a convincing presentation about a 250-seat blended wing body aircraft recently. I don't know if he has or is willing to spill the details, though. That would be great to see as a response to the Boeing MOM, though I think they're probably too conservative to do it. I wouldn't mind a windowless cabin as long as the seats and aisles are spacious. (How small can BWB scale down to efficiently, anyway?)

2) unducted fun


current ideas is to use tail structure around fun as noise shield (Aurora D8 and other models (cant find now))

is there possible to invent well-CFRP unducted fun with low noise and no sonic boom?

You've seen and responded to my thoughts on unducted fans/propfans in the Why didn't McDonnell-Douglas get bailed out? thread a few weeks ago. I'll also add that the low-noise, no sonic-boom UDF existed in the 1980s, and the technology was rejected for reliability and maintenance reasons, and not because of acoustic/speed performance. McDD took executives and media on test flights and got a favorable reaction. They also took it to Farnborough 1988 for daily flights. The company wouldn't be dumb enough to put on a thunder show in front of the public if it wanted to sell the MD-91/92 as a passenger airliner.

Douglas begins MD-90 hard sell (Flight International magazine, February 27, 1988)

This month Douglas stepped up its MD-90 sales campaign by flying executives from these and other airlines in its propfan-powered MD-80 ultra-high-bypass (UHB) demonstrator.

If these flights prove anything, it is that the engine's unusual configuration is not an issue. Airline executives were mainly interested in the engine's cost and its reliability and maintainability. Passenger acceptance seems certain, although Douglas and GE have still to achieve the promised "completely vibration-free cabin environment".
…
Douglas claims that the MD-90s will be the ' "quietest aircraft in the industry." Watching the demonstrator take-off with another load of airline executives aboard, just after a Boeing 727 and before an MD-80, one could see this prediction coming true—especially bearing in mind the continued development being applied to both airframe and engine.

3) unusual planes

this boeing picture looking for me as common biplane/strut monoplane with combination of disadvantages
but this backed to 2010
https://www.nasa.gov/topics/aeronautics ... lanes.html
and still here
https://www.airlineratings.com/news/boe ... ng-design/

joined wing seems no useful too.

i am personaly prefer triplane (avanty) layout with one big prop between tales plus one common jet engine for takeoff and backup

full or almost-full electro planes is too different on topic imho.

whats is top on the line now?

I like the truss-braced wing, but Boeing seems to be taking its sweet time in developing the plane. I bet we don't see much difference in airplane design in the 2030s -- maybe longer landing gear or gull wings to accommodate larger GTFs, and that's it. Especially if you leave things to the market and the current crop of airlines. It will take some sort of outside interference -- government emissions regulations, MHI/Japan building an unconventional new plane with support from their domestic airlines, or the same from China -- to end this caution (or cowardice, depending on your point of view).

I cannot find the concept I was discussing.

This one is similar, but two engines:
http://zeger.eu/en/portfolio/bwb-passenger-cabin/

However, there is a flaw in the concept above. Using winglets as rudders is a huge safety flaw. This is why all BWBs revert to 3 or 4 engines.

The concepts of T-tail BWBs do not make sense to me. That voids a huge amount of the drag and weight benefit of a BWB. They are artist conceptions ignoring physics.

I'm personally a fan of podded engines out above the wings, but that only works on larger concepts.

Too many of the OP designs are optimized for Mach 0.65. hint, look for wing sweep. Flights over 1000nm require speed.

Lightsaber

TSS wrote:

Wow... what all is going on in that rendering?!?

1. BWB / "Flying Wing"- Okay, proven as a concept but not without serious challenges when one tries to adapt it to a passenger-carrying role.

2. Attaching a T-tail to a stubby BWB? Completely unnecessary because: A. BWBs are perfectly capable of controlling pitch without a separate tail plane, B. Because of its close proximity to that long (near the fuselage) chord BWB wing, a T-tail in that application would have almost no control authority at low speeds.

3. If you're going to have engines in that position, why not attach them to the fuselage rather than suspend them on struts attached to and behind the wing?

That design requires a huge tail in an engine out situation. It is a horrible design from the efficiency standpoint in commercial duty.

The compass rose highlights the AirForce sale... (Their EAFB flight test center).

Lightsaber

lightsaber wrote:

TSS wrote:

Wow... what all is going on in that rendering?!?

1. BWB / "Flying Wing"- Okay, proven as a concept but not without serious challenges when one tries to adapt it to a passenger-carrying role.

2. Attaching a T-tail to a stubby BWB? Completely unnecessary because: A. BWBs are perfectly capable of controlling pitch without a separate tail plane, B. Because of its close proximity to that long (near the fuselage) chord BWB wing, a T-tail in that application would have almost no control authority at low speeds.

3. If you're going to have engines in that position, why not attach them to the fuselage rather than suspend them on struts attached to and behind the wing?

That design requires a huge tail in an engine out situation. It is a horrible design from the efficiency standpoint in commercial duty.

The compass rose highlights the AirForce sale... (Their EAFB flight test center).

Lightsaber

Efficiency is way down on the list compared to cargo capability and everything that comes with that. If that wasn't the case then Boeing would have pitched the 787 for the tanker, and Airbus the A350.

TSS wrote:

Wow... what all is going on in that rendering?!?

1. BWB / "Flying Wing"- Okay, proven as a concept but not without serious challenges when one tries to adapt it to a passenger-carrying role.

2. Attaching a T-tail to a stubby BWB? Completely unnecessary because: A. BWBs are perfectly capable of controlling pitch without a separate tail plane, B. Because of its close proximity to that long (near the fuselage) chord BWB wing, a T-tail in that application would have almost no control authority at low speeds.

3. If you're going to have engines in that position, why not attach them to the fuselage rather than suspend them on struts attached to and behind the wing?

1. This is not even being considered for PAX.

2. It's almost literally the back end of a C-5 attached to new structures.

3. Attaching them to the fuselage reduces cargo space due to everything attached to the engine. It would also make this particular setup prone to sitting on its ass.

https://www.flightglobal.com/news/artic ... pt-459783/
https://www.airbus.com/newsroom/news/en ... neers.html



Airbus showed even more crazy pics.

looks like cheap PR on nothing. - 4 props on small aircraft (even if only two engines its out of economical reason), no vertical tail, funny but unknown reason multiwingtips (of course f1 guys can draw even more planes)
props looks too small for so much gull wing, centerplane itself with no frame continuity, etc,etc.

even for fun they can draw more realistic pics.

torn british flag is another one joke.

Armadillo1 wrote:

https://www.safran-group.com/media/safran-celebrates-successful-start-open-rotor-demonstrator-tests-new-open-air-test-rig-southern-france-20171003

Interesting is anywhere more info about this design

There was this thread, starting in 2017: viewtopic.php?f=5&t=1375967
The most detailed article is in Flug Revue (German): https://www.flugrevue.de/flugzeugbau/tr ... tor/747206

lightsaber wrote:

This one is similar, but two engines:
http://zeger.eu/en/portfolio/bwb-passenger-cabin/

However, there is a flaw in the concept above. Using winglets as rudders is a huge safety flaw. This is why all BWBs revert to 3 or 4 engines.

The 11-abreast, 80-passenger regional jet version looks cool, but it appears you have to crawl to enter the aircraft?

Can somebody elaborate on the two bolded sentences?

===

Concerning unducted fans/open rotors, there are a couple of creative propeller concepts where the front and back propellers are swept coaxially in opposite directions.

One is NASA's "inherently ducted prop" (https://www.techbriefs.com/component/co ... inery/5420), where the front and back propellers are swept toward each other. The blades of the larger-diameter back prop extend forward around the end of the front prop, forming sort of a spinning shroud to suppress noise from the front prop. However, there seems to be nothing else on the internet about inherently ducted props, so it may be dead.

The other is the Boxprop from Chalmers University of Technology in Sweden (https://www.chalmers.se/SiteCollectionD ... 821_v1.pdf). Pairs of blades in the forward-swept front propeller are attached at their tips to reduce tip vortexes, which lowers noise and lets designers avoid shortening the back blades (the typical solution for reducing drag/noise caused by vortexes interacting with the back propeller, but at the cost of reduced thrust). GKN appears to be one of the sponsors of the research, so it looks like there's more support for the Boxprop.

CowAnon wrote:

Armadillo1 wrote:

https://www.safran-group.com/media/safran-celebrates-successful-start-open-rotor-demonstrator-tests-new-open-air-test-rig-southern-france-20171003

Interesting is anywhere more info about this design

There was this thread, starting in 2017: viewtopic.php?f=5&t=1375967
The most detailed article is in Flug Revue (German): https://www.flugrevue.de/flugzeugbau/tr ... tor/747206

lightsaber wrote:

This one is similar, but two engines:
http://zeger.eu/en/portfolio/bwb-passenger-cabin/

However, there is a flaw in the concept above. Using winglets as rudders is a huge safety flaw. This is why all BWBs revert to 3 or 4 engines.

The 11-abreast, 80-passenger regional jet version looks cool, but it appears you have to crawl to enter the aircraft?

Can somebody elaborate on the two bolded sentences?

More engines means you need much less yaw authority. So maybe that's why more engines are better for a BWB?

CowAnon wrote:

The other is the Boxprop from Chalmers University of Technology in Sweden (https://www.chalmers.se/SiteCollectionD ... 821_v1.pdf). Pairs of blades in the forward-swept front propeller are attached at their tips to reduce tip vortexes, which lowers noise and lets designers avoid shortening the back blades (the typical solution for reducing drag/noise caused by vortexes interacting with the back propeller, but at the cost of reduced thrust). .

thank you
i try to imagine variable pitch on this thing

Armadillo1 wrote:

CowAnon wrote:

The other is the Boxprop from Chalmers University of Technology in Sweden (https://www.chalmers.se/SiteCollectionD ... 821_v1.pdf). Pairs of blades in the forward-swept front propeller are attached at their tips to reduce tip vortexes, which lowers noise and lets designers avoid shortening the back blades (the typical solution for reducing drag/noise caused by vortexes interacting with the back propeller, but at the cost of reduced thrust). .

thank you
i try to imagine variable pitch on this thing

Look at page 24 on the attached presentation, it appears to show each 'Boxprop' blade rotating as a whole. My curios side wonders if you could have a boxprop whereby there was a degree of independence in the two sides being able to twist with some flex.

Fred

Starlionblue wrote:

CowAnon wrote:

lightsaber wrote:

This one is similar, but two engines:
http://zeger.eu/en/portfolio/bwb-passenger-cabin/

However, there is a flaw in the concept above. Using winglets as rudders is a huge safety flaw. This is why all BWBs revert to 3 or 4 engines.

The 11-abreast, 80-passenger regional jet version looks cool, but it appears you have to crawl to enter the aircraft?

Can somebody elaborate on the two bolded sentences?

More engines means you need much less yaw authority. So maybe that's why more engines are better for a BWB?

Okay, but with the airlines seemingly allergic to anything with more than 2 engines these days, does that mean there's no chance for BWB aircraft to break into the airliner market?

flipdewaf wrote:

Armadillo1 wrote:

CowAnon wrote:

The other is the Boxprop from Chalmers University of Technology in Sweden (https://www.chalmers.se/SiteCollectionD ... 821_v1.pdf). Pairs of blades in the forward-swept front propeller are attached at their tips to reduce tip vortexes, which lowers noise and lets designers avoid shortening the back blades (the typical solution for reducing drag/noise caused by vortexes interacting with the back propeller, but at the cost of reduced thrust). .

thank you
i try to imagine variable pitch on this thing

Look at page 24 on the attached presentation, it appears to show each 'Boxprop' blade rotating as a whole. My curios side wonders if you could have a boxprop whereby there was a degree of independence in the two sides being able to twist with some flex.

Fred

The geometry of the paired blades and variable pitch is confusing. The inherently ducted prop article had a related concept where the aft blades were also attached at their tips. I guess with forward sweep, the blades may need that extra reinforcement to handle the stresses.

A Romanian flying saucer called ADIFO made headlines last year. It can supposedly fly at supersonic speeds.

https://newatlas.com/adifo-flying-sauce ... ian/58999/

Airbus revealed its MAVERIC blended wing body concept yesterday.

https://www.cnn.com/travel/article/airb ... index.html



Avio Aero, Leonardo, GE, and Dowty are working on IRON, which looks like a UDF-style contra-rotating open rotor engine, but only the front propeller rotates. The back propeller does have a variable pitch mechanism to capture the swirl energy resulting from the front propeller. The engine is attached to the horizontal stabilizer instead of directly to the rear fuselage. IRON is targeted for 90 and 130-seat planes.

https://www.magazineabout.com/Research- ... he-horizon (video embedded in article)

The composite cycle engine from Bauhaus Luftfahrt (a consortium between Airbus, MTU, and a couple other German entities) combines piston and turbofan technology to reach a pressure ratio of over 300 and a bypass ratio of 33.7. (For comparison, GE's UDF had a BPR of 35.) However, it's targeted for 50-seat planes, since it only produces about 5 tons of thrust but weighs over 7 tons.

https://www.bdli.de/en/innovation_of_th ... discovered
http://www.ultimate.aero/media/Technica ... 0sheet.pdf

main difference for airbus BWB is vertical stabilisers. may be solution for balance issues, but i still wonder about various parasite drag for any bwb