sibibom wrote:

Technically ATR is part-owned by Airbus.

And what is now Bombardier was owned by Boeing in the 1990s

32andBelow wrote:

Ok well this is an aviation website not USA Today. People here should know they turboprops are jets engines.

If you want to get pedantic then:

Turboprop is not a jet engine.
Turboprop is a gas turbine.

Most jet engines are also gas turbines.

"Airbreathing jet engines are gas turbines optimized to produce thrust from the exhaust gases, or from ducted fans connected to the gas turbines. Jet engines that produce thrust from the direct impulse of exhaust gases are often called turbojets, whereas those that generate thrust with the addition of a ducted fan are often called turbofans or (rarely) fan-jets."

"A turboprop engine is a turbine engine that drives an aircraft propeller using a reduction gear."

Did anybody read the question? The question was about Boeing and Airbus. The poster didn't say Antonov or BAE or Bombardier, Dornier, ATR,LET etc. I believe he asked Boeng and Airbus...

Matt6461 wrote:

aeromoe wrote:

Matt6461 wrote:

Additional drawbacks of high wing:
-Requires T-tail, which is structurally inefficient.

Umm...no it doesn't. Ever seen the AN-124 and AN-225?

I stand corrected. Thank you.

A more accurate statement would be there must some mechanism - either elevation of the Hstab or enlargement - that accounts for greater wing-Hstab interference with a high wing.

The most common mechanism is the T-tail.

An-124/225 appears to place the Hstab higher than, or at least level with, the wing by curving the rear fuselage upwards and reducing taper on the north end of the fuselage y axis. That's not a free adjustment. It's still paying an Hstab price for the high wing, just not in the currency of T-tail.

In the end the tail has to be much larger/heavier? Thank you for the detailed explanation.

32andBelow wrote:

afterburner wrote:

N766UA wrote:

Of course they are. They’re just not turbojets...

Turboprop and turboshaft are gas turbine engines, just like turbojet and turbofan. However, the majority of people don't know (or don't care) about what type of engine inside an engine cowling. When there is a propeller attached to it, it isn't a jet engine to them.

Ok well this is an aviation website not USA Today. People here should know they turboprops are jets engines.

Being pedantic, no they're not. The thrust is not the result of a jet exhaust, it's the result of the attached propellor.

As mentioned, they both use TURBINES at the core, but a (turbo)jet engine - unsurprisingly - uses the JET for thrust, while a turboprop uses the PROP for thrust.

And being even more pedantic, no modern aircraft uses jet engines!!! They use turbofans. where the FAN provides most of the thrust...

Kent350787 wrote:

sibibom wrote:

Technically ATR is part-owned by Airbus.

And what is now Bombardier was owned by Boeing in the 1990s

Only deHavilland Canada was owned by Boeing (Canada) for a few years jointly with the Ontario Government... and it was sold to Bombardier who already owned Canadair, but Boeing never owned Bombardier.

caflyboy wrote:

Did anybody read the question? The question was about Boeing and Airbus. The poster didn't say Antonov or BAE or Bombardier, Dornier, ATR,LET etc. I believe he asked Boeng and Airbus...

citationjet wrote:

AtomicGarden wrote:

So we can all agree that high wing commercial jets exist but none is large or particularly succesful.

Yes, and also that no high wing commercial jets are made by Airbus and Boeing, which was the question originally asked by the OP.

citationjet wrote:

rutankrd wrote:

Suppose we ignore the following

BAE 146 SERIES
BAE RJX SERIES
DORNIER 328JET
ANTONOV 148
ANTONOV 158
ANTONOV 72
ANTONOV 74
BAADE 152 abject failure admittedly

None of the above are/were high wing then ?

Read the OP. He is asking why Airbus and Boeing don’t build high wing commercial jets. None of your examples are Airbus or Boeing products.

citationjet wrote:

sibibom wrote:

well do ATRs and Bombardiers count?

sholmes wrote:

I would say no: the question is on "commercial jets".

More specifically, the OP's question was why doesn't Airbus and Boeing not build commercial jets with the wings on top. Last I knew, ATRs and Bombardiers were not built by Airbus or Boeing.

citationjet wrote:

bennett123 wrote:

How about the BAE 146

TheFlyingDisk wrote:

Or the Dornier 328 Jet. Or the An-72/74

vhtje wrote:

Whatchu talkin' 'bout, Willis?

The thread title didn't specify manufacturer, but the OP's question was: why Airbus and Boeing never make an airplane with the wing on top?
Sure, there are examples of high wing commercial jets, but none of these were built by Airbus or Boeing.

In fairness, the title is a much broader question: “Why no commercial jets airlines build with wing on the top?”

I think it is not an unreasonable assumption to make when reading the thread title and the opening post together that the original poster was asking about large commercial jet airliners (they specifically mentioned something in the scale of the C-5), and naming Airbus and Boeing as the primary examples of manufacturers of such aircraft, as opposed to specifically wondering why the Boeing Company and the Airbus SE as two companies have not embraced such a configuration.

They are probably not intending a discussion of Dash 8s and ATRs, although those two aircraft are good examples of two different methods of addressing the landing gear issues of high wing aircraft, or about other 70 seat and under turboprops. However the BAe-146 and derivatives and the An-148 and related aircraft may well be of tangential interest since they are 100 seat or more turbofan aircraft.

SomebodyInTLS wrote:

32andBelow wrote:

afterburner wrote:

Turboprop and turboshaft are gas turbine engines, just like turbojet and turbofan. However, the majority of people don't know (or don't care) about what type of engine inside an engine cowling. When there is a propeller attached to it, it isn't a jet engine to them.

Ok well this is an aviation website not USA Today. People here should know they turboprops are jets engines.

Being pedantic, no they're not. The thrust is not the result of a jet exhaust, it's the result of the attached propellor.

As mentioned, they both use TURBINES at the core, but a (turbo)jet engine - unsurprisingly - uses the JET for thrust, while a turboprop uses the PROP for thrust.

And being even more pedantic, no modern aircraft uses jet engines!!! They use turbofans. where the FAN provides most of the thrust...

At the risk of further thread drift, some regulatory regimes simply refer to turbojet and turbopropellor aircraft, lumping turbofan aircraft in the former category (even though there are some very significant differences between turbojets and turbofans from an engineer’s perspective). Also, while the term has mostly dropped out of favour now, there was a period of time where turboprops were referred to as jet-props (I believe trying to make the appeal that they were “modern jet engines” at heart, as opposed to traditional reciprocating engines).

Clipper101 wrote:

It is due to Stability & Control issues that characterize high wing profiles in contrast to low wings:

High wings are more stable at low speeds, less stables at high speeds contrary to low wings which are less stable at low speeds & more stable at high speeds.

In my (admittedly not extensive) reading about aircraft stability and control, I’ve not come across this distinction between high and low wing confirgurations before with regard to speed regime. Could you please elaborate a bit more on it and the factors behind it?

V/F

ZKNCI wrote:

On the positive side, the lifting surface is uninterrupted…

Lots of good stuff there! Just this little bit, I would call into question. In aerodynamics, both sides of the wing are important. Both sides of the wing are involved in generating lift. A clean underside is as beneficial as a clean topside. It's just easier to hang engines from beneath a wing, than to create the structure required to hold them above. Plus, maintenance is easier with the engine below. In fact, the ideal design for a wing is with the engines somewhere else altogether.

In my understanding, the more clean both sides of the wing are, the better. There's no advantage to to having one side clean versus the other.

Many disadvantages, but aerodynamical it's better.

One un-interupted, high aspect ratio lift surface.

Matt6461 wrote:

aeromoe wrote:

Matt6461 wrote:

Additional drawbacks of high wing:
-Requires T-tail, which is structurally inefficient.

Umm...no it doesn't. Ever seen the AN-124 and AN-225?

I stand corrected. Thank you.

A more accurate statement would be there must some mechanism - either elevation of the Hstab or enlargement - that accounts for greater wing-Hstab interference with a high wing.

The most common mechanism is the T-tail.

An-124/225 appears to place the Hstab higher than, or at least level with, the wing by curving the rear fuselage upwards and reducing taper on the north end of the fuselage y axis. That's not a free adjustment. It's still paying an Hstab price for the high wing, just not in the currency of T-tail.

It's not a price for location in lieu of a t-tail, it's getting the fuselage mounted tail (and rear fuselage) up and out of the way for clearance of the rear door. In a way, it's avoiding the t-tail and paying the least price possible by mounting the tail as low as they can.

keesje wrote:

Many disadvantages, but aerodynamical it's better.

One un-interupted, high aspect ratio lift surface.

That's a nice image and all, but I fail to see how the top of the fuselage is acting as a lifting surface, given the absence of leading edge, trailing edge, and underside, all of which are required for an aerofoil to function. Unless the high wing is on struts, raised above the fuselage like an old biplane/triplane, then its lifting ability is still being interrupted by the fuselage.

rutankrd wrote:

Suppose we ignore the following

. . . .
. . . .
BAADE 152 abject failure admittedly

None of the above are/were high wing then ?

The Baade 152 was a minimum change airliner based on the OKB-1 Alekseyev 150 bomber plane, which also failed to be produced and fly as more than prototype.

It had high wing so the wing main spar wouldn't interfere with the bomb bay.

Concept and time frame was identical to the Douglas A3D Skywarrior, which in many ways made Douglas able to respond fast on the Boeing 707 with the DC-8.

The OKB-1 Alekseyev 150 was also designed by Dr. Brunolf Baade, but that was before he was released as slave worker under slave master Semyon Alekseyev.

Why not Baade 151? Since there was a straight line back to the Junkers factories, and its successful Ju 52, then 152 was a very fitting name.

aerolimani wrote:

keesje wrote:

Many disadvantages, but aerodynamical it's better.

One un-interupted, high aspect ratio lift surface.

That's a nice image and all, but I fail to see how the top of the fuselage is acting as a lifting surface, given the absence of leading edge, trailing edge, and underside, all of which are required for an aerofoil to function. Unless the high wing is on struts, raised above the fuselage like an old biplane/triplane, then its lifting ability is still being interrupted by the fuselage.

The body is also generating lift, specially under angles (of attack).

http://freeware.aerosoft.com/forum/scre ... 667e5e.jpg

I'd also argue there's limited market. Most don't need it. I can see places in the north of Canada that are remote for example needing to land on gravel runways and modern high bypass turbofans not able to run those routes. But thats a limited market. There's a reason why they're still flying and upgrading those old 737-200s with gravel kits. I'm not familiar with it but I'm thinking Antonov may have had the same thoughts before things turned bad with the ex soviet world for Ukraine.

It's the same reason why Australia/New Zealand/South Africa/Argentina and Chile have to get used to ETPOS330. Nobody is going to develop an efficient and modern Quad or Trijet just for to serve these smaller markets. There's just not a business case for it.

Some excellent comments regarding engineering and operations of high wing commercial aircraft.

Thank you !

sholmes wrote:

sibibom wrote:

well do ATRs and Bombardiers count?

I would say no: the question is on "commercial jets".
A few commercial jets have however been built with wings on the top, as also recalled in some posts above.

Well a turboprop is a jet engine that spins a propeller.

Can we sum up to:
- landing gear needs space and the wing-box has already the space + it is already robust enough
- With low-wing you have less drag than with high-wng because you do not need both wing-box and MLG box
- fuselage internal space is optimized
- Any positive aspects of high-wing are not relevant in modern airports for passengers airplanes (cargos have different needs)

keesje wrote:

aerolimani wrote:

keesje wrote:

Many disadvantages, but aerodynamical it's better.

One un-interupted, high aspect ratio lift surface.

That's a nice image and all, but I fail to see how the top of the fuselage is acting as a lifting surface, given the absence of leading edge, trailing edge, and underside, all of which are required for an aerofoil to function. Unless the high wing is on struts, raised above the fuselage like an old biplane/triplane, then its lifting ability is still being interrupted by the fuselage.

The body is also generating lift, specially under angles (of attack).

http://freeware.aerosoft.com/forum/scre ... 667e5e.jpg

I really don't think that bump between the wings is doing anything to generate lift. It's just there because the structure that most efficiently supports the wings is passing through. If that part of the fuselage is aerodynamically important to lift-generation, then why is there no deicing boot up there?

As I said, an effective aerofoil functions as a complete and specific shape. Simply continuing the top profile of the aerofoil over the top of the fuselage does not magically turn the fuselage into a lift-generating device. At very best, it will make for some smoother airflow over wing roots, allowing more of the wing to effectively generate lift. That area itself, however, is not doing anything to lift the plane into the air.

aerolimani wrote:

keesje wrote:

aerolimani wrote:

That's a nice image and all, but I fail to see how the top of the fuselage is acting as a lifting surface, given the absence of leading edge, trailing edge, and underside, all of which are required for an aerofoil to function. Unless the high wing is on struts, raised above the fuselage like an old biplane/triplane, then its lifting ability is still being interrupted by the fuselage.

The body is also generating lift, specially under angles (of attack).

http://freeware.aerosoft.com/forum/scre ... 667e5e.jpg

I really don't think that bump between the wings is doing anything to generate lift. It's just there because the structure that most efficiently supports the wings is passing through. If that part of the fuselage is aerodynamically important to lift-generation, then why is there no deicing boot up there?

As I said, an effective aerofoil functions as a complete and specific shape. Simply continuing the top profile of the aerofoil over the top of the fuselage does not magically turn the fuselage into a lift-generating device. At very best, it will make for some smoother airflow over wing roots, allowing more of the wing to effectively generate lift. That area itself, however, is not doing anything to lift the plane into the air.

The lift is generated by under pressure on the wing surface. If it is there and has the underpressure it provides significant lift. Contrary to a low wing.

aerolimani wrote:

keesje wrote:

aerolimani wrote:

That's a nice image and all, but I fail to see how the top of the fuselage is acting as a lifting surface, given the absence of leading edge, trailing edge, and underside, all of which are required for an aerofoil to function. Unless the high wing is on struts, raised above the fuselage like an old biplane/triplane, then its lifting ability is still being interrupted by the fuselage.

The body is also generating lift, specially under angles (of attack).

http://freeware.aerosoft.com/forum/scre ... 667e5e.jpg

I really don't think that bump between the wings is doing anything to generate lift. It's just there because the structure that most efficiently supports the wings is passing through. If that part of the fuselage is aerodynamically important to lift-generation, then why is there no deicing boot up there?

As I said, an effective aerofoil functions as a complete and specific shape. Simply continuing the top profile of the aerofoil over the top of the fuselage does not magically turn the fuselage into a lift-generating device. At very best, it will make for some smoother airflow over wing roots, allowing more of the wing to effectively generate lift. That area itself, however, is not doing anything to lift the plane into the air.

A fuselage definitely contributes to the lift. It isn’t anywhere near as effective as a wing, but it would be incorrect to say it produces zero lift. Any 3 dimensional object travelling through the air at an angle of attack will generate lift, but it won’t do it nearly as effectively as an aerofoil.

V/F

I've seen this lift argument in about six different forums now.
Anything "can" generate lift. A sphere can generate lift. Anything can also generate zero lift. It's an endless debate.

VirginFlyer wrote:

aerolimani wrote:

keesje wrote:

The body is also generating lift, specially under angles (of attack).

http://freeware.aerosoft.com/forum/scre ... 667e5e.jpg

I really don't think that bump between the wings is doing anything to generate lift. It's just there because the structure that most efficiently supports the wings is passing through. If that part of the fuselage is aerodynamically important to lift-generation, then why is there no deicing boot up there?

As I said, an effective aerofoil functions as a complete and specific shape. Simply continuing the top profile of the aerofoil over the top of the fuselage does not magically turn the fuselage into a lift-generating device. At very best, it will make for some smoother airflow over wing roots, allowing more of the wing to effectively generate lift. That area itself, however, is not doing anything to lift the plane into the air.

A fuselage definitely contributes to the lift. It isn’t anywhere near as effective as a wing, but it would be incorrect to say it produces zero lift. Any 3 dimensional object travelling through the air at an angle of attack will generate lift, but it won’t do it nearly as effectively as an aerofoil.

V/F

Indeed. Just as one can feel the effect of AOA when you stick your arm out the window of a moving vehicle. As to airpoanes, increased lift from increased AOA comes from increased pressure underneath the entire aircraft; wings and fuselage. And that is doing more to lift the plane than any little bump in the top of the fuselage between the wings of a high wing.

Both surfaces of a wing are generating lift. The reason the top surface is kept so meticulously clean is because the low pressure above, which the shape of the wing creates, is very easily disrupted. It’s why spoilers work. The high pressure created below the wing is much more robust.

I’ll believe that the continuation of the wing profile over the top of the aircraft is is helping to keep the aerodynamics as clean as possible for the top of the wings. I won’t believe that it’s turning the two separate wings into one gigantic lift-generating surface. More importantly, I don’t believe it’s offering any particular advantage over a low wing, as far as aerodynamics are concerned.

aerolimani wrote:

VirginFlyer wrote:

aerolimani wrote:

I really don't think that bump between the wings is doing anything to generate lift. It's just there because the structure that most efficiently supports the wings is passing through. If that part of the fuselage is aerodynamically important to lift-generation, then why is there no deicing boot up there?

As I said, an effective aerofoil functions as a complete and specific shape. Simply continuing the top profile of the aerofoil over the top of the fuselage does not magically turn the fuselage into a lift-generating device. At very best, it will make for some smoother airflow over wing roots, allowing more of the wing to effectively generate lift. That area itself, however, is not doing anything to lift the plane into the air.

A fuselage definitely contributes to the lift. It isn’t anywhere near as effective as a wing, but it would be incorrect to say it produces zero lift. Any 3 dimensional object travelling through the air at an angle of attack will generate lift, but it won’t do it nearly as effectively as an aerofoil.

V/F

Indeed. Just as one can feel the effect of AOA when you stick your arm out the window of a moving vehicle. As to airpoanes, increased lift from increased AOA comes from increased pressure underneath the entire aircraft; wings and fuselage. And that is doing more to lift the plane than any little bump in the top of the fuselage between the wings of a high wing.

Both surfaces of a wing are generating lift. The reason the top surface is kept so meticulously clean is because the low pressure above, which the shape of the wing creates, is very easily disrupted. It’s why spoilers work. The high pressure created below the wing is much more robust.

I’ll believe that the continuation of the wing profile over the top of the aircraft is is helping to keep the aerodynamics as clean as possible for the top of the wings. I won’t believe that it’s turning the two separate wings into one gigantic lift-generating surface. More importantly, I don’t believe it’s offering any particular advantage over a low wing, as far as aerodynamics are concerned.

Hi, I think the lift contribution of the underpressure over a typical airfoil is much bigger than the contribution of overpressure under the wing.


https://www.physicsforums.com/threads/pressure-and-lift-around-a-wing.944142/page-7

A low wing has many advantages, optimal lift is not one of them.

keesje wrote:

aerolimani wrote:

VirginFlyer wrote:

A fuselage definitely contributes to the lift. It isn’t anywhere near as effective as a wing, but it would be incorrect to say it produces zero lift. Any 3 dimensional object travelling through the air at an angle of attack will generate lift, but it won’t do it nearly as effectively as an aerofoil.

V/F

Indeed. Just as one can feel the effect of AOA when you stick your arm out the window of a moving vehicle. As to airpoanes, increased lift from increased AOA comes from increased pressure underneath the entire aircraft; wings and fuselage. And that is doing more to lift the plane than any little bump in the top of the fuselage between the wings of a high wing.

Both surfaces of a wing are generating lift. The reason the top surface is kept so meticulously clean is because the low pressure above, which the shape of the wing creates, is very easily disrupted. It’s why spoilers work. The high pressure created below the wing is much more robust.

I’ll believe that the continuation of the wing profile over the top of the aircraft is is helping to keep the aerodynamics as clean as possible for the top of the wings. I won’t believe that it’s turning the two separate wings into one gigantic lift-generating surface. More importantly, I don’t believe it’s offering any particular advantage over a low wing, as far as aerodynamics are concerned.

Hi, I think the lift contribution of the underpressure over a typical airfoil is much bigger than the contribution of overpressure under the wing.

https://www.physicsforums.com/threads/pressure-and-lift-around-a-wing.944142/page-7

A low wing has many advantages, optimal lift is not one of them.

I didn't say that the top of the wing was unimportant and insignificant. I get how the profile of the wing creates the low and high pressure zones. What I'm saying the little bump you're showing me across the fuselage and between the wings of that Fokker 50, is there because structure is passing through the area, and not for lift. It carries across the same profile as the wing, so that the aerodynamic properties of the wings remains as undisturbed as possible. Given that the airflow coming at that portion of the fuselage, between the wings, is likely rather disturbed by the fuselage, I still very much doubt it is having any lifting properties itself. While there are exceptions, certain planes at certain altitudes and speeds, most planes cruise with a slightly nose-high attitude.

Further, if that area of the fuselage is generating lift, then why don't we do that on low-wing aircraft too? Put a little bump in the top of the fuselage to add some lift?

And, if it is really an aerodynamically superior design, you'd think that more military jets would take advantage of this. Even the U2 which thrives on maximum lift doesn't do it. They don't have to worry about passenger comfort, and even the SR-71 does not do this. Then, there's the C-5 Galaxy. The wing is soooo close to the top of the fuselage. It could have been just a tiny bit higher, and yet, it isn't.

Your original diagram (pictured below) paints a picture where the lift generated is even greater over the fuselage than it shows at mid-wing. For an overwing such as the Fokker 50 example you posted, I feel the truth is closer to diagram (a) than to diagram (b).



Edit: I should probably not refer to fighter jets, as supersonic aircraft have different aerodynamic needs. Nonetheless, I believe my examples of the U2 and the C-5 are relevant.

northstardc4m wrote:

Kent350787 wrote:

sibibom wrote:

Technically ATR is part-owned by Airbus.

And what is now Bombardier was owned by Boeing in the 1990s

Only deHavilland Canada was owned by Boeing (Canada) for a few years jointly with the Ontario Government... and it was sold to Bombardier who already owned Canadair, but Boeing never owned Bombardier.

Fair clarification. I supoose what I was meaning was the what became the Q series was marketed as a Boeing for a while.

Not commercial but the Boeing B-47, B-52 , and many other types of military jet aircraft are high winged and don't have T-tails. Another common one, Il-76. Turboprops , the Lockheed hercules , An-12, shorts 330/360/skyvan and even the twin otter and many others . Talking 'bout engines turboprops and turbofans and of course turbojets are all different types of jet engines, so are pulsejets and ramjets.

As fan diameter increases, might we see an engine protruding essentially straight ahead of the wing with much of the fan above the wing, or an engine mounted on a pylon extending above the wing thereby providing more space (along with a new maintenance challenge)?

NameOmitted wrote:

As fan diameter increases, might we see an engine protruding essentially straight ahead of the wing with much of the fan above the wing, or an engine mounted on a pylon extending above the wing thereby providing more space (along with a new maintenance challenge)?

Above, like the Fokker 614?