Why design a passenger aircraft with a high wing?

[India Four Two]

The vast majority of multi-engine passenger aircraft have low-wings, while relatively few (for example F-27, Herald, Dash-8, An-24, Bae 146) have high wings.

I can see the benefit of a low floor height for a cargo aircraft, but from a design point-of-view, what other reasons are there to choose a high wing layout?

[FlightTester]

India,

One reason may be FAR 25.810 (Escape routes). Basically if the exit is more than six feet from the ground with the LG extended, then a means to reach the ground must be provided (i.e. an escape chute). This adds complexity and weight to the door design, complexity and weight to the Flight Test program, and complexity is generally directly proportional to increased cost during the service life of the aircraft.

So, in order to lift xx number of pounds/pax off the ground we need a given amount of lift, therefore wingspan. In order not to get a tip strike on landing you need to make sure that the geometry of the undercarraige is right i.e. a short stroke undercarriage sits lower to the ground, therefore beyond a certain length of wing a tip strike is a given - like the U2 for instance.

Therefore in order not to incur the penalty of heavier and more complex doors, resulting in a decrease in the amount of payload, one design workaround is to sling the fuselage low and the wing high, thus allowing a short stroke undercarriage, a low step down height and still maintain a long span wing.

That's my two cents anyway:)

Also, the aircraft you mention - Dash 8, BAe 146 etc are designed to allow operations from austere airfields - keeping the wing high also keeps the engines high and reduces the risk of fodding an engine.

[On-MarkBob]

There are a number of advantages for having a high wing. First, they have what is known as 'pendular stability' which means that the wings don't necessarily have to have dihedral, which means that the wing can be made as a one piece unit with a straight spar for ease and cost of production. The wing is simply mounted on top of the fuselage. Secondly, look at the Shorts 330/360, the fuselage accounts for a large proportion of the lift, something that cannot be done too easily with a low wing aircraft. The wing can thus be either shorter, or thinner for a higher aspect ratio and thus more economical with regard to performance and that also increases the payload capability, or allows the manufacturer to use smaller engines. Everything in aircraft design is a compromise. A high wing is often used for rough field operations, since it is well out of the way and is less susceptible to damage from debis on badly prepared runways. Often aircraft with high wings do not need fuel pumps, because they have the advantage of gravity feeding, all these little things ad up to a cheeper aircraft.

[ICT_SLB]

Another reason, for the majority of the aircraft you quote, is that they're all derived from military transports with rear ramps. Dash 8 followed on from the Caribou (via the dash7) and the 146 was a civilian rework of the HS681 V/STOL transport with twin Pegasus originally. The Shorts aircraft all came from the Skyvan & went back to the Sherpa.

[chevvron]

But the ATR 42/72 series aren't are they?

[safetypee]

ICT SLB, I think that you are mistaken re the origins of the Dash 8 and BAe146.
The 146 evolved from UK studies into RTOL and STOL. Both concepts had high wings. RTOL was the larger project (200 pax) and used 2xRB 211; STOL was the smaller project (but larger than the 146) and used 4xRB410.
From the documentation that I have, the driver for the high wing appears to be performance with good handling – including steep approach.
A low wing appears to offer lower cost of operation, but the high wing would be better on short sectors in conjunction with a shorter field length – also a better climb gradient in the 4 engine case.
There were noise advantages in placing the engine ‘well’ below the wing, i.e. not like 737.

Freighter studies were based on the larger RTOL project (2xRB211), but the airliner lineage dropped the ‘RTOL’ concept and became the UK Airbus (via BAC 3-11?), the final proposals resembling the A300.
The 146 was a smaller version of the STOL project (108 pax reduced to 80). Subsequently a true military version of the 146 was considered (not the STA), but never built.

[Ex Cargo Clown]

But the ATR 42/72 series aren't are they?

You can have larger radius props with a high wing design.

Can't think of many modern prop driven aircraft with a low wing other than the ATP :D

[ICT_SLB]

Safety,
I worked on BAC 1-11 when the HS146 was launched & I assure you the baseline aircraft was definitely the HS681 - the reason for the 4 Lycomings is that the blown flap needed 4 jets to replace the twin peggies (think QSTOL Buffalo).

I also did the outline wiring harness for a very early 3-11 concept. It was the competing rear-engined European JET design to the Airbus 300. If anything, the 3-11 came about after the great performance numbers from the RB-211 testbed VC-10 (twin Conways replaced by a single 2-11). Just have to wonder what a straight twin 2-11 VC-10 would have done.

Cargo,
Saab 340/2000?

[chevvron]

Cargo: Presumably the Swearingen Metro/Merlin have such tall undercarriages because of this
I remember the HS681 proposal (about '64 ish?) Wasn't it killed off by Labour at the same time as TSR 2 so the americans could sell us Hercules instead? It definitely had a similar layout to the later HS 146 which Labour first refused to back, so Hawker Siddeley put it on the back burner, then Wedgie Benn re-discovered it and it was resurrected when HS were by this time part of BAE.
I'm sure there were other proposals at the same time as the '681 one being with normal engines rather than Pegasus.

[safetypee]

ICT SLB, thanks for you assurance. Although I flew the 1-11 and in a very small way was part of the 3-11 concept, my information comes from being very much closer to the 146 project.
The reference document was “A summary of the work and conclusions arising from the 1972/73 joint HMG/BAC funded programme of R/STOL studies.” 18th July 1974.

Surprisingly the STOL project in the studies always had 4 engines, whereas the RTOL/conventional aircraft (CTOL) evolved from a high wing, 2 eng aircraft to the low wing 2/3 eng ‘Airbus / 3-11’ idea.
Whilst my information does not refute an association with the HS 681, I suggest that some of the essential components were not the same as the 146, e.g. fuselage diameter, wing sweep, and pontoon main gear.
Many of these aspects were discussed in the research document. In particular, the ‘blown flap’ (internal and external) aspects of STOL performance and gear shape / location. Whilst the 146 might have a very small ‘blown flap’ component of lift, it is miniscule in comparison to what was considered in the research. Some of the concerns were with pitch control, this required very large tail surfaces, possibly powered controls and leading edge flaps.
The simpler, lower risk concepts were followed, which I suggest are considerations in the choice of wing location – 146 manual controls, no leading edge flaps.

A simpler fuel system was another advantage of the high wing; emergency gravity feed to under wing engines and no fuel pipes in the cabin – unfortunately the 146 failed with the second aspect.

[VortexGen300]

Why design a passenger aircraft with a high wing?

Maybe the simple answer to this difficult question is:


BECAUSE IT IS POSSIBLE AND IT IS NOT UNSAFE?

As it will often depend on the likes and dislikes of individuals which design is utilized rather than any real reasons? (But that is only my opinion)

VG300

[twochai]

High wing vs low wing was a raging argument during the conceptual design phase of both the Dash 7 and the Dash 8. All of the foregoing points certainly tend to favour a high wing over a low wing layout for any aircraft with pretensions to austere runway operations.

An additional, but important factor is the reduced touchdown dispersion of a high wing aircraft during landing, due to diminished ground effect in the flare with a high wing configuration.

[chevvron]

Dornier 228, 328 and 328J??

[Capot]

It's simply a matter of prop clearance, isn't it? Most high-wing aircraft are propeller-driven, and some high wing jets are derivatives of prop-driven aircraft. (See above?)

Low-wing prop aircraft fuselages must be high off the ground, therefore needing big ladders, cargo-lifters etc, and even then they have very little prop clearance off the ground, so they pick up all sorts of stuff to damage the props, especially on un-paved strips.

[Allan Lupton]

Quote: I worked on BAC 1-11 when the HS146 was launched & I assure you the baseline aircraft was definitely the HS681 - the reason for the 4 Lycomings is that the blown flap needed 4 jets to replace the twin peggies (think QSTOL Buffalo).

Er, no.
If there had been any carry-over from that generation of military VTOL aeroplanes, it would have been from the DH129 not the HS (né AW) 681 as the 146 was a Hatfield product .

The progression from DH126 small feederliner via the HS136 rather less small one (with RR Trent engines - no not the later huge ones, nor the earlier turboprop ones!) and other project aeroplanes to the AVCO-Lycoming powered high-wing 146 was the result of shifting targets for size, range and complexity being matched to shifting availability of suitable power units.
The 146 has not and had not blown flaps. The flaps are behind the engines, and there is doubtless a bit of fan-induced extra velocity but blown flaps as normally understood are very different.
The 146, although the most numerous British-built airliner, seems to be very poorly understood if this thread is anything to go by.:)

[John Farley]

Interesting bunch of views with respect to the origins of the 146.

My input is that when I was interviewed by HSA in 1966 for a test flying job at Dunsfold it was made clear to me by Harry Broadhurst that if they did not eventually get a contract to produce what became the Harrier I would have to go to Hatfield and do the 146. John Stamper took me through the design philosophy and said that it was intended as a hub and spoke aircraft to open up Africa. At the end of the spoke was just going to be a strip - not what we would recognise as an airfield – with negligible facilities. This meant that the aircraft had to have four small engines because they needed a three engine ferry capability to return to the hub to do the donk change. The high wing was to get the engines as far away from the FOD issues of strips as possible. Everything else stemmed from these two criteria.

In the event as we know HSA decided not to launch the aircraft. That was left to BAe many years later.

[D120A]

Very interesting, John. Surveying the ramp at Los Angeles International in the late 1980s and seeing 146s in a variety of liveries, everywhere, one could be forgiven for thinking the aircraft had been intended to open up the West Coast of the USA! :)

The four small engines had conferred another benefit - low noise - which made the 146 acceptable in Orange County and other noise sensitive areas. A case of "not quite what the designer intended, but jolly good anyway". The massed ranks at LAX of a British design were a pleasing sight.

Graham Perry

[Double Zero]

John,

A very interesting point, it reminds me a lot of Neville Shute Norways's books, after he founded Airspeed - as to the early 146 designs, I like yourself have seen them supposedly mounting 2-4 vectoring Pegasus engines on proposals - presumably only proficient piano players need apply !

I can't help wondering if the good old as became the norm' 146, with it's STOL capability ( & hopefully the freight version ) would be very usefull now in sandy places, if only to insert/ recover some people & kit...

[John Farley]

Double Zero

There may be some confusion between AW681 and the original HS146 in some peoples minds. I am not aware of any connection between the two beyond the choice of a high wing for both

JF

[galaxy flyer]

Later, in service, the HS 146 was frequently referred to as "the best three-engine plane built" due, no doubt to the choice of engines-Lycoming ALF502. Obviously, the three-engine ferry was a good idea for a rather ironic reason. A friend of mine called them hand grenades disguised as jet engines.

GF

[Wings Of Fury]

Capot, I think that you have the main points,
One more is less ingestion upon applying reverse thrust? Like less prop damage, I remember the E110 props taking a punishing on unprepared strips.
The ATR looks like a good design.

[Allan Lupton]

I'm glad John Farley's potential redeployment to Hatfield never happened, as he'd never have been able to demonstrate a 146 as impressively as a Harrier!

Apart from that, without looking it up I'd have put the 146 as slightly later than 1966 and I think we were only up to 144 by then. But as he says, and as I implied, it was designed as a third-world feeder liner with similar short and rough strip capability to the Avro 748 and that had been the design aim from the beginning. Another design aim was quietness, and Orange County was a good example of the extra destinations that become available as a result. London City's another (and it's also pretty short).

The 146 was launched by Hawker Siddeley, but put to one side as a consequence of the 1973 oil crisis and the inflation that ensued. By the time things cleared up sufficiently for a re-launch, we were nationalised as British Aerospace.

As for three-engined ferrying, during the early development flying starter quill-shaft breakage was rather common and I recall one flight which therefore took off on three but flew and landed on four after a windmill in-flight start!

[barit1]

Can't think of many modern prop driven aircraft with a low wing other than the ATP

...or the SAABs & Brasilia. IIRC the 340 was 100# PER PAX lighter than the Dash 8.

[WHBM]

High wing advantages :

No worry about prop clearance so props can be large/not close to the ground for rough field/gravel operations (what sold many of the F27s compared to the 748 in the 1960s-70s).

No wing spar through the cabin which you still get on smaller low-wing types like the Jetstream.

Same is true for jets, especially the clearance. Note the smaller types are either high wing (146 and Do328 jet), have to be rear engined (RJs and business jets) or have bizarre inefficient configurations (VFW614 with engines on top of the wing).

[org]

I remember the PSA pilots referring to them as "four oil leaks connected by an electrical fault." The Lycs were indeed a disaster (at least the early aircraft); the company I worked for had three aircraft and in the space of a year we had 12 engine changes, about half of them inflight failures.

[WHBM]

I remember the PSA pilots referring to them as "four oil leaks connected by an electrical fault." The Lycs were indeed a disaster (at least the early aircraft); the company I worked for had three aircraft and in the space of a year we had 12 engine changes, about half of them inflight failures.
The strange thing then is that, nearly 25 years after they were first delivered, these same ex-PSA airframes are still in everyday service over here in Europe on trunk routes, including a number on the various business services out of London City - an airport where almost all the commercial operations are by various high-wing types such as 146, F50, Dornier 328, Dash-8, etc.

[RugGun]

First time poster & boffin not pilot, so be gentle:) Long-ish post too:8

I'm a systems guy nowadays but was once educated in the dark arts of the 'future concepts' bit where you come up with an aircraft configuration.

There's really only two good reasons to build a high wing aircraft, and they're not mutually exclusive

1) Cargo handling/ground access to the fuselage
2) to put the engine intakes clearly out of the way of FOD (note intakes, not props)

Cargo handling covers both putting the floor near the ground handlers and making a nice big rectangular box. Most high-wingers have the wing cutting through the fuselage where it's otherwise too narrow to be of use to the cargo area.

So for pax aircraft, you do it because you anticipate operating places that don't have airstairs or other heavy support equipment. The SLF can get on & off using only what the aircraft brought with it. There is a side advantage here that the turn-around time is reduced, since you don't have to wait for any outside kit to move about - so you save a time on each turn around. I'd guess that's why the ATR & Dornier x28s are high up - I'm not aware of them being rough field capable but haven't played with them.

(Aside - that's why most biz jets are rear-engined, because otherwise the ground clearance would be so high, kit would be needed to get the Pax off - but the drag penalty of a high wing is too much)

And FOD - on a high wing, the fuselage can be relied on to block all of the nosewheel debris & spray. With a low wing (wing-mounted or rear engines), you have to assume likely spray & debris weights - and paths - only as far as the regulations say you do. A high mounted engine means that's not an issue. You've only got to worry about the engine sucking stuff up directly.

There's only a small lift benefit from the high wing, a big drag penalty - doubly so at >Mach 0.7-ish & it will always weigh more than mid/low wing, so you need a distinct operational reason to want to pay that. With the same engines, you can almost always make the low wing have better field performance for a given range-payload than a high wing due to structural weight.

Any stability benefits are secondary - you don't configure the airplane to make the flight control guys job any easier.

[John Farley]

RugGun

I would be interested to know why you assert that a high wing layout will always be heavier than a low or medium one.

JF

[RugGun]

To some extent, it depends on the choice of engine mounting position. I think a rear engine mount is the heaviest at most Pax aircraft sizes (a la MD-80, not DC-10). This is size dependant - smaller you get, less the problem is.

The fuselage floor must, in some manner, be supported by the wing. In a low & mid wing, the job of the fuselage structure is basically not to collapse under bending & its own weight during manoeuvring and to cope with aero loads & pressure differences.

Structurally (big simplification coming) a low or mid wing airplane is two box sections assembled in a cross, bolted to each other, with a stiffened balloon or tent for the fuselage.

A high wing has the same two primary members, but also needs a support frame at least 5 feet high between them.

As a result, in a high wing, the fuselage bending is exactly the same as any other configuration with the same engine loc'n relative to the wing - so the skin thickness is at least the same as the low. But you also need to thicken the centre section to transmit floor loads up to the wing.


In the event that you fuselage mount the main gear, although you can save undercarriage length - and the associated weight too - you need an additional lump of structure approximately like the wing centre box sitting between the gear, which I think more than cancels it out. Or you need to further thicken the centre section skins.

You only do that if you want to absorb high sink rates (easier with legs that are shorter once loaded) and/or house the tyres in the belly because the engine nacelles are too small or unusable. The tyre size is only a feature of the desired bearing ratio/ground pressure.

I'm afraid I don't have the numbers to hand - I can dig something open source up over the weekend comparing high/low & underwing engine/tail mounted.

[John Farley]

Thank you

JF

[FE Hoppy]

Embraer are currently developing a freighter based on the very successful 190 series. It's almost the same aircraft but with the wing mounted high and a cargo ramp added. The reason given to me by my friends in San Jose dos Campos is get the engines away from the ground and the ramp close to the ground.

[barit1]

That's the classic configuration for a purpose-built freighter. Ben Howard of DGA fame designed a small twin about 1939 with high wing, ramp-loading tail, called it DGA-10. Never built, unfortunately, but it had plenty of follow-ons by Curtiss (http://en.wikipedia.org/wiki/C-76_Caravan), Budd (http://www.microworks.net/PACIFIC/aviation/rb_conestoga.htm), Fairchild, Lockheed, DHC & McD-D - plus the Argosy and Transall in Europe - and the Il-76 and Antonovs etc etc.

[old,not bold]

I was sent to Hatfield in 1981 to evaluate the 146, as a replacement for twin t/props, especially on hot 'n high operations with unsupported stops at very basic airfields. I don't think it had even flown by that time.

I remember a great deal being made of the fact the the aircraft could carry a complete spare engine, in a number of boxes, in the hold.

I mentioned that in my report as a huge advantage, to the amusement of the boss, an aircraft engineer by background.

"Why do you think they're promoting that?" he said, roaring with laughter, "it's because they're expecting lots of engine problems". He also suggested that I was a "gullible plonker", which was probably right.

[fastener]

Hence the reason for the company name change from H.S. to BAe.
BAe= Bring Another engine.

I'll be off then.

[Allan Lupton]

Joking aside, it was often a serious problem for the operator if an engine did go u/s at an outstation.
With the 146 it was sometimes possible to ferry back to somewhere sensible and do an engine change in comfort, but in general if you were stuck at a difficult airfield (and Sod's Law says you would be), only another 146 could bring spare engine modules in. However it could do that, which most of the opposition couldn't.
You didn't have that problem with mainliners connecting "proper" aerodromes.

[fastener]

The ATP was also knicknamed the "Sky Skoda". For me the early ATP DV window seal was a nice touch, a piece of sticky foam that looked like old fashioned draught excluder from B&Q.:ugh:

[code0]

I believe the main two pillars of aircraft designing are

- Range and
- Capacity

Every decision is taken to satisfy these two criteria correlated to financing and practicality of physics.

When you say passenger aircraft, you need to specify if it is a short range small to medium capacity aircraft or a medium, extra range/long range aircraft.
For instance an aircraft that fly short range with medium capacity may not require to gain a faster speed and high service ceiling. Hence, a design with straight wings, turbo prop engines would be feasible. Generally, passenger aircraft such as F-27 is designed as hi-wing for certain reason.

- Since the range and capacity is short and small, no need of jet engines, but couple of turbo prop engines would do the job in a most economical way
- Using prop blades need some ground clearance
- Since, airplanes with short range and low capacity doesn’t require higher speed, their wing construction is less complicated (tapered rectangular wing) than of a high speed jet. So most of turbo props place the simple wing on top of the fuselage as it doesn’t require heavy “reinforced wing-carry box” , which is heavy and complicated.
- Hi-wing is aerodynamically has good characteristics at lower speeds-perfect for small/medium props. (pendulum effect)


On the other hand, fast jetliners have totally opposite characteristics. Most passenger jets such as Boeing 777 are having low wing configuration. Following are some of the reasons for selecting a low wing configuration for such aircraft.

- As their capacity is high and range is longer, they require to gain much more speed than others. Jet engines serves this purpose in the most economical way.
- Low wing with high swivel angles has good aerodynamic characteristics at higher speed.
- Since the wing is complicated* in a long range hi speed jet the construction require a heavy wing carry box, which is most unluckily to be place on top of the fuselage.

(* Flaps, slats, ground breaks, ailerons, outboard flaps, inboard flaps, outboard air breaks , in board air brakes, wash out airfoil construction, thinner airfoil with small LE radius, variable sweep angles, etc. These kind of complexity is not seen in prop/turbo prop aircraft)

To summarize all: every aircraft is designed initially looking at two main criteria which are “range” and “ capacity”. All other decisions are taken once these two are defined. so a short range less capacity aircraft may not require to fly fast and at high altitudes. Hence the hi wing arrangement has the best aerodynamic characteristics for such an aircraft. On the other hand a plane with long range with heavy capacity may require to fly fast, at high altitudes which can be complimented by having a low wing configuration.

(some of the fast military jets have hi-wing configuration.Military aircraft design is totally different to designing civil jets. Certain rules and criteria do not apply to military aircraft design. )

[Genghis the Engineer]

Gosh, a good old fashioned thread Necromancer!

I believe the main two pillars of aircraft designing are

- Range and
- Capacity

Every decision is taken to satisfy these two criteria correlated to financing and practicality of physics.





When I used to teach this stuff, we were left to our own devices how (universities are great like that), I actually decided we had four pillars


- Role
- Operating environment
- Available technology
- The regulations

Range and capacity will sort of sit between role and environment. Your discussion about the alternate benefits/disbenefits of different engine types and wing configurations pretty much falls into "available technology".

I absolutely agree that swept wings give better transonic performance by modifying Mcrit, but disagree that a low wing improves high speed performance particularly. It's more I suspect a case of since the length of the fuselage necessitates a long undercarriage, a high wing would put the engines too far off the ground.

G

[Ex FSO GRIFFO]

And, on a lighter note....

In the smaller aircraft range - I much prefer the high wing concept.

It makes it ever so much easier to stand under - in the shade and / or out of the rain - on one of 'those' days....... :ok:

Cheers from 'Dunnunda'. Stinkin' Hot one day, rainin' the next.....:)

[code0]

at G

The four facts you have mentioned, I am not saying incorrect. Of course Range and the Capacity are not the only to be considered. My point was at the outset the main two decisions are nothing but Range and Capacity. of course all other factors come afterwords. and also mind that I am talking about civil designs.

Low wing has few advantages over high wing at high speeds. forget about aerodynamics!, it will be practically impossible to put a swept back wing with all flaps/slats, air break, ground breaks, spoilers, etc on the top of the fuselage. If so, you will have to build a heavy wing box and make it structurally heavy: that will block the fuselage : reduce the effective capacity of the area.

Also another reason is to with stand the stress and force on the structure at higher speeds. In a low wing, having a wing carry box and putting the landing gear and fuel tanks make the wing box act like a center weight to the plane as well. Also the wing box can be made to with stand more stress than of putting in on top.

summarized: a transonic wing is most unlikely to be configured as a high wing but low wing configuration give more benefits. Hence most of the turbo jets/fans mission-ed to transport passengers medium to long range, place their transonic wing under the fuselage with a reinforced wing carry box.

(feel free to make a list of passenger aircraft with hi-wing with turbo jet/fan that fly at transonic speeds and same with low wing. you wont believe what you will find out.lol).


I agree for what you have said about "available technology" and of course we can't expect any extraterrestrial knowledge transform.

most importantly, don't take this personally. you may have spent all your life in teaching in the academic area or I respect you for whatever you have done. anyhow I wish if you could keep that dignity when you put your thoughts into words as well.

code0

[Jig Peter]

:8Thread drift here - sorry - but you're a bit off-beam about any A300/BAC311 link.
In the "original" Airbus studies, British participation was largely from Rolls, with Hawker Siddeley to do the wing. Vickers/BAC were not involved in the least, but later came up with the rival 311 which got nowhere when the government of the day would only support (tepidly?) one big civil airliner project, plus the RB211 for the 1011.
Rolls were offering fantastic thrust levels (for the day) from their big 3-shaft fan engines, to match the then A300's DC-10-width fuselage ("Grosse Julie"). When Rolls turned their attention to the lower power needs for the Lockheed 1011, they left the A300 as it then was, powerless.
Airbus, under Roger Beteille, then turned to GE whose CF6 was being developed to a thrust level suitable for a higher AUW version of the DC10, and at the same time reduced the fuselage diameter to the 222-inches which became the "standard" Airbus wide-body size, and thus the "old" A300 became the A300B, with HSA's wing. :8

[STOLskunkworks]

Personally I believe the biggest advantage is big props with a high wing mean fewer RPM's which means quite for Turbo Props. It also means way more acceleration or deceleration at low speed. Those of you who flew a Dash 8 or similar know what I mean. You just put it in Discing after touch down no brakes or reverse. Also even with jets it helps prevent FOD and prop damage on turboprops.

[theficklefinger]

High wing / Low wing, is really the discussion of antiquated designs.

Designers trying to squeeze speed/range/efficiency...doing the most with the least amount of engine and fuel, will end up with a Piaggio Avanti type of design.

I'd get writers cramp discussing all the advantages, but the rear wing being higher then your typical low wing has the advantage of gravity feed, more ground strike clearance, engines getting better inflow and FOD protection.

When they start slinging Williams on the Avanti, about the time that fuel hits $9 a gallon, I suspect even the airlines will start pushing Boeing to reconsider where they put the wings...

Most of the supersonic designs on tap, looks like a Delta with a canard.

[WorkingHard]

Just a pilot here folks but it strikes me that nature has perfected design over a very long period and so only has high wing birds flying!

[Tarq57]

WH, that may be because the power-plant for a bird has to be underneath the propulsion/lifting surfaces, since muscles only produce power by contracting.

[WorkingHard]

Targa 57 I never thought of that which is probably why I stick to flying machines and not designing them. Thanks, you made me smile.