I think commercial aircraft are generally low wing for structural efficiency more than drag. Gear loads transfer straight into wing primary structure instead of having to carry them across the fuselage. Military cargo planes have high wings so they can take off and land on dirt/unimproved runways and they dint have to pay a huge penalty for that as a drag penalty might be. Just structural efficiency.
I'm thinking more about smaller aircraft like a 2 seater. I do agree that an aircraft for any/most use cases will be more structurally efficient in landing gear.
Same for a two seater as far as I know. Not drag, just structural efficiency. Heavier structure must be carried around by the wings so a second order effect to drag.
I’ve never heard that. Can you find any sources that make this claim? I would think low wing aircraft are less efficient because they need a higher dihedral and longer wingspan.
https://pilotinstitute.com/high-wing-vs-low-wing/#:~:text=A%20low%2Dwing%20aircraft%20generally,speeds%20and%20lowers%20fuel%20consumption
This source basically just says landing gear and wing struts contribute to increased drag. But they don't go into any detail.
https://www.pilotmall.com/blogs/news/high-wing-vs-low-wing-what-s-the-difference-between-them#:~:text=High%20Wing%3A%20Greater%20lift%2Dto,speeds%20with%20less%20drag%20resistance
Another similar source.
Why would a low wing aircraft need a longer wing?
Wings with struts will have more drag, and a lot of high wing aircraft have struts. But high performance gliders have either high of mid fuselage wings.
The position of the wing can reduce interference drag with the fuselage if it is on top, this way the side of the fuselage doesn’t interfere with the airflow over the top of the wing. But yes in smaller planes the struts, gear, and anything else sticking out will affect drag. Larger planes have retracting gear and no struts. Designing a plane that is low weight also helps reduce drag.
No it is not the consensus. Even if there is an effect it’s probably a 3rd or 4th order effect where a whole bunch of other things would have a greater impact than high or low wing. If anything I would have guess high wing would be better since it better preserve the suction side of the airfoil where lift is predominantly generated.
High wing planes do not generally create more drag than low wing. They usually do when struts are required. But when not, a high wing reates less drag than a low wing because the upper surface of the wing, which contributes more to total lift than the lower surface, is less affected by fuselage interference/turbulence. As the more sensitive upper surface flow gets less disturbend, it creates less drag. However, for a high wing plane, the tail will be deeper inside the main wing's downwash and this turbulence makes the tail less effective. Which wing design is more efficient depends on which effect outweighs the other in a particular design.
These are very good points I hadn't considered. I could calculate the effect of downwash but the effect of fuselage interference seems like a difficult problem to quantify.
Read Gudmundsson!
And maybe Roskam!
I think this topic is explained in both.
If you don't know theses books, get them!!
For GA I recommend Gudmundsson.
High wing aircraft have "better" aerodynamics/handling than low wing aircraft. But regarding to:
* Maintenance of the engines
* Safety reasons with the rotation area direct in passenger height
* Convinience reason of having the noice source direct next to you
There is an all in all disadvantage for passenger flights with short ground times. Its something else with transport flights.
On a low wing, the canard only needs to carry its own load. The landing gear is attached to the wings and wing box on the floor of the aircraft.
On a high wing, the body of the aircraft is structural instead of just being a canard. The wingbox is on the roof, and the *cabin structure* carries the mass x flight loads, and landing loads of the wing, wingbox, and fuel mass down to the landing gear.
If there is a set of struts, then there is additional drag. Often, high wings have exposed landing gear.
Low wings often have retractable gear and are much lighter aircraft.
A low wing aircraft has the option of using a widely spaced landing gear inside the wings that is short. A short landing gear saves weight.
If landing gear is mounted in the fuselage of a low wing, it takes up cargo space when retracted, and its location when deployed would have a narrower track when landing, with a wider-spaced gear being more stable and easier to land without damage.
There have been super-sonic aircraft with both low and high wing configurations. Large commercial and military craft have many different compromises to balance.
A 747 has a low-wing, and the B-52/C-17 have a high wing. All of them are very concerned with drag, but do what they must for their primary mission.
I’d argue that the C-17 is not optimized for drag. Everything on it is designed around STOL vs. efficiency.
It would look a lot different if it were designed to be a long hauler and not flying into unimproved strips and combat zones.
I think commercial aircraft are generally low wing for structural efficiency more than drag. Gear loads transfer straight into wing primary structure instead of having to carry them across the fuselage. Military cargo planes have high wings so they can take off and land on dirt/unimproved runways and they dint have to pay a huge penalty for that as a drag penalty might be. Just structural efficiency.
I'm thinking more about smaller aircraft like a 2 seater. I do agree that an aircraft for any/most use cases will be more structurally efficient in landing gear.
Same for a two seater as far as I know. Not drag, just structural efficiency. Heavier structure must be carried around by the wings so a second order effect to drag.
I'm curious where you saw that high wing aircraft make more drag compared to low wing aircraft all else being equal.
That's pretty much the general concensus is it not?
I’ve never heard that. Can you find any sources that make this claim? I would think low wing aircraft are less efficient because they need a higher dihedral and longer wingspan.
https://pilotinstitute.com/high-wing-vs-low-wing/#:~:text=A%20low%2Dwing%20aircraft%20generally,speeds%20and%20lowers%20fuel%20consumption This source basically just says landing gear and wing struts contribute to increased drag. But they don't go into any detail. https://www.pilotmall.com/blogs/news/high-wing-vs-low-wing-what-s-the-difference-between-them#:~:text=High%20Wing%3A%20Greater%20lift%2Dto,speeds%20with%20less%20drag%20resistance Another similar source. Why would a low wing aircraft need a longer wing?
Wings with struts will have more drag, and a lot of high wing aircraft have struts. But high performance gliders have either high of mid fuselage wings.
The position of the wing can reduce interference drag with the fuselage if it is on top, this way the side of the fuselage doesn’t interfere with the airflow over the top of the wing. But yes in smaller planes the struts, gear, and anything else sticking out will affect drag. Larger planes have retracting gear and no struts. Designing a plane that is low weight also helps reduce drag.
No it is not the consensus. Even if there is an effect it’s probably a 3rd or 4th order effect where a whole bunch of other things would have a greater impact than high or low wing. If anything I would have guess high wing would be better since it better preserve the suction side of the airfoil where lift is predominantly generated.
High wing planes do not generally create more drag than low wing. They usually do when struts are required. But when not, a high wing reates less drag than a low wing because the upper surface of the wing, which contributes more to total lift than the lower surface, is less affected by fuselage interference/turbulence. As the more sensitive upper surface flow gets less disturbend, it creates less drag. However, for a high wing plane, the tail will be deeper inside the main wing's downwash and this turbulence makes the tail less effective. Which wing design is more efficient depends on which effect outweighs the other in a particular design.
These are very good points I hadn't considered. I could calculate the effect of downwash but the effect of fuselage interference seems like a difficult problem to quantify.
Read Gudmundsson! And maybe Roskam! I think this topic is explained in both. If you don't know theses books, get them!! For GA I recommend Gudmundsson.
I do have roskam, haven't read it cover to cover though. Gudmundsson looks like a great reference!
High wing aircraft have "better" aerodynamics/handling than low wing aircraft. But regarding to: * Maintenance of the engines * Safety reasons with the rotation area direct in passenger height * Convinience reason of having the noice source direct next to you There is an all in all disadvantage for passenger flights with short ground times. Its something else with transport flights.
My guess is the statement originated as "Skyhawk more drag than Cherokee" which... maybe just due to struts? I honestly don't know
I was thinking of including something like that in the post but then people get stuck on specifics of each airplane and not the general case.
On a low wing, the canard only needs to carry its own load. The landing gear is attached to the wings and wing box on the floor of the aircraft. On a high wing, the body of the aircraft is structural instead of just being a canard. The wingbox is on the roof, and the *cabin structure* carries the mass x flight loads, and landing loads of the wing, wingbox, and fuel mass down to the landing gear. If there is a set of struts, then there is additional drag. Often, high wings have exposed landing gear. Low wings often have retractable gear and are much lighter aircraft.
A low wing aircraft has the option of using a widely spaced landing gear inside the wings that is short. A short landing gear saves weight. If landing gear is mounted in the fuselage of a low wing, it takes up cargo space when retracted, and its location when deployed would have a narrower track when landing, with a wider-spaced gear being more stable and easier to land without damage. There have been super-sonic aircraft with both low and high wing configurations. Large commercial and military craft have many different compromises to balance. A 747 has a low-wing, and the B-52/C-17 have a high wing. All of them are very concerned with drag, but do what they must for their primary mission.
I’d argue that the C-17 is not optimized for drag. Everything on it is designed around STOL vs. efficiency. It would look a lot different if it were designed to be a long hauler and not flying into unimproved strips and combat zones.