MolaKule Q&A on Aircraft Structures VI WIngs

[MolaKule]

Before we discuss wing box construction we know wings can be attached to the bottom fuselage, mid-fuselage, and at the top of the fuselage.

Wings also can possess "hedrals."

Name an aircraft that has an Anhedral wing and name an aircraft that has a Dihedral wing.

For reference: https://eaglepubs.erau.edu/introduc...ehicles/chapter/wing-shapes-and-nomenclature/

 

[Langanobob]

I learned a few things from that Ambry-Riddle site. I believe Lockheed’s F-104 Starfighter had anhedral wings. The Lockheed Constellation had dihedral wings. Some Constellation trivia I picked up somewhere: it shared airfoils with the P-38.

 

[Dodgetracker]

B25 and Corsair

 

[Cujet]

The Falcon 50 has a slight Anhedral to the wings.

And then there is the AN225

 

[Astro14]

F-8 Crusader had anhedral wings that also happened to be variable incidence.

The F-4 Phantom had dihedral wings.

The F-4 Corsair had a bit of both.

 

[barryh]

I thought the idea of dihedral wings was to improve stability in roll so why would an aircraft want anhedral wings unless stability wasn't the objective as in a fighter jet. The AN225 seems curious in this respect. A flat wing would become dihedral in flight but the AN225 wings would have too far to go.

 

[MolaKule]

Great answers, folks.

The primary purpose of a wing, of course, is to provide lift for the rest of the structure.

Wing box construction usually consists of a main (or front) spar and a rear spar, stringers, ribs and wing skins.

What are the functions of wing spars?

For reference: https://aerotoolbox.com/wing-structural-design/

 

[Skippy722]

The spars like the main support for the wing, I can’t think engineering term for it though.

 

[MolaKule]

"...The primary objective of the wing’s internal structure is to withstand the shear and bending moments acting on the wing at the Ultimate load factor. The secondary objective is to make the wing as light as possible without compromising the structural integrity of the design as described above..."

https://aerotoolbox.com/wing-structural-design/

 

[MolaKule]

Ribs: What are the purpose and function of the wing's ribs?

 

[Cujet]

Here is a really cool picture of a wing spar on a folding wing. The glider here is a Stemme S-10vt, with a 75 foot wingspan. The wings fold so the thing can be managed. The spar has components that locate it in place and carry the load.

Interestingly Stemme determined that the mix of fiberglass and carbon fiber is the way to achieve trouble free bonds. The wing skin is carbon, the ribs are fiberglass. And if you look carefully, the spar is a mix of the two! Also the area forward of the spar is the fuel tank. It is simply the hollow area boxed in by the wing skin and the spar. Put in the wrong fuel, (like that new GAMI 100UL which acts like paint stripper and eats epoxy) and enjoy a destroyed wing.

The Rotax 914 turbocharged engine is under/behind the wing, and is running in this pic, hence the camera prop distortion.

 

[Cujet]

Great answers, folks.

The primary purpose of a wing, of course, is to provide lift for the rest of the structure.

Wing box construction usually consists of a main (or front) spar and a rear spar, stringers, ribs and wing skins.

What are the functions of wing spars?

For reference: https://aerotoolbox.com/wing-structural-design/

Most wings do have wing spars. As I mentioned in the other thread, Gulfstream jets do not use wing spars. They rely on extremely thick wingskins to carry the load. A structural inspection of the wing consists of a detailed look at the exterior!

The Gulfstream tail is made similarly, with a mini-spar for the attach point hinge, as the tailplane moves through quite an arc.

 

[MolaKule]

Most wings do have wing spars. As I mentioned in the other thread, Gulfstream jets do not use wing spars. They rely on extremely thick wingskins to carry the load. A structural inspection of the wing consists of a detailed look at the exterior!

Ribs determine the shape of the wing, the airfoil shape or profile, and determine its lift/drag ratio. Stringers also help to carry the bending, shear, and twisting loads spanwise.

If thin wing panels (skins) are used, multiple spars have to be present to react to the bending, shear, and twisting loads and help support the lifting forces.

If no wing spars are implemented, alternative methods to carry the loads must be used, such as thick wing panels and larger stringers or stringers and ribs made of stronger materials.

The point is, there are many approaches to wing design, with the design being a result of many iterations involving weight versus load-carrying capabilities versus cost of materials.

Just to add that wing ribs have the same function as fuselage frames; they determine the shape of the structure on which the skin panels are affixed.

 

[MolaKule]

@Cujet Can we assume that in your wing fixture pic that that both wings have been joined?

 

[Cujet]

@Cujet Can we assume that in your wing fixture pic that that both wings have been joined?

MolaKule, that is a horizontal stabilizer, and yes it is one piece. In this case, the Horiz Stab had a tiny spot of corrosion on the lower skin and the skin was replaced under a managed warranty program. A pic of the new lower skin. Here is a better view of the structure:

 

[MolaKule]

Lift assist and other devices are attached to a wing to improve the performance of the aircraft in different flight regimes.

Name a wing device that increases lift at takeoff and landing.

Name a wing device that assists in the braking of the aircraft upon landing.

 

[fdcg27]

Lift assist and other devices are attached to a wing to improve the performance of the aircraft in different flight regimes.

Name a wing device that increases lift at takeoff and landing.

Leading edge flaps?

Name a wing device that assists in the braking of the aircraft upon landing.

Spoilers or speed brakes.

 

[MolaKule]

Slats and Flaps decrease the stall speed for landing and takeoff.

Slats are integrated into the leading edge of the wing with links whereas flaps are integrated into the trailing edge of the wing. Both are moveable and may slide or point downward at an angle when deployed. Slats, flaps, and spoilers must be deployed symmetrically for obvious reasons.

Flaps may contain from one to three or more separate flap sections connected by links, and are moveable for both extension and downward angle positioning.

A spoiler is a flap on top of the wing and is deployed upon landing, rising vertically to spoil or disrupt the airflow over the wing. A spoiler also creates a net downward force on the wing to improve tire braking. Some commercial transport aircraft may have as many as 4 or more different spoiler panels.

 

[MolaKule]

Next Wing question: What is an aileron, and how does it affect or control the movement of the aircraft?

 

[Astro14]

The 747 has six individual spoiler panels on each wing. The 767 has six. So does the 757.