Questions tagged [aircraft-structures]

For structural engineering questions about airframes and the mechanical structures aboard aircraft

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8
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1answer
424 views

How do weapon pylons attach to a fighter's wings?

How do weapon pylons attach to a fighter's wings? I'm particularly interested in the inner structure.
14
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3answers
18k views

How are engines mounted onto wings?

I've heard that the engines on a commercial air transports are typically mounted with 2 or 3 bolts. Is this true? If so, how big are these bolts and what are they made of? I'm optimizing a bolted ...
1
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2answers
96 views

Aerodynamic Pressure Loads in FEA of Lifting Surfaces - Query

Let me give a brief summary of the process involved in the FEA of lifting surfaces with the wing as an example: 1. The wing is modelled as a hollow surface body in Ansys, meaning only the exterior ...
1
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1answer
87 views

How do the wings connect to the centre wing box?

First of all does the centre wing box form part of the fuselage as it's in the centre of the fuselage? Secondly how does the wing spars connect to this centre wing box to hold everything together?
6
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1answer
745 views

On a large transport aircraft where exactly is the Forward pressure bulkhead?

Is the Forward pressure bulkhead in front of the pilots.. I.e when you lift the Radome for maintenance is that the Forward pressure bulkhead you can see? Some images or a diagram would be great.
4
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1answer
98 views

What is the difference between a wing station and wing buttock line?

Can someone explain (with images) what the difference between a Wing Station and Wing Buttock Line is, in terms of aircraft structures location identification? The text I'm reading states: W. STA ...
3
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1answer
199 views

Can structural damage be detected or predicted using historical data?

Can software simulations and structural health monitoring techniques accurately predict damage occurrence in aerospace structures using historical data(...
4
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1answer
87 views

What is pressurization influence (if any) on maximum G load an airliner can withstand?

Reading here about skin thickness of airliners I was wondering if, considering some pressurized airliner at cruise altitude, there are differences in maximum operational acceleration loading the ...
4
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1answer
137 views

What exactly are the “sealed” leading-edge slats in B737 short field performance aircraft?

"The 737 design enhancements allow operators to fly increased payload in and out of airports with runways less than 5,000 feet long. The design enhancements include a two-position tail skid that ...
9
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2answers
735 views

What could cause the Boeing “Pickle Fork” issues?

The Boeing 737-NG has been in the news recently regarding cracks discovered in the "pickle fork" assembly which transfers loads from the wings to the body of the aircraft. The "pickle fork" was ...
0
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0answers
58 views

Wing fuselage joint in small aeroplanes [duplicate]

I know that there are bolts to connect the centre wing boxes of the fuselage and wings in large aircraft, but what are the methods of connecting the wings and fuselage of small aeroplanes? I’m mostly ...
6
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1answer
312 views

Why does taxiing produce large lateral loads on the 747's engine pylons?

While reading through a bunch of old AARs recently, I found (in the context of a 1993 747 in-flight engine separation) this interesting tidbit: [...] Boeing engineers report that the modifications ...
20
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2answers
4k views

Why do T- tail airplanes have a shorter vertical stabilizer?

Airplanes with a T-tail design have a shorter vertical stabilizer than the conventional design , what is the reason?
15
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2answers
3k views

Why does the Pilatus PC-24 have such a large “Airplane Support”?

The PC-24 has, under the fuselage, a kind of huge support to hold the wings. If we compare with the Citation CJ4 or the Phenom 300, this difference is quite significant. Why??
14
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1answer
2k views

What are the tube shaped structures on the back of the fuselage of this 737?

A previous question asked what the little metal plates between the horizontal and vertical stabilizer were (they are vortex generators), however I am much more interested in what the gray tube shaped ...
18
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2answers
2k views

How strong is aircraft-grade spruce?

I have been trying to find some real numbers on how strong a single solid piece of aircraft graded spruce wood timber is, but haven't had much luck and the numbers that I have found so far were either ...
5
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1answer
178 views

What adds more weight to a twinjet? Tail-engines or wing-engines?

Let's say we have a large commercial jet, with exactly 2 engines, capable of holding at least 200 passengers. It could be a traditional jet like the Boeing 777, where both engines are in the wing. Or ...
0
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1answer
67 views

What are the effects of dihedral on net lift of a wing? [duplicate]

I read somewhere on the internet that dihedral decreases wing lift,so my question is will dihedral decrease the lift of an airplane wing since the wings are attached to the fuselage at an angle ? If ...
2
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4answers
107 views

Where is the compression on a compression strut in a tube and fabric airplane coming from?

I understand the functions of every part of a tube and fabric (two spar) ultralight wings and the loads they carry but what keeps puzzling me is the compression strut of a two spar wing as seen above. ...
2
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2answers
129 views

How does fuel efficiency depend on wing configuration?

Which of the following wing configurations is the most fuel-efficient?
5
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2answers
127 views

What is the function of cross bracing of interplane strut?

Pic 1 is the top and lower wing of a biplane called Bloop Ultralight,what is the function of the cross bracing between the interplane struts as seen in pic 1(I'm not talking about landing and flying ...
3
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2answers
205 views

Accounting for torsional forces during wing load tests

According to this aviation.se question, wing load tests are done by placing weights on the wings (upside down). This unfortunately only tests the wings bending loads (for cantilever wings) and the ...
1
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1answer
72 views

Structural rating of aircraft to withstand storm induced structural stresses

I was watching an accident report where an aircraft crashes when a storm destroys a wing spar. I'm curious is this only a danger for small aircraft or are there ...
1
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2answers
426 views

What is the function of interplane strut of a Biplane?

What kind of load does the interplane strut(s) carry,is it compression, tension or shear? In order words,what's their function and how do you calculate the force that the interplane strut carries?
2
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2answers
172 views

Compression and tension members of a biplane wing

I get why the upper wing of a biplane is a compression member (because the flying wire is attached to it at an angle) but what I fail to understand is why the lower wing is the tension member of a ...
6
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7answers
11k views

What is the definition of load factor and how do you apply it?

I'm a little confused about the definition of the load factor, n, as the definitions I found seem to contradict its application in force and moment balance analysis of an aircraft structure. The ...
1
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1answer
307 views

What is this loose object above the flap fairing? [duplicate]

During my flight, I noticed a loose object above one of the flap fairings. You can see it in this video: https://imgur.com/wCPSEem. Is it normal or should I notify the airline? People pointed out to ...
2
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2answers
395 views

How much lift does the wing attach fitting actually carry?

How do I calculate the lift force that the the bolt that join the wings to the fuselage of a strutted or braced airplane carry? I know in a cantilever airplane,the bolts have to carry all of the lift ...
2
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4answers
253 views

How to determine the compressive force in the spars of a strutted wing?

How does one calculate the compressive force that the inner section of a strutted or braced wing (from the strut attach point to the wing root) experiences? I know how to calculate the tension in the ...
4
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3answers
416 views

Why are Vertical tails generally tapered?

I'm just intrigued to know why the vertical tail of a majority of aircraft is tapered? Is it due to aerodynamics, structural design or due to some instrumentation or multiple other reasons?
2
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3answers
432 views

Why doesn't Stratolaunch have connected tailplanes like it has connected wings?

As a complete layman, the design of the Stratolaunch airplane, especially when reminding myself of its size, seems too flimsy, in that the only connection between the two fuselages is the center wing. ...
0
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0answers
17 views

Is it possible to evaluate all critical load cases in FEA when the masses may change depending on the load case and/or flight condition?

I want to run a linear static finite element analysis on a global airplane model and capture the critical loading conditions. Meaning, the payload and fuel masses may change position and magnitude ...
10
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3answers
3k views

Could winds of up to 150 km/h impact the structural loads on a Boeing 777?

From 15 October 2016, AI 173 from Delhi to San Francisco started flying over Pacific. Jet streams over Pacific helped Air India in reducing the flight time by 2 hours, despite increasing the travel ...
7
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1answer
3k views

How are folding wings managed?

There exist several aircraft - especially carrier-based ones - that have folding wings, to save space. How is this structure strong, taking into account the considerable amount of force on the hinge-...
1
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1answer
660 views

Question about Eurofighter structure

I was researching for the Eurofighter and I came up with a picture of its structure. I have three questions about its parts. I can't understand the role and the usage of them. Can anyone help me? ...
8
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2answers
383 views

What is the aerodynamic purpose of an Acorn?

This is an IL-62. On the tail of the aircraft, there is a large cone, protruding out of the vertical and horizontal stabilizer which is called acorn. I am trying to figure out what is the aerodynamic ...
53
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8answers
28k views

Why are fuel tanks located in wings?

Passenger aircraft have fuel tanks in the wings. Why? What are the advantages and disadvantages of this location ? examples of disadvantages I would suspect: added weight increases the structural ...
8
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4answers
1k views

Why do cargo aircraft still have floors?

Even with dedicated cargo aircraft built as cargo aircraft (rather than converted from a passenger-carrying configuration), the cabin is virtually always still divided into an upper and a lower lobe (...
9
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2answers
2k views

What is the function of the leading edge strip?

I understand the function of every wing part labelled above except the leading edge strip,what is its use in a fabric wing and will the wing function normally without it,if removed?
1
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1answer
378 views

Is the shear centre of a wing the same as its aerodynamic centre?

How can the shear centre of a wing be located and is it the same as the aerodynamic centre of a wing? Lastly, I know how the centre of pressure interacts with the aerodynamic centre but not the wing'...
-1
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1answer
53 views

How can you relate structural forces to load factors and inertia force [closed]

Our professor in aircraft structures asked us to research how can you relate structural forces to load factors and inertia forces and i dont have a clue. Help
0
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3answers
438 views

Bed sheet as wing skin?

https://en.m.wikipedia.org/wiki/Aircraft_fabric_covering This article states several early aircrafts that successfully used cotton as wing skin including Wright flyer. "Colditz Cock" glider had its ...
1
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1answer
358 views

How do you load test a wing rib?

When builders say they load tested a wing, most of the time what they are saying is that they load tested the wing spar(s) by turning the plane upside down and putting weights on the wing. This ...
0
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2answers
229 views

How can one calculate the maximum instantaneous bank angle a plane can do in a certain time? [duplicate]

I know that there is a limitation to do an instantaneous banking angle a plane can do. These limitations are due to the airplane (infrastructure - aerodynamics) and limitation on the pilot (due to his ...
-2
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2answers
2k views

Pilot seat - primary or secondary structure? [closed]

For design of pilot seat, would the seat be considered as primary or secondary structure?
6
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2answers
1k views

What material is used for the floor panels in the main cabin for Boeing 747-400?

Just conducting some research into materials used in construction for Boeing 747-400 and Douglas DC-3. I just found out that in a DC-3 the floor panels in the main cabin and companionway are of ...
3
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1answer
663 views

What is the structural significance of 'dimples' on the fuselage of a Boeing 747?

I recently watched the following video: In the video there is a mention that there are 'dimples' visible on the fuselage of a Boeing 747, when it is on the ground. It ...
4
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1answer
783 views

How does wing bending relief of an a340 compared to an a330 allow it to carry 30t more fuel in a center section of nearly identical wings?

From this question this reference in ymb1's answer states that the a340 and a330 have nearly identical wings. Because of bending relief from the weight of its outboard engines, the bending moment ...
6
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1answer
1k views

What is the average weight difference between composite and metal airliners?

Is there any rule of thumb for weight savings using composite materials. For example, is there an early model large airliner like the B747 or even B737 that later was modified with composite wings or ...
6
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2answers
2k views

How does the fuselage handle the different loads?

I have been trying to find out how the loads experienced by a fuselage are transferred between structural members (bulkheads, formers, frame assemblies, skin, longerons, stringers). I understand that ...