Questions tagged [aircraft-structures]

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

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17
votes
6answers
6k views

Do aircraft have accelerometers?

Do modern aircraft employ accelerometers or other similar equipment to measure g-forces on the aircraft? I could imagine this being used as an inspection/service indicator, particularly after hard ...
7
votes
1answer
336 views

Stress on wing/fuselage-joint of aerial water tanker aircraft - and possible mitigating measures

Following the unfortunate crash of a C-130 aerial water tanker aircraft in Australia, a friend brought to my attention a 2002 C-130 tanker crash in the US. As can also be seen in this video, the wings ...
1
vote
1answer
95 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
votes
1answer
775 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
votes
1answer
171 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 ...
4
votes
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
votes
1answer
166 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
votes
2answers
756 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
votes
0answers
60 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 ...
8
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1answer
475 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.
6
votes
1answer
334 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 ...
15
votes
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??
19
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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
votes
1answer
184 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
votes
1answer
70 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
votes
4answers
119 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. ...
5
votes
2answers
141 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 ...
2
votes
2answers
134 views

How does fuel efficiency depend on wing configuration?

Which of the following wing configurations is the most fuel-efficient?
1
vote
1answer
80 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
447 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
votes
2answers
182 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 ...
1
vote
1answer
310 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
votes
2answers
415 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
votes
4answers
279 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
votes
3answers
469 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?
0
votes
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 ...
1
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2answers
106 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 ...
2
votes
3answers
440 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. ...
1
vote
1answer
715 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? ...
9
votes
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 (...
53
votes
8answers
29k 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
votes
2answers
389 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 ...
9
votes
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?
3
votes
2answers
216 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
vote
1answer
440 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
votes
1answer
54 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
votes
3answers
453 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 ...
0
votes
2answers
245 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
3k views

Pilot seat - primary or secondary structure? [closed]

For design of pilot seat, would the seat be considered as primary or secondary structure?
4
votes
1answer
814 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
votes
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 ...
3
votes
1answer
673 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 ...
6
votes
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 ...
5
votes
1answer
351 views

What's the name for the structure that helps stop the nose wheel in Boeing 747-400?

From my understanding the nose wheel of a Boeing 747 does not have brakes, and as such when it is retracted it is still spinning. However, there are two "plates" that make contact with the wheels and ...
1
vote
1answer
756 views

How to identify load paths? [closed]

How would you go on about identifying the load paths on an empennage structure, wing and fuselage (in a general sense)?
1
vote
1answer
373 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 ...
6
votes
3answers
608 views

How can filling a tube with foam help prevent buckling?

How can filling the empennage (aluminium tube) with Styrofoam stiffen it to avoid buckling as seen in Whingding ultralight?
0
votes
2answers
201 views

Are aircraft wings airtight?

Is there any no air proof design for the wings? Or are some of the parts are equivalent to outside pressure and some have gauge pressures? Are some parts airtight and others not?
5
votes
1answer
546 views

What physical tests are involved with verifying a wing spar is suitably constructed for a homebuilt aircraft, such as the piper cub kit from wicks?

During construction how is a spar tested to ensure it can adequately cope with bending and twisting forces of the completed structure, or is this performed after complete?
6
votes
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 ...