Questions tagged [aircraft-structures]

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

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5
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2answers
307 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 ...
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1answer
571 views

Is it viable to put an engine at the rear of the plane like in this photo?

I saw this image on a NASA page talking about hybrids and I was wondering if the back-engine placemente is actually viable and if it is why hasn't been done yet?
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2answers
1k views

Is it ever permissible to takeoff on an aircraft heavier than its MTOW?

I'm thinking in terms of the Concorde accident in 2000 having just read part of the report which states that they were in effect several tonnes heavier than they should of been factoring in the ...
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1answer
417 views

Why isn't aircraft structure inspection done by robots? Is there any known active research on the subject?

From my research I've found that (correct me if i am wrong): Structure inspection (in B,C and D Checks) including (visual, thermography, ultrasonic inspections) looking for structure damage of ...
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4answers
232 views

Could the experience of inflatable structures in boats be applied to large aircraft design?

Inflatable structures in boats have proved extremely successful and versatile since they began to find widespread use in the 1930s. I'm aware that experiments have been made with inflatable wings - ...
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2answers
459 views

Would climbing onto fighters placed on display cause damage?

The question is about any more or less modern plane similar to Su-27 in its fuselage design. It's not uncommon to install retired planes as monuments. Here's one example in Eastern Europe (image from ...
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1answer
1k 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 of ...
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1answer
1k views

Why does the aspect ratio of a wing become less important at supersonic speeds?

My understanding is that an increase in the aspect ratio (AR) of a supersonic wing won't increase the efficiency like it would for a subsonic wing. If the subsonic induced drag is: $C_{D_i} = (C_L^2)...
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2answers
924 views

What is the effect of wingspan on wing stiffness?

In an article in aviationweek about flight testing the GE9X, this statement is made. To reduce aeroelastic interaction between the testbed and the big engine, GE has also stiffened the wing by ...
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1answer
97 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
303 views

How are further structural failures prevented if an aft pressure bulkhead fails?

In a modern airliner, if the aft pressure bulkhead experiences a structural failure, what design features are incorporated into the empennage to prevent the empennage from being overpressurized (i.e. ...
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0answers
534 views

How much does a Boeing 737 wing bend/deflect in cruise conditions?

As a part of my ongoing research of a structural joint analysis of a Boeing 737, I have been looking for sources where I may be able to find the bending/deflection data during cruise conditions. I ...
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4answers
1k views

Why landing gears still need bungee springs?

While studying landing gear, I came across this term 'bungee spring' to which there was no definitive explanation in text with regards to its usage. So in the image, you can see for the jury strut/ ...
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5answers
2k views

Why don't aircraft (commercial and military) use reflective visor windshields?

Just like those used on an astronaut's helmet, these reflective visors can help in better visibility when facing the sun (or any bright light source). But the windshields of most aircraft (commercial ...
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2answers
352 views

Is pilot alerted of any physical or structural failures?

Current crew alerting system messages, I believe, are displayed basing on the software detection of the failures basing on the sensor information. What kind of structural failures can occur to an ...
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3answers
523 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. ...
3
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1answer
282 views

Is all the extra lift from flaps added upstream where the spars sit?

Flaps can significantly increase the lift for a wing, is all that extra lift added upstream where the spars sit? I ask this question because the flaps in airliners seem to be only connected by a few ...
3
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1answer
764 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 ...
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2answers
305 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 ...
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1answer
574 views

Which FAA or EASA regulation does prevent a high wing to cross the passenger compartment?

I'm looking for reference subpart and eventually chapter in either FAA or EASA regulation where it is stated that for passenger aircraft with high wing passenger compartment can not be interrupted by ...
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4answers
268 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. ...
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4answers
685 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 ...
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2answers
2k views

How does a full fuselage and structure inspection happen in practice ? (for modern Civil airliners)

What are the intervals at which a full structure inspection take place ? How much time does a test commonly take for narrow and wide body aircraft ? Is every part in the structure manually ...
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2answers
680 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 ...
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2answers
483 views

How does an outflow valve work mechanically?

Under Environmental control and oxygen systems chapter of Aircraft Maintenance and Repair book by M. Kroes, there's an topic of working of the outflow valve The diagram is of a valve that also works ...
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2answers
318 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 ...
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1answer
436 views

In which cases the lift distribution is not elliptical? (i.e. e≠1)

I understood that Oswald coefficient doesn't modify the induced drag (i.e. =1) if the lift distribution is elliptical. When is the lift distribution not elliptical? What are the physical or ideal ...
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1answer
105 views

How do I find the shear center of an unsymmetrical airfoil?

I'm quite a newbie of these systems and I am designing the wing box of a drone. I know where I want my shear centre. However, I have been trying to determine the shear centre of my idealized airfoil. ...
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2answers
227 views

How does fuel efficiency depend on wing configuration?

Which of the following wing configurations is the most fuel-efficient?
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2answers
877 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?
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1answer
9k views

What are the differences between types I, II, and III emergency doors? [duplicate]

What are the differences between types I, II, and III emergency doors?
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1answer
2k views

Why is the wing bending so much in this video? [duplicate]

On a recent vlog, YouTuber CGP Grey mentioned how much the wing of the plane he was on bent. I understand that wings are designed to bend a little, but what actually causes so much deformation? ...
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1answer
1k 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? ...
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1answer
1k views

How to identify load paths? [closed]

How would you go on about identifying the load paths on an empennage structure, wing and fuselage?
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1answer
118 views

Can buckling of wing skin panels occur without external compressive loads?

State whether True or False: In general, the buckling of thin and slender structures occurs under applied axial compressive stresses. In the case of wing skin panels, they can fail in buckling even if ...
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1answer
183 views

In wing design, how is factor of safety related to G-limits?

What does factor of safety mean with regard to the maximum G force an aircraft is rated for? Does a rating of 3Gs mean the same as a safety factor of 3? Or is there some extra margin?
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1answer
131 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 ...
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1answer
1k 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'...
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2answers
204 views

What is the structural impact on the wing if no fuel is stored in the wings and just in the fuselage?

What is the structural impact on the wing if no fuel is stored in the wings and just in the fuselage and how to counter possible advantages/disadvantages? Has this topic already been researched?
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1answer
348 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 ...
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1answer
1k views

What are the advantages/disadvantages of ultrasonic in aircraft structure inspection?

What i mean by structure is (different composite materials and aluminum). What are the cons in terms of time required to test the full body of the aircraft (B747 for example) in C and D checks ?
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1answer
545 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?
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2answers
204 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 ...
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1answer
467 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 ...
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0answers
56 views

Texts on aero-engine structures

I have been scouring the web for resources on aero-engine structures and structural design (preferably civil turbofans) but unfortunately it seems like they are hard to come by. I would like dedicated ...
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0answers
52 views

Are the firewall and forward pressure bulkhead different components? [duplicate]

Suppose in a single engine aircraft, where the engine is located near the nose of the aircraft. If the cabin is pressurized, I know there will be a requirement of pressure bulkheads, both in the rear ...
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0answers
110 views

How do I reinforce a tubular spar that has been drilled vertically for an attachment bolt?

Previously posted a question about lift strut attachment to tubular wing spar with a bolt vertically through the spars. See drawing below. I tried using Bruhn's analysis book to formulate a a ...
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0answers
45 views

Is TGA analysis required for composites used in low speed subsonic aircraft?

I need to analyse the temperature drop effects on glass-fiber reinforced polymer (GFRP) used in aircraft subjected to icing, how can it be done? Does thermogravimetric analysis (TGA) help or is it ...
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0answers
62 views

How are the structural failures reported to pilot [duplicate]

For instance an engine separated from aircraft (though most unlikely 1E-13 probability) or wing got damaged, how is it reported to the pilot? Will it be reported as 'Engine Fail' or 'Left Wing Fail'?...
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2answers
686 views

What are different components of an engine pylon?

What are the different structural components that are inside the fairing of engine pylon and what are the functions of each part? The pylons for each aircraft are made of Ti-64 alloys, can they be ...