Questions tagged [aircraft-structures]
For structural engineering questions about airframes and the mechanical structures aboard aircraft
151
questions
5
votes
3
answers
2k
views
What drives the mechanical challenges which make trailing-edge flaps an (almost) ubiquitous solution vs leading-edge flaps?
(Apologies for the mouthful of a title.)
I was thinking about canard aircraft and how trailing edge flaps (TEF) are actually counterproductive for them. Leading edge flaps (LEF) could theoretically ...
- 5,462
1
vote
0
answers
101
views
How to calculate wing deflection?
I can calculate deflection for a single beam, but I do not know how to calculate deflection for the whole wing section. I do not know how to calculate deflection for the two spars simultaneously.
I am ...
- 11
5
votes
3
answers
2k
views
Structure that holds the twin-engine on an aircraft
What is the name of that big structure (in red) that holds the engine?
- 51
1
vote
4
answers
386
views
How do the landing gear support so much mass?
The first thing that one notices after seeing an aircraft, is that it's quite a heavy flying machine. And so, one would expect monumental tires on these vehicles, yet they don't exist.
How is it that ...
- 404
0
votes
1
answer
179
views
fuselage structure
How can a mechanic measure the distance of underlying structural elements of fuselage skin (e.g. stringers, internal doublers around door cutouts) from a specific cracked fastener hole in the fuselage ...
12
votes
6
answers
6k
views
Why aren't aircraft built with carbon fiber tubes?
Though carbon fiber is more expensive than aluminum as a base material, one of its biggest costs is creating the final composite parts made of carbon fiber (molding, layering, resin, curing, baking, ...
- 4,843
4
votes
1
answer
519
views
How can tailplane force imbalance twist a tailcone off?
http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/LaudaAir/LaudaRPT.html#2.2.3
2.2.2 In-Flight Breakup Sequence
The analysis of the major structural damage showed that the ...
7
votes
2
answers
5k
views
Is there a common name for ailerons, elevators and rudder?
Since ailerons, elevators and rudder are all designed in a similar way, that is, they are attached to a fixed structure from where they move in both direction on that particular axis.
For example on a ...
- 4,843
2
votes
1
answer
84
views
Material Shape Parameter (n)
In order to calculate the plasticity reduction factor given in Michael C.Y. Niu's book a constant (n) is being multiplied which is called the material shape parameter, does anyone know the meaning of ...
- 33
0
votes
2
answers
189
views
Is there a clear cut method for cutout on structural members?
I have been looking into fuselage cutouts especially, window cutouts on the skin panel for a school project. Reading Bruhn and Niu Books, both state that there are no clear cut methods for fuselage ...
- 33
2
votes
2
answers
511
views
How is a turboprop engine mounted to the wing?
For a given turboprop plane such as the ATR-72, there doesn't seem to be a pylon as on turbofan driven planes. This question: How are engines mounted onto wings? has answers that detail how a pylon is ...
- 23
2
votes
2
answers
534
views
Bulkhead (Forward and Rear) positions in civil aircraft
I am looking for general positions of forward and rear bulkheads in the civil aviation aircraft. Like, at what percentage of fuselage length from fuselage nose or any other reference point?
Any ...
1
vote
1
answer
113
views
What is the material of the wing spar on the Mitsubishi MU-2?
I read that the spar on Twin Commanders are made of steel. Is this also the case for the MU-2?
- 13
2
votes
0
answers
82
views
Anyone knows where i could find the McMaster, H. C., “FAR 23 LOADS”, Aeroscience Software, 2.02 Edition?
I am currently conducting research on wing lift distributions and came across the existence of a software tool called "FAR 23 LOADS," developed by McMaster, H. C. (Aeroscience Software, 2.02 ...
2
votes
2
answers
324
views
Should composite ribs be made in the same way as metal ones?
A lot of metal ribs are made from bending or stamping sheet metals. So we see shapes which have lots of discontinuities in the flange area for ease in manufacturing. My question is - is it the most ...
- 1,222
0
votes
0
answers
77
views
what is Limit load factor structural and aerodynamic envelope at structural design gross weight and maximum gross weight?
As an aerospace engineer, as soon as I saw the words "structural and aerodynamic envelope" the first thing that popped into my mind that is it V-n diagram? But when I searched about it in ...
0
votes
1
answer
493
views
What does this part on a vertical stabilizer do? [duplicate]
On a B787 vertical stabilizer shown in the image, there's this small fin at the leading edge that connects to the fuselage.
It seems too small in size to be considered a dorsal fin. Simply adding this ...
- 415
13
votes
2
answers
4k
views
Why do windowless cargo Metroliners still have overwing-exit hatches?
One of the variants of the Metroliner, the SA227-AT Expediter, is a dedicated cargo aircraft with strengthened floors, an increased MTOW, and a windowless cabin.
However, despite being a cargo ...
- 28.5k
0
votes
3
answers
237
views
How much of an effect do structural overloads have on an airframe's safe fatigue life?
Most aircraft1 are built primarily out of various aluminium alloys. Aluminium and its alloys have multiple physical and chemical properties that make them terrible choices as structural materials, ...
- 28.5k
0
votes
1
answer
726
views
How many fuel vents are there in DA40NG airplanes? (Tank Air Outlet)
How many fuel vents (Tank Air Outlet) are there in DA40NG airplanes? I wonder how many there are under each wing surface. I know that the hole on the round cover we see in the first photo is "...
- 2,237
2
votes
1
answer
472
views
What is the function of the pipe referred to as "Venting Pipe" in the picture and how is it different from the exhaust pipe?
What is the function of the pipe referred to as "Venting Pipe" in the picture and how is it different from the exhaust pipe? The two photos you see in the picture are the "Venting Pipe&...
- 2,237
8
votes
2
answers
957
views
Where exactly is the engine compartment, remarked in yellow?
Where exactly is the engine compartment, remarked in yellow? We know that normally the air going to the engine passes through the air filter. But when we open the alternate air valve, where does the ...
- 2,237
1
vote
0
answers
133
views
Wing Structural Load Test Simplification
I'd like to perform a static structural load test of a wing for a UAV. The wing is a rectangular planform of constant thickness throughout the wingspan with no twist, dihedral, or sweep.
During steady-...
- 93
1
vote
0
answers
1k
views
Fuselage Bending Stress Calculation Approach
Does the approach below seem reasonable for a first-order estimate of the bending stress on a fuselage? I want to specifically confirm the end result, which shows that the maximum bending moment, and ...
- 93
0
votes
0
answers
129
views
Why are weapons pylon fittings usually tension fittings?
As far as I see, most of the fighter jet pylon fittings are tension fitting instead of the shear fitting. What is the logic behind that?
-1
votes
2
answers
681
views
What are the loads in a horizontal stabilizer? [closed]
I am doing a project and I can't really find any complete information on how to estimate and calculate de loads (lift, weight, drag...) in a horizontal stabilizer.
If someone could give me good papers ...
3
votes
2
answers
847
views
How do the orientation of spars and ribs affect the aerodynamic efficiency of wing?
There are various ways the ribs and spars can be oriented in the swept wing. Do the placement of ribs and spars affect the aerodynamics? And, what are the structural advantages of both orientations ...
- 1,567
0
votes
2
answers
153
views
Does the weight of a pilot exponentially affect the necessary weight of man-powered aircraft?
The MIT Daedalus, a man-powered craft, weighed about 31kg. This will be significantly lighter than its pilot during its record setting trip, though I can't confirm his exact weight. Still, this raises ...
- 43
0
votes
1
answer
283
views
Can the torsional strength of a wing be increased by adding more ribs?
I understand increasing the skin thickness is the best way to increase the strength in torsion, but if that is not an option will just adding more ribs work?
In a composite wing skin, will adding a ...
- 1,222
2
votes
1
answer
359
views
How deep do lift pins go inside the wing in gliders?
In the photograph below, how are the lift pins structurally attached to the ribs and how far does its support structure run inside?
Does the discontinuity in the torsional flow in the wing skins pose ...
- 1,222
1
vote
2
answers
412
views
In aircraft with single spar in each wing, are the spars at different chord locations?
In aircraft like the Pipistrel Virus, there's a single spar in each wing which is held with steel pins inside the fuselage.
Are these spars offset along the chord line or are they bent at an angle for ...
- 1,222
9
votes
2
answers
1k
views
Why does the hardpoint mechanism on sweep wings produce a contact trace in front of the axis?
The basic structure and photos have already been explained on this site and on Wikipedia:
How does a variable-sweep-wing aircraft keep wing-mounted payloads straight?
Variable-sweep wing, Wikipedia
...
- 91
4
votes
1
answer
2k
views
How to estimate the ribs spacing?
I would like to know what is the general logic behind the choice of the rib spacing in the thin-walled load bearing structure of a straight or swept all-metal wing? Is it the global or local ...
0
votes
1
answer
534
views
What happens to Lift and Drag on aircraft (and its components) when sideslip is increased gradually from 0 degrees to 90 degrees?
I possess an Aerospace Engineering background, and work as a Aerospace structural analyst at a local firm. A portion of my job is dedicated to determining the critical conditions that the aircraft and ...
- 351
3
votes
1
answer
1k
views
What is the difference between a tear strap and a doubler?
Is there a difference between a tear strap and a doubler? If I get it right, the tear strap reinforce the main structure locally and prevent the propagation of tears, while the doubler, well, it has ...
- 33
0
votes
3
answers
900
views
Is Peter Sripol’s Mk4 ultralight design safe and/or practical? [closed]
I recently rewatched Peter Sripol’s Mk4 ultralight video
Obviously, the aircraft flew, but I have several questions as a result.
First and foremost, is a vinyl-covered ...
- 2,500
2
votes
1
answer
3k
views
How should I decide on the type of stringer to be used in an Aircraft's wing and fuselage?
I am trying to add stringers on the skins of an aircraft's wing as well as fuselage, for the same reason why they are present in most of the aircrafts i.e. to resist bending (and a possible buckling ...
- 351
4
votes
2
answers
259
views
How is it possible that the design criteria for turbulence intensity has nearly doubled, but the manoeuvring load factor is the same?
https://www.law.cornell.edu/cfr/text/14/25.341
Here it says the turbulence intensity used for certification is 90 feet per second. Before, it was 50 feet per second, that section was added in 1981. So ...
4
votes
1
answer
634
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 ...
- 1,222
1
vote
1
answer
559
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 ...
1
vote
2
answers
389
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?
- 111
1
vote
1
answer
1k
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?
- 1,222
5
votes
2
answers
653
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. ...
1
vote
0
answers
64
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 ...
- 43
20
votes
1
answer
2k
views
Why are Stratolaunch's engines so far forward?
Stratolaunch's engines hang from pylons, not under the wing, but entirely forward of the wing's leading edge. (Even farther forward than, say, the 747's.) What benefit does this have, to compensate ...
- 12.6k
0
votes
1
answer
398
views
Is there any advantage to having both wings integrated into a single wing unit, rather than being attached separately to the fuselage?
if I have a wing, which is split in the middle of it and attached at each side of the aircraft (like in any commercial aircraft today), I get a bending moment at the root of the wing.
What if I have ...
- 1
2
votes
2
answers
2k
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 ...
- 601
0
votes
0
answers
75
views
Why is the assumed Lift-to-Weight-Ratio for the limit drop test for heavy aircraft (FAR-25) higher than for small aircraft (FAR-23)?
The FAR-25.725 assumes a Lift-to-Weight-Ratio L/W = 1 for the landing gear drop test while the FAR-23.725 assumes only L/W=0.667. This factor affects the load inertia factor n which is also needed for ...
- 1
8
votes
1
answer
3k
views
What's the difference between multiple disc brake and segmented rotor brakes?
Going through FAA's aircraft maintenance manual I came across a topic under braking systems, which had two different types of brakes: multiple discs and segmented rotor disc brakes
Looking at the ...
- 601
10
votes
2
answers
337
views
What is dual mode adaptive landing gear system?
Referring to the NASA document Design and Development of the Blackbird:
Challenges and Lessons Learned.
On page 31, there's a mention of dual-mode adaptive landing gear, which is quoted below.
...
- 601