Questions tagged [aircraft-structures]

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

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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 ...
keg504's user avatar
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2 votes
2 answers
139 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 ...
Abhishek Dhiman's user avatar
1 vote
1 answer
89 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?
javiation's user avatar
2 votes
0 answers
52 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 ...
Martin Moreno Vega's user avatar
2 votes
2 answers
145 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 ...
Mridul's user avatar
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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 ...
Sudipto Tushar's user avatar
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1 answer
231 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 ...
Frank's user avatar
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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 ...
Vikki's user avatar
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3 answers
143 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, ...
Vikki's user avatar
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38 views

How does the air taken from the Gearbox Air Inlet provide the Gearbox cooling? (Also about "Main Gearbox Cooling Air Inlet")

How does the air taken from the Gearbox Air Inlet provide the Gearbox cooling? Is the air taken from the outside transmitted directly to the Gearbox, or is there a separate system? Also, I couldn't ...
pilot162's user avatar
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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 "...
pilot162's user avatar
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2 votes
1 answer
231 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&...
pilot162's user avatar
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8 votes
2 answers
852 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 ...
pilot162's user avatar
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1 vote
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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-...
Seth's user avatar
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0 answers
640 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 ...
Seth's user avatar
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122 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?
alexandra's user avatar
-1 votes
2 answers
353 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 ...
Martin Moreno Vega's user avatar
3 votes
2 answers
443 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 ...
Auberron's user avatar
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0 votes
2 answers
140 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 ...
Nail's user avatar
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1 answer
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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 ...
Mridul's user avatar
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2 votes
1 answer
252 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 ...
Mridul's user avatar
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1 vote
2 answers
277 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 ...
Mridul's user avatar
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8 votes
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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 ...
TN Japanese's user avatar
4 votes
1 answer
1k 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 ...
Nikolai Kanchev's user avatar
0 votes
1 answer
339 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 ...
Rameez Ul Haq's user avatar
3 votes
1 answer
752 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 ...
ahahfilip's user avatar
0 votes
3 answers
565 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 ...
MD88Fan's user avatar
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2 votes
1 answer
2k 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 ...
Rameez Ul Haq's user avatar
5 votes
2 answers
235 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 ...
Lars Knowles's user avatar
4 votes
1 answer
546 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 ...
Mridul's user avatar
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1 vote
1 answer
382 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 ...
Arush Kumar Singh's user avatar
1 vote
2 answers
338 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?
mldmnn's user avatar
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1 vote
1 answer
751 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?
Mridul's user avatar
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5 votes
2 answers
524 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. ...
Pedro Brandão's user avatar
1 vote
0 answers
62 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 ...
haukit's user avatar
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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 ...
Camille Goudeseune's user avatar
0 votes
1 answer
308 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 ...
Lucas's user avatar
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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 ...
Salmonbeing00's user avatar
0 votes
0 answers
59 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 ...
Paul G's user avatar
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8 votes
1 answer
2k 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 ...
Salmonbeing00's user avatar
10 votes
2 answers
320 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. ...
Salmonbeing00's user avatar
1 vote
2 answers
3k 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 ...
Hamza Khalid's user avatar
32 votes
3 answers
16k views

Why are commercial aircraft windows typically oval instead of circular?

Pretty much what the title says. Surely a circular window would allow more window area while not compromising on strength? Some planes(Gulfstream jets) do have circular windows. Is there a reason for ...
pirocks's user avatar
  • 680
0 votes
1 answer
1k views

How does the B777 Side brace locking mechanism work?

The B767 has jury strut actuators and their working is pretty straight forward. They oppose the collapsible geometry of jury strut and lock them in the over centre locking position. But for B777 this ...
Salmonbeing00's user avatar
0 votes
1 answer
2k views

What materials form the structural elements of the Boeing 737?

What materials form the structural elements (leaving the spars, ribs etc) of the B737? It was tough to get any information on the kind of composites used on the 737 structure. Hoping to get some ...
Salmonbeing00's user avatar
3 votes
4 answers
3k 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/ ...
Salmonbeing00's user avatar
1 vote
0 answers
55 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 ...
Ashutosh Mukherjee's user avatar
0 votes
2 answers
242 views

Could abrupt flight controls input cause damage in these circumstances?

I went flying yesterday with a friend in my 1972 Grumman AA-5. She's a good copilot for someone who doesn't know much about flying. I showed her how you can pitch up and down, cause 0G, and float, ...
Charles D.'s user avatar
0 votes
1 answer
184 views

When does an UAV need an internal structure?

I´ve seen some UAV models without internal structure (stringers, longerons and frame). I guess the drone´s shell is the frame itself. So what is the best approach to calculate the shell thickness to ...
VicenteC's user avatar
  • 127
37 votes
3 answers
17k views

Why does the second floor of the Boeing 747 occupy only part of the plane?

Why does the second floor of the Boeing 747 occupy only part of the plane, while the second floor of the Airbus a380 occupies the entire space of the plane?
JeanExtreme002's user avatar