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Aircraft Design describes the different choices that aircraft designers (typically aerospace engineers) make to create an aircraft.

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Are there any specific weight or structural reasons to choose low vs. high wings for a cargo aircraft?

I have a large cargo aircraft concept and I am debating between a high or low wing. It seems like both are viable, but intuitively it seems structurally harder to support a high wing. Alternatively ...
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0answers
46 views

Can someone please explain lifting line theory in a simplified way please [on hold]

I'm currently revising lifting line theory for an exam (2nd year aero eng) and don't quite/fully understand the topic, even though I've dug through a few webpages and lecture notes. The explanations ...
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1answer
155 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 ...
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2answers
93 views

How do gull wings help? [duplicate]

I know that gull wings are shaped how they are for maximum help with a decrease in induced drag and increase in lift, but how do they do it? This is my homework!!!
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2answers
139 views

Can autothrottle be used without autopilot (and vice versa)?

In commercial passenger aircraft: Can autothrust be used with A/P disabled ? And can A/P be used without using autothrust? Citable references very welcome! If the question depends on a specific ...
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1answer
154 views

Why are smaller wings in the front with these VTOL aircraft?

I would think it would be better to put the larger wings under the front or middle closer the the payload/center and have the smaller wings in the tail? Why would these designs do the opposite? With ...
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0answers
39 views

How to compute actuator torque requirement for Variable pitch mechanism??

Suggest me any reference to compute the torque requirement for actuator/motor to control the pitch angle of propeller (Variable Pitch Propeller). Thanks in advance Arun Ravindran
6
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1answer
224 views

What is the purpose of the serrated trailing edge spoilers on the B52?

At around 50 seconds on the linked video you can see the serrations on the trailing edge of the B52's spoiler. What purpose does it have, and what gives it advantage/disadvantage over the standard ...
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1answer
57 views

How to calculate the amount of weight my plane can takeoff with?

This is how I approached this problem- My takeoff run is limited. So, depending on my configuration I calculated the maximum possible velocity I can attain in my groundroll. I assumed that at the end ...
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2answers
129 views

Why do drones look different from common airplanes? [duplicate]

In this video is shown Top 5 Military Drone. As we may see, the shape looks different than usual airplanes. My concern is especially with the tail. Normally we know that the tail is vertical. But from ...
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2answers
90 views

How to calculate the forces and moments required to aerodynamically actuate slats?

I am trying to make a wing where slats automatically deploy once it hits a higher angle of attack, let's say right before stall. I need to roughly estimate the forces and moments acting on the ...
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0answers
51 views

What is the material and font used on the panels of most cockpits?

I am working on a project for one of my aerospace engineering classes and was curious to see if anyone knew what type of material is used to make the panels of a cockpit (preferably a 737) as well as ...
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2answers
131 views

Would a pure flying wing in straight and level flight have zero NET wing loading?

In studying the NASA 247 foot wingspan solar powered Helios aircraft it seemed that evenly spacing the weight would create a Net Zero Load across its span when in flight, as gravity and lift forces ...
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0answers
173 views

When were the last subsonic turbojet-powered airliners retired from commercial passenger service?

The very first jetliners (Comet, Tu-104, Caravelle I-VI, 707-120/-220/-320, DC-8 series 10-30, original 720, CV-880) all used turbojet engines, turbofans not being available until later; when ...
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0answers
21 views

Calculating induced drag approximation using XFoil generated parasitic drag

I am trying to do rough predictions of induced drag using the XFoil results for parasitic drag. To do so, I am using the lifting line equation for induced drag and the Oswald efficiency number: $C_D=...
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2answers
227 views

Why overhead bin was put on top of passengers head?

Hello I'm just curious about the reason to why the overhead bin was most commonly being put on top of our seat and head.
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0answers
25 views

How to calculate the shear centre of a wing?

How is shear centre of a wings calculated? i.e. how can I calculate the wing shear centre of a two spar wing with main spar at 0% of wing chord and rear spar at 75% of wing chord? (Assuming the two ...
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3answers
102 views

Could the center of rotation of a spinning aircraft move away from CG?

Legend has it that the center of rotation in a spinning aircraft can "move back" when as the spin progresses. This seems logical as an aerodynamicly asymmetric object (fuse and empennage) in rotation ...
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1answer
59 views

Which pressure mode of operation has the most stress on aircraft frame

So I am want to know which mode of pressurization has the most demand on the airframe Isobaric mode constant - differential mode unpressurized I hope to get an answer because I have an exam and ...
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5answers
84 views

Is there any effect that contributes to roll stability even in the absence of sideslip?

Is there any physical dynamic-- involving high wing placement, "pendulum" effect of CG far below wing, or anything else-- that contributes to roll stability in a way that is NOT dependent upon the ...
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6answers
166 views

Which way (if at all) do the ailerons need to be deflected in a full-rudder sideslip in a Cessna 152 or 172?

Do you typically have to maintain an aileron deflection in a constant-heading full-rudder sideslip in a Cessna 152 or 172? If so, in which direction? And why -- what is the source of the roll torque ...
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2answers
89 views

Different between Angle of Incidence (AoI) and Angle of Attack (AoA)

Following discussion here, I am still confused about the difference between AoI and AoA. As I read in many references and watched in many YouTube videos especially this one: 1). AoI is tje angle ...
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1answer
46 views

what's the difference between priority and sequence valve in aircraft?

What roles do they play during retraction and extension of a landing gear ?
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3answers
366 views

Why do stealth aircraft generally lose in maneuverability?

Whilst stealthy built aircraft have (or claim to have) many anti-detection systems, they seem to have to compromise on less maneuverability features, and even have to keep their missiles inside, not ...
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2answers
156 views

Must quadcopters have the same propeller sizes?

I was flying quads today and it just suddenly popped up into my mind — do the propellers all have to be the same size in quadcopters? Mine are, but What if two propellers were larger and the other two ...
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1answer
58 views

What is compressibility drag?

I don't mean wave drag here. What is compressibility drag, which is understood to be a form of miscellaneous drag?
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2answers
107 views

What is the feasibility of solar powered drones?

What is the feasibility of solar powered drones? From my understanding, solar panels are becoming more and more efficient, in terms of weight vs energy captured, and in terms of surface area vs energy ...
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0answers
16 views

How can I use the “control hinge-moment coefficient due to tab” for sizing a trim tab on an elevator?

I calculated the control hinge-moment coefficient due to tab by using the dimensions of a tail and its elevator. However, the trim tab dimension parameters in the calculations were approximated values ...
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1answer
261 views

Why aren't there any jets with horizontal-stabilizer-mounted engines?

Looking at the spectrum of where jet aircraft put their engines, there are examples of almost every place that could conceivably used to carry a jet engine: slung under the wings buried inside the ...
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1answer
96 views

What is the function of a sweep cable?

This is Goat3 ultralight with sweep cables,what is the fuction of these sweep cables?
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1answer
93 views

Which airfoil would be optimum for a glider?

The glider I am designing has a mission requirement to fly for as much time as possible. It will fly in the low Re range of about 150,000 to 250,000. While comparing different airfoils I am looking ...
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0answers
30 views

Does Froude Efficiency represent an upper bound for propellers in certain flight / aircraft conditions?

I used the Simple Propeller Theory to calculate the Froude Efficiency for my theoretical propeller-driven craft (at 65k feet). Here are the results: https://ibb.co/kPPqzU. My results were that, for ...
2
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2answers
154 views

What was the first aircraft designed with a plug-system fuselage, and why?

Nearly all modern transport aircraft are designed with a plug-system fuselage, allowing longer and shorter variants to be built by adding or removing plugs. In addition, the plug system simplifies ...
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2answers
147 views

Again, where is the pivot point in pitch

In regards to recent question about neutral point, as being defined as center of lifts from wing and tail, could one also define a "neutral point" for down forces CG AND down force (up elevator) from ...
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2answers
68 views

Could reduced-lift wingtips allow an airplane to generate less wake turbulence?

Would it be possible to weaken the wake vortices generated by a large aircraft (which can be dangerous to smaller aircraft behind the large aircraft, and are the limiting factor determining how ...
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0answers
100 views

Which aircraft/powerplant manufacturers use metric hardware?

The vast majority of airframes and powerplants use U.S. standard/SAE hardware. Which manufacturers of engines and airframes use metric hardware?
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1answer
9k views

Why does the A380 not have front windows on the top floor?

The title says it all. On the 747, the cockpit is in the upper level and in the lower there's equipment (radar, avionics, etc.) But on the A380, the cockpit is in the lower floor and there's no ...
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2answers
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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?
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1answer
72 views

Why does the Aurora D8 have vents on the bottom of its fuselage?

The Aurora D8 is a concept of an experimental aircraft (not an actual aircraft for now), described in this site. It's discussed in this question here on Aviation.SX. I was watching the embedded video ...
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2answers
105 views

In the attached image of the Hoffman development of Arup design, the wing is shaped in a somehow anhedral way. Why?

Most airplanes of its days had a Dihedral, or a wing thickness tapering with a 'V' shape, this one is the opposite, hints exist as done to avoid: 'Dutch Roll', or that the ordinary way will impair ...
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1answer
35 views

What is the relation between hinge moment at the control surface and servo torque? [closed]

I am trying to estimate the required servo torque for my design using hinge moment at the elevator. XFOIL results were as follows- I am getting a Hinge moment of about 0.06-0.08 Nm. for the given ...
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3answers
97 views

Finding the center of gravity/centroid of an airfoil?

I'm in the process of building myself a wing frame out of balsa wood. However, as a high school student that's just started aerospace engineering, I'm not really sure how to go about it in some ways. ...
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1answer
69 views

Difference between Mach buffet and shock stall

What is the difference between Mach buffet and shock stall?
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2answers
3k views

Why aren't there any widebody propliners for the high-density short-haul markets?

Jetliners come in both narrowbody (one aisle) and widebody (two or more aisles) versions, but all propliners, to the best of my knowledge, are narrowbody aircraft. Now, granted, one of the big ...
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1answer
114 views

How do you know the maximum load a control surface can withstand?

source This is a separate strength testing (load testing) of the elevator of an airplane, how was the load determined? How did the engineers determine the maximum elevator load?
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1answer
39 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
71 views

What are the rules of airfoil thickness from root to tip on tapered wings?

I'm doing some research on wings and airfoils used in the 30s and 40s, and I'm trying to understand the rules about airfoil proportional thickness changes across the wing (root to tip) on tapered ...
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4answers
232 views

Does the required torque to spin a propeller increase with RPM?

I‘ve currently been experimenting with different propellers: 12x12 prop, 16x12 prop (both two blades) and a 22x14 (6 blades) prop. They were propelled by a 2.4 kW electric motor with 260 kV on a 6S/...
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1answer
75 views

In xflr5,how is the value of Fz calculated?

I am building an conventional plane with AR=6 and I find the wing area,A.So I have selected an airfoil for building my plane that is sd7062. Using xflr5 I got a cl vs alpha graph and I took the cl ...
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0answers
36 views

Is there any fixed-wing UAV common research model available?

Is there any source of structural specifications data available for a particular fixed-wing UAV, that can be used for comparison with a resulting structure, obtained by a structural optimization ...