Questions tagged [aircraft-design]

Questions about the different choices that aircraft designers (typically aerospace engineers) make in order to create an aircraft.

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17
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3answers
15k views

How strong is the A380 fuselage-wing joint?

The Airbus A380 has a maximum take-off weight of almost 600 tons. How strong does the joint between the wings and the fuselage have to be so it doesn't break? And how could it be trusted unless real-...
22
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2answers
10k views

Why doesn't the 737 have a fuel dump nozzle?

I was watching a documentary on aircraft incidents which mentioned that the 737 does not have the facility to dump fuel. Instead they're required to fly in circles to burn off excess fuel in an ...
13
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3answers
41k views

How does wing sweep increase aircraft stability?

I was told at one point that the sweep of a wing can help with the straight line stability of the craft, in fact I think it's one of the main systems that keeps flying wings flying straight (like the ...
4
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3answers
2k views

How reliable are stick shakers?

I've read many accident reports, and seen reconstructions, where instrument failures, disagreeing sensor sources and auto pilot faults have led pilots into believing that they are over speeding when ...
67
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5answers
33k views

What determines the maximum altitude a plane can reach?

What factors determine the maximum altitude for a plane? Is it limited by wing design, engine thrust, and so on? Is there a formula by which one can calculate the maximum altitude a plane can reach?
5
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3answers
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Are there any twin engine aircraft without counter-rotating props?

All the twins I have checked have counter-rotating blades, so I was wondering if this was true for all twins of if there are any twins that have both blades turning in the same direction.
2
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0answers
119 views

Why do newer commercial aircraft have their wingtips curved up? [duplicate]

Lately I've seen a lot of aircraft that have the wingtips curved up. What is the reason for this?
20
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6answers
31k views

Why do most single propellers have a clockwise rotation?

Why do most single propellers have a clockwise rotation (seen from the pilot's point of view)? There are though multi-engine planes that have each propeller rotating different directions, but in the ...
22
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6answers
8k views

Is triskaedekiphobia (fear of the number 13) the reason commercial planes normally do not have a row 13?

When I first time heard this "legend" I couldn't believe it. I was really surprised, if not shocked, to actually find row 13 missing on my next passenger flight. (I believe it was a Boeing 737.) Is ...
14
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3answers
8k views

What are the advantages and disadvantages of having landing gear doors?

To make comparison easy, let us take the example of B737 and A320, both similar aircrafts with retractable landing gear. As seen on the photo below, the B737 doesn't have gear doors for the wheels, ...
59
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4answers
30k views

Why can't jet engines operate with supersonic air and how do they slow it down?

Typically jets cannot operate when intake airflow is supersonic relative to the engine. Why is this so? Also, why are scramjets able to use supersonic air? To slow down the air to subsonic speeds, ...
13
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4answers
1k views

How to do a Rapid Descent in a jet with inoperative spoilers?

So, let us assume you are in a simulator for your favorite jet plane, and the instructor gives you a LOFT (Line-Oriented Flight Training) scenario that goes as follows: A normal takeoff and climb to ...
15
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4answers
7k views

How is the weight of an airplane measured?

Many very large airplanes have specific information of their empty weight. For instance the weight of an empty, regular 747-400 is 393,263 lb (178,756 kg) according to Wikipedia. The Concorde is 78,...
42
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10answers
15k views

What stops planes from being stolen?

Related question: do planes have keys? Let's say I happen to spot a fine-looking plane at my local airport and decide the owner probably wouldn't mind if I borrowed her for a little while - what ...
9
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3answers
12k views

How is the cargo hold volume for passenger aircraft designed?

An A380 has up to 2 decks for passengers and only 1 deck for cargo (for passenger's luggage), whereas a B777 has 1 deck for passengers and 1 deck for luggages. It looks like the volume of luggage per ...
26
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1answer
3k views

What is the purpose of the extremely high cabin altitudes in military aircraft?

The Lockheed SR-71 and the (old) Lockheed U-2 were engineered to maintain cabin altitudes in excess of 25000 feet AMSL at an altitude of more than 70000 feet AMSL. However, in both airplanes, pilots ...
4
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2answers
1k views

if temperature is increased but the volume contained in a area, will an air balloon lift?

I understand the archimedes principle as it relates to water, but am having trouble reconciling a thesis related to a hot air balloon. If theoretically, I could increase the temperature of air ...
38
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3answers
10k views

How does an aircraft form wake turbulence?

This question discusses how wake turbulence can affect planes flying in formation. It got me wondering, how do aircraft (the wings in particular) form wake turbulence to begin with? It can't be as ...
7
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2answers
2k views

What is the advantage of increasing an aircraft's horizontal tail surface area?

Most aircraft have horizontal tails. What is the advantage of increasing the horizontal tail surface area?
8
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3answers
3k views

What radios are airliners / large aircraft equipped with?

I know that pilots have to talk to the tower over the radio, and apparently you have to tune the radio to the right tower frequency. I've also heard that in an emergency, you're supposed to "squawk ...
12
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3answers
3k views

Is there a best number of wheels per bogie?

I understand the need of having more wheels when the aircraft is designed to be heavier. The number of wheels per bogie and the number of bogies differ from an aircraft to another. For example, there ...
59
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10answers
19k views

Why is there really only one basic design for passenger airplanes?

So when I look around on the airport, I don't really see many differently shaped airplanes. They all look pretty much the same, only subtle differences. Image: Aircraft Recognition Why is this ...
29
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2answers
30k views

How can a helicopter be designed without a tail rotor?

How will the main rotor torque be balanced if a helicopter doesn't have a tail rotor?
18
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3answers
10k views

Is the hydraulic fluid artificially colored?

A normal aircraft has multiple hydraulic circuit, identified by colors (e.g. according to the ATSB final report of the QF32 the green hydraulic line was disabled; according to the BEA final report of ...
27
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10answers
41k views

Can a plane fly without the Vertical Stabilizer?

What would happen if a plane (for the sake of the question let's say that the plane is an Airbus A380) lose its Vertical Stabilizer?
26
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3answers
3k views

Is wingtip design mature?

There are many wingtip design, all made to reduce vortex related drag, and neither boeing nor airbus seems to prefer one over another. They move from one design to another at each new aircraft, always ...
19
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3answers
9k views

Why is the Tu-144 the only commercial airplane with canard configuration?

I understand the delta wing was chosen because of the supersonic cruise (like the Concorde), and canards were added to reduce the approach/landing speed. But canards may be used without delta wing (e....
2
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1answer
4k views

Antennas on airliner wings? [duplicate]

From the question about sharp pods under airliner wings, I think the right term is anti-shock bodies, or flap actuators/track fairings. What's the little antenna looking thing extending off the rear ...
19
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2answers
5k views

Why is the APU located in the tail for almost all commercial aircraft?

I know there are planes whose APU (Auxiliary Power Unit) is located elsewhere, but for the most common commercial jet aircraft (A320, B737, B747, A330,...), the APU is located in the tail. Is there a ...
8
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4answers
4k views

Why is the fatality rate in the Diamond DA40 so remarkably lower than the SR20/22?

I assume it has a lot to do with the stall characteristics, but with the SR20/22 having a combined 1.6/100,000 Fatal rate and the DA40 having .35/100,000 Fatal, it seems like a very stark difference. ...
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2answers
2k views

Why were the specifications of the Pipistrel Panthera downgraded?

I'm curious if this was a failure of the simulations or a result of the engine swap they did at the last moment. Originally, they said they could cruise at 200kts @ 10g/h fully loaded. Now its down to ...
18
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3answers
11k views

How does the hinge mechanism of plug-type pressure doors work?

Many pressurized aircraft have the type of plug doors that open by first swinging inside, rotating about at least two axes, then moving through the opening and ending up outside parallel with the ...
16
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1answer
33k views

How to calculate the required motor power and rotor size with respect to the weight of quadcopter?

I want to build a quadcopter but don't have any idea about motor and rotor size selection. Is there a formula or equation to use? What are other things that need to be considered? Trial and error ...
6
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2answers
1k views

What are the states that the landing gear can be in?

What are the valid set of enumerated states for landing gear? My current working set is: DOWN DOWN & LOCKED STOWED STOWED & LOCKED INOPERATIVE CYCLING_UP CYCLING_DOWN Also, are there any ...
10
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1answer
859 views

What is the metal plating on the back of the A-6 for?

What is the perforated metal plating on the back of the A-6/EA-6 for? Source: Wikipedia
34
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9answers
31k views

Why do airplanes not have manual transmission?

I have limited experience with flight simulators but I have never bumped into a plane with manual transmission while, on the contrary, it's very common for other means of transportation (like cars and ...
10
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2answers
2k views

Why did moving the CG aft on the Wright Brother's plane improve handling?

In response to Peter Kämpf's answer to this question, why did moving the CG back on the Wright Flyer improve its stability?
32
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3answers
32k views

Are fighter jets designed to be so inherently unstable that a human can't fly one unassisted?

I'm told that in order to be more maneuverable fighter jets are designed in a way that makes them impossible for a human to control without the help of a flight computer. Is this actually true? ...
2
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2answers
2k views

What do the terms “Landing Since New”, FC, and FH mean on a Landing Gear RDAS?

Could anyone able to tell me the "Landing Since New" Meant? and what is the FC and FH in here? Thanks
20
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3answers
21k views

What is a high speed stall?

I'm told that planes can actually stall when the airflow over the wing goes past Mach 1? Why does this happen and how do you design an aircraft to avoid it?
64
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3answers
58k views

What is the purpose of the sharp pods under airliner wings?

What are the pods with the sharp trailing edges underneath the wings of large airliners, as shown in the image below? My best guess would be fuel tanks
26
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2answers
17k views

How much force does a 747 land with?

I've been told before that the runways for large commercial aircraft have to be built to withstand a large amount of force. But I'm wondering exactly how much it is? When a 747 touches down, how ...
49
votes
3answers
39k views

Why are the Boeing 737 nacelles odd shaped?

Why is a Boeing 737 NG engine not completely round in shape? It seems to be flat at the bottom and round at the top and sides. Earlier Boeing 737 versions (100 and 200) seem to have a more rounded ...
7
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3answers
4k views

What's the minimum roll rate a commercial airliner would have with maximum aileron deflection?

If the maximum aileron deflection possible was commanded on a commercial airliner, how fast would the aircraft roll? I don't think there's many reasons to bank a large aircraft quickly, but what I ...
11
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4answers
9k views

Why don't planes have a reverse propeller as air brakes?

When I first heard the word air brakes it came to me that maybe the engine start rotating in the opposite direction for that, but since that's not possible, why can't we have an extra engine for air ...
20
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1answer
3k views

What is the purpose of the three cylinders under the engines of the Junkers 52?

They're mounted underneath each engines on the JU-52. I saw them up close at the museum. Each one consists of bundled half-inch pipes running through the whole length, open at both ends.
6
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2answers
5k views

What are the properties of the wing (airfoil symmetry, angle of incidence) of an aerobatic aircraft?

On an aerobatic aircraft, such as an Sbach342, what type of airfoil does it have and what angle of incidence does it have in relation to the fuselage?
9
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1answer
1k views

Minix wingtip vortices mitigation - How does it work?

I stumbled upon this article: Minix wing tip device promises 6% gain in fuel efficiency for airliners. Such an economy is appealing and I must confess the design is "sexy". Could someone expand a ...
14
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1answer
2k views

Why simple paper planes fly better than most “realistic” paper plane models?

Just a A4 paper sheet folded into a plane seems to fly decently. But a model of actual (big) plane made out of paper is only good at falling... What is different for paper planes? Are there "modern ...
21
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3answers
5k views

Why is the use of tail-down force so common?

Why is the use of tail-down force so prevalent in aircraft design? Why not use canards to avoid induced drag?