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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1answer
211 views

There is any technical reason for the new Airbus shades? [duplicate]

There is any technical reason for the new Airbus shades? Or they exists just because it is sexy?
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1answer
126 views

Is the Airbus approach more friendly (in case of incapacitated pilots) in terms of a passenger being able to fly the plane? [closed]

Is the Airbus approach technology more friendly to a new pilot or passenger than a Boeing haptic approach?
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2answers
217 views

Why do we use composite aluminium or titanium stacks in airplanes? [closed]

Why do we use composite aluminium or titanium stacks in airplanes? What are their machining conditions?
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0answers
98 views

Why is Roskam's aircraft design methodology divided into two classes?

In a book titled "Airplane Design" by Jan Roskam, why has he divided the complete design cycle in Class 1 and Class 2 methods, where Class 1 involves fewer calculations (data-based estimation) while ...
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1answer
117 views

Does the F-16's neutral stability also extend to the negative-G flight regime?

If an F-16 pilot pushes the stick forward hard enough to send the aircraft into negative-G flight, does the jet tend to accentuate the new flightpath, requiring the pilot to counter that, or not?
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2answers
251 views

If, one day, we have an electric airplane, will it be easier to control than a fuelled airplane?

Elon Musk said that Tesla will make battery which can last for million miles. So probably in the next few years there will be a (small) airplane powered by an electric motor rather than by fuel. If ...
4
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1answer
207 views

Is it coincidence that the B-2 and YB-49 flying wings have exactly the same wingspan?

Development of the Northrop Grumman B-2 Spirit began as far back as 1979; however, this was nearly thirty years after the last flight of Northrop's earlier flying wing the YB-49. There aren't many ...
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2answers
395 views

Is it possible to have a fully electric airliner?

Is it possible to have a fully electric airliner? How much room would have to be sacrificed for a power bank in these aircraft to allow similar range to the current models (e.g., A320, 737, etc.)? ...
6
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1answer
163 views

Why do UCAV/UAV designs mostly use lambda wings instead of pure delta wings?

Why do recent UCAV/UAV designs mostly use lambda wings (such as Taranis and Dassault nEUROn) instead of pure delta/diamond wings (such as X-47A Pegasus and Lockheed D-21)? As for stealth ...
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0answers
36 views

Where can I find data comparing coefficient of lift (and drag) curves for any airfoil with and without flaps deployed

I'm doing my masters thesis on a FISHBAC wing so I'm hoping to find coefficient of lift and drag curves for any airfoil with and without (any type of) flaps deployed (and preferably leading edge ...
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1answer
120 views

Can pressurized aircraft be flown without pressurizing

Are there any pressurized aircraft models which can also be flown without pressurizing the cabin? For example, if there were a short ferry flight, or a flight where the aircraft never got high enough ...
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0answers
40 views

MTOW Calculation with Roskam Wempty and MTOW corellation

I'm an aerospace engineer and as a semester project, I've been assigned to do a conceptual design of a wide-body passenger aircraft(320 PAX, 9500 NM, M=0.89). Our handbook uses Roskam's equation, ...
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0answers
108 views

Did the “feeler” ailerons of the B-52A-F make air-to-air refueling easier than with the B-52G/H?

The B-52G/H uses 8 spoilerons (so it has 8 burning and 8 turning on its wing) and a shortened vertical stabilizer. Spoilerons seem to be very effective for this design, further reducing the need for ...
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2answers
38 views

Change of Roll moment with change of wing position (z-direction)

If I compare two identical configurations, which only differ from each other in low wing and high wing position. We assume that the lift and drag remains constant. Will I get the same coefficients in ...
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2answers
89 views

Why do we need a negative derivative of the pitching moment? restoring moment should be enough?

I am wondering why I read everywhere, that for static stability (longitudinal) the slope of the lift coefficient has to be negative. Imagine a curve (cm= coefficient of moment , alpha = angle of ...
2
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2answers
190 views

How to calculate position of a canard?

does anybody know how one can calculate the position, shape and size of an aircraft with a canard? So the main goal of a canard configuration: increase lift + increase agility/maneuverability So at ...
6
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1answer
172 views

Why are some aircraft's life limited by both cycles and flight hours?

For instance the Pilatus PC-12 life is either 27,000 cycles or 30,000 flight hours, whichever comes first. I understand that the limit life in cycles is mainly due to fatigue in terms of ...
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0answers
98 views

Why don't commercial aircraft have variable sweep wings? [duplicate]

I was wondering why commercial aircraft don't have variable sweep wings just like the Bell X-5 did? By sweeping the wing further at high altitude it helps the aircraft move faster and also it helps ...
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1answer
95 views

Why does the moment coefficient for angle of attack = 0° not have to be negative?

I know for static stability reasons, the derivative of the moment coefficient of an aircraft has to be negative. What I do not understand, why the moment of coefficient (cm) at all is allowed to be ...
1
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1answer
57 views

What is the sense of the Aerodynamic Centre for Design Process?

This topic has been discussed already several times, but I do not really get it. I think this one is a quite nice explenation: enter link description here So I understand that the Aerodynamic Centre ...
6
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1answer
375 views

Why does the A330 sit nose-down on the ground?

The passenger versions of the A330 have a small but noticeable nose-down angle when sitting on the ground: (Image by contri at Flickr, via russavia at Wikimedia Commons.) In contrast, A330s built as ...
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2answers
107 views

Is potentially dangerous to select the take-off power on airliner lower that temperature at the moment on the airport? [closed]

Is potentially dangerous to select the take-off power on airliner at lower settings value due to the temperature that could be increased by the time the aircraft will go up?
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1answer
375 views

Why was the tip of the B-52's vertical tail chopped off in 1959?

When Boeing switched over from the B-52F to the B-52G in 1959, they (among other changes) lopped off the top 2.4 meters (8 feet) of the aircraft's vertical tail: Original-height tail (here on a B-52F)...
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1answer
464 views

Calculating lift with lifting-line theory in MATLAB

I am attempting to calculate the lift generated by a model wing (~0.8$m^2$ wing area) using Prandtl's lifting-line theory in MATLAB. I am starting with the equation below from Anderson's 2005 book ...
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1answer
59 views

Can accelerations be used to calculate load factors?

Can I use the z accelerations to calculate the load factor in that axis? Please explain how or why not.
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2answers
488 views

Why was the B-52's wet wing more susceptible to fatigue than its dry wing, and not less?

After years of carrying all its fuel in the fuselage, the B-52 transitioned to a wet wing (where the wing structure is used as one or more fuel tanks) with the B-52G. This caused severe problems with ...
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0answers
165 views

Why did the B-52 never have a JT4A-powered version?

All versions of the B-52 use the Pratt & Whitney JT3C turbojet (except for the last version, the B-52H, which uses the JT3D low-bypass turbofan instead). Problem: the JT3C is a horribly anemic ...
6
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2answers
293 views

What is the aerodynamic reason that the An-225's vertical stabilizers are not simply vertical?

I am trying to understand the aerodynamic consideration that the two vertical stabilizers of this gigantic Antonov An-225 are not simply made vertical and are slightly pointing in. Then my questions ...
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1answer
105 views

What are the advantages of centerline armament?

In the ME 109, Messerschmidt went through a lot of effort to squeeze a cannon into the fuselage firing between the piston banks of the DB engine, exiting the spinner. Why not just put the cannons in ...
8
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1answer
4k views

Does the Antonov An-225 have an Auxiliary Power Unit (APU)?

Most APUs are installed in the rear, see the above image of an Airbus A380 as an example. On the An-225, no APU exhaust is visible at the rear of the aircraft. So does the An-225 have an APU, and if ...
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7answers
1k views

Why wasn't the 737 MAX's landing gear lengthened enough to mount the engines under the wings, rather than in front of them?

The reason Boeing originally added the MCAS to the 737 MAX was to compensate for a slight pitch-up moment generated by the engine nacelles at very high angles of attack. This pitch-up moment occurred ...
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2answers
132 views

Does every control surface need to have a counterweight?

Is it not a good idea to balance all control surfaces, no matter what they weigh? I am building a small plane, with small control surfaces. There are many of the same type of plane flying. Most have ...
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7answers
6k views

Why was the DC-9-80/MD-80 so successful despite being obsolete almost from birth?

The McDonnell Douglas DC-9-80/MD-80 series of narrowbody jetliners was the second-to-last DC-9 major version produced (from 1979 through 1999), the second-largest, the most-produced (just under half ...
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1answer
120 views

Solutions to improve the aerodynamic behavior of a UAV

So I'm working at a project of a UAV with the follow characteristics: Rectangular planform Conventional tail The fuselage is just a metal/aluminum rod So we need to improve its aerodynamic behavior/...
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0answers
282 views

Why does the KC-46 use an MCAS?

The KC-46 tanker aircraft (the U.S. military's designation for the 767s it uses as tankers, and which every other country calls the KC-767) uses an early version of an MCAS.1 This was ostensibly ...
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1answer
192 views

Do the F-18's leading edge flaps deflect symmetrically in rolls?

When the F-18 Hornet does rolls, do the Leading Edge Flaps (LEFs) deflect symmetrically or is the deflection different on the left and right LEFs?
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0answers
106 views

The F16 stick movement is little. But how? [duplicate]

The F16 stick movement is very little, is 1/8inch. So there is just a stop point at the end of the movement, or the stick is hard all the time, but move a bit ? There is increase in stiffness to ...
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1answer
204 views

How to change 737 Max to 737 NG?

With the on going grounding of 737 Max, if some airlines want to change their 737 Max to 737 NG what modification is needed? The main change would be the engine and control system. Any other change is ...
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3answers
159 views

Do modern airliner wings suffer from a “gap” in safe AOA flight? [closed]

The supercritical wing is really great for cruising at high Mach numbers with little change in AOA.
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0answers
60 views

Wing fuselage joint in small aeroplanes [duplicate]

I know that there are bolts to connect the centre wing boxes of the fuselage and wings in large aircraft, but what are the methods of connecting the wings and fuselage of small aeroplanes? I’m mostly ...
12
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2answers
3k views

Why are the angle-of-attack sensors on most airplanes mounted on the forward fuselage rather than at the wing roots?

A source of reliable angle-of-attack information is important for airplanes, as flight at an excessively-high angle of attack can cause the airplane to stall, which is generally considered to be an ...
2
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2answers
140 views

Is a chambered fan more efficient than a ducted fan?

A chambered fan is not exposed to the oncoming airflow in forward flight. I am working on a VTOL design that uses a chambered fan. There will be a wing attached to top of the thrust arms. Could it ...
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1answer
115 views

How do individually controlled feather like winglets work?

I want to know how the individually controlled feather like winglets work on controlling and rolling by reducing drag.(concept of airbus bird's of prey) I just need a detailed review of the ...
4
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1answer
114 views

Is the “wing area” of a biplane the projected area or the total area?

When you specify the wing area of a biplane, do you specify the planform area (the projected area) or do you specify the effective area of both the wings?
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1answer
141 views

How can a runaway trim become so difficult to fight when all a pilot has to do, is “grasp and hold?” [closed]

and how can you even tell the pilots did “grasp and hold” during an investigation? Is it determined based off what they say?
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4answers
160 views

Why don't nonrigid airships have multiple gas cells?

Nonrigid airships (blimps) differ from rigids and most semirigids in having the entire envelope form a single large gas chamber, rather than dividing the lifting gas among several redundant gas cells. ...
3
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1answer
131 views

Does the aerodynamic center always have to lie on the chord line?

A lot of resources online state that the aerodynamic center is the "point on the body of an airfoil with respect to which the moment coefficient does not change with angle of attack." However, does ...
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1answer
89 views

External Batteries [closed]

As a part of a project for a class we were tasked with trying to cut emissions/energy waste of airplanes. Now we've realized that running the apu on the ground at the gate and taxiing is a serious ...
3
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1answer
200 views

Do ducted fans have a future in forward flight aircraft? Can they be made more efficient than open rotors?

I'm fascinated by how ducted fans have the ability to be more efficient than open propellers of equal diameter in vertical flight through the use of tight tolerances, lightweight duct material, proper ...
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1answer
160 views

When aircraft rolls across airport field, uses its main engines or any kind of chassis gears? [duplicate]

Taxiing, turns, approach to gates - everything is done without the loud sound of motors

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