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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5
votes
2answers
455 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 ...
2
votes
0answers
160 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
votes
2answers
281 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 ...
0
votes
1answer
103 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
votes
1answer
3k 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 ...
11
votes
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 ...
3
votes
2answers
128 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 ...
16
votes
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 ...
2
votes
1answer
114 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/...
1
vote
0answers
265 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 ...
6
votes
1answer
173 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?
1
vote
0answers
104 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 ...
1
vote
1answer
187 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 ...
-5
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3answers
157 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.
0
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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
votes
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
votes
2answers
134 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 ...
1
vote
1answer
84 views

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
votes
1answer
101 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?
-1
votes
1answer
132 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?
1
vote
4answers
151 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
votes
1answer
125 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 ...
0
votes
1answer
86 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
votes
1answer
176 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 ...
-1
votes
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
0
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1answer
74 views

What provides a higher lift to drag ratio, a thick laminar wing or a thinner wing with a vortex generator

Recent readings have shown the benefits of "boundary layer tripping devices" or vortex generators for reducing drag and maintaining attached air flow at higher angles of attack. It seems these ...
3
votes
1answer
370 views

Why do wings prefer laminar flow if cd is lower for turbulent flows?

Can anyone please explain to me why we prefer to maintain laminar flow over wings, despite the fact that the overall coefficient of drag appears to reduce as the Reynolds Number increases? I have read ...
3
votes
1answer
76 views

Can surface roughing effects on an airfoil Reynolds number be quantified?

I am building balsa free flight gliders with a chord of 0.10 meters and a velocity of around 3 meters per second. This works out to a Reynolds number of around 15,000. The wings are around 1 meter ...
24
votes
5answers
7k views

Could the principle of owls' silent flight be used for stealth aircraft?

I was wondering about the ability of owls to fly so silently. Is it because they flap gently, they flap less often or do is their structure responsible? I was thinking their principle of stalking can ...
2
votes
1answer
135 views

What angle are front rotors of tandem helicopters tilted and why this value?

I've read that the front rotor of tandem helicopters are tilted forward so that you can get a forward velocity with no nose-down pitching of the fuselage, but what angle is used for this tilt and why ...
3
votes
1answer
124 views

Is there a minimal legal ground clearance to use an international airport?

The question arises while I was looking at the evolution of the B737 engines and the lower and lower space available between ground and engines. Then I realized that ground clearance is also low for ...
2
votes
2answers
146 views

Why did the DC-3 have a much higher cruise speed than the HP.42, despite their similar weight and power?

A review of the classic DC-3 and the Handley Page HP.42 yielded a surprisingly close match in empty and max gross take off weight at around 18,000 and 28,000 lbs for the HP.42 and 16,000 lbs and 25,...
1
vote
0answers
175 views

If an fighter jet that it have twin rudders, in use the angle of deployment it is not identical. Which is more deflected and why?

If an aircraft have two vertical tails then pilot push in the rudder pedal the rudders will not be deployed at the same angle.It is used throughout the all envelope of flight or is it possible only ...
3
votes
1answer
151 views

What's the aisle width of long range business jet?

What's the average aisle width for long range business jet such as Gulfstream G500?
12
votes
3answers
6k views

How are Aircraft Noses Designed?

Look at the Learjet, Embraer and Boeing noses which are kinda pointy - drag efficiency aside, how do they come to the final design of the nose? I’m talking from an aesthetic point of view - how do ...
-2
votes
3answers
361 views

Why the pitch control of helicopter is named Collective Control? And why does it located at the left side of the pilot seat?

This is probably a very trivial for some of you. But sometimes a name not representing the function become a question, just like this Collective Control, which its function is to pitch up the blade ...
11
votes
1answer
600 views

What is the purpose of these movable panels on the MiG-35?

The MiG-35 has movable panels on the LERX (leading edge root extensions). There are a number of images around the web showing these panels deployed during slow flight and retracted otherwise. When do ...
4
votes
3answers
4k views

Is aerodynamics study compulsory for building a plane? [closed]

I want to make a plane like a trike. I have a design and some knowledge about plane requirements.
7
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2answers
2k views

Why is the empennage design of this Lockheed 1049E so complicated?

Photo. What is the reason for making the empennage of this Lockheed L-1049E Super Constellation's design look so complicated with two vertical horizontal stabilizers? In my understanding, the more ...
8
votes
1answer
329 views

Why does the MCAS use the horizontal stabiliser rather than the elevators?

The Maneuvering Characteristics Augmentation System (MCAS), found, in two slightly-different variants, on the 737 MAX and KC-46, provides nose-down pitch inputs in certain very-high-angle-of-attack ...
3
votes
1answer
101 views

Why do some airplanes have a vertical rudder hinge while some others are canted?

I was thinking that canted rudder hinges are used for modern aircraft while the vertical ones are used for old slow airplanes. But it seems that I was wrong since the SST Tupelov Tu-144 and the ...
2
votes
1answer
488 views

What is this “stick” on top of Cessna 152's wing, and how does it work? [duplicate]

What is this device? What is it for? Seems that some variants have only one, while some others have two. Added: As some have two, so what are they? The answers and comments have not explained which ...
0
votes
0answers
74 views

what are the winglets on C17's air inlets useful for? [duplicate]

the winglets are clearly visible on this photograph, are they connected with air flow instability?
-1
votes
1answer
115 views

In fighter jets, is the minimum speed calculated with the flaps in the down position or up? [closed]

I asked that question because F16 flying straight and level at minimum speed does not have flaps down. So how is the minimum speed calculated by aircraft designers?
4
votes
4answers
2k views

What is the first fighter jet which was built with twin engine and tail configuration?

What is the very first fighter jet that pioneers the twin engine and twin vertical stabilizers over the engine just before the exhaust (like the F-14, F-15, F-22, Su-35, etc)?
0
votes
1answer
219 views

What are the holes on the top side of the canard of Eurofighter Typhoon for?

The Eurofighter Canard has some holes on top side. What are these holes for? ?
0
votes
2answers
228 views

Why the Mig21 don't use the ailerons like control surfaces on delta wings at landings or take off?

Mig21 is a delta wing , so why do not use the ailerons like any other delta's ? For lowering the approach and touch down speed. It is not possible that?
4
votes
2answers
121 views

How is lift transferred from rotor to chassis (or weight, the other way around)?

I am trying to find out how a helicopter rotor's lift is transferred to the chassis. Equivalently, how is the weight of the helicopter transferred to the rotor blades? While looking for this online, ...
1
vote
2answers
579 views

When a B-2 takes off, does it use some device to ionise the airflow in front it?

At takeoff, does the B-2 use some sort of ionization device in the leading edges of its wings?
15
votes
2answers
3k views

Why does the Pilatus PC-24 have such a large “Airplane Support”?

The PC-24 has, under the fuselage, a kind of huge support to hold the wings. If we compare with the Citation CJ4 or the Phenom 300, this difference is quite significant. Why??

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