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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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How did shortening the 707 increase its range?

According to the Wikipedia entry for the 707-120: The 707-138 was a −120 with a fuselage 10 ft (3.0 m) shorter than the others, with 5 ft (1.5 m) (three frames) removed ahead and behind the wing, ...
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182 views

Why are all-moving horizontal stabilizers common but all-moving rudders rare on fighters?

According to Wikipedia Stabilators were developed to achieve adequate pitch control in supersonic flight, and are almost universal on modern military combat aircraft. All non-delta-winged ...
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3answers
460 views

Why does the B-52 have such a tiny rudder?

The B-52 (aka Stratofortress, aka Grey Lady, aka BUFF) has a minuscule rudder for an aircraft of its size and wing-mounted engine placement: Compare to, for instance, the rudder on a 747: The B-52’s ...
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164 views

What are the issues involved in converting a quadjet into a twinjet?

As you are probably all aware already, the fewer engines you have, the better your fuel efficiency; that’s why the airlines are selling off their (quadjet) 747s and buying (twinjet) 777s, why they’ve ...
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1answer
128 views

Why weren’t the Comet’s overhead ADF windows roundified along with its passenger windows?

Following the crashes of two Comet 1s in early 1954 due to metal fatigue, all future Comets (and the few surviving Comet 1s that were rebuilt rather than scrapped, all of them in military service) ...
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36 views

Are there any special considerations involved in designing manual flight controls for supersonic/hypersonic aircraft?

What things, if any, might need to be taken into account in the design of manual flight controls for supersonic or hypersonic aircraft that wouldn’t need to be taken into account with manual controls ...
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73 views

Force Balance in Wind Tunnel

I am considering a model wing inside a wind tunnel supported from underneath from its center of mass. Two load cells can be used, when properly oriented, to measure the lift force and the drag force. ...
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136 views

What is the most effective of propeller's rotation in a two-propeller engine airplane?

Consider two-propeller airplane as picture below (picture 1 (the above) and picture 2 (the below)). Which one is the most effective configuration to produce thrust power, stability, structural design, ...
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415 views

Did the cusp in the Boeing 377/C-97/KC-97’s fuselage structure cause fatigue problems?

The Boeing 377 Stratocruiser - a civilian adaptation of the C-97, a military transport which would also later be developed into the KC-97 - were derived from the B-29/B-50 family by grafting a large, ...
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1answer
242 views

Why did most WWII Allied piston engines not use fuel injection?

One would think that given the huge push for ever more performance and reliability on piston engines during the heat of WWII would push the designs to their absolute limits, however, most American ...
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2answers
263 views

Why don't commercial aircraft have drag chutes for aborted takeoffs? [duplicate]

We were watching the program Air Crash Investigation and there was an episode where it was too late to abort the take-off and the pilots had to attempt to climb still but since an abort was not ...
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152 views

Who should design the nozzle of jet engines on aircraft?

There is a question in my mind that which company should design the nozzle of jet engine - the aircraft designer or the engine designer? If you watch this documentary: BBC Documentary Rolls Royce ...
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2answers
171 views

Is the Meredith effect utilized in the cowling design of air-cooled engines?

The P-51 is famous for its advanced-for-its-time aerodynamics, the prime example of which is the radiator design under the belly which utilizes the Meredith effect to, in effect, turn it into a mini ...
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4answers
242 views

Why do carburetors tend to produce richer mixture at higher altitude?

The pressure drop in the venturi is proportional to air density and the fuel is at ambient pressure in the float chamber, so I would expect the fuel flow to reduce proportionally with density, and ...
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1answer
220 views

If a twin-engine airplane's propellers both rotate in the same direction, do they still produce a left-turning tendency?

If an airplane with two propellers has both propellers with the same rotation direction (say, both the propellers rotate counter-clockwise as seen from nose to the tail), will be the four left-...
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1answer
2k views

Do rivets on airframe need special sealant to be airtight on pressurized airliners?

Do rivets on airframe need a dedicated sealant, e.g. epoxy, to be really airtight on a pressurized airliner, or is the expansion of the rivet shaft already sufficient? As a side note, how are carbon ...
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376 views

Why Western fighters' afterburner glow is reddish orange while Eastern Bloc fighters' is blue?

Recalling what little physics I know, this could be explained by two factors: The blue color is given by the characteristic EM radiation of C-H bond breaking, C- and H- radicals forming and ...
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62 views

What airfoil type is used on the B727-200F?

What airfoil type is used on the Boeing 727-200F? Is it a NACA profile or something else?
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1answer
162 views

Why is YF22 designed with conventional rudders while YF23 with all-moving rudders?

Are all-moving rudders more stealthy? If so, how come YF22 which is just as fixated with rear body stealthiness as the YF23 comes with conventional ones? Also, all-moving rudders have fixed camber, ...
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1answer
189 views

How do flaps deploy and stow with very large wing flex?

On large airliners, the wings are generally of the high aspect ratio types and hence very flexible. Now the flaps are attached to wing only through a series of tracks, and as the wings flex, these ...
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2answers
162 views

How do you use a flexible drive shaft?

Saw it on a 747 freighter nose door, see it again on an F16's M61A1 gun assembly. How do you design with a flexible shaft? In what situation do you use it to replace a bunch of rigid shafts and gears?...
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148 views

What percentage or airplanes have engines [closed]

I heard that some airplanes don't have engines. how many airplanes in the world have engines?
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106 views

Can roll be controlled through elevators in a fixed-wing aircraft? [duplicate]

In fixed-wing aircraft, roll is typically controlled through ailerons. But I am wondering if roll could also be controlled through split, independently controllable left/right elevators?
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3answers
243 views

Do large non-pressurized metal planes have a maximum fatigue cycle?

For example the DC3. The way I understand it, the only thing that "ages" the airframes of DC3 is the landing/takeoff cycles and the accompanied periodic force loading/unloading. Do planes such as this ...
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4answers
224 views

What changes are needed for a piston-prop aircraft to withstand saltwater environment?

I'm interested in WW2-era piston-prop aircraft. I want to know what changes are needed to make the aircraft withstand saltwater corrosion. Presumably these are different and more expensive than the ...
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1answer
109 views

Fuel De-aerating Tank?

I know turbine engines (bearings) are cooled by oil jets and that when oil is scavenged from the bearings it is more of a mist than a liquid, hence the need for various types of de-aerating this mist ...
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1answer
44 views

What to be considered in designing airplane tail (vertical and horizontal stabilizer, elevators and rudder)? [closed]

I would like to make a small amateur triplane with it maximum weight approximately 400 kgs with maximum speed 100 knots (180 kph). I have read many discussions about how to calculate the wing ...
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0answers
65 views

Why does the Comet's horizontal stabilizer have so much dihedral?

The Comet's horizontal tail has a noticeably extreme amount of dihedral compared to that of, say, a 707: (Image by MilborneOne at Wikimedia Commons.) Note how the Comet's tail has about twice as ...
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4answers
152 views

Why some WWII fighters still have fabric/wood control surfaces?

I've heard people say that the reason US in WWII preferred designs with fabric control surfaces with either a metal or plywood frame is they can sustain some small arms fire without disintegrating. Is ...
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3answers
474 views

Do fighter jets have deicing in their wings?

If there is such thing as deicing for fighters? If so, is bleed air or electric heating preferred? I could not imagine that a $50MLN fighter jet would not be able to get the ice off its wings.
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4answers
238 views

How is vertical speed managed in Airliners? [duplicate]

When an Airplane starts to take off, the Horizontal velocity would generate it the necessary lift, and then Airplane pitches up to further increase the lift. As the Airplane is climbing up, the net ...
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2answers
440 views

Can an Airbus A380 or Boeing B747 fly with only 2 engines?

If during cruising with full load, these two kinds of airplane got two of their engines failure: With one engines fails in each side (so, only one engine works every side). With 2 engines fail in one ...
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1answer
342 views

What is the purpose of this item next to the cockpit window on the B737?

Hello does anybody know what the purpose of this odd looking shape is
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3answers
356 views

Is the MD-11's third engine slightly nose up?

From my visual inspection, the third engine (the engine on the horizontal stabilizer) is slightly "nose up", especially compared to the engines on the wing. That means, the front part of the engine is ...
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89 views

Difference between FMCF and AIMS on B777?

What is the Difference between Flight Management Computing Function and Airplane Information Management System on B777?
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133 views

Where can I find complete aircraft blueprints for the purpose of study?

Where can I find aircraft blueprints for the purpose of study? I find that I learn a lot more when I am able to get the big picture of a machine that is used in real life (for example, to understand ...
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1answer
4k views

Why doesn't a full yoke deflection also change the stabilizer trim on the Boeing 737 MAX?

Various websites have stated that during the 737-MAX crash in Indonesia, the pilots could not pitch up because of a faulty AOA sensor pitching the plane down. The stabilizer has a rear fulcrum and ...
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2answers
204 views

Why the Antonov AN-225 has negative dihedral wings combined with a positive dihedral horizontal stabilizer?

I know the reason why it has negative dihedral wings, but I do not really know why it is combined with a positive dihedral horizontal stabilzer, which are the benefits this configuration provides?
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3k views

Why didn't Boeing or Douglas make a jet airliner before the British DH Comet?

I was looking at the history of commercial aircraft and was wondering why UK-based De Havilland was the first to produce a jet powered airliner (the DH 106 Comet) when the US had a much bigger civil ...
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2answers
425 views

What is this unusual leading edge flap on a B737-200?

On this video of Air North's gravel runway-equipped B737-200, there's what appears to be a small leading-edge flap (Krueger flap?) inboard of the engine. Refer to the screen shot below. What is this?...
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1answer
61 views

Where should the support points be for testing a model wing in a wind tunnel?

When testing a certain wing profile inside a wind tunnel where should the model, small scale wing be supported? Should the support be under the center of mass of the wing or under the aerodynamic ...
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4answers
316 views

Why are the leading edges of wings not always made as 'sharp' as possible?

Why is an airplane's wing (the leading edge) not made as sharp as possible to break the air, in the same way that a ship's hull is made sharp to easily break the water? This is unlike Concorde's nose ...
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2answers
86 views

Would a sharper leading edge increase lift and reduce drag at lower speeds?

A recent scratch built glider kept turning to the right even after painstaking efforts to match the wings perfectly. Extensive addition of fin area to the tail failed to correct it. Closer ...
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38 views

How could I measure frontal area based on a technical drawing?

I want to compare frontal surface areas of two airplanes, and I have their digital technical drawings and wingspan data. What program could I use to obtain the surface area using this data? Esentially ...
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2answers
140 views

In an airplane wing, which one is primary, and which one is secondary

I got this device detail of a wing. Those parts are: 1: wingtip fence, one of the wingtip device beside winglet. 2 & 3: aileron. 4: flap track. 5 & 6: slat. 7 & 8: flap. 9 & 10: ...
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57 views

How do we derive Lift Coefficient of an airplane's wing?

In many references I read that lift coefficient ($C_l$) is a product of wind tunnel test. But many times I read the formula to calculate the coefficient of lift. From the lift equation, $$L=\frac{1}{2}...
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95 views

How many variations are there of the Avro Lancaster?

How many different variations of the Avro Lancaster are there?
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94 views

How do endplates reduce induced drag?

I have heard the explanation which states that the endplates reduce the tip vortex formation thereby reducing induced drag. From what I understand induced drag is the backwards component of the total ...
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3answers
330 views

Why did narrowbody jetliners take so long to switch over to high-bypass engines?

High-bypass turbofans were introduced into the airliner market around 1970, when the first widebody jetliners were released (the 747 was first, followed in rapid succession by the DC-10, L-1011, and ...
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87 views

What was the Airfoil of Handley Page P.115?

This extreme sweptback delta was built to test the Concorde wing at low speeds, sources say it had a biconv 6% airfoil, but I failed in finding data about it.