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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What methods are used to calculate the geometry needed to obtain a bell-shaped lift distribution?

In aerodynamics, what methods do people use to calculate the geometry of a wing (and body) needed to obtain a bell shaped lift distribution? Please go into as much detail as possible for a stack ...
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1 vote
1 answer
116 views

What is the purpose of the small vertical dorsal fin about halfway along the fuselage of the Boeing 737? [duplicate]

I've searched for an answer to this question on this site and others: What is the purpose of the small vertical dorsal fin about halfway along the fuselage of the Boeing 737? See the attached image ...
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1 vote
2 answers
119 views

What does deploying landing flaps do to the (L/D)max and minimum drag speed of an airplane?

I thought that deploying flaps will increase both the drag and lift, thus increasing L/D ratio? But do they increase proportionately? And how exactly does that correlate with the increase/decrease of ...
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3 votes
3 answers
156 views

Why are conventional gear planes designed with the nose pointing up?

Most of the tricycle gear planes have a level or mostly level posture when on the ground. Why weren't coonvention gear planes designed like this? It would give pilots better visibility and give ...
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3 votes
1 answer
164 views

Why do so many UAVS use a V-tail configuration?

How different is V-tail from a conventional tail in the perspective of aerodynamics & flight dynamics of aircraft? I have seen that many UAVs, like the General Atomics MQ1 Predator, LSI Amber, ...
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6 votes
5 answers
390 views
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Aircraft pitch and AOA change during a coordinated turn maneuver

Let us say I am flying a constant airspeed turn while maintaining my altitude, when I enter into the turn, lift has to be increased and since airspeed remains constant, the AOA has to be increased to ...
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6 votes
8 answers
2k views

Can an encapsulated airfoil generate enough lift to lift the capsule?

Can an airfoil generate enough lift, if it is contained in an enclosed space, to lift the enclosed space? Assume that there would be sufficient airflow over the foil to generate lift if it was not in ...
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4 votes
4 answers
417 views

Why would an airplane with fixed-pitch propeller(s) and no supercharging have manifold pressure gauges? (E.g. Ford Trimotor)

I had recently had a look at the Ford Trimotor NC9645 (link), currently on an EAA-sponsored tour. The propellers were fixed pitch (possibly adjustable by mechanic on ground), and the engines were not ...
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-1 votes
2 answers
254 views

Has there ever been a VTOL aircraft thruster that generated lift through the use of a drag force?

I have been recently thinking about a conceptual VTOL aircraft thruster that should generate lift through the use of a drag force and I am very curious to know if such a thruster has ever been built ...
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0 answers
44 views

Bell Shaped Lift Distribution Literature [closed]

Context: I am very interested in learning about the bell shaped lift distribution (BLSD) for the purpose of designing a flying wing with this lift distribution. This is the first academic topic I am ...
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8 votes
2 answers
734 views

Why does the hardpoint mechanism on sweep wings produce a contact trace in front of the axis?

The basic structure and photos have already been explained on this site and on Wikipedia: How does a variable-sweep-wing aircraft keep wing-mounted payloads straight? Variable-sweep wing, Wikipedia ...
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4 votes
1 answer
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How to estimate the ribs spacing?

I would like to know what is the general logic behind the choice of the rib spacing in the thin-walled load bearing structure of a straight or swept all-metal wing? Is it the global or local ...
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3 votes
1 answer
314 views

Could the Wright Flyer II takeoff without wind?

The Wright Flyer II could reach about 20 mph of airspeed on the track alone. The aircraft needed an airspeed of about 30 mph to make a proper takeoff (without hanging in ground effect). Before the ...
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2 votes
1 answer
133 views

What is the modern approach to extract vehicle system responses to control input? [closed]

What is the modern approach to extract vehicle system responses to control input? Is everything thrown into a CFD simulation and the responses recorded or is something else done? Are wind tunnels ...
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1 vote
2 answers
105 views

Is it possible to reduce the angle of fully extended flaps of an aircraft without affecting lift generated?

I think flaps are inspired from eagle feathers which increase the overall wing surface area and help provide the necessary lift at lower speeds. However, fully extended flaps hang lower and cause more ...
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2 votes
0 answers
114 views

Is there a difference from alignment with the fuselage between J79 and Spey engine versions used in the F4?

Is there a difference between the J79 and Spey engine versions used in the F4 Phantom in terms of alignment with the fuselage? It looks to me like the Spey nozzles are pointing downward.
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2 answers
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Do helicopters use Ground speed or True airspeed?

Is there a limit on the speed and minimum altitude of the helicopter before switching between the two?
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6 votes
0 answers
141 views

How was the problem of dive bomber scope fogging resolved during WW2?

During the first half of 1942, US Navy SBD bombers had problems with their bomb aiming scopes fogging over, which reduced the accuracy of their bombing during several early war operations. Was this ...
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2 votes
2 answers
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Will the electric motor work well in ultralight aircraft?

I'm trying to replace the 20hp gasoline engine in my ultralight aircraft (trike) to 10kw BLDC motor, asking to know if the 10kw BLDC motor will work Motor+battery weight, is less than the actual ...
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8 votes
2 answers
611 views

Is the movement of the leading edge flaps not symmetrical on the MiG-29?

Original: russianplanes.net On this Mig29 in above picture leading edges are at different angles not in line. Same thing happens in flight times when rolling?
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-1 votes
1 answer
239 views

Why does the aileron on this jetliner swing?

The picture I took here is left wing of a jetliner and it shows how the flap works during take off and landing. In that video is the inboard aileron, and it shows that the inboard aileron is not ...
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1 vote
2 answers
213 views

There is any kind of advantage and disadvantages in making the blades of a helicopter off-center?

So, english isn't my first language, so I probably couldn't find any kind of information about it due to not being able to define what I'm asking. Anyway, helicopter blades are normally like this: An ...
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14 votes
4 answers
4k views

Do airlines use GPS for critical purposes? If so, why?

It is being reported that airlines in Finland have noticed interference with their GPS signals near Russia. This is causing them to be unable to land at at least one airport: Lithuanian airline ...
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0 votes
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Is there an equation for how fast air accelerates into lower-pressure regions?

I’m designing a propeller, and I want to plan the shape of the trailing edge of each blade such that (as much as reasonably possible) the pressure comes out as an “equal” line. Thus - I'm wondering ...
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8 votes
3 answers
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What "designs" the dihedral angle in modern airliners?

Is this an accurate description of the design process for modern jet airliners? If not, why not? What other factors come into play in determining the choice of dihedral angle? Designer starts by ...
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1 vote
3 answers
184 views

How has Computational Fluid Dynamics improved commercial airliner wing design?

Starting the 1980s, extremely powerful computational fluid dynamics software has been used to design wing sections and whole wings. I am going to focus on the Boeing 777 as an example of CFD applied ...
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6 votes
1 answer
996 views

What is this part in Embraer Legacy 650 and what is it function?

The picture I took from here. If you want to see, just click the link, it will take you to the part I want to show and ask. What I want to know is its name and its function.
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1 vote
1 answer
106 views

Is a wing lift distribution smooth in the presence of a prop?

Wings designed to minimize induced drag have a smooth distribution of lift from root to tip. Whether elliptical for span constrained wings or more bell shaped to minimize structural weight, ideal ...
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9 votes
2 answers
3k views

How have engineers managed to increase commercial airliner wing aspect ratios over time?

Over time, the wing aspect ratios of commercial airliners have increased. For evidence ,see the following data: 1980s: Boeing 747-400: 7.91, Boeing 757-200: 8.0 Boeing 767-300: 8.0 Airbus A310: 8.8 ...
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3 votes
1 answer
200 views

What is a "grid construction" airframe?

Could you please help to clarify this question I have in examples of PPL exam questions. It's confusing for me since I'm not able to find "Grid construction" definition at all. There is ...
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-1 votes
1 answer
155 views

What is the average height above ground of the wings of a 777-200?

I have read somewhere that this is 18.4 to 18.6 m but not sure of the source. Is this information is correct?
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3 votes
0 answers
166 views

What was the tactical purpose of the unusual flight control system that allowed the Northrop YA-9 to generate sideforce without banking?

What was the tactical purpose of the unusual flight control system that allowed the Northrop YA-9 to generate sideforce without banking? (And, how was the system controlled by the pilot?) (Image is ...
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0 votes
3 answers
199 views

Aspect Ratio conceptual estimate

so I know that AR=b^2/S. But let’s say that I don’t know b or S, how can I estimate the optimal AR if I know only this: How many passengers are going to be onboard, cruise velocity (subsonic), ...
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1 vote
1 answer
82 views

The Effect of Pitching Moment on Aircraft Stability

I'm designing a small RC plane and I'm currently at the first iteration of airfoil selection. I have converged to Clark-Y, NACA-2412, NACA-2415, and S-8036. In comparing the four, I noticed that all ...
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6 votes
2 answers
2k views

Why are there no high wing Canard airplanes?

Just had a thought about canard airplanes while looking at the Tu-144 that features a canard surface on the top of its fuselage. Are there any high-wing aircraft with a top or bottom mounted canard? ...
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0 votes
0 answers
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Why are C17's horizontal stabilizer mounted so high? [duplicate]

The C17 has its horizontal stabilizer mounted at the top of the vertical stabilizer, way above the plane of the wing but most aircraft, including other large aircraft made by the same manufacturer (...
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3 votes
1 answer
143 views

Are Airbus A320 Cabin Door Exterior & Interior Levers Linked?

Was looking at this video on Airbus A320 Cabin door procedures and was wondering if the exterior door lever is mechanically linked to the interior lever? It seems as if the exterior lever will open ...
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0 votes
3 answers
133 views

Calculate Rudder Angle by Bank Angle [closed]

My question: Is rudder angle equal to bank angle? Or, does rudder angle has some relationship with ROT formula? Below is my steps trying to solve this question. Step 1: Found below graph from this ...
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0 votes
1 answer
72 views

What is the windshield Heating Element (Thin Cable) for Aircraft or Rotorcraft?

My question is related with the heated windshield employing the some type of heating elements. Very very thin metalic cables are in use between two glasses of windshield. I have searched but noting ...
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5 votes
1 answer
1k views

Why not use the alternate static port at all times?

One of my club's small planes apparently has an intermittent problem with moisture in the static port line, so the recommendation is to always fly with the alternate static port open. That leads me to ...
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0 votes
3 answers
203 views

Calculate speed by turn angle and distance [closed]

I'm trying to combine two rate of turn formulas, which I found it online this and this. The first is ROT = 1091 * tan(bank angle) / speed in knots The second is <...
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0 votes
1 answer
173 views

What are the basic principles of making fighter jets manoeuvrable [closed]

Disregardimg thrust vectoring and other computer-aided functions, what are all the basic factors of making a fighter jet manoeuvrable? Using basic physics design principles such as high thrust to ...
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4 votes
1 answer
188 views

Can a jet-engine aircraft fly all the way to its service ceiling at its maximum takeoff weight? [closed]

I am trying to understand how high an aircraft can get to at its maximum takeoff weight (minus whatever fuel is consumed in getting to that altitude). Can it make it all the way to its service ceiling?...
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7 votes
3 answers
279 views

Why do smaller RC helicopters have visible twist in their rotors, and slightly bigger ones do not?

Smaller, cheap, RC helicopters generally have very pronounced twist in their blades, and also vary their chord - slightly larger, slightly more expensive RC helicopters have no visible twist or chord ...
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3 votes
1 answer
154 views

Are horizontal engine pylons generally shaped to provide lift (in either direction)?

Most civil multiengine jets and some civil multiengine propeller aircraft have engines mounted in nacelles on the ends of pylons extending some distance away from the wing or fuselage. Wing-mounted ...
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-4 votes
1 answer
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Would blade-less (Dyson style) jet engines work? [duplicate]

Is it possible to design an aircraft with blade-less (same concept as Dyson) design to generate thrust? What are some of the key benefits, drawbacks and examples of attempts (if any) at this kind of ...
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10 votes
2 answers
1k views

How exactly do the Beechcraft 1900's stabilons work?

The Beechcraft 1900, in addition to the usual wings and vertical and horizontal stabilizers, and the extra vertical tail surfaces added for improved directional stability, has a pair of horizontal ...
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2 votes
0 answers
131 views

Why do white marks on the spinners in front of engines have different patterns? Not Yellow? Omitted for some models?

In aeroailas' answer I understand that the cones in front of the props/fans are called spinners. In Farhan's answer I understand that the ehite marks painted onto the spinners act less as scarecrows ...
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4 votes
1 answer
249 views

What CAD software is most commonly used for aircraft design?

What is most commonly used CAD software for aircraft design? AutoCAD, CATIA..?
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7 votes
2 answers
353 views

What is the difference between the series and parallel yaw-damper systems for the 707?

Some excerpts from the Pan Am 707 AOM indicate that the 707 can have one of two different yaw-damper systems, "series" and "parallel", with differing capabilities: YAW DAMPER The ...
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