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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0answers
88 views

Why are the wingtips of the Fairchild-Republic A-10 bent downward? [duplicate]

Why are the wingtips of the Fairchild-Republic A-10 bent downwards?It is subsonic aircraft .
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51 views

Are the firewall and forward pressure bulkhead different components? [duplicate]

Suppose in a single engine aircraft, where the engine is located near the nose of the aircraft. If the cabin is pressurized, I know there will be a requirement of pressure bulkheads, both in the rear ...
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1answer
221 views

How can jet engines be more efficient than propellers? [duplicate]

If jet engines are smaller in diameter than propellers, is it fair to say that propellers accelerate a lot of air a little while a jet engine accelerates a little air a lot? Basically, a jet engine ...
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1answer
72 views

Will a quad fan arrangement on an aircraft help with pitching moments during VTOL flight transition?

The phenomena of ducted fan assemblies inducing pitching moments whilst in transition from vertical to horizontal flight paths is a problem I have seen mentioned by many designers and engineers of ...
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0answers
95 views

How much thrust does the Lilium aircraft produce?

I have been researching the Lilium aircraft and can’t find information about thrust. An early version of this aircraft was 2 seats with a loaded weight of 1,400 lbs, 36 ducted fans and 320 kW peak ...
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66 views

How can we find maximum lift coefficient of Airfoil?

I am trying to find the maximum Lift coefficient for airfoil NACA 64A-404. I chose this airfoil for wing. I am stuck at finding the Clmax. I tried to use javafoil but javafoil is showing Cl less than ...
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1answer
121 views

Why do small jets usually have one low flap setting?

For example, the CRJ has a flap setting of 0, 8, 20, 30, and 45 degrees. The Learjet has similar features across their models, as far as I can see which is 0, 8, 20, and 40 degrees Why do smaller ...
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2answers
232 views

Does the payload of an ICBM or regular airplane bomber explode if the ICBM or bomber is shot down?

As the top says, does the payload of an ICBM or regular airplane bomber (please excuse my ignorance) explode if the ICBM or bomber is shot down? So, say a defense laser in space (yes, I know; this is ...
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1answer
82 views

How do the vortex created by wing tips affects the lift? [duplicate]

I’ve been reading about how improve the aircraft performance and I found that for low aspect ratios, the vortex created by the wing tips decrease the lift generated by the wings. Why is this happening?...
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4answers
224 views

Why should I not use a “lifting tail” on my ultralight design?

In my misspent youth I designed and built many rubber, gas, and RC models. When I wanted good climb and glide I used a aft CG [60 to 80%] and a lifting tail. I had no stability or control problems, ...
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1answer
94 views

At what point of the design process the manufactures build their first prototype?

I would like to know when the aircraft manufactures decide to put in practice their designs building the first scaled prototype (or maybe the actual size). Does the design have to accomplish a list of ...
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1answer
174 views

Relationship between wing aspect ratio and speed [duplicate]

For some reason, I cannot find a relatively straightforward source online which discusses the relationship of wing aspect ratio and how it affects speeds of an aircraft. Specifically, is there a ...
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1answer
668 views

Why does pitching moment coefficient decrease with an increase in the angle of attack?

Slope of Cm vs alpha graph is negative, why it is so? The attached graph is from https://en.m.wikipedia.org/wiki/Pitching_moment , this graph is for cambered airfoil, as pitching moment is zero for ...
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2answers
1k views

Does an increase in lift always cause an increase in lift-induced drag?

An increase in lift causes an increase in drag. Is it always true? I am confused with two points. Lift increases with an increase in airspeed but induced drag reduces with an increase in airspeed. ...
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2answers
395 views

What is Neil Armstrong teaching in this image?

It seems to me that in this image Neil Armstrong is teaching something related with aerodynamics forces (lift, drag...), but I don't know exactly what is that "Triangle" that He drew (It doesn't seem ...
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1answer
85 views

What are the applications, advantages and limitations of Gyrodyne rotorcraft?

Gyrodyne is a VTOL rotorcraft. It has ability to power both rotors and propellers for generating lift and thrust. What makes it of lesser popularity than helicopters. Are there any applications of ...
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1answer
3k views

In aircraft construction, what is the difference between a firewall and a bulkhead?

I'd like to know the difference between a firewall and a bulkhead. They both separate segments of an aircraft, so how are they different as it pertains to their design and purpose in aircraft ...
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75 views

How to create a simple forces diagram using only lift and drag forces?

I would like to create a simple forces diagram (like a sketch). The lift produced by the wing depends upon to the distance from the the longitudinal axis, but, in order to make it easier, I’m taking ...
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61 views

How is the wingspan of a wing measured if it has a dihedral? [duplicate]

I am having some confusion regarding how the wingspan is measured, I just wanted some clarity because this was bugging me while I was reading about aircraft wings. According to NASA's "Wing Geometry ...
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1answer
367 views

How do aircraft window size compare to each other? What are some possible improvements on them?

I'd like to see a comparison about the window sizes of various commercial aircraft, maybe to give evidence of eventual progress in it over the generations. For example, I surely know that the B-787 ...
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1answer
311 views

How do Airbus and Boeing aircraft handle Dutch roll?

I have some homework about Dutch roll filters. Dutch roll is something that is corrected by yaw damper systems, but I would like to know the different ways Boeing and Airbus deal with the issue of ...
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1answer
97 views

How does the RQ4-Global Hawk improve stability? [closed]

I have seen several videos recorded from an UAV in which the stabilization of the camera is almost perfect. Cameras are installed in a gimbal, of course, but do new drones introduce some new ...
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1answer
142 views

When does an UAV need an internal structure?

I´ve seen some UAV models without internal structure (stringers, longerons and frame). I guess the drone´s shell is the frame itself. So what is the best approach to calculate the shell thickness to ...
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2answers
110 views

How can we physically define reynold number variation in terms of characteristic length? [closed]

How can you define it physically that greater the characteristic length in $Re=\frac{\rho v L_c}{\mu}$ greater the Reynolds number. Like on wing surface $Re$ is higher than the horizontal tail surface ...
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1answer
151 views

Why do airlines not paint the wings on their livery? Why? [duplicate]

Does anyone know why airlines do not paint the wings on their aircraft? What is the reason why?
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1answer
468 views

Why aren't 757 scimitar winglets flush with the ailerons?

Over my many past flights aboard 757s, I have seen changes being implemented with their design. One of which was notably their refit of scimitar winglets. Although one of their most notable ...
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1answer
147 views

Does increased fineness ratio decrease skin friction drag?

From the Wikipedia article on parasitic drag: a designer can consider the fineness ratio, which is the length of the aircraft divided by its diameter at the widest point (L/D). It is mostly kept 6:1 ...
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2answers
1k views

Why do some T-tail aircraft have a protrusion on the top front of the tail? [duplicate]

Aircraft like the Tu-154 and VC-10 have a "point" on the T-tail, while others like the 727 do not. Is this structure a shock body, or otherwise related to the tail's aerodynamics? And why is it only ...
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1answer
424 views

Why are some A350s missing SSA probes on their nose?

I recently just noticed that some A350s are missing their iconic set of 3 main SSAs (Side Slip Angle Probes) on their nose. I'm not sure if its an issue of newer variants or varied airline options, ...
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3answers
192 views

Can an automatic gearbox improve engine transmission for an ultralight? [duplicate]

I am working on my dream to build and fly an ultralight aircraft so I wouldn't like to know the following: Does adding a motorcycle automatic gear box to an engine improve on the strength for an ...
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1answer
206 views

Why does the Embraer E-Jet Family have doors of different sizes?

I just noticed yesterday that the right and left forward doors of all E-Jet Family aircraft have different sizes (both in height and in width). What is the reason behind this design difference?
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2answers
471 views

Can aircraft fly without wings? [duplicate]

Is it possible that a aircraft can fly without having wings? I am wondering if somehow it can fly then will aircraft will be able to maintain the balance.
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2answers
221 views

Would this hovercraft be stable? [closed]

Would this two-rotor hovercraft design work? The bold black line is weighted metal on the lower to stable it. If it helps, this is a human sized hovercraft. Would it work if: prop1 lift > prop2 lift ...
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4answers
200 views

When was the first THS (Trimmable horizontal stabilizer) used and on what aircraft?

When was the first THS (Trimmable horizontal stabilizer) used and on what aircraft? Has any UL or GA trimmable stabilizer?
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0answers
31 views

What design characteristics influence helicopter wind gust spread tolerance during takeoff and landing

Not considering pilot reaction time, what factors influence a helicopter's ability to survive high wind gust spreads (from any direction) during takeoff and landing? I have considered: Swash plate ...
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2answers
238 views

Why did the Wright brothers take steps to increase the amount of vertical surface area forward of the CG on some of their aircraft?

Why did the Wright brothers take steps to increase the amount of vertical surface area in front of the CG on some of their aircraft? Could this have actually improved the flight characteristics in ...
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2answers
62 views

How to calculate CL with the use of MTOW?

I have a problem that it gives us the MTOW of a UAV (200 kg), the speed and the reference area. So its probably easy to find the CL knowing that it flights at steady level flight (L = W). I'm confused ...
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123 views

What are aerodynamical reasons behind slight dihedral or no dihedral at all? [duplicate]

Regarding general aviation single engine high wing aircrafts in particular, what are the reasons for some of them to have no dihedral at all on their wing, or slight positive dihedral angle for other? ...
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53 views

Why did the dividing wall separating the engine intakes of early twin-engine Westland Wessexes cause difficulties with intake anti-icing?

The Rolls-Royce1 Gnome-engined variants of the Westland Wessex helicopter family (i.e., the twin-engined versions)2 draw air for both engines from a common intake (having been designed prior to the ...
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3answers
1k views

What are the disadvantages of fitting underwing flaps to a Mirage III/5 fighter jets to lower landing speeds?

The Mirage III / 5 series of fighter aircraft are versatile aircraft, but has a high approach speed of 180 knots and a high landing speed, requiring long runways. Underwing flaps, like those of the ...
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3answers
2k views

Can I use motorcycle engine in aircraft [duplicate]

I am trying to build an Aircraft, The weight of the Airplane will be around 40 Kg with engine and 8 liters of fuel and with me the total weight will be around 90 to 100 kg and I want to use a ...
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3answers
258 views

Is it possible to have an angle of incidence for a vertical stabilizer?

horizontal surfaces in airplane have small angle of incidence in general, Is it possible to have an angle of incidence for a vertical stabilizer? Please help me to find it. Thanks!!
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1answer
164 views

Calculating thrust and required propeller size for a given engine power

I am looking to build an Airplane, the weight of Airplane will be around 20 to 25 kg and I am going to use a 70cc motorcycle engine as an Airplane engine. I want to know how I can calculate the ...
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0answers
28 views

VLM at High Speeds and High Angle of Attack

I want to analyze a plane of the size and speed of a commercial jetliner. I have made the model of it on OpenVSP. I am using VSPAero's Vortice Lattice Method for the same. I want to analyze the plane ...
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0answers
20 views

Is there any go to formula in the designing of a winglet? [duplicate]

we have to design a commercial airplane as a part of a college assignment and i was wondering if there are any rule of thumb /formulas involved in the designing of winglets? Or does one have to assume ...
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1answer
126 views

What is the role of discontinuous surfaces on the inside and outside elevons of the F-117?

Why are there discontinuous surfaces on the inside and outside elevons of the stealth F-117? Will that not be highly reflective to the radar?
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1answer
43 views

Is the ratio of HP to weight constant for identical air frames of different sizes? (See Scenario)

In my head it seems logical that there would be a proportion between engine HP and empty weight. For example, the Wright Flyer weighed around 600 LBS empty and had a 12 HP engine. If I were to make an ...
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1answer
59 views

What is the threshold between high Aspect Ratios and low Aspect Ratios?

Oftentimes when describing flying organisms and vehicles, their wings are said to have a "high aspect ratio" or a "low aspect ratio". Sometimes the papers (that I read) gave the numbers, but more ...
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1answer
267 views

How can I calculate the C.G height for an Aircraft?

before I continue I would like to thank you guys beforehand for the help. I am new to this forum and in aviation in general. I am helping my professor to obtain the C.G coordinates in x, y , z for a ...
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1answer
403 views

Why does the P-3 Orion use an engine driven compressor instead of bleed air for pressurization?

In another question, an answer mentions that the P-3 Orion uses a gearbox driven compressor for cabin pressurization, even though the aircraft uses T-56 turbine engines that supply bleed air in other ...

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