Questions tagged [aircraft-design]

Questions about the different choices that aircraft designers (typically aerospace engineers) make in order to create an aircraft.

77 questions with no upvoted or accepted answers
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119 views

Why was the minimum turbulence intensity that commercial airliners have to withstand increased?

From 50 fps turbulence intensity at VC to 90-100 fps turbulence intensity at VC. The amended FAR design criteria was introduced in 1980 or 1981 for commercial airliners. What prompted this change?
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203 views

What different intake designs are there, and what are their pros and cons?

I noticed that over the years (on fighter jets specifically) there have been many different methods of directing air into the engines. Primarily, the nose-intake, side intake, and underbody intakes ...
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580 views

What is the total lift equation of a helicopter with 3 Flettner rotors?

I'm doing research regarding the possiblity of using Flettner rotors on helicopters. I would like to derive the total lift equation for a helicopter that consist of 3 Flettner rotors. Given that: ...
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1k views

What is the minimum price for a full Glass cockpit for the size of 6 passengers aircraft?

I am working on my final project at school and currently looking for the information about avionics system. We design a concept amphibious aircraft with the info as listed below: 2 pilots in the ...
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201 views

Has there been any research on plasma-producing planes?

Many years ago I read in an expository scientific journal[1] an article about what the future of high speed aviation could be. It said that there were studies on airplanes capable of "plasma-izing" ...
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1answer
110 views

What is the comparative roughness of fabric surfaces?

"The Design of the Aeroplane" by Darrol Stinton (1983) lists comparative roughness of aircraft skin material (pg 154). Unfortunately it does not list dope & fabric. What is the comparative ...
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64 views

Do high wings aircraft create an additional vortex in the middle?

At the same time, the air on the upper surface has a tendency to flow in toward the fuselage and off the trailing edge. This air current forms a similar vortex at the inboard portion of the trailing ...
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78 views

Matching the Drag Equation to Real Airplane Data

I am trying to compute airplane performance for a piston-driven airplane with constant speed prop using the standard equations for Lift, Thrust and Drag. I have found that there are a couple of useful ...
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103 views

What effect did the AWACS radar dome have on the stability of the 707?

The large disc shape of the AWACS radar dome, and its attachment pylons to the fuselage, above and behind the wings, seem to have the potential to actually improve the pitch and yaw stability of the ...
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1answer
105 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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128 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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137 views

How does the 'efficiency' of a cyclorotor compare to helicopters and fixed wing aircraft?

I recently rediscovered the cyclorotor concept. There is a good example on youtube here. Ignoring the mechanical complexity to an extent how does the 'efficiency' compare to conventional designs? When ...
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170 views

Why don't I see this kind of split ailerons on aircraft?

Why don't I see split ailerons that work like spoilers going up and like normal ailerons going down? Isn't that a good way to get rid of adverse yaw?
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46 views

How are Fan pressure of and Static pressure in the turbofan engine related?

If the fan air is ducted to the rear, the total fan pressure must be higher than the static gas pressure in the primary engine's exhaust, or air will not flow. By the same token, the static fan ...
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101 views

How can I design a slotted flap?

I have not been able to find satisfactory methods on design of slotted flaps, or flaps in general. Most of the answers are about eyeballing or experience. Can you guide me on what could be good ...
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1answer
138 views

How do I find the shear center of an unsymmetrical airfoil?

I'm quite a newbie of these systems and I am designing the wing box of a drone. I know where I want my shear centre. However, I have been trying to determine the shear centre of my idealized airfoil. ...
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47 views

How much does the design, implementation, test and certification of a Passenger-to-Freighter Conversion cost?

This question answers how much it costs to convert a given aircraft from passenger to freighter once the STC is approved by the FAA. How much does it cost to obtain the STC in the first place? If this ...
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149 views

How hot is the outer casing of a turbofan engine?

I am able to find temperatures inside different components of turbofan engines, but I can't seem to find what would be the temperature of the external casing/shell of the engine. For example, ...
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118 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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110 views

How do jetliners age (major or notable checks and part replacements)?

As commercial airliners can be (and are) operated for many years (or even decades), I've started to ponder - how do they actually age? Or - in other words - what are major or notable maintenance-...
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196 views

Are there design guidelines for sizing vent/surge tanks?

Could someone explain the sizing process of Vent/ Surge tank of Aircraft fuel system? I understand the Vent tank is to collect fuel overflow from the main fuel tanks. The reason could be due to Fuel ...
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134 views

Definition of Critical Part in type certification process

first time here :) I'm part of the team at Flytrex (flytrex.com) and we're working with the Aircraft Certification Office to certify one of the first UAS systems (drones) under new initiative to ...
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398 views

In a Boeing 767, what percentage of the aluminum is in structural components?

For a Boeing 767 (model year 2000), does anyone know how much aluminum is in 'structural' components, as a percentage of the total amount? And specifically the wings?
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219 views

Are there any airplane designs that are (relatively) insensitive to the effects of airframe icing?

Snow and ice buildup on airplanes (especially the wings) is a well-known and feared hazard of cold-weather operations; it roughens the surface of the wings and changes their profile, which combine to ...
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117 views

What‘s the diameter of the engines of the Airbus E-Fan?

does somebody know the diameter of the E-Fan‘s engines ? To me the look like around 80cm or what do you think ? Also, with more and wider blades and 60 kW motors instead of 30 couldn‘t they get much ...
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281 views

What Inertial effects should be considered to achieve blade stability on a Variable Pitch Propeller tailoredby aerodynamic loads?

I am developing a self adjusting variable pitch propeller tailored by its pitching moments due to aerodynamic loads setting the blade rotation axis in an offset from the aerodynamic center as shown ...
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36 views

What are typical values for CLmax in clean configuration?

I know typical cruising CL tends to be in the range of 0,5. Maximum CL I'm guessing around 1. Does anyone know typical values?
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101 views

Why doesn't the -30% SFC fully account for the dramatic reduction in fuel consumption compared to the 1960s?

In looking at the specific fuel consumption (SFC) of some aero engines I find that for example, the Rolls Royce Conway turbofan engine had typical cruise SFC of 0.874 lb/(h lbf) whilst the most modern ...
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57 views

Texts on aero-engine structures

I have been scouring the web for resources on aero-engine structures and structural design (preferably civil turbofans) but unfortunately it seems like they are hard to come by. I would like dedicated ...
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68 views

Do modern aircraft still use load bearing ribs in wing construction?

Modern aircraft are generally of monocoque construction. Does this apply only to the fuselage, or are modern wings made without load bearing ribs as well? Are they just for shaping of the metal skin?
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196 views

During WWII, what did internal bomb bays and turret layout look like on flying boats?

I am writing an alternate WWII story, and I was wondering if you fine fellows on this site could help me. I am trying to make a fantasy bomber version of the USN Boeing C-98 Clipper, AKA the Boeing ...
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142 views

Can a modern airliner handle turbulence forces of +5/-3G?

In the BOAC Flight 911 accident the 707 likely experienced around positive 5G and negative 2-3G. The wings of the 707 were only about as 50% as flexible as the wings of airliners today. How would a ...
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56 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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115 views

How do I reinforce a tubular spar that has been drilled vertically for an attachment bolt?

Previously posted a question about lift strut attachment to tubular wing spar with a bolt vertically through the spars. See drawing below. I tried using Bruhn's analysis book to formulate a a ...
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122 views

How is roll control achieved for the space ship two?

When looking at scaled composite 339 space ship two I fail to see control surfaces on the trailing edge of the wing. For me, it seems that the only moving surface on the wing is the feathering ...
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209 views

Carpet Plots for Aircraft Sizing

Generally, Carpet Plots are constructed to find out an optimal design which will satisfy all the performance needs and is least in weight & cost. I want to know how to construct a carpet plot? I ...
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71 views

Is there any bibliography for triplane aircraft design?

I've been tasked with designing an RC aircraft that has the greatest lift force for a specified wingspan, total length and takeoff velocity, and thus have been studying the different wing ...
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0answers
41 views

What is the effect of wing flex on wing's airfoil shape and its performance effect on wing?

There are good amount of discussion on wing flex in this forum. I am more interested in understanding the effect of flex on aerofoil shape of the wing and its impact on flight performance. Do ...
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0answers
213 views

How efficient would it be to have a plane with the cockpit in the back?

Would it be efficient to have a passenger planes cockpit move to the back of the plane, rather than the front? What I have in mind is cameras on the fuselage and nosecone that connects to the cockpit ...
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0answers
456 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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47 views

Looking for Polars for Liebeck LI74 with a Cl of 4.8!

Looking for Polars for Liebeck LI74 with a Cl of 4.8!! Does anyone have any info on this foil?
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936 views

What is the relationship between the Center of Pressure and flap deployment?

I have been reading regarding the Center of Pressure of an airfoil (Cp) and the relationship with angle of attack. What is a good way to explain in layman's terms why the pressure changes in such a ...
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46 views

What is a typical Cd0 value for single-slotted flaps?

I've been having trouble finding any source for what a typical value would be for single-slotted flaps. I haven't been able to find any information within Anderson's Aircraft Performance and Design or ...
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0answers
67 views

How to compute actuator torque requirement for Variable pitch mechanism??

Suggest me any reference to compute the torque requirement for actuator/motor to control the pitch angle of propeller (Variable Pitch Propeller). Thanks in advance Arun Ravindran
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513 views

What aircraft has the highest critical Mach number?

What aircraft has the highest critical Mach number? The highest I heard of was BAC/English Electric Lightning at Mach 0.95. Are there planes with higher Mcrit. and is it plausible to go higher than ...
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0answers
2k views

What is the purpose of a fuse pin in a turbine engine?

what's the difference betweeen fuse pin and mounting bolts of an engine ? Are they the same ? Any digram of a GE-90 engine showing those would be appreciated.
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299 views

How does the Bombardier CSeries compare to existing single-aisle jet-liners?

With news breaking in that Airbus will acquire a large part of Bombardier's CSeries program, I'm curious, just how much better are the new planes from Bombardier compared to single aisle planes like ...
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0answers
84 views

What useful data can be obtained by using building and flying a scale model of a fighter aircraft design?

The use of scale models in the design of modern fighter aircraft seems to be rare, wind tunnel models and software is used instead. Is building and flying a scale model of a jet fighter or trainer ...
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0answers
433 views

What are the specifications for the CFE738-1-1B?

I'm designing an aircraft for fun, and I've selected a CFE738-1-1B as the engine. It's never going to fly outside of X Plane, but it's still fun, so I'd like to make the X Plane version as realistic ...
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1answer
122 views

What is the "mass growth factor" of an aircraft?

How to understand the aircraft mass growth factor? Which physical meaning does it hide? Which are the practical applications?