Questions tagged [aerospace-engineering]

Aerospace engineering is the primary branch of engineering concerned with the research, design, development, construction, and testing of aircraft and spacecraft.

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How to make smoke for a small wind tunnel?

I am making a small (desktop) wind tunnel for educational purposes, I want to have 10 fairly thick smoke-streams about 3cm apart. I have experimented with incense but the stream is not thick enough ...
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Is interference between aircraft an issue for fly-by-wireless technology?

I was reading up on fly-by-wire development, and I saw a short section about fly-by-wireless technology. It seems like a great idea, with the potential to lower costs, weight and complexity. I can see ...
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What is the difference between aeronautical and aerospace engineering?

Every time I search for "aeronautical engineering" on Google I see a few results about aerospace engineering. So they must be similar, but what is different about these careers?
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How is lift related to airspeed?

Lift produced by an airplane wing is related to airspeed - this much is clear; a plane moving too slowly will stall. But what is that relation? Linear? Quadratic? Exponential? I don't need the exact ...
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Would a "lifting body" design be useful for a train car?

Lifting Body The idea of a lifting body design is to shape a vehicle's body in such a way as to produce lift without wings. Research has shown that this can be an efficient method of reducing drag ...
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How are wind tunnel models used when designing supersonic aircraft?

There are two things involved: wave drag and boundary layer separation. The wave drag depends on the Mach number while the latter depends on the Reynolds number of the flow. It's easy to maintain the ...
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Could air-launched space planes reach escape velocities?

Rockets like the Ariane 5 weigh hundreds of tons, but with about 85% of that weight being fuel, the payload fraction is only about 3% (~10-20 tons). Virgin Galactic is building suborbital space ...
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MIMO (multi input - multi output) system decoupling method

A MIMO system with 2 input and 2 output decoupling method to a SISO system is described in many articles and books. How about m*n size transfer functions systems? How can we generalize the method for ...
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Efficiency in a gas turbine or aircraft engine

Most modern aircraft engines, such as the one depicted below taken from Wikipedia, are composed of several compressor stages which are driven by a turbine (or several), and a combustion chamber in-...
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What are the advantages of chemical oxygen generation over compressed tank storage?

Chemical oxygen generation (COG) is used in commercial airliners to supply emergency oxygen to passengers and crew if the plane is depressurized. Weight for weight it produces far more oxygen than ...
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7 votes
3 answers
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Why use non-dimensional coefficients?

Aerospace engineering textbooks make frequent use of non-dimensional coefficients like $C_L$, $C_D$ and a whole host of others. Usually, for equations of motion, it is preferred to replace variables ...
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6 votes
1 answer
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Convergent-Divergent Nozzle Design from Exhaust Velocity

I'm working on designing a Cold Spray system that uses a convergent-divergent nozzle to achieve a 800 m/s exhaust velocity. I'm assuming 400 psi nitrogen at room temperature is provided at the inlet ...
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2 answers
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Does every engineering design needs to have a complete theoretical backing or may experimental data suffice?

This may sound rather vague on its own so I will explain with examples. The solid booster rockets used by NASA space shuttle used a central bore design because it had a certain characteristic on ...
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What are the engineering challenges in WIG craft development?

Wind In Ground (WIG), is an old concept. In short: Wing-tip vortices create an additional drag on the aircraft known as the induced drag. However, when the flying craft (or bird) flies close to the ...
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Do all airfoils have a lift curve slope of $2\pi$?

I know that according to the thin airfoil theory all airfoils (symmetric or not) have lift curve slope of $2\pi$. I also know that finite wings should have less inclined lift curve because of the ...
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6 votes
1 answer
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Did Otto Lilienthal ever experiment with non-human-powered aircraft?

Otto Lilienthal, sometimes hailed as the first aviator, became famous for his many gliders, which pioneered new experiments in aeronautics. However, powered aircraft didn't take off - pun intended - ...
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Do regulations in the United States limit the size of aerial wind turbines?

What with all the work done by the FAA recently on regulating drone usage, I thought it would be nice to turn my eyes to the sky for another, less-known type of aerial denizen: the aerial wind turbine....
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What is the equation to calculate the Thrust coefficient within a set of parameters?

In the book, Design of Liquid-Propellant Rocket Engines, there is a practice problem written as such. "Determine the design values of $(C_*), (C_f), and (I_s)_t$ for the engine thrust chambers of ...
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2 answers
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Could adding extra engines to AMELIA disrupt airflow from the other engines?

AMELIA is the product of a partnership between NASA and the California Polytechnic State University. One of its innovations is circulation control. An engine is mounted over each wing, and high ...
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6 votes
1 answer
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I have a problem with my representation of roll in Simulink

I am currently an engineering student and a member of the aerospace club of my engineering school (ESILV) which is called LéoFly. We’re a team of 12 students and are building a Fusex (...
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6 votes
3 answers
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Need some advice, control system animation. Appreciate some help!

I would like to have a 3d simulation of a helicopter landing on a ship. I thought about using matlab for this, as a far as I know you can connect models from Simulink to virtual worlds using blocks, ...
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4 answers
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Should Engineers Understand Equations without Relying on Derivations?

As I've progress through my undergraduate engineering program, I've noticed a shift away from physical intuition - understanding why certain phenomena or equations make sense because of basic patterns ...
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5 votes
1 answer
111 views

Why don't propeller designers use multiple profiles?

I'm designing a ducted fan, and I'm deciding on the airfoil profile. NACA 16-series profiles are well-suited to M > .5 or .6, but they're not particularly efficient at lower Mach numbers. On the other ...
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5 votes
1 answer
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Logic behind location of shear centre

When we apply a vertical shear force Sy and the structure is symmetric about x axis, then why is it logical to have the position of shear center at the location of intersection of line of action of ...
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1 answer
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Calculating real or more accurate specific impulse

This may fall a little under chemistry processes but I felt it has enough pertaining to aerospace to put it here. Basically, I'm in the process of attempting to develop a way to derive $I_{sp}$ as ...
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5 votes
1 answer
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How hot does a rocket nose cone get during launch?

More specifically, I'd like to know if unmanned rockets need to be specially designed to withstand the heat generated from air friction and shock waves during launch. I found the diagram below on the ...
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5 votes
1 answer
772 views

Why does flow seperation cause low pressure zone?

I know that flow seperation occurs when the fluid adjacent to a body deviates from the contours of the body . This occurs because the pressure increases in the direction of flow and velocity decreases ...
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5 votes
1 answer
493 views

What is "Bernoulli-Lift", and why does it only account for 20% of an airplane's lift?

Whenever the question "Why do airplanes fly?" is asked (e.g. »What really allows airplanes to fly?«, »How an airfoil works?«) at a certain point the following is cited: Bernoulli's principle ...
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5 votes
1 answer
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Would a partial space elevator work? [closed]

Background The normal space elevator (that reaches from the Earth's surface to a counterweight beyond geostationary) needs a material that's strength/weight ratio is better than any material we have ...
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5 votes
3 answers
429 views

Questions about the level flight lift equation

In level unaccelerated flight we have relation $$ W=L=\frac{1}{2}\rho\cdot V_{stall}^2\cdot S\cdot C_{l,max} $$ taken from book Daniel P Raymer "Aircraft Design: A Conceptual Approach" equation (5.5) ...
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5 votes
1 answer
715 views

Coupling in a twin engine, tandem rotor power train

Consider a transmission for a tandem rotor helicopter with two engines and two main rotors such as the one below. Both engines are connected with sprag (one-way) clutches such that an engine's speed ...
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2 answers
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In case a plane stalls, what should stall first, the tip or the root of the Wing? Why?

In case a plane stalls, what should stall first, the tip or the root of the Wing? Why?
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4 votes
4 answers
765 views

Do all supersonic airliners have a high angle of attack when landing?

The Concorde had a famously high angle of attack (and pitch angle) when landing. This led to its famous droop nose: The Concorde's Russia counterpart, the Tupolev Tu-144, had the same issue. These ...
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4 votes
4 answers
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Resonance vs flutter

Is there any difference between resonance and flutter. Both of them are related to overlap of external excitation frequency and Natural frequency then increase in amplitude even inifite amplitude ...
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4 votes
5 answers
2k views

Can vacuum balloon become possible with this idea?

As it is well known, a vacuum balloon using the materials we have at our disposal is not possible, because of the sheer force they have to resist from the air outside. I asked this question on ...
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4 votes
2 answers
1k views

3D Transformation Between Two Cartesian Coordinate Systems Using Euler Angles

I am trying to transform any arbitrary vector $\bf{v_{1}}$ in a Cartesian frame $\mathscr{F_{1}}$ into a different Cartesian frame $\mathscr{F_{2}}$. Both $\mathscr{F_{1}}$ and $\mathscr{F_{2}}$ have ...
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4 votes
1 answer
863 views

How do I cut a crack into a polymer/plastic?

We need to cut a very thin crack into a polymer plate for a research project. The closest thing to what we are looking for is Wire EDM but since the polymer we are using is not conductive we cant use ...
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4 votes
1 answer
117 views

Sliding mode surface derivative using numerical method

In the article Controller Design using Bifurcation Map for Aircraft Spin Recovery, the sliding surface derivative is obtained using a numerical method. The steady space system is defined by the ...
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4 votes
1 answer
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Does a rotating platform on a space vehicle affect the vehicle's trajectory?

Recently I watched The Martian and the space vehicle Hermes in the movie had a rotating platform. I wonder if that would significantly cause the vehicle to be inclined in direction? Does a spinning ...
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4 votes
2 answers
105 views

Eulerian description of fluid flow

In Eulerian description of fluid flow, we observe how the properties of the fluid are changing at a point. Since a point has zero dimension hence a zero area, how can we make sense of the 'finite ...
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4 votes
1 answer
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How to design the right input to obtain a desired output for a linear system?

If I have a state-space model, so that matrices $A$, $B$, $C$ and $D$ are known, how can I design the right input $u$, so that $y$ is a desired signal, say, a sine wave with constant amplitude? $$\...
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4 votes
0 answers
50 views

Could a Fuel Breathing Engine Rather Than an Oxidizer Breathing Engine Work?

Here on Earth, the atmosphere is ideal for jet engines which combust a fuel using the native oxygen as an oxidizer. On another planet, might it make sense to carry oxidizer in the fuel tanks and scoop ...
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3 votes
2 answers
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What is the purpose of building multistage rockets, rather then packing more fuel into a single stage?

Reading an article about multistage rockets (not educated at all on the topic), and from the get go it seems to assume they are used/need to be used.
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3 votes
1 answer
800 views

What is the effect of changing the angle of a helicopter flybar?

A helicopter flybar is a kind of gyroscopic stabilizer which acts in feedback to the pitch of the blades. The effect, in words, is that as the helicopter starts to pitch or roll in a particular ...
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3 votes
1 answer
126 views

Are there any specific plans for the other parts of the 747s scavenged to make the Stratolaunch carrier aircraft?

I'm not sure quite how many people are familiar with the Stratolaunch project, so I'll give a quick summary. Paul Allen and Burt Rutan (of Scale Composites) teamed up a few years ago to create a ...
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3 votes
3 answers
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Can superhydrophobic surfaces be used to reduce drag?

I am mainly interested in reducing drag in aircraft and I have an idea that I want to learn more about... Can a superhydrophobic coating reduce drag in water-craft such as boats and submarines? If ...
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3 votes
1 answer
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Development of an interstellar mission: should I design the propulsion system or the main hull of the ship first?

I am currently developing an interstellar mission for a school project. I am thinking whether to design the propulsion system (Bussard scoop) or the main hull and structure of the spaceship first. ...
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3 votes
1 answer
149 views

What does high coefficient of moment mean for an aircraft?

After designing an aircraft idea I had in XFLR5, I noticed that it had a really high coefficient of moment (Cm) compared to other wings of similar size. What does this mean? I played around with my ...
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3 votes
1 answer
43 views

Finding Source of Heating Rate Equation

I am currently working on creating a tool to calculate the maximum heating rate on a re-entry vehicle given starting conditions and coefficients. I am using Re-Entry Aerodynamics by Wilbur L. Hankey ...
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3 votes
1 answer
1k views

Torsional Constant of Thin-Walled Multi-Cell Structures

I'm asked to analytically calculate the composite torsional constant of the following structure. No other information is given, such as the applied torque. I know how to calculate the torsional ...
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