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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750 views

Meshing Complex models in abaqus

I'm trying to mesh a model of a morphing wing in Abaqus and have been running into issues. It was recommended that I partition the model into smaller parts, but it seems that the more I try to ...
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1answer
377 views

What is the straightest, longest and strongest pole that could be launched into space?

Which of these poles would be straighter and stronger then the others? These are some poles that are compacted making them possible to send to space. Sending a single solid pole .5km long will not be ...
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What does 'Analysis Model Value' in NASTRAN optimization mean?

I am new to MSC NASTRAN and PATRAN. I am running a simulation on composite laminate optimization. While creating the design variables for the study, I noticed that there is a parameter called '...
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1answer
22 views

Contact Motion Analysis (CMA) [closed]

In this solution Helicoptor Fire Control System CMA is used. For motion analysis we use computer vision and image processing. But what is special about CMA.
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2answers
59 views

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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1answer
24 views

Vibe Table: Increase Peak Force Capability?

I'm driving a small, benchtop vibe table (shaker) with two Crown DSI-1000 PA's, and also cleaning my signal with a DBX 231s EQ. Currently running the system at 6.8 GRMS, but I'm looking to increase my ...
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1answer
116 views

simulation of an attitude optimal Backstepping controller based quaternion for a UAV in MATLAB

I'am trying to implement this open access research article Attitude Optimal Backstepping Controller Based Quaternion for a UAV I did not find the same result in this paper Can anyone tell me where my ...
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1answer
103 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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2answers
390 views

How do solar balloons work at high altitudes?

I am interested in the challenges that Solar Balloons face when flying. For example, the high altitude could cause drastic changes in: Wind speed Temperature Moisture How does the unique design of ...
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1answer
133 views

Calculate attitude quaternion from 2 vector measurements

I am using a method proposed by R. G. Reynolds to estimate attitude based on two vector measurements, taken from: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990052720.pdf Suppose we ...
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2answers
88 views

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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3answers
186 views

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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1answer
106 views

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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1answer
122 views

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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400 views

Beam element stiffness matrix for variable area cross section with mass and shear center not coinciding

I would like to find the full (12 by 12) Timoshenko beam element stiffness matrix for a variable cross section with mass center axis and elastic center does not coincide. I have the full stiffness ...
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3answers
111 views

Aircraft carrier arresting cables

I recently was at the Naval Air Museum in Pensacola Florida. There are lots of models of aircraft carriers, including the latest class (Gerald Ford class as I recall). This latest class has ...
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0answers
41 views

What is the theoretical relationship between sound and mass with respect to the sound barrier as a max velocity?

First post here, forgive me any faux-pas. In regards to compressible flow and accelerating a mass flow, such as in a converging nozzle, I know that you can't accelerate a mass past the speed of sound (...
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2answers
5k views

What is the difference between shaft power and brake power?

I know little about internal combustion engines and I feel a little confused about brake and shaft powers. I read a book that only talks about shaft power, and other that only talks about brake power, ...
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1answer
86 views

What filter is this?

I am implementing a second order filter. It simulates hydraulic servo on an airplane. Its about 35-40 years old. What confuses me is the notation. Like "2(.7)(52)S", what does it mean? If its just ...
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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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1answer
37 views

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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2answers
751 views

How do jets/airplane cold start?

If a jet starts in extreme cold, i.e cold starts, then the jet cannot power the heat exchangers to heat the fuel. Then how do they heat the fuel to start the jets? Obviously you can't use batteries/...
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0answers
36 views

Given Pitch and Roll in one Heading, convert to co-planar pitch and roll for North

I have been pouring through countless articles about Euler's angles, rotation matrices, Rodriguez Rotation Formula, Quaternions, trying to understand how to generate an algorithm for this problem and ...
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1answer
125 views

Propeller design

I see on internet, that aircraft propellers most effective blades angle only 15 degrees on every blade. Why propellers not use 45 degrees angle on propeller's blade that give more thrust on the ...
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1answer
65 views

Rotation of aircraft's body-frame

There are Tait-Bryan angular changes $(\dot{\phi}, \dot{\theta}, \dot{\psi})$, which describe the angular change rates of the body-frame within the inertial frame (world frame). And then there are ...
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1answer
222 views

Advice for designing internal structure of glider wing

I am interested in designing a scale model semi-monocoque wing for a glider. I've done some research on the framework and internal structure. I have found out about the spars, ribs and stringers and I ...
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1answer
100 views

Axial compressor - change of temperature not proportional to number of blades and their geometrical properties?

I'm learning theory of axial compressors for my summer internship and I find some of the equations puzzling, although I do understand the way they were derived. The equation bellow is for temperature ...
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1answer
38 views

Triple point storage in space travel

Watching Apollo 13 and rereading Lost Moon, Jim Lovell's exciting recollection of the events on the crippled spaceship, I began to wonder. Why does NASA maintain the gasses at the triple point? A ...
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1answer
37 views

Help me find a paper/textbook on axial compressor in turboshaft engine [closed]

I'm trying to calculate the values of pressure, temp, speed and density of air going through an axial compressor (12-stage) a helicopter. I've read a few bachelors' thesis and papers but wasn't able ...
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1answer
114 views

Wind resistance inside turbulent flow ("prop wash")

I have an object that is launched from the side of a plane (it is a flare). The question is: what does the flare do while it is proximate to the plane? Will it hit the tail? After accounting for ...
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2answers
838 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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1answer
40 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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4answers
2k views

J2 orbit propagation problem in MATLAB (solver instability)

The problem is that when I try to solve the following equations of J2 perturbed gravity: ...
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1answer
620 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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3answers
3k views

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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2answers
96 views

Rocket to slow freefall

I read that a human https://www.google.co.uk/search?client=ms-android-samsung&ei=l0_EWNjsHKXEgAafuIUg&q=john+stapp+45+g&oq=john+stapp+45&gs_l=mobile-gws-serp.1.0.0.6460.9902.0.10829....
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1answer
101 views

Name of a keel between the bilge keel and the main keel

I'm working on a seaplane and find myself doubting about the specific nautical term for a keel placed between the bilge keel and the main keel. This might be a bit academic in nature since I have a ...
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3answers
589 views

Difference between seat belts

Today, I was thinking about seat belts. On that note, why do the ones in cars and planes differ? Planes have only belts on the waist, but cars have waist and diagonal. Is there a reason that this is ...
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2answers
3k views

How to scale airfoil coordinates to achieve the required size?

I'm using airfoil data that is generated by a program. The generated airfoil has a chord length of 1 unit. I want to know how to scale up this airfoil to required chord length. My airfoil series ...
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1answer
3k views

Using a PID to control rotation

I've been working on simulating drone flight in Gazebo (an open source robotics simulator). Currently, I'm trying to control the drone's pitch / roll rotation using PIDs. It's important to remember ...
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1answer
94 views

Can Voyager 1 or 2, theoretically, return to earth if given instructions before their electronic instruments shut down in 2025?

According to the NASA Website, the Voyager probes will begin powering down electrical components soon with all electronic functions ceasing some time around 2025. With no ability to transmit back to ...
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2answers
75 views

Largest possible navigable blimp

From a pie in the sky approach, similar to the question of whether a jetliner could be theoretically solar powered, what are the limiting factors on the magnitude of lifting capability of a ...
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1answer
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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3answers
376 views

Can you postcure epoxy composites outside the mold?

Say I make a fiberglass/epoxy part on a plastic mold, and it cures at room temperature. The epoxy system calls for a postcure at 250F, but the mold cannot withstand 250F. If I take off the part and ...
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1answer
6k views

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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3answers
213 views

Questions about helicopter rotors - conservation of angular momentum

I have two basic questions about helicopters. Let's say the z-axis is the vertical axis from ground to sky. I know the tail rotor is there to counteract the angular momentum effects of the main rotor, ...
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1answer
987 views

Wingspan formula for an Ornithopter

How do i figure out what the wing area/sqft needs to be for a functioning wing-flapping ornithopter? Lets say for example there is 500# of force moving the wings up and down, and the wings and ...
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3answers
365 views

Can a blimp enter Mar's atmosphere as a glider?

I saw a high altitude jump where someone had exceeded the speed of sound before the air slowed him down enough to deploy a parachute. While inflated in space could a blimp enter the atmosphere while ...
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1answer
94 views

Alternatives to shimming valve springs

Generally, in a pressure drop control valve that uses a piston and a spring (for example, in jet engines to control fuel flow), there is always potential for error in terms of the height of the spring....
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1answer
279 views

What prevents the use of electric engines to assist with spacecraft launches? (Space Shuttle Booster Supplement)

Much power is used to get rocket off the platform on the initial launch? Could electric engines used like booster rockets work similar in the way they launch planes of an aircraft carrier? The ...