Questions tagged [theory]
Questions about the theoretical aspects of aviation.
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Coordinate system for describing 3D target position relative to plane FRD
I'm trying to understand what is the most popular convention for describing the position of a point in 3D space relative to a plane's body frame, with axis "front", "right" and &...
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Why does this curved wind tunnel rotate?
Why does this curved wind tunnel rotate, why is it not just curved?
A curved wind tunnel has a radial pressure gradient, but this pressure gradient doesn't exist in a real turn, so how do you get ...
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What does the C* (Cstar) parameter demand ?(A320)
I have been reading a LOT of research papers and many articles, but none of them tell how the C* parameter in Airbus is used for the vertical augmentation of the aircraft.
I am aware that with a ...
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Gyroscopic Precession in Coaxial Helicopters
I'm trying to understand gyroscopic Precession in the case of coaxial helicopters. Obviously the effect still exists. But if gyroscopic Precession is a result of counter torque. Shouldn't the effect ...
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In general, how much is V/V∞ ratio at upper wing surface?
Airflow on upper surface is always faster then freestream, in general, how much is airflow speed to freestream speed ratio(V/V∞, max values) at upper wing surface, are we talking about 1.1 to 2 or 2,3,...
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Why induced drag shows up as reduced pressure downstream of the wing?
Quote from book (Understanding Aerodynamics: Arguing from the Real Physics, Doug Mclean):
"When we look at the force/momentum balance, the induced drag shows up in the flowfield primarily as ...
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A transfer function relating jet engine thrust to pitch angle during a phugoid motion
Crossposted on Mathematics SE
I am doing a school project that requires me to find a transfer function that relates the thrust of a jet engine (which could change with time in one way or another) and ...
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"Pure" Aerospace engineering vs mechanical engineering/pathway aerospace?
Does "pure" aerospace engineering give better aero-knowledge then mechanical engineering/pathway aerospace?
What is point of specialization aerospace at mechanical engineering, isn't ...
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ATPL theoretical course hours per subject
do someone know what is the hours per subject mandatory for ATPL (A) EASA program. In the Easy Access Rules for Aircrew (PART FCL) it said:
The 750 hours of instruction should be divided in such a way ...
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Difference between velocity potential and stream function?
I am currenty reading Fundamentals of aerodynamics(sixth edition) Jhon Anderson and in sections 2.14, 2.15 was introduced stream function and velocity potential concepts. I understand that both of ...
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How would the shock-ramjet engine work?
I discovered a new theoretical engine called the shock-ramjet (schramjet) and I was wondering, how would it work exactly? I've read that its a high-speed engine that could be used around Mach 10, but ...
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What is a wing theory?
I have an assignment to summarize the topic "wing theory", with the preferred reference used is the book Fundamentals of Aerodynamics by John D. Anderson. But there's no dedicated chapter ...
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Energy Maneuverability Theory Applied to WW1 Fighters
I am trying to test the Fokker D.VII, Spad S.XIII, Sopwith Camel, Nieuport 28, and the Se5a using the model in this paper:
https://apps.dtic.mil/sti/pdfs/ADA066034.pdf
It's called Combat Performance ...
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Is Biot–Savart law physical in aerodynamics?
Biot–Savart law comes from electromagnetics theory.
Vorticity behind the wing(in the wake) induce downward vertical velocity upstream of the wing, so effective AoA of the wing is reduced.
Is this ...
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Has resultant pressure vector backward component at 2D airfoil in viscid flow?
When we integrate static pressure around 2D airfoil that produce lift(viscid flow), has resultant pressure vector backward component?
I think pressure vector will point slighlty back, so it has some ...
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Why total drag formula include drag at zero lift?
Total drag = Do + DL
Why total drag include drag at zero lift if we are interested at drag when wing produce lift?
We cant assume that friciton and particularly pressure drag at zero lift AoA dont ...
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Does induced drag drop when wing is stalled?
From formula, induced drag is function of lift. When wing stalls, lift is reduced so induced drag must also be reduced?
Stall decrease static pressure at suction side of wing, so I know pressure drag ...
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Why are aircraft piston engines are so low rpm lazy engines?
I understand that the propeller speed should not be too much otherwise it will stall at the tip and be useless so higher rpm engine would be useless when we first think about it. However, we can put a ...
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Why does a wing's pitching moment distribution tend towards zero at the tip instead of towards cm0?
I am currently playing around with XFLR5 and am trying to wrap my head around the following:
For airfoils, my understanding that the pitching moment has a component that is independent of lift, which ...
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How to compute the direction of the vector perpendicular to the wing?
I'm trying to compute the direction of the vector that extends perpendicularly up from the top of the aircraft's surface.
Is there a way to compute the vector's 3-dimensional parameters in Cartesian ...
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Immobile pressure-sensitive stick [duplicate]
I was reading the Japanese sci-fi novel Yukikaze (greatly recommended btw) again and I came across a detail that describes that the stick of the fighter plane the main character is flying is fixed in ...
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How does deploying full flaps affect Takeoff run and distance?
There is a question in EASA Question Bank (AviationExam) that asks:
How will the takeoff distance change if the flaps are increased from 0 to full?
(a) Reduce (this is marked as correct since many ...
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What flying sources does Richard Feynman consider incorrect? [closed]
In this VIDEO from 1:09-2:15 Richard Feynman talk about some flying sources that he considers incorrect.
What is the theory that he refers to?
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If induced drag is caused by the downward deflection of the air streaming around the wing,why airfoil(that also deflect air down) has induced drag=0? [duplicate]
In this site induced drag is often explain as downward deflection of the air streaming around the wing.
Airfoil (2D) also deflect air downward(otherwise it would not produce lift), why then airfoil ...
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Is induced drag zero for finite wing with constant lift distribution (dΓ/dy=0)?
Part 1
Observing how induced drag is derived, induced drag is loss of kinetic energy due to total vorticity that is produced by wing.
I want to find induced drag of finite wing with L=const over span.
...
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Does Navier-Stokes "recognize" existence of induced drag, can we get induced drag from them?
"Early aerodynamic mathematical methods rely on potential flow concepts that formally isolate aerodynamic drag into a profile and an induced drag component. The more recent evolution of Navier–...
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Does wing really "feels" effective airflow or it is just theory to fits numbers with experimental results?
Theory predict downwash that will cause reduction in airflow angle,this we call effective airflow.
Does wing of aircraft during flight really "feels" this effective airflow or this is just ...
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how are the properties of canards affected when they are angled compared to normal canards?
So i recently saw an image of the natf-23 a modified(more like completely redesigned) yf-23 and one of the interesting things it had were canards that were angled. What would the benefits and drawback ...
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Vertically moving wings
Would there be a benefit to vertically adjustable main wings?
I recently watched this anime series and got curious if the wing moving mechanism could have any plus points, or if it was likely just ...
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Would aft stabilisers, that can move up and down, have any benefits?
I was looking at some aircraft as an inspiration for a project and found the X-02 Wyvern from the Ace Combat series and one feature that seemed interesting (let's ignore its Swiss Army knife wings) ...
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2D to 3D Non-Elliptical Lift Curve Slope Correction Factor Reference
I'm working on automating some aerodynamic calculations for a particular multidisciplinary design tool and in the course of setting it up I ran across this formula from the input theory manual
$$
{CL_\...
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How to determine the base of stratus clouds? [closed]
For cumulus clouds this applies
Calculate the 'spread,' where you're taking the current surface temperature and subtracting the dew point.
Divide the spread by 4.4 (if temperatures are in °F) or 2.5 (...
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Takeoff-chart Interpolating Numbers from a range
I'm studying for my AIRAT (Instructor Written) in Canada using Nizus, but I've always had trouble answering the questions about takeoff distances at 27 ºC when given a chart with 20 ºC and 30 ºC, even ...
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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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Is aerodynamics science still being discoverd? [closed]
Is aerodynamics science still being discovered(like mathematics for example) or everything has already done?
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How calculate lift/drag using static pressure taps in wind tunnel test?
An airfoil section in a wind tunnel has many static taps on its upper and lower surface. These static ports can only read static pressure which acts perpendicularly to the local airfoil surface.
In ...
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Help with calculate forces from pressure distribution
V=50m/s
deltaPg= -981 Pa
deltaPd=490,5 Pa
c=1m
r.com/PCshZ.png
Above is calculate Fz with integrals and with average pressure.
Why F3 is calculate from 0 to C/2 if pressure distribution is drawn at ...
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How long is a BAK exam valid for? (CASA Australia))
I am looking to get back into flying, and I passed my BAK theory in 2016. Is that still valid? I want to go straight to PPL so I will be doing PPL theory anyway, just would save me a step, unless I ...
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EASA PPL theory instrumental approaches rules
I am learning for EASA PPL in Czech.
I noticed that in some of the books there is chapters about Instrumental Approaches Air Law rules.
For example -
ILS approaches
Parallel approaches
Simple ...
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How to choose the right map projections for flight plan?
There are 2 projection of maps that I saw online. UK CAA is a transverse projection map, while ICAO maps are conical.
It seems that transverse map is easier for flight planing as straight lines are ...
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If aircraft specific energy is a combination of kinetic and potential energy, why is altitude not a variable in the energy-maneuverability theory? [closed]
The Energy-Manueverability formula is
$$ P_S = V \left( \frac{T - D}{W} \right) $$
with velocity $V$, thrust $T$, drag $D$ and weight $W$.
$P_s$ represents specific energy, which is a combination of ...
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Which source(s) provides the most authorative and correct flight dynamics theory? [closed]
Just like many curious people, the question: " How airplanes actually work?" occupied my mind for a long time.
Different sources gave different answers where most claimed the Bernoulli ...
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Is it possible for an airplane to enter another airplane? [duplicate]
I was making some cool fictional airplane designs and realized that most of my larger airplanes have a bay inside that stores a plane or two. But then I thought, is it even possible to make a plane ...
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Relation between lift force and torque produced in propeller used for vertical take-off and landing aircrafts
There are many answers for this question but none of them are specific.
I need to find the exact relation between the lift force of a propeller of specific pitch, attack angle , dimensions and ...
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Is it incorrect to say that "passenger jets like to cruise at higher altitudes because there's less drag"?
I hear it stated quite often that aircraft like to fly high because there's less drag at higher altitudes.
$$ \text{Range} = \frac{V}{g} \frac{1}{\text{SFC}} \frac{L}{D} \ln \left( \frac{W_\text{...
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Is the well known textbook-formula for net-thrust oversimplified or do I have a misinterpretation?
In order to understand how Jet-Engines works I came across the "famous" formula for net-thrust:
https://en.wikipedia.org/wiki/Turbojet#Net_thrust
$F_{thrust} = Q_{out} \cdot v_{out} - Q_{in}\...
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Why is the aerodynamic center for most airfoils located at the quarter chord location?
I've been reading several sources on the location of the aerodynamic center
https://web.mit.edu/16.unified/www/FALL/fluids/Lectures/f03.pdf
https://en.wikipedia.org/wiki/Aerodynamic_center
John ...
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Could gliders be a clean, practical alternative to other forms of transport?
Would it be possible to use pure gliders as an eco-friendly mode of transport?
From what I have read so far, gliders can travel at a speed of 100-170 km/h. That would not be able to compete with a jet ...
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Could propeller wash provide sufficient lift to take off - even in theory?
I know this seems a crazy thing to ask but it is not the same as lifting oneself by the bootstraps. If you try to lift yourself that way, there are two equal and opposite forces, yet there are ...
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Is the Batjet Design Physically Feasible?
I realize the plane is fictional. However, in the Batman Animated Series by Warner Bros, we see this Batjet.
So this got me thinking (and I'm not a physicist): is this air frame configuration even ...
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