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Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aircraft design.

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58 views

What are dimensions of the B-17 propellers?

I'm curious about the aerodynamics of the Boeing B-17 propeller, as the proportions looks perfect for a project I'm working up. Does anyone out there know where to find the specs/dimensions/models for ...
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2answers
62 views

Vmc, flaps, and performance

A study guide I recently found indicates that Vmc and aircraft performance improve with takeoff flaps set. The Vmc improvement makes sense but the performance improvement does not. At a basic level ...
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1answer
2k views

Does a headwind/tailwind affect your rate of climb?

I am still confused whether a head wind or tailwind would affect the rate of climb. Since in a HW/TW condition our a/c is basically still climbing in the same parcel of air, it is just that parcel of ...
2
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1answer
201 views

Why are fighter jets equipped with dorsal fin?

I don't really get whats the purpose of dorsal fins and what they do with the flow over the vertical stabilizer. I noticed on most single tail configured aircrafts are equipped with a dorsal fin like ...
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3answers
83 views

What does the extending the flaps do (or any high lift device) to the Rate-Of-Descent of an airplane?

I know that deploying flaps will increase both drag and lift, thus increasing L/D ratio. But how exactly does that correlate with the increase/decrease of the rate-of-descent?
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1answer
56 views

What effect does downwash have on the horizontal stabilizer

Fighter aircrafts usually have their horizontal stabilizers in lined with the main wing which would subject it to downwash. How does this effect the stability of the aircrafts and the effectiveness of ...
2
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1answer
123 views

What can cause a sudden jump in Indicated Air Speed?

My aircraft heading is 321 with constant Static pressure, wind speed and steadily increasing Ground Speed. Meanwhile, there was a sudden jump of 10kts in IAS from 140 to 150 kts withing a span of 1 ...
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0answers
18 views

What are the benefits of “fixed wing with different swept angles on the trailing edge”? [duplicate]

Take Boeing 767's wing's trailing edge for example, it starts at the root with being perpendicular to the fuselage, then it swept back like the leading edge. What is the technical term used for this ...
3
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1answer
108 views

Definition of a Deep Stall

I've been doing some research for a uni assignment and I noticed that the RQ-11B uses a "deep stall landing" to get back onto the ground. What I don't understand though is how this aircraft gets into ...
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1answer
120 views

Why is polar curve of a glider dependent on flight load?

This is my first question here. I'm just a glider in education phase and not yet a pilot, but because I'm also physicist, I'm interested in some details more than other people. My question is simple:...
4
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0answers
53 views

What is the relation between flap setting and aileron droop on the A350?

The A350 has a aileron droop function, which is linked to the flap setting. In contrast to other aircraft with aileron droop, the A350s ailerons do not droop when the flaps are fully extended. I ...
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3answers
171 views

Can an aircraft fly without wings and stabilizers?

Can there be an aircraft (not an airplane like in this other question) without wings and stabs (rudders and elevators)?
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3answers
286 views

What constrains a paraglider vertically?

I recently flew on a tandem paraglider for the first time. Since then I keep asking myself a question I have no clear answers to. While flying I clearly perceived the lift generated by the airfoil,...
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0answers
109 views

Can be the divergence Mach be greater than 1?

I am wondering if this is possible. I know that by decreasing t/c and increasing the sweep angle it is possible to increase the divergence Mach. Where is the limit? I am calculating the Mach for a ...
0
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1answer
84 views

Is there a difference in stability between a tail downforce (cg ahead of ac) and a tail upforce (cg behind)?

So from what I understand, having a - 1.cg ahead of the neutral point(ac) with a tail downforce and 2.cg behind ac with a tail upforce are both stable configurations.(Please correct me if I'm ...
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0answers
104 views

How can I calculate the required thrust of a rotary wing?

I am working on a project that requires a propeller. Please understand that my background on propellers and rotary wings is limited. I am trying to figure out the thrust required for a vehicle ...
1
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1answer
121 views

What is the 'end plate' effect?

When talking about T-tail configuration, I don't understand the statement that, "The vertical tail can be shorter due to the end plate effect of the horizontal tail." What exactly is the endplate ...
7
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1answer
347 views

Do airliner spoilers really “spoil” lift?

The two illustrations below show the typical spoiler location and the lift distribution of a wing. For comparison a third picture shows the location of spoilers on a glider. It appears the airliner ...
4
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1answer
420 views

What are the consequences of attaching an unused extra engine under Boeing 747 wing?

It turns out Boeing 747 can carry an extra engine under its left wing in case there's need to transport an engine somewhere far away. The engine is attached between the body and the left inner engine ...
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1answer
61 views

Is using flaps the same as increasing the AOA? [duplicate]

The purpose of trailing edge flaps is to give the aircraft more lift at lower speeds. But do simple flaps beneficent more than increasing the angle of attack? The image looks like part of the wing ...
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2answers
120 views

What aerodynamic phenomenae can decrease the pressure gradient in Boundary Layer Ingestion?

I'm exploring a question concerning whether or not boundary layer airflow presents physical limitations that are too great for current technologies to overcome (I'm holding the position that it is in ...
1
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1answer
84 views

Do the elevators generate vortices? [duplicate]

I want to know whether the elevators generate vortices like the wings do? If yes, then where do the vortices form?
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0answers
39 views

How does an aircraft's weight affect the V-n diagram?

I have a reasonable understanding of what a V-n diagram shows and what the envelope and the boundaries mean. However, the question I have is how does the weight of the aircraft specifically affect the ...
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0answers
36 views

How can I find or calculate typical flutter velocities for different wings?

I need to validate a code I wrote for calculation of dynamic aeroelastic response of a wing for my aeronautical engineering Master thesis. I'd like to ask if anyone may provide me a list with typical ...
6
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3answers
327 views

Can airplane performance be increased by cruising “on step”?

Old timers swear aircraft performance can be increased by getting an aircraft "on step" similar to how boats are operated. They claimed a couple extra miles per hour (airspeed was in MPH then) were ...
8
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3answers
378 views

Is this paragraph about the dihedral effect in the FAA's Glider Flying Handbook correct?

I've been reading the FAA's Glider Flying Handbook, 2013 (FAA-H-8083-13A). In chapter 3 ("Aerodynamics of Flight"), the book is discussing stability. On page 3-12, it states: Dihedral is the upward ...
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1answer
213 views

How does a Hawk jet avoid pitching down when its air brake is applied

Some aircraft have air brakes in an aerodynamically neutral position with respect to rotational forces on the airframe (e.g. F-15)... source ... more often, others have brakes that are ...
2
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1answer
105 views

Why does aircraft stability increase when it transitions from subsonic to supersonic flight?

I am puzzled why would the aircraft be more stable at high speed flight at high altitudes. Given that the Centre or Pressure moves gradually towards the 50% MAC region, once past Mcrit. Has this got ...
41
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5answers
6k views

Why do most biplanes have their top wing slightly forward of the lower wing?

In most of the biplanes, the top wing is located a little forward of the lower wing. What is the use of this? Also, how does this affect stability of the aircraft.
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0answers
23 views

How do I find experimental Cp, Cd and Cl values for a NACA0012 airfoil? [duplicate]

How can I get experimental Cp, Cd and Cl values for a NACA0012 airfoil where Chord length=240mm and Re=4.6e5? I'm looking for both 2D and 3D airfoil/wing (infinite span). I understand that plenty of ...
7
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1answer
144 views

In a jet, are Vy and Vx achieved at a constant AOA at all altitudes?

It is known that in terms of IAS, Vx (best climb angle speed) rises with altitude, and Vy (best climb rate speed) decreases with altitude, until they converge at the plane's absolute ceiling. http://...
2
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1answer
80 views

Why changes the lift during turning with sidewinds? Why is there relative wind in the wind-frame?

I started doing some simulations with XPlane and could observe a very interesting effect when doing turns in the presence of constant wind: All simulations are done with the XPlane Cessna 172 (?) ...
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1answer
55 views

Why is the Aerodynamic Centre not affected by changes in Angle of Attack? [duplicate]

I understand that the Aerodynamic Centre (AC) is the point in the aircraft where the pitching moment never changes with a change in Angle of Attack (AoA). My understanding of the Centre of Pressure (...
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0answers
50 views

How does a mixer reduce noise in a turbofan engine?

I want to know how does a mixer reduce noise in a turbofan engine? How does its shape influence the flow and the acoustics of the output air generally?
2
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2answers
144 views

Why does the stagnation point on airfoil move with the angle of attack?

What is the physical explanation for the reason the stagnation point is where it is? And, why does it move further down the lower side of the airfoil with an increase in angle of attack?
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1answer
132 views

Are there multiple reasons for the decrease in pressure over a wing?

I'm aware that the decrease in pressure over the wing is due to the curvature of the airfoil which causes a pressure loss due to the spreading of the air as it is redirected. But is it also due to ...
3
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1answer
52 views

How does the position of the center of pressure change with the use of different high lift devices?

How is the position of the center of pressure affected by different high lift device deployments? My guesses are: When I use a high lift device that just increases the chord length, it moves ...
5
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1answer
195 views

“Fundamental of Aerodynamics” 5th editon, example about oblique shock. Is the author's solution wrong?

I am reading "Fundamentals of Aerodynamics" 5th edition, J.D.Anderson. If you have the book, go to chapter 9: Oblique shock and expansion waves. Please look at example 9.2, page 618: Consider a ...
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0answers
61 views

Why does a 3D wing's CL keep increasing even after 50° AOA in XFLR5?

Can you please tell why my 3D wing in XFLR5 keeps increasing it's lift even after 50 degree AOA, while it's 2D profile stalls after about 10 degrees ? More details on simulation setup: Airspeed is ...
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2answers
62 views

How can larger wingspan decrease the strength of wingtip vortices?

In the last paragraph from the link below, it states that Vortex Strength is inversely proportional to Wingspan. Why is this? http://avstop.com/ac/flighttrainghandbook/wingtipvortices.html EDIT: ...
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0answers
68 views

How can I calculate the lift force on an aircraft pulling out of a dive?

Any ideas on how this question is answered? Consider an aircraft dived [sic] along a path inclined to horizontal, perhaps even a vertical path. The manoeuvre whereby the aircraft recovers from ...
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2answers
82 views

How can I calculate CLmax for a wing with multiple airfoils?

How should I do the math to find the CLmax of a wing that has more than one airfoil, each with a different CLmax? I am trying to make a model with a portion of the wing tip with a airfoil that has a ...
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2answers
106 views

Is the lift produced by a wing with a 10° flap equal to the lift created by a wing with 10° AOA but with no flap?

After reading this article I would like to know if the lift produced by a wing with a 10° flap is equal to the lift created by a wing with 10° AOA but with no flap?
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0answers
46 views

What does “lower flatness” mean in airfoil terminology?

What does lower flatness mean in these parameters of a Glenn Martin airfoil?
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0answers
201 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 ...
3
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3answers
180 views

Aerodynamics of double winglets

I've read here on Aviation SE that the aerodynamics of winglets on an aircraft are easily described as "extending the airfoil". Thus, as I understand it, a winglet is like stretching the airfoil a ...
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1answer
397 views

Can an aileron stall in-flight?

Horizontal stabilizers stall, so I was wondering, is it possible for an aileron to stall? If yes, at what angle of attack?
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2answers
88 views

Does Karman line depend on the wing area, and if not, why?

The Karman line is the altitude at that the airspeed required to generate the sufficient lift to support itself exceeds the orbital speed. Looks like the Karman line is defined as some fixed value, ...
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1answer
74 views

Where can I find this transonic prop airfoil?

I am interested in identifying this prop airfoil due to its uncommon high .92% efficiency (the best metal props are closer to 83-87%). I have done an exhaustive search for it. It is labeled "NACA RML ...
3
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1answer
126 views

When are winglets most effective?

If winglets reduce induced drag, induced drag is greatest at slow speeds. When are winglets most effictive?