Questions tagged [flight-dynamics]
Flight dynamics is the study of the physics driving the performance, stability, and control of aircraft. It is concerned with how forces acting on the aircraft influence its speed, altitude and attitude with respect to time.
245
questions
0
votes
1
answer
110
views
Yawing during turns
This is a question about aeronautics. Does an airplane yaw while it is turning?
0
votes
1
answer
68
views
Entry to back-side of power curve
When entering slow flight, when do we enter the back side of the power curve? Is it when we reduce the throttle or when the airspeed decreases to just above 5 knots from the stall speed?
- 1
4
votes
2
answers
200
views
Why does the turn tighten in a Spiral Dive as it progresses? Even without applying any elevator control?
Why does the turn keeps getting tighter as the spiral dive develops?
Use of elevator control makes sense as it would increase the horizontal lift vector inside the turn. But even without any elevator ...
- 609
3
votes
3
answers
903
views
Taxiing with a crosswind
Let us say we have a right quartering headwind, we should “fly into the wind” so yoke to the right then that our right aileron will deflect up and left aileron down. How does this avoid the chances of ...
- 81
3
votes
7
answers
593
views
If in a coordinated turn, the horizontal lift vector is equal to the Centrifugal force. Then how is the aircraft still turning?
Image source
How does the Aircraft continue to turn when the both the Horizontal component of lift and the centrifugal force are equal?
- 609
0
votes
1
answer
88
views
What are the effects of whiteout (snow) and brownout (sand/dust) on helos?
Is there any other effect besides low visibility?
Both seem to show very similar conditions.
1
vote
2
answers
141
views
What differences would a helicopter designed to withstand many negative Gs have compared with a normal one?
There are a few helicopters that are able to take negative G's, and to this day only one can actually perform aerobatics (ie. Chuck Aaron's BO-105). The BO 105 is a rigid rotor helicopter that has ...
6
votes
2
answers
3k
views
Why is a flat turn less efficient than a coordinated turn?
How I understand a flat (rudder-only) turn:
AOA between relative wind and the fuselage of the airplane causes a sideslip in the direction of yaw.
Vertical stabilizer weathervanes into the relative ...
- 75
3
votes
1
answer
214
views
What is the theoretical justification for "proportional navigation (PN)" guidance law?
In missile guidance theory, one of the fundamental guidance algorithms is the so-called "Proportional navigation", which directs a constant-speed missile into a collision course with the ...
- 131
0
votes
1
answer
171
views
What would happen to the aircraft and its control surfaces immediately after the loss of all hydraulics?
In cases like the DHL shoot-down in 2003 or the Sioux City crash, both aircraft lost all of their hydraulics because of a catastrophic failure of aircraft structure.
What would happen if the aircraft ...
- 603
0
votes
3
answers
194
views
Does AOA become 0 after the aircraft flies in a particular attitude for sometime as the relative airflow has changed and how does it affect Stall AOA?
As AOA is the angle between relative airflow and Chord Line. Then after you increase the angle of attack and fly at that angle of attack for some amount of time and the relative airflow changes ...
- 609
1
vote
2
answers
194
views
why lift coefficient decreases at supersonic flow?
In Anderson's performance book, he wrote that the higher the speed, the greater the pressure difference between two points, and as a result, the lift coefficient is greater.
But when we reach the ...
- 103
3
votes
1
answer
242
views
Could you use the flaps to recover from a flat spin
If the plane is in a flat spin, what would happen if you put the flaps down to cause the backward turning wing to be pushed down, and the forward turning wing up, to tip it out of the spin.
- 313
0
votes
0
answers
36
views
Maximise Range Vs Pitching Down while flying a Glider in a Downward Air Mass
While flying a glider, if I encounter a downward moving air mass (i.e. sink) while on final, should I fly to maximise range (best lift to drag ratio) or should I pitch downward in order to exit the ...
- 101
1
vote
0
answers
145
views
What can cause an unstable phugoid mode?
For clarity, I am wondering about how aircraft design can lead to the phugoid poles becoming complex with a positive real part, so an oscillation with increasing amplitudes.
My understanding of the ...
- 11
1
vote
3
answers
178
views
Can the use of wide-chord supercritical airfoil blades in a helicopter with coaxial counter-rotating rotors solve retreating blade stall?
The problem with retreating blade stall is that it limits the VNE and the overall top speed of helicopters. Retreating blade stall is basically the tip of the retreating blade having too much AoA at a ...
1
vote
1
answer
128
views
Wing incidence angle of tandem wing aircraft
I'm trying to design a tandem wing model aircraft with both wings with the same wingspan. The front wing will have 2 and the rear will have 1 deg of incidence angle, also the front wing will have ...
- 467
8
votes
4
answers
3k
views
If I am at absolute ceiling, can I climb further by trading airspeed for altitude?
If I am flying at absolute ceiling, can I still climb by trading airspeed for altitude?
- 349
8
votes
3
answers
4k
views
Flying upside down without feeling it
A friend of mine told me that several years ago she flew on a two-seats general aviation aircraft. She does not remember the exact model, but she remembers well that the pilot flew upside down for a ...
- 263
1
vote
0
answers
46
views
How elevator and ailerons affect attack and roll angles?
I was trying to model the flight of an aircraft and i need some function that expresses the change of attack and roll angle in function of the elevator and ailerons (respectively).
Does anyone have an ...
- 111
2
votes
2
answers
95
views
Longitudinal/Lateral CG envelope for hoist operations
Does a Rotorcraft hoisting CG chart show what the CG will be as the load is hoisted from top to bottom or vice versa?
- 491
4
votes
2
answers
170
views
What open-loop control inputs can guarantee non-divergent descents in fixed-wing aircraft?
(Inspired by What's the best way to get through clouds when not instrument rated? which has at its heart a good question, but isn't getting good answers because everyone is jumping on the "...
- 4,974
5
votes
6
answers
3k
views
How to slow down while maintaining altitude
Is reducing throttle/power already enough? Or do I have to adjust the pitch as well? If so, I suppose pitching up as well? If pitching up is needed as well, is it because as speed decrease, there is ...
- 349
0
votes
3
answers
123
views
Simultaneous yaw damping and sideslip control of aircraft with rudder?
Yaw damping is achieved by using the rudder to generate a yawing moment that opposes any yawing motion. Also, rudder is used to correct sideslip by applying a rudder input in the opposite direction of ...
- 165
0
votes
4
answers
595
views
How does increasing the angle of attack increase the lift?
When the pitch of a plane increases (facing upwards), it has a positive angle of attack, and when it decreases to face downwards, it has a negative angle of attack.
Increasing the angle of attack ...
- 35
3
votes
8
answers
741
views
How does the lift force stop increasing itself after a certain point?
I am currently trying to create a basic flight simulator and am very confused by the concept of lift. This is the equation of lift shown below that I found on the internet.
$$
F_l = \frac{1}{2} \rho v^...
- 35
3
votes
1
answer
157
views
Why does the maximum allowable load factor vary with airspeed in some aircraft?
In this ASE answer What is the maximum safe bank angle of a 747?, the author writes:
If we stay with stationary turns (without the "falling out of the sky"
part), the maximum bank angle is ...
- 21.8k
8
votes
3
answers
2k
views
Why does a sudden tailwind/headwind change IAS?
I read the following statement: “tailwind quickly changing to a headwind causes an increase in airspeed and performance.
Conversely, a headwind changing to a tailwind causes a decrease in airspeed and ...
- 151
-1
votes
4
answers
268
views
How is Vx speed and Vy affected when climbing?
If my speed for best angle of climb is 60 and rate is 79, if I kept a 500 fpm climb to my cruise altitude of let’s say 4500, would those speed change?
The flights are being done on separate occasions.
- 889
4
votes
4
answers
830
views
Why the heavier the aircraft is, the higher the airspeed must be to obtain the same glide ratio?
I know weight does not affect glide ratio. But why does higher weight need higher gliding speed?
- 349
1
vote
1
answer
124
views
How does elevator control effectiveness change with altitude/ air density?
Suppose an unpowered, rigid, mechanical, lightweight aircraft (e.g. sport glider) is descending at a steady glide in a constant trim (hands off) configuration in a standard atmosphere. The pilot ...
- 143
0
votes
1
answer
150
views
FAA's Airplane Flying Handbook says more lift is necessary during a climb. Isn't it the opposite? [duplicate]
"If a climb is started from cruise flight, the airspeed gradually decreases is the airplane enters a stabilized climb attitude. The thrust required to maintain straight-and-leve flight at a given ...
- 349
9
votes
1
answer
214
views
Did the dog-tooth notches in the wing of the F-8 Crusader really have anything to do with "yaw stability"?
What was the real function of the "dog-tooth" notches in the leading edge of the wing of the Vought F8U crusader?
Wikipedia says:1
Vought's design team... produced... a relatively ...
- 21.8k
1
vote
1
answer
151
views
Why does bank angle have no effect on pivotal altitude?
Pivotal altitude is the height for a given ground speed at which the line of sight from the cockpit directly parallel to the lateral axis of the aircraft will remain stationary on an object on the ...
- 75
26
votes
5
answers
5k
views
Why a kite flying at 1000 feet in "figure-of-eight loops" serves to "multiply the pulling effect of the airflow" on the ship to which it is attached?
In CNN's June 30, 2023 Giant kites could pull cargo ships across the ocean – and slash their carbon emissions
“What differentiates it from other wind solutions,” says Bernatets1, “is that the wing is ...
- 5,768
0
votes
1
answer
79
views
Can engines with a fixed nozzle in the angle of attack have the same effect as the thrust vectoring?
If the figure above represents a missile at the angle of attack and we vector resolution the thrust output from the nozzle, we can see that the thrust is divided into sine and cosine parts. Does the ...
- 103
9
votes
6
answers
1k
views
What is the load factor in a descending turn?
Possibly related to How does the load factor vary when the aircraft pitches up/down?
Could you help to settle a debate? I have recently flown a dead-stick approach with a CFI in the right seat. ...
- 588
1
vote
2
answers
110
views
How to prevent altitude loss or keep flight path angle constant while doing aileron maneuver?
I am trying to perform an aileron roll maneuver for an un-manned aircraft in a simulation. The lateral control architecture is that I am controlling roll rate (stability) with aileron stick and side-...
- 13
2
votes
3
answers
222
views
Does CG change airspeed in a descent or glide?
If the CG of an airplane moves forward, would it fly a faster or slower airspeed in a descent?
Usually during a descent or landing, you'd use pitch to change airspeed and power to control descent rate....
0
votes
1
answer
172
views
effect of wing chord length on lift coefficient
In the bertin's Aerodynamics book
It is written that reducing the wing chord increases the lift coefficient( decreases stall angle) and as a result, the wingtip stalls earlier than the wing root
how ?
- 103
0
votes
0
answers
76
views
why induced drag decreases in supersonic speed?
In John Bertin's book Aerodynamics, it is written that the induced drag at subsonic speed decreases with the increase in wing aspect ratio but the opposite happens at supersonic speed so that in ...
- 103
0
votes
1
answer
229
views
How to convert body frame-relative aerodynamic coefficients to wind frame-relative aerodynamic coefficients
I have a rocket flight simulator that takes in aerodynamic coefficients defined relative to the vehicle body frame axes (Cx, Cy, Cz). These are in a lookup table based on mach.
I have some aerodynamic ...
- 337
0
votes
1
answer
106
views
wingtip vortex in negative angle of attack
If a wing is at a positive angle of attack, then the vortices produced at the wingtip will generate downwash and induced drag
but on the contrary, if the wing is at a negative angle of attack, then ...
- 103
1
vote
1
answer
158
views
Why do dihedral wings increase induced drag?
I read somewhere before that the effect of the dihedral wing is similar to the swept wing so dihedral wing increase wingtip loading and increase induced drag
Can anyone tell me how physically this is ...
- 103
2
votes
3
answers
647
views
Airplane speed retention question? [closed]
Imagine the scenario when a plane is flying, then it turns off its engine and nose dives. After gaining a lot of speed, if the pilot pulls the stick back and the plane now points upwards again, will ...
user68613
0
votes
2
answers
406
views
How does a zero g aircraft work?
In upward motion, drag and gravity is in the same direction (both in downward direction). So in this situation G is negative or less than 1 or something else?
In downward motion with thrust greater ...
- 103
4
votes
2
answers
238
views
How does conical camber decrease roll due to sideslip?
I was reading Ray Whitford's Design for Air combat and came upon a passage that said that on the SR-71 conical camber "gives a useful reduction in the otherwise very high rolling moment due to ...
- 41
10
votes
3
answers
4k
views
Can we see evidence of "crabbing" when viewing contrails?
Can we see evidence of "crabbing" when viewing an aircraft leaving a contrail?
Such as, in the form of an angular misalignment between the longitudinal axis of the aircraft (i.e. the ...
- 21.8k
3
votes
1
answer
184
views
Why would a ram air parachute need less brake input to stall at a higher altitude?
I have some anecdotal evidence that a ram air sport parachute requires less toggle input to stall at higher altitudes. A pilot needed one wrap of the brake lines around the hands to quickly, ...
- 143
0
votes
1
answer
79
views
How do hybrid control surfaces work?
I am trying to build a self-stabilized model rocket with actuated fins. Suppose the rocket has 4 fins. The diagonal fins must rotate together to control the yaw/pitch motion, and all the fins are ...
- 103