50
votes
Accepted
Why is this airplane flying in circles randomly?
What you observed is probably a Gulfstream production test flight, either an initial or a snag clearance flight, or possibly a Customer Acceptance from Savannah Air Center, which is a completion ...
- 134k
38
votes
Accepted
Can a plane bank without turning?
Yes it can. The steady-heading sideslip (SHSS) maneuver is used in flight testing to demonstrate static lateral/directional stability (similar maneuvers exist as sideslip approach in crosswind, or ...
- 11.1k
25
votes
What does it mean when an aircraft is statically stable but dynamically unstable?
Static stability means that a deviation from a trimmed state produces forces which return the system to this trimmed state.
If these forces produce an overshoot which increases over time, such that ...
- 236k
24
votes
Why is this airplane flying in circles randomly?
The fact that it's near Savannah and tracking within a confined airspace, I'm fairly certain this is a flight test being carried out by Gulfstream.
- 11.1k
24
votes
Can gliding your plane save fuel?
This approach of using an engine is called pulse and glide. It generally works because each engine has an optimal power setting at which it converts fuel into power most efficiently.
If the most ...
- 12.2k
19
votes
Accepted
What does it mean when an aircraft is statically stable but dynamically unstable?
If an aircraft is statically stable, it will always return to equilibrium after a disturbance. But what happens after can either show instability or stability. This is where the dynamic stability ...
- 1,963
17
votes
Can a plane bank without turning?
Yes, it's entirely possible. You can use the rudder to oppose the turn induced by the roll, and thus fly straight. However, doing so means that your nose is pointed off at an angle from your direction ...
- 12.8k
17
votes
Can gliding your plane save fuel?
Here is one thing that WILL save fuel-- where possible-- such as when flying VFR.
Note that this strategy only applies within the layer where thermal convection or orographic uplift are significant, ...
- 23k
15
votes
Is a trimmed flight not always an unstable system?
But assume, there comes a wind gust, and the angle of attack will
increase. This causes the center of pressure to move forward in front
of my gravity location. So the aircraft will become instable ...
- 23k
12
votes
What is causing these "corners" on this F-104 V-n diagram?
what is causing the "corners" that we see at the following points?
Compressibility. Close to Mach 1 the lift curve slope increases according to the Prandtl-Glauert rule with the factor $\...
- 236k
12
votes
Is a trimmed flight not always an unstable system?
I think you misunderstand how it works, and how you would respond to changes in wind. Increases in airspeed impact all flight surfaces, including the elevator, so a change in airspeed due to a gust ...
- 54.2k
11
votes
How can L/D Max be both Best Glide speed and Max Range speed?
I'm going to answer with the caveat that I don't have as deep of an understanding of this as I would like, and someone smarter than me may be able to correct or expound on my response.
Best Glide is a ...
- 400
10
votes
Accepted
Where is the 'zone of reversed commands...'?
This is commonly known as the Speed Stability, not to be confused with speed stability in the sense of static longitudinal stability. I think there's some common confusion with this phenomenon. The ...
- 11.1k
10
votes
Accepted
What is the effect of thrust vectoring effect on the rate of turn?
The standard equation applies to any coordinated level turn (so that the G felt is "straight down" to an occupant of the aircraft, in an aircraft frame of reference). Matters not how it's ...
- 52.6k
10
votes
Accepted
Increasing bank angle, load factor and rate of turn
You are right, of course. B is also correct. Never put too much stock in the so-called "right" answer to a test question. It is extremely common to find mistakes in these materials.
Here's ...
- 23k
9
votes
What exactly happens when power is reduced in trimmed, straight and level flight?
This makes sense and is approximately what happens if you reduce thrust during trimmed straight and level flight. The aircraft will go though a series of damped oscillations, called 'phugoid' until it ...
- 83.8k
9
votes
Why is the L/D ratio numerically equal to the glide ratio?
The sum of all work done on the airplane must be zero in a glide. That is, the work done by gravity must equal the work done by drag. Note also that lift equals the force of gravity in equilibrium
...
- 13.7k
8
votes
What is the effect of thrust vectoring effect on the rate of turn?
With thrust vectoring you no longer turn (as in: the wing creates the force that accelerates you in the desired direction) but you do post-stall maneuvering. Next, you need to distinguish between ...
- 236k
7
votes
Where is the 'zone of reversed commands...'?
Both are right in their own ways.
First the basics: Power is thrust times speed and is constant over speed for variable-pitch propeller-powered piston aircraft. Therefore, propeller thrust is ...
- 236k
7
votes
Accepted
What exactly happens when power is reduced in trimmed, straight and level flight?
You are very perceptive to note that for a given angle-of-attack, a return to the exact airspeed that allowed level (horizontal) flight would indeed imply a return to level (horizontal) flight. But ...
- 23k
7
votes
Can a plane bank without turning?
Here are two questions back at you.
Can a plane turn, with banking?
Yes, of course it can, the normal way using the ailerons to tilt the airplane and thus change the angle of lift. You already know ...
7
votes
Accepted
Why do airplanes start descending when we initiate a left turn?
This is because when you roll left (or right), the lift changes from pushing up to pushing up + left (or + right). This is what makes you turn. Since some of that lift is being used to the left (or ...
- 659
7
votes
What causes the ball to not be centered in a slip/skid?
It is the same thing that makes you slide sideways in your seat going around a corner in your car.
Or the same thing that would cause you to slide sideways the other way if you were driving straight ...
- 27.2k
7
votes
Is a trimmed flight not always an unstable system?
Don't overthink it too much. Simplify in your mind. Trim is used to pre-set hands-off angle of attack. Static stability forces will focus on regaining the trimmed angle of attack if the plane is ...
- 134k
7
votes
Accepted
Did SR-71s have a switch for seat height adjustment for the pilot or were there strict height requirements in order to fly it?
According to the POH the pilot could indeed move the seat up and down
(source)
Its worth noting that the SR-71 was a spy plane and visibility from the cockpit was not necessarily a critical aspect of ...
- 102k
6
votes
In simple mechanical stick linkages, is there crosstalk between the aileron and the elevator movement?
In simple mechanical stick linkages, is there crosstalk between the aileron and the elevator movement?
In almost all cases, there is no intentional-- or discernable-- mechanical coupling between ...
- 23k
6
votes
Accepted
In simple mechanical stick linkages, is there crosstalk between the aileron and the elevator movement?
As drawn, that linkage would cause elevator movement if you moved the stick in a perfectly lateral direction. But when you roll into a turn, you normally apply a little up elevator
anyway, and in ...
- 134k
6
votes
Why is this airplane flying in circles randomly?
I would second what John K said, it’s most likely a GAC factory flight test or demonstration flight. Also with the airplane identified as GLF6 and, most likely going be the call sign “Gulf Test six” ...
- 74.5k
6
votes
Can a plane bank without turning?
Can planes bank without turning
Yes, a plane may fly in a banked attitude without turning.
But when the plane is tilted to the left or right relative to Earth's
surface and gravity, shouldn't it be &...
- 23k
6
votes
What does it mean when an aircraft is statically stable but dynamically unstable?
Lots of good information in answers posted so far but I think it is also useful to point out that with no static stability (in the pitch axis), the aircraft wouldn't be trimmable. With positive ...
- 23k
Only top scored, non community-wiki answers of a minimum length are eligible