52

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 center across the ramp from Gulfstream. It could be possibly an experimental test flight if Gulfstream runs experimental flying from Savannah (I think they have a ...


38

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 stabilized control with one-engine-inoperative at low speed). In this maneuver, rudder is applied to hold a sideslip, which generates an opposing side force and ...


25

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.


25

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 the system oscillates around this trim point with increasing amplitude, the system is dynamically unstable. The long period oscillation (phygoid) of gliders is ...


24

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 efficient power is higher than is required, something should be done to accumulate and later use the excess energy. Raising the vehicle up looks like a solution, ...


18

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 comes in. You can think of an aircraft at equilibrium at a particular speed, altitude and angle of attack and it is suddenly faced with a disturbance which changes ...


17

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 of flight, so this dramatically increases drag. In fact, this is a common technique (at least among general aviation pilots) for losing altitude without ...


16

There are multiple configurations which are possible with tail or canard, which based on their locations and whether they produce lift or down-force, results in a stable or unstable aircraft (taking the aircraft center of gravity into account). The figures below show some of the possible configurations. Source: f-16.net In the most general case, there is ...


16

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, not at higher altitudes where the air is generally not rising or sinking to any significant degree (apart from wave lift in which case the strategy will still ...


12

Of course, just put the center of gravity back to its rear limit and fly slowly. Then all of them will produce positive lift on their tails. Stability is not produced by a downforce at the tail. The newest book I read which claimed this was from 1911 (I happened to read the 1913 edition). Stability is produced by making the lift per area of the forward ...


10

A tandem wing airplane has two sets of wings, each providing upward lift. One is near the front of the plane, one is near the back, and the center of gravity is between them. (source: nurflugel.com) The Rutan Quickie is one such plane: (souce: wikimedia) This design is actually fairly old; it even predates (successful) heavier-than-air flight, as it was ...


9

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 first part of this answer addresses the OP's question; the second part clarifies a common confusion. 1. Main Answer In level flight (i.e. zero vertical rate), ...


9

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 finds its new equilibrium state. The new state will be the original airspeed, but now in a constant descent.


7

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 proportional to speed inversed. The minimum power required coincides with the point of maximum excess power since it needs the lowest power setting for trimmed flight. ...


7

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 that's not what we expect to happen when we reduce the power. Hopefully this answer will help you to understand why not. When you elevator trim to fly ...


7

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 all about that. Can a plane turn, without banking? Yes, it can; by using the rudder to do the turning it can pull off a “flat turn” as it were. OK... are you ...


6

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 aileron deflection and elevator deflection. However in the Schleicher Ka-6 sailplane, the mechanical linkage is designed to raise both ailerons a little bit, ...


6

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” would pretty much confirm that suspicion. You will also see similar flights down to Brunswick Golden Isles airport (KBQK), as Gulfstream does a lot of flight ...


6

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 "pushed" to the left or right? Yes, whenever a plane is banked and the wing is generating lift, the lift vector has a horizontal component that tends ...


6

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 Work is force times distance. If gravity is X times larger than drag, this means that the distance in vertical direction must be X times smaller than in the ...


6

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 purely aerodynamic concept. There is no powerplant involved, so you're simply converting potential energy (altitude) into forward motion, at a rate and L/D ...


6

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 static stability (in the pitch axis), you can trim for a given airspeed, and if you then pull the stick aft, you'll feel an increasing forward pressure on the stick, ...


5

Right side slip from left rudder, rudder stalls, what happens? This is comparable to a wing stalling in that it is caused by the rudder/vertical stabilizer exceeding a critical angle of attack. There for, it has passed its maximum deflection potential. The result will be the fuselage slip will reduce until the rudder/vertical stabilizer assembly unstalls....


5

Short answer yes, a powered aircraft at any given airspeed in straight and level flight (note that a glide path is also "level", at constant airspeed) needs to use the same amount of energy to over come drag as the glider. The potential energy for the glider is altitude. The potential energy for the powered aircraft is fuel. The conversion of potential ...


5

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 any case the tendency is to make allowance for that kind of displacement with subtle stick movements without really realizing it. In light aircraft it's more ...


5

Your question should emphasize "still air" conditions and not get into exploiting vertical air motion, which is a separate issue completely. For normal airplanes, the basic issue is, you want to spend the enroute phase of the flight at the end of an optimal climb profile, with an optimal cruising altitude (which will depend on winds) for as long as ...


5

This is because when you roll left (or right), the lift changes from pushing up to pushing up + left. This is what makes you turn. Since some of that lift is being used to the left, not as much is pushing up, causing the plane to lose a bit of altitude. On FlyByWire aircraft, since it is computer controlled, the computer automatically compensates for this by ...


4

Yes it can - to an extent, depending on: amount of CG shift; airspeed; aircraft weight (actually Moment of Inertia); maximum deflection rate of elevators/ailerons. If the airframe has aerodynamic static stability, a disturbance in Angle of Attack Creates aerodynamic forces that return the aircraft attitude back to neutral. If the Centre of Gravity shifts ...


4

The short answer is yes. A coordinated turn has both bank and yaw induced simultaneously in the same direction. If you induce enough yaw in the opposite direction of the bank, the aircraft will fly in a straight line even though the wings are not level. You do this by cross controlling the aircraft. In laymen’s terms, that means you turn the yoke to the ...


4

Keep in mind that no mechanical, power producing system can operate with 100% lossless efficiency. In heat engines, like those in aircraft, the Carnot model describes the theoretical maximum efficiency (power produced vs lost) in any given design. Another way of asking your question would be, "Can I save fuel by taking my foot off the accelerator in my ...


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