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41

This is the difference between flying and in orbit. In orbit, you are indeed falling toward the earth, but the spacecraft is too, and you're going fast enough that you keep missing the earth. In an aircraft, because it's staying aloft due to lift, it is not falling. This is why you experience the pull of gravity on a plane. Some aircraft are designed to ...

34

You only feel the acceleration downward. In roller-coaster this sensation is maximized for maximum thrill. A stall isn't instant: some parts of the wing can be stalled while the rest still provides proper lift. Once the airplane is near or at terminal velocity in a stall it will feel no different from regular straight and level flight. The onset of the ...

27

Birds regularly experience up 10-14 G according to this website. After looking at how birds and insects fly, scientists came up with the conclusion as to how birds cope with this is because: Animals will always have some advantages over machines, such as the ability to use their nervous systems to sense subtleties about the environment around them and ...

26

You only feel the plunging sensation during the initial downward acceleration. Once stabilized at a constant rate of descent, things feel normal again. The other thing is, the amount of vertical acceleration from a stall type maneuver does not result in 0 or negative G, just less than 1. You'll feel getting light in the seat, you won't lift right out and ...

25

Why do we feel gravity on a plane? Exactly for the reasons we feel gravity when traveling on a train: We're not free falling (the cabin floor prevents this to happen). We're not at orbital speed which is about 28,460 km/h. We're not flying very tight curves that could create a free fall (but only for a few seconds anyway). Gravity and weight Everything ...

24

You are absolutely right, a load factor of greater than 1 is impossible to avoid in a proper barrel roll. The barrel part of its name comes from the spiral path the aircraft needs to perform in order to add a centrifugal acceleration which is greater than gravitational acceleration at the top of the roll. This is the condition to ensure a still positive ...

22

The formula for the load factor $n_z$ in a turn is $$n_z = \frac{1}{cos\phi}$$ where $\phi$ is the bank angle. This makes the load factor in a 45° turn 1.414 or $\sqrt{2}$. Since Michael correctly mentions the simplifications in his comment, let me expand the formula above. In case of a climbing turn, the load factor depends on the coordinate system used. ...

17

At 0 G the plane does not need to generate any lift, therefore there is no critical angle past which the airfoil cannot generate the lift required. In addition, a sustained 0 G maneuver is a parabolic arc, which means that in theory your flight path should keep your angle of attack at zero the entire time (in a theoretical, symmetrical airfoiled aicraft). ...

13

It's probably more accurate to say "you cannot maintain 0 G in a stall". Even a stalled airfoil generates some lift -- the stall just means that the lift coefficient drops below the best the airfoil can do, not that it becomes zero. Since the stalled wing produces lift, and this lift is generally not in a direction where it can be canceled out by thrust, it ...

12

The short answer is that at negative 2 G, the airframe limit for the A7-E, it took little effort to keep your feet on the rudder pedals. In controlled flight there are aircraft limitations on both positive and negative G. I flew the A7-E for the US Navy and have some operational experience that might offer some context to the question. I believe the ...

12

The G forces (also known as the load factor) experienced by an aircraft and its occupants do not scale linearly with the bank angle of the aircraft. Assuming constant vertical speed, coordinated flight (unchanging rate of climb or descent, ball centered), the load factor at a bank of 0° is 1.00. As the bank angle increases, this grows – slowly at ...

11

You never actually “feel gravity” at all†, not in orbit, not on a plane and not on solid ground either. What you do feel on ground is the earth pushing against your feet, with a force that exactly cancels out the gravitational acceleration. As soon as you stop that force, e.g. by cutting the ropes in an elevator, the gravitational ...

9

You are forgetting one large difference between an aircraft moving through the air (still generating some lift), and an object in free-fall. Constant velocity in a gravity well (such as on the Earth) will cause you to still experience the acceleration due to gravity. It's when you're accelerating that you feel different. Think of it this way - imagine ...

8

Basically, you're asking 'Can you achieve orbital velocity in atmospheric conditions?'. Orbital velocity is approximately equal to $$v_o \approx \sqrt{\dfrac{GM}{r}}$$ which, if we fill it in at Wolfram.alpha, yields a velocity of almost 8km/s (yes, per second), or almost 18000mph, or a Mach number of 23.23. The current speed record for sustained ...

7

We are, the speed is not sufficient for this to be easily observable. We are actually a little bit lighter while in a plane, because it is also circling the Earth, just like a spaceship does, but even for SR-71 at top speed (assuming 3540 km/h = 983 m/s) the effect is too small to be sensible: $$g = \frac{V^2}{R} = \frac{(983\frac{m}{s^2})^2}{6400000 \ m} =... 7 I'm not sure if you've come across this or not, but the paper Recovery from Gz-lnduced Loss of Consciousness:Psychophysiologic Considerations has some details on this phenomenon. It describes the tests carried out on eight volunteers. This does not appear to be very common- five 'dreams' were recalled out of 21 acceleration runs. The subjects seem to have ... 7 In the takeoff run, the acceleration is less with headwind, but once in flight, the airplane flies within the mass of air. The fact that that mass may move in relation with the ground doesn't affect the magnitude of the forces involved in flight, so accelerations are not affected by the wind. 6 I can't find solid references, hopefully someone will come along who can. A 30 degree bank, the most you will normally experience, exerts a force of 1.15g, or 0.15 greater than normal acceleration you feel when motionless. The autopilot is generally designed to begin descents and climbs with no more than 0.25g and are generally calibrated to manoeuvre in 0.... 6 Look at it backwards. Why are you at zero G? Because your downward acceleration is equal to the acceleration due to gravity. Why are you accelerating downwards so fast? Because you're not creating any lift to counteract gravity. Why are you not creating any lift? Because you are at zero degrees angle of attack! And that's why you can't stall at zero G. ... 5 I read that very high g forces could kill a pilot, brain pushing into the skull. High G-Forces cause blood flow to the brain to be impeded due to blood pooling low in the body under high acceleration. This causes the pilot to black out eventually. Is there a way of decreasing or surviving these forces and how would it work if you ignore aircraft ... 5 Critical angle of attack or stall angle of attack is by definition the maximum angle at which the stream over the airfoil is still attached. It is also the angle of maximum lift. Beyond this angle, the stream over the airfoil becomes unattached, leading to a sudden decrease in lift. Now, I think the article is somehow misleading. I think what they mean by ... 5 Yes, as long as you continue the loop, and don't fly the plane in the upside-down position. See, for example: Barrel roll with a glass of water on a glider 5 It is not a gravity, you feel, but the floor (seat etc.) pushing against you. You never feel gravity per se, you feel forces on your body which counteract gravity pull. In the flying airplane these forces come from wings' lift, but in the orbit, there is no such counterforce, so you feel weightless despite gravity is till there. All the feeling of weight ... 5 I fly part 103, specifically a Hy-Tek Hurricane. I also have a G meter on board. It is a Dynon D2, which features an artificial horizon (attitude indicator) and also a G meter. The average G's on takeoff is pretty small, usually around 1.1 to 1.2 Gs. I can also tell you it is impossible to pull anything over 2 G's during takeoff. I actually performed this ... 4 Well, 2 G's is 2 G's, regardless of what speed you're flying. A level (coordinated) turn with 60 degrees of bank is 2 G's, regardless of your airspeed. What changes is your turn rate and turn radius; at 20 knots, a model plane at 60 degrees bank can probably complete a 360 degree turn in a few seconds and a radius of maybe 10 yards. At 300 knots and 60 ... 4 I fly an aerobatic airplane. My G meter goes to -5 and I've pegged it before. My plane (& most aerobatic planes I've seen) don't have foot straps. During a negative G maneuver, it's pretty easy to push on both pedals at the same time thus bracing your legs against any tendency for them to slide off. It doesn't take much effort and I don't think ... 4 Can one fly up side down while a glass of water keeps full? Yes, but given the speed of the aircraft, it must fly a more or less tight loop. For an aircraft at 160 km/h the radius of the turn must be smaller than 200 m. On the other hand for a fighter at 500 km/h, the radius may be as large as 2 km. In both cases the force due to the turn is 1G positive (... 4 An aeroplane flying does not fly fast enough to become weightless. A person inside an aircraft flying at constant altitude becomes weightless if the centrifugal^1 force F_C = ( m \frac{V^2}{R}) from following the curvature of the earth equals the force from gravity (m \cdot g).$$ m \cdot \frac{V^2}{R} = m \cdot g \Rightarrow V = \sqrt {R \cdot g} ...

4

Can excessive G-force break or dislocate bones during pilot maneuvers? Yes. Even if the pilot remains conscious. For example see http://medind.nic.in/iab/t00/i2/iabt00i2p1o.pdf which describes compression fractures suffered by pilots.

4

The G-limit for the Extra 300 (the parent airplane to the 330): The Extra 300 is stressed for ±10 G with one person on board and ±8 G with two So it is certainly possible from an airplane perspective that you pulled that many Gs - in an aerobatic airplane, it's not unheard of to pull 1G less than the aircraft limit (usually there is a large margin of ...

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