# Tag Info

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 ...

36

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 ...

30

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 ...

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 ...

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 ...

23

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. ...

16

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 ...

13

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 ...

10

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

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: $$g = \frac{V^2}{R} = \frac{(983\frac{m}{s^2})^2}{6400000 \ m} =... 8 Basically, you're asking 'Can you achieve orbital velocity in atmospheric conditions?'. Orbital velocity is approximately equal to$$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

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

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. ...

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

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 ...

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

Sensation of motion can come through three of the physical senses. Each of the three senses is successively unavailable as we move through the examples of an amusement park ride, the plummeting elevator, and AF447. Vision This sense is fairly well understood, so I'll limit this bullet point to pointing out that the visual sense is correlated in the human ...

6

I presume, an implicit assumption in your question is that we are flying a perfect glideslope, that is, a straight line with a constant speed, and without disturbances. If this is the case, the acceleration will be zero by definition, and the only effect we (and an accelerometer) will feel is gravity. The 'G-meter' shows the acceleration (incl. gravity) with ...

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

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

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 ...

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 ...

5

A few things. That accident took place at night and in IMC while the aircraft was passing through a storm which I suspect had quite a bit of turbulence in its core. This would most likely have caused enough vestibular disturbance for the crew to make the acceleration towards the deck go unnoticeable. Secondly the crew was on an IFR flight which means ...

5

the G meter measures acceleration. If you are descending at constant vertical speed or climbing at constant vertical speed, it will read 1G. The difference in the force of gravity between that at the earth's surface and that at 35,000 feet is far too small to be detected by an aircraft's G meter.

5

There are two misconceptions here, lets sort them out first: pressurization has absolutely no effect on G -forces. For any maneuver they will be exactly the same, wheter you are in a pressurized, unpressurized, or even an open cockpit or passenger compartment. G forces other than the normal G can only be felt (or registered) when there is a change in the ...

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