When you jump out of a skydiving plane, terminal velocity is not immediately achieved – it takes a little time. At the point you first jump out, you are actually thrown forward on the same trajectory as the plane (that is going forward at around 100mph).
Note that over the course of the next 10 seconds, this forward momentum is overtaken by the effect of gravity as you travel on a big graceful arc into freefall. This is referred to in skydiving as “going down the hill” as it visualizes a curve.
What is Terminal Velocity?
Terminal Velocity, however, means the top speed an object can achieve when it falls through the air. When an object (like a skydiver) falls freely through a medium, such as water or air, the force of gravity pulls it toward Earth. As the object falls, its velocity increases as it accelerates toward Earth. In other words, it begins to fall faster and faster toward Earth thanks to gravity.
Gravity is not the only force working on the object though. Air molecules collide with the falling object, pushing it upward against gravity. Scientists call this force air resistance. As the velocity of the falling object increases, so does air resistance.
Eventually, air resistance will equal the weight of the object in free fall. When this occurs, the object reaches terminal velocity. This simply means that the falling object has reached its maximum velocity and acceleration is now zero.
Have it in mind that the magnitude of terminal velocity depends on the weight of the falling body. For a heavy object, the terminal velocity is more or less greater than a light object. This is because air resistance is proportional to the falling body’s velocity squared.
Note that for an object to experience terminal velocity, air resistance is expected to balance weight. An example that shows this phenomenon was the classic illustration of a rock and a feather being dropped simultaneously. In a vacuum with zero air resistance, these two objects will experience the same acceleration.
But on the earth, this is not true. Air resistance will equal weight faster for the feather than it would for the rock. Thus the rock would accelerate longer and experience a terminal velocity greater than the feather.
Additionally, another crucial factor that affects terminal velocity is the orientation at which a body falls. If an object falls with a larger surface area perpendicular to the direction of motion it will experience a greater force and a smaller terminal velocity.
Meanwhile, if the object fell with a smaller surface area perpendicular to the direction of motion, it will experience a smaller force and a greater terminal velocity.
What is the Terminal Velocity of a Skydiver?
Notably, the terminal velocity for a skydiver was found to be in a range from 53 m/s to 76 m/s. Four out of five sources quoted a value between 53 m/s and 56 m/s. Principles of Physics stated a value of 76 m/s. This value differed significantly from the others.
Then again, the value is variable since the weight and the orientation of the falling body play critical roles in determining terminal velocity.
Terminal velocity is often reported to be approximately 60 m/s for a typical skydiver in free fall. Exceptional skydivers are able to increase this value considerably by diving head first with their arms against the sides of their bodies, legs held firmly together, and toes pointed.
This posture presents a minimal projected area perpendicular to the direction of motion thus reducing aerodynamic drag. Special helmets and slick body suits reduce drag even further.
Notable Terminal Velocity Rates When Skydiving
The most common number you will find when searching for information about how quickly you fall while skydiving is 120 miles per hour.
However, how big and how heavy the diver is, is what causes them to speed up, but the shape of an object, and again how big it is – creates drag through the air causing it to slow down. The maximum speed at which something can fall with these forces all working on it is its terminal velocity.
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Terminal Velocity of a Skydiver
Note that the downward speed achievable by the human form in freefall is a function of several factors–including the body’s mass, orientations, skin area, and surface texture–but the usual math standardizes all that. For a human-shaped object, the equation spells out a terminal velocity of 60 meters per second–about the terminal velocity of the typical skydiver, which clocks in at 55 meters per second.
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Terminal Velocity of a Belly to Earth Skydiver
Skydiving doesn’t really revolve around tandem jumping. It doesn’t also revolve around the type of skydiving–called Relative Work, or “RW”–that involves falling with your belly pointing toward the Earth.
Howbeit, since different skydives result in different air resistance, they end up resulting in what can be very different terminal velocities. For instance: In a stable belly-to-earth position, a jumper’s terminal velocity hangs out at 120 mph.
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Terminal Velocity in Wing Suit Flying
Wing suit flying strives to translate as much of the downward speed of a skydive into forwarding speed. Terminal velocity drops precipitously so that the throttle forward can roll way the heck back. Therefore, wing suit pilots (as indeed, pilots they very much are) integrate ram-air airfoils into their suits.
They pressurize in similar ways as a parachute and fly using many of the same dynamics as an airplane. Even though some of these designs have three distinct ram-air wings (which connect the arms to the torso and the legs together) and some are mono-wing (which turns the whole suit into one large wing with a human floating around in the middle somewhere), the overview of the design is the same.
Note that a wingsuit puts together various materials in order to construct an airfoil around the frame of the human body, converting downward speed to forward. Since the discipline of wing suit flying has advanced, the results have been nothing short of incredible.
One instance shows a vertical velocity of a scant 25 mph–100 miles an hour less than the average 125 mph. Nonetheless, the speed at which the wingsuit pilot pierces forward through the sky zooms over 100 km/h in some instances.
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Terminal Velocity of a Head Down Skydiver
Have it in mind that once you change that body position to head-down, then you have just ramped up that terminal velocity to around 150-180 mph. It is fast enough to result in damage to both parachute and skydiver if that skydiver doesn’t do him/herself a favor and slow down by changing position and waiting before pulling.
There are ways to minimize that drag even further by streamlining the body, which allows for speeds in the vicinity of, say, 300 mph.
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Terminal Velocity with an Open Parachute
Always remember that the mass of the jumper and the size of the parachute regulate the terminal velocity that is reached while under the canopy. Canopies now are square and contemporary parachutes constructed with RAM-air airfoils. These airfoils pressurize and convert downward speed into forward momentum.
In a discipline called “swooping”, by initiating advanced maneuvers and utilizing steep turns, the downward speed of the canopy pilot is translated into incredible forward speeds.
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Terminal Velocity in Speed Skydiving
Speed skydiving is a skydiving discipline that has supported competition divisions since the mid-2000s. It’s a huge enough deal that it has its own association–the International Speed Skydiving Association. It has the aim to “achieve and maintain the highest possible terminal velocity.”
Speed skydiving is the fastest non-motorized sport on Earth. Note that the tricks of the speed skydiving trade have been developed to cheat nature as much as possible. Notably, the skydiver cannot increase his or her mass enough to significantly increase his or her terminal velocity.
In addition, the skydiver can’t change his or her shape much beyond the use of an aerodynamic helmet. Have it in mind that the primary tool in a speed skydiver’s kit is the reduction of friction. Therefore, competitive speed skydivers often prefer to wear slick bodysuits and skilfully maintain a strictly streamlined head-down body position to minimize the coefficient of drag.
They have to do all of that lickety-split after exit too, in order to hit that maximum speed high enough up that the air is extra-thin. It’s a challenging discipline and can be too hard to predict.
Conclusion
Indeed, terminal velocity is not a single set speed and can be affected by various factors. The speed of 120 mph is what you hear most because it is kind of true and is a nice round number that people have a frame of reference for. However, the true terminal speed of a single skydiver or a tandem pair can change not only from one person to the next but also during a single skydive as small alterations in body position affect how fast you are skydiving.
All rate can even be changed by the weather. On a cold day, the air is denser than on a hot day, which means the molecules are smooched closer together and your body has to work harder to fall through them – which means you go slower.