Skydiving and BASE jumping are two of the most exhilarating adrenaline‑pumping activities, but they offer vastly different experiences, both in terms of physical sensations and the underlying physics at play. The intense rush of freefall, the rush of air against the skin, and the sense of weightlessness are just some of the feelings that skydivers and BASE jumpers experience. Yet, despite the similarities, the two activities are fundamentally different in the way they unfold, the physics involved, and how they feel during the jump.
In this article, we will explore the physics of both skydiving and BASE jumping, examining the differences that contribute to the distinct sensations of each activity.
The Basics: Understanding the Physics of Freefall
Before delving into the differences between skydiving and BASE jumping, it's important to first understand the core physics behind freefall. Freefall occurs when an object, such as a skydiver or BASE jumper, is falling under the influence of gravity but has yet to deploy a parachute. During freefall, there are two key forces at play:
- Gravity : The force that pulls the jumper toward the Earth, accelerating them downward.
- Air Resistance (Drag): The force exerted by air molecules on the jumper's body, opposing the downward pull of gravity. This force increases with the velocity of the fall.
At the beginning of freefall, the gravitational pull is stronger than the drag, causing the jumper to accelerate rapidly. However, as the speed increases, so does the air resistance, until both forces balance out. This point is known as terminal velocity, the speed at which a jumper no longer accelerates and instead continues to fall at a constant rate.
In Skydiving:
- Terminal Velocity : In typical skydiving, a jumper can reach terminal velocity at around 120 mph (193 km/h) in a belly‑to‑earth position. This happens after a few seconds of freefall, when the drag force becomes large enough to balance out the force of gravity.
In BASE Jumping:
- Terminal Velocity : In BASE jumping, the jumper generally reaches a lower terminal velocity because of the lower altitude and the typically more vertical body position (compared to skydiving). This results in a faster rate of deceleration due to air resistance, but it doesn't have the same ability to accelerate as skydivers from a higher altitude.
Difference in Sensations:
- Skydiving: The jumper experiences a gradual increase in speed before reaching terminal velocity. At this point, the fall feels almost like floating, with the body accelerating quickly to the point of no further acceleration.
- BASE Jumping : The jump is usually shorter, and due to the lower altitude, the sensation of freefall may feel more intense. Because the jump is much faster and more controlled, the sensation is much more abrupt, and the time at terminal velocity is shorter.
Jump Altitude: Why It Changes the Experience
One of the most significant differences between skydiving and BASE jumping is the jump altitude. Skydiving typically occurs from altitudes ranging from 10,000 to 14,000 feet (3,048 to 4,267 meters), while BASE jumping is typically from heights ranging from 100 to 3,000 feet (30 to 914 meters). This difference in altitude dramatically influences the entire experience, particularly when it comes to time spent in freefall and the deployment of the parachute.
Skydiving:
- The higher altitude in skydiving allows for a longer period of freefall, which translates to more time to experience the rush of falling at terminal velocity. Skydivers can also perform acrobatics or changes in position (such as flipping or spinning) before deploying their parachute.
- The higher altitude also allows for more time to deploy the parachute, typically done at around 2,500 feet (762 meters) to give ample time for the canopy to fully open and to respond in case of emergency.
BASE Jumping:
- Due to the low altitude, BASE jumpers experience a significantly shorter freefall time, meaning that they don't reach the same speeds as skydivers. This rapid descent doesn't allow for much time to make adjustments or experience the gradual buildup of terminal velocity.
- The parachute in BASE jumping is deployed much sooner, often at altitudes of 1,500 feet (457 meters) or lower, requiring jumpers to be highly focused and efficient in their movements. The speed at which they must act gives the jump a more intense, quicker feeling.
Difference in Sensations:
- Skydiving : The longer freefall time gives the skydiver a sense of calm and control after they reach terminal velocity, allowing them to experience the exhilaration of the jump for an extended period.
- BASE Jumping : The jump is much more immediate and intense. BASE jumpers don't have the luxury of time to adjust, making it feel more like a sudden plunge into the air with little time for reflection.
Body Position and Aerodynamics: The Role of Drag and Lift
Both skydiving and BASE jumping require precise body positioning to control the fall, but the way jumpers use their bodies to manipulate aerodynamics varies between the two sports.
Skydiving:
- In skydiving, jumpers typically start in a belly‑to‑earth position , where the body is horizontal relative to the ground. This position maximizes the surface area exposed to air resistance, allowing the jumper to control their speed of descent by adjusting body angle.
- Skydivers can manipulate their fall further by changing their body position (e.g., arching their back, bending their knees, or deploying specialized equipment like a wingsuit), affecting their fall speed and direction.
BASE Jumping:
- BASE jumpers often jump from a more vertical position, especially if they are jumping from cliffs, buildings, or bridges. In this position, the body's surface area is reduced, allowing the jumper to descend more quickly.
- The parachute used in BASE jumping is often smaller than the one used in skydiving, and it opens much faster, which can lead to more intense feelings of deceleration when the canopy inflates.
Difference in Sensations:
- Skydiving : With more body control and the ability to adjust the position over a longer period, skydiving feels more like a gradual, controlled freefall.
- BASE Jumping: The immediate, rapid descent makes the experience of falling feel much more dramatic and intense, with the body's position being less about floating and more about descending quickly to the ground.
Parachute Deployment: Timing Is Everything
The timing and mechanics of parachute deployment play a significant role in the sensations experienced during both skydiving and BASE jumping.
Skydiving:
- Skydivers have the luxury of deploying their parachute at much higher altitudes, which gives them more time to handle the deployment process. Most skydiving centers also use Automatic Activation Devices (AADs), which automatically deploy the reserve parachute if the jumper fails to activate the main chute at the correct altitude.
BASE Jumping:
- In BASE jumping, parachute deployment is much more critical and time‑sensitive due to the lower altitude. Jumpers must deploy their parachute almost immediately after exiting the platform, and in some cases, the parachute is designed to open quickly at lower speeds. The entire experience feels far more abrupt compared to skydiving.
Difference in Sensations:
- Skydiving : After the initial freefall, there is a sense of anticipation before deploying the parachute. The deployment itself is typically smooth and controlled, with jumpers able to adjust to the new sensation under canopy.
- BASE Jumping : The rapid deployment of the parachute and the quick deceleration often result in a more jarring experience. The sudden transition from freefall to the slowing effect of the canopy can feel much more intense and sharp.
The Final Descent: A Change in Perspective
Both sports ultimately culminate in a parachute descent, but the difference in altitude and the type of parachute used creates contrasting experiences.
Skydiving:
- The descent under the canopy is typically much longer, and skydivers have more time to enjoy the view and adjust their flight path before landing.
BASE Jumping:
- The descent under the parachute is usually brief and can feel more like a controlled fall rather than a leisurely glide.
Difference in Sensations:
- Skydiving : The feeling of drifting gently towards the ground is often accompanied by a calm sense of accomplishment.
- BASE Jumping : The shortness of the descent, combined with the rapid fall, makes the parachute descent feel almost like an afterthought, as the jump is more about the thrill of the fall.
Conclusion
While both skydiving and BASE jumping share the same underlying physics of freefall, the differences in altitude, body position, equipment, and timing create two distinct experiences. Skydiving offers a longer, more controlled fall, with the luxury of time to adjust and enjoy the sensations of freefall. BASE jumping, on the other hand, is a more immediate, intense experience, with a focus on quick decisions and rapid deployment of the parachute. Understanding these physical and psychological differences helps explain why the two activities, though seemingly similar, feel so radically different to those who take the leap.