In broad outline, how a modern ram canopy parachute deploys is pretty much the same, barring emergencies. The skydiver extracts a pilot chute that fills with air and tugs on attached lines. Those lines are also attached to the main canopy that is pulled from the D-bag in the backpack. It in turn fills with air. Simple.
But within that broad outline many variations are possible. Those details, heavily dependent on the skydiver himself, can influence how the canopy behaves. That behavior has a big effect on the skydiver himself.
That behavior starts before you ever get in the air. How the chute is packed plays a role. That’s why it’s advisable as students move from first-timer to intermediate that they should learn to pack their own chutes. The more you know, the more you can connect how one thing influences another. Hands-on experience is one of the best teachers.
Once in the air there are many new factors that come into play. Height is one, since air pressure and temperature, wind speed and direction, and others are different at different elevations.
But usually even more important is how the skydiver uses his or her own body. Body orientation and configuration has a huge effect on the terminal velocity. Altering your body position can change your terminal velocity from 120 mph to 150 mph (193 kph to 241 kph) very easily. The speed you’re traveling when you deploy greatly affects the forces on you at release. That has a large effect on whether canopy release is a gentle and gradual slow down or a very rude jerk. Orientation also affects whether the forces at work are distributed across the body or concentrated in one area.
Canopy design helps minimize those effects. Under a wide range of circumstances a canopy will deploy slowly no matter what you do. That leads to a more gradual deceleration from the initial terminal velocity to the new one, say from 140 mph (225 kph) to 10 mph (16 kph) within five seconds.
But canopy design can only do so much.
If you pack your rig in a certain way, extra airspeed can produce an opening that results in a painful yank as you decelerate. A better packing results in a smoother, gentler decrease.
Where you look when you start to deploy affects your body configuration and position, which in turn affects how your canopy and harness produce forces on you. Looking over your shoulder, for example, almost invariably tilts your shoulders. But a flat body surface toward the Earth produces a different result than one in which your body is angled, providing less wind resistance.
If you look down at the ground as your canopy deploys, your body tends to tilt forward. That increases your airspeed and produces a smaller angle with the ground. That increased airspeed can lead to a bigger jerk, as discussed above. And the angle produces a larger rotation of your body as the flying canopy moves you into the sitting position. That angle and rotation causes more leg swing and a higher force on your shoulders.
Looking toward the horizon instead, tends to keep your head from moving down. That leads to a more even distribution of the force of opening. Instead of being concentrated at the shoulders, it’s distributed across the entire harness. That produces a smoother, gentler, more gradual opening with less swing.
Think about your speed and body position. Practice proper orientation. You’ll have a safer, more comfortable deployment.