Ram-Air Parachute Design: How Ram-Air Parachutes Actually Fly

How a Ram-Air Parachute Opens

The opening sequence of a ram-air parachute happens fast, but there's a specific order to how it all comes together. After you throw your pilot chute, it catches air and pulls the closing pin, which opens your container. The deployment bag comes out, and as the lines stretch tight, the canopy begins to slide out of the bag.

The center cells inflate first. Air rushes into the open nose cells at the leading edge, and because the trailing edge is sewn shut, that air gets trapped inside. That's the ram-air principle — air is forced in and has nowhere to go, which pressurizes the wing into its airfoil shape.

From the center, inflation spreads outward toward the wingtips. Meanwhile, the slider — a rectangular piece of fabric that sits at the top of the lines — works its way down. The slider's job is to control the opening speed. Without it, the canopy would snap open so fast it could injure you. As the slider travels down the lines toward the risers, the canopy reaches full inflation and you're under a flying wing.

The Four Forces of Flight

Understanding why a parachute flies comes down to four forces: gravity, thrust, drag, and lift.

Gravity (Weight)

Gravity is the force pulling you and all your gear straight down. In skydiving, we usually talk about this as exit weight — your body weight plus everything you're wearing and carrying. This matters because the amount of weight under your wing directly affects how it performs.

Thrust

An airplane has engines to push it forward. A parachute doesn't. So where does forward movement come from? The answer is built into the design. The suspension lines are trimmed so that the front lines (A-lines) are shorter than the back lines (D-lines). This tilts the wing slightly downward, nose-first. Gravity pulls you and your gear down, and that downward force on a tilted wing translates into forward movement. Your weight is the engine.

The steepness of that tilt — the trim angle — varies by manufacturer and model. Some parachutes are designed to fly flatter and more floaty. Others are trimmed steeper and come out of the sky faster. That's a design choice made by the manufacturer, and it's not something you can easily change.

Drag

Drag is the force that resists forward movement — essentially air friction. An object with more surface area encounters more air molecules and produces more drag. That's why race cars and airplanes have streamlined shapes: they're reducing drag to go faster. On a parachute, the lines, the slider, the pilot chute, the risers, and even you hanging under the wing all contribute drag.

Lift

Lift is the force that opposes gravity and keeps you from plummeting to the ground. It's generated by the airfoil shape of your canopy. An airfoil is a structure with curved surfaces that produces a favorable ratio of lift to drag while moving through air.

You can see airfoils everywhere in nature. Birds' wings are airfoils, and just like parachutes, different birds have different wing shapes depending on whether they're built for soaring, diving, or long-distance gliding. An albatross has a very different wing cross-section than a hawk. Same principle applies to canopy design — the airfoil shape the manufacturer chooses determines a lot about how the parachute flies.

Anatomy of a Ram-Air Wing

Before you can have a useful conversation about parachute performance, you need to know the terminology. Here are the parts of a ram-air canopy:

Line Groups

The suspension lines connect the canopy to the risers on your harness, and they're organized into groups based on where they attach from front to back. A-lines attach at the leading edge and are the shortest. B-lines are next, then C-lines, then D-lines at the trailing edge, which are the longest. Brake lines (also called toggle lines or steering lines) attach at the trailing edge and are what you use to steer and flare.

The difference in line lengths is what creates the trim angle — that slight nose-down tilt that gives the wing its forward drive.

Six Design Variables That Determine How a Parachute Flies

John LeBlanc, a parachute designer at Performance Designs, has outlined six primary variables that determine how a canopy is going to fly. Understanding these helps you move beyond marketing language like "semi-elliptical" or "high performance" and actually understand what makes one parachute different from another.

1. Size (Area)

This one is straightforward — how many square feet of canopy do you have overhead? A bigger canopy has more surface area to generate lift and more drag to slow you down. A smaller canopy has less of both. The relationship between the canopy's size and the weight underneath it is called wing loading, which is one of the most important numbers in canopy piloting.

2. Airfoil Type

The airfoil is the cross-sectional shape of the wing. Different airfoil profiles generate different amounts of lift and drag. Just like airplane designers choose different airfoils for aerobatic planes versus gliders versus commercial jets, parachute designers choose airfoils based on what they want the canopy to do.

3. Trim Angle

The trim angle is the angle between the wing's chord line (an imaginary line from nose to tail) and the horizon. A flatter trim angle means a more floaty parachute with a longer glide. A steeper trim angle means a canopy that comes down faster and is more "ground hungry." This is set by the manufacturer through the line lengths and isn't something you can easily adjust.

4. Aspect Ratio

Aspect ratio is the relationship between wingspan (side to side) and chord (front to back). It's calculated by dividing the span by the chord.

5. Anhedral Arc

When you look at a canopy in flight from the front, you'll notice the wingtips hang lower than the center. The angle of that downward slope from the center to the tips is the anhedral arc. Different canopies have different amounts of anhedral, which affects stability and responsiveness.

6. Planform

Planform is the shape of the canopy when you look straight down at it from above. Some canopies look mostly rectangular. Others are tapered toward the tips. Some are more rounded or elliptical. Here's what's interesting though: planform alone doesn't tell you as much as you might think. As the video discusses, if you overlay the planform of a Saber 2 (an intermediate canopy) and a Velocity (a high-performance canopy), they're surprisingly similar. The differences in how those canopies fly come from the other five variables working together.

Evaluating Parachute Performance

When you're comparing canopies or thinking about what you want in your next main, it helps to break performance into three phases: openings, in-air characteristics, and landing.

Openings

Snatch force is the jolt you feel when the lines go tight and take your weight. Some canopies hit harder than others. Snivel time is how long the slider stays up before traveling down — a longer snivel means a slower, more gradual opening. An on-heading opening is when your parachute opens and begins flying in the direction you were facing, while other parachutes are known to search around a little bit before settling.

In-Air Characteristics

This is where the day-to-day flying happens. How flat or steep is the glide path? What's the control range like — can you hang out in brakes comfortably, or does the canopy get unhappy in deep brakes? How responsive is it to toggle input, front riser input, rear riser input, and harness turns? And what's the recovery arc — when you make a turn and then let up, how quickly does the canopy return to straight flight? A short recovery arc means it comes back quickly. A long recovery arc means it stays in the dive longer, which has major implications for landing.

Landing

For most skydivers, this is the most important part. How much flare does this canopy give you? Some canopies respond better to a single-stage flare (one smooth input), while others perform better with a two-stage flare (an initial input followed by a second deeper input at the bottom). The amount of flare power you get depends on all those design variables working together — especially aspect ratio, trim, and wing loading.

Choosing a Main Parachute

If you're working toward your B license, you're probably starting to think about buying your first rig or at least your first main canopy. This is also the stage where downsizing conversations start happening — and understanding the design variables above will help you have better conversations with your instructors and coaches about what's right for you.

Choosing a main canopy is a lot like choosing a vehicle. What you want to do with it — your goals and how you plan to use it — should guide your decision. A minivan, a sedan, an SUV, and a sports car all have four wheels, but they're designed for very different purposes. Same thing with parachutes.

The major manufacturers you'll typically see at US dropzones include Performance Designs, Aerodyne, and Icarus Canopies. All three make student canopies, beginner-to-intermediate canopies, and high-performance canopies. Where a specific model falls on that spectrum isn't just about the model itself — it also depends on how heavily you're loading it. A Saber 3, for example, is often considered a fine beginner canopy when loaded lightly, but it becomes more of an intermediate canopy as the wing loading increases.

Frequently Asked Questions