Month: June 2019

The Main Canopy

The Main Canopy has a variety of designs from 7 Cell to Cross Braced and Square to Fully Elliptical. The design of the Canopy influences its flying characteristics, pilot skill level and pack volume. In addition, canopies are made of different materials which influence the pack volume.

Many thanks to Tom Hill for writing this article and for taking the pics.

Materials

Manufacturers use different materials for their canopies from Zero Porosity to Low Pack Volume and F-111. Some materials are chosen over others for their performance and others to produce a lower pack volume.

Zero Porosity

This material does not let any air through and is found in many canopies. This material has a high pack volume

Low Pack Volume Material

Also known as Low Porosity. This material reduces the pack volume of the Canopy although has a higher porosity than Zero Porosity material. Some manufacturers have developed their own patented system for canopy materials. Low Pack Volume Material is used to manufacture Reserve Canopies.

Hybrid Canopies – This uses a combination of Low Pack Volume and Zero Porosity Material for example a Low Pack Volume Material bottom skin and Zero Porosity top skin.

F-111 Nylon

F-111 Nylon is used on older Main Canopies although should be avoided due to its high porosity on old equipment.

Maximum Suspended Weight – Abbreviated to MSW. This is the maximum weight that can be suspended from the Canopy. This includes your body weight, clothes, helmet, altimeter and Rig. This weight must not be exceeded. If it is exceeded, serious injury or death is possible along with equipment damage. Furthermore, the suspended weight influences the flying characteristics of the Canopy.

Shape and Cells

The shape of the Canopy greatly influences the flying characteristics. Square canopies are docile whereas Fully Elliptical canopies are for high performance. Always speak to an Instructor before selecting a canopy and consider your experience level. In addition, check the operating procedures of a dropzone you are visiting, especially in a foreign country as they may be more restrictive than your home dropzone.

Square

Used on student equipment and many sports canopies. The square shape provides a docile canopy.

Figure 36: An illustration of a Square canopy.

Semi Elliptical

Also known as Slightly Tapered. Where the ends are tapered so they are narrower than the middle.

Figure 37: An illustration of a Semi Elliptical/Slightly Tapered Canopy. Note the rounded tips.

Fully Elliptical

Also known as Highly Tapered. Where the ends of the Canopy are shorter than the centre. A characteristic of high performance canopies.

 

Cross Braced

Found on high performance canopies used for swooping and piloted by very experienced jumpers. The cross bracing is reinforcement to increase the strength and rigidity of the canopy wing.

 

7 Cell Canopy

A Canopy with 7 cells. Used for Canopy Formation and for Reserves. Their use on Reserves is so the Canopy is docile and has a lower pack volume.

9 Cell Canopy

The most common configuration of Main Canopies and allow a range of performances and designs.

Line Types

The Line Type used on a canopy varies with the performance of the Canopy. High Performance Canopies are likely to use Vectran® or HMA whereas normal sports Canopies are likely to use Microline also known as Spectra® however Vectran® is being used on normal sports canopies. Not all line types are available on every type of canopy. The strength of the line is determined by the preceding number for example 550 Microline states this is Microline with a 550 lb breaking strain.

Dacron®

Dacron® is the largest and most forgiving of the lines. While it is the bulkiest of the lines and will increase the pack volume, the lines stretch which give softer openings and is a popular choice on student equipment. Dacron® does not deform due to heat meaning the Canopy will retain its trim however it has a low abrasion resistance. When it wears, it turns a dull grey and has numerous frayed edges.

Microline

Also known as Spectra®. Microline is found on many sports canopies and has the highest abrasion resistance of any line type. However, it will shrink with usage meaning the canopy will become out of trim. When this happens, the line set will need replacing. Relative to size, Microline is stronger than Dacron®.

Vectran®

Often used on high performance canopies although is used on normal sports canopies. It has a slightly orange colour although do not confuse this with Orange Vectran® which is used on high performance canopies. Vectran® holds its trim as it does not shrink with heat however it susceptible to abrasion damage.

HMA (High Modulus Aramid)

Commonly known as HMA which is an acronym for High Modulus Aramid and sometimes known by the brand name Technora®. Similar to Vectran® however it has a slightly lower pack volume and less drag. HMA has poor resistance to Ultraviolet light unless it is treated.

Main Pilot Chute, Bridle and Pin

The Pilot Chute has the role of deploying the Main or Reserve Canopy and the incorrect Pilot Chute can result in a hard deployment because it produces too much drag or might not deploy the Main Canopy if it is worn out. The Pilot Chute can become neglected because it is dragged over the Drop Zone so it is important to keep them in good condition.

Many thanks to Tom Hill for writing this article and for taking the pics.

Despite all Pilot Chutes having the same role, there are different types of Pilot Chute and Netting depending on the discipline.

28” Zero Porosity

The standard Pilot Chute used by Skydivers.

30” F-111

Used to produce more drag due to the larger surface area however they do not last as long as Zero Porosity Pilot Chutes. Sometimes used by Wingsuiters because of the lower speeds therefore requiring a larger Pilot Chute to generate the force required and reduce the risk of a Pilot Chute in Tow malfunction.

Low Drag Netting

The standard netting used on Pilot Chutes.

High Drag Netting

Used on Pilot Chutes where high drag is required, for example Wingsuiting or Canopy Formation where vertical deployment speeds are much lower.

The Bridle and Pin

The Bridle connects the Pilot Chute to the Main Deployment Bag and can be a standard piece of webbing, contain a kill line or shock cord to collapse the Pilot Chute. The shock cord option is rare amongst sport Skydivers. A collapsible Pilot Chute is required for higher performance canopies.

Tape Bridle (No Kill Line)

The Bridle which is found on student equipment and does not contain a Kill Line to collapse the Pilot Chute after deployment.

Kill Line Bridle

Also known as a Centre Kill Line, the most common bridle amongst sport Skydivers which uses a centre cord that is shorter than the Bridle to collapse the Main Pilot Chute after deployment. The Pilot Chute is cocked when packing to ensure the Pilot Chute functions correctly. A cocked Pilot Chute will show a different colour in the window, a gap in the Bridle. You can tell if the Kill Line is too short as it will be taught inside the Pilot Chute. A line that is the correct length will have some slack.

Figure 34: A cocked Main Pilot Chute showing green in the viewing window, hence the term Green in the window.

Shock Cord Kill Line

A Bridle that uses a bungee shock cord to collapse the Pilot Chute. Rarely seen on sports Skydiving equipment and must not be used with F-111 Pilot Chutes.

Wingsuit Bridle

Usually 3 foot longer than a standard bridle, favoured by some Wingsuiters because it is more likely to clear the large burble created by the Wingsuit.

Lolon® Cable

This replaces the curved metal pin and is favoured by some skydivers due to the long length. Therefore, the risk of a premature deployment as a result of pin movement is lower.

Figure 35: Lolon® cable replacing the metal Curved Main Closing Pin.

In the next blog article, we move on to the meaty subject of parachute. There’s a bewildering choice of options, manufacturers and sizes which we will look at under the microscope (or sewing machine!)