Crossbraced canopies (or a canopy made up of Cross Brace Tri-cells) means the cell is divided into three chambers instead of two, with the chambers diagonally braced to force each cell back into shape. Viewed from the front, a canopy normally has a zigzag appearance. The cells are deformed due to a lack of internal support, with only a free floating, non load bearing rib between them. But if you look at the front of a crossbraced canopy, both the upper and lower surfaces appear smooth.
Where did the idea come from?
PD originated the idea with a parachute called the Excaliber, in the late eighties. It was a rectangular, F-111 Cross Brace Tri-cell, and in its day it was awesome. The Excaliber out performed anything else available at the time. It was eventually superseded by Zero-P parachutes, which out performed the Excaliber using only conventional construction.
What are the advantages?
There is less drag because there are less lines. In effect the canopy is a 7 cell not a 9 cell, yet is almost an 11 cell in shape.
The canopy is more rigid in flight. Due to the triangulation of the cell structure the cells are ‘locked’ into position rather than being free floating and able to breathe.
The canopy surfaces are less distorted. Basically all these things mean you are getting a more responsive, faster, more rigid, stable and powerful wing. Our high performance wings are crossbraced for this reason.
Disadvantages of crossbraced wings
There are a couple of unavoidable trade-offs with this design. Pack volume and price will undoubtedly put a few people off.
- Pack volume – A regular 9 cell canopy consists of 40 different panels. Crossbraced wings have many more panels and an increased amount of material is required to support the cell structure. Consequently a 104 sq. ft. crossbraced canopy could pack up similar to a 125 sq. ft. regular ZP canopy – an approximate 20% increase in pack volume. You will undoubtedly go down in canopy size but you probably will not want to go down 20% to get the equivalent pack volume (unless you were intending a reduction anyway). You may end up with a bigger rig than with another canopy.
- Price – Material and construction time involved is significantly increased when manufacturing a crossbraced canopy. They have more fabric and take a lot longer to manufacture as a conventional canopy. As there are only 8 line groups the loading is a little higher on each line attachment point so reinforcing is sewn throughout the entire parachute.