I also get approximately 5 for the Yeti UL (the planar rescue) by roughly estimating the projected area (a little more than half of 19 m², so about 10 m²) and counting the squares on top, of which there are 25, those on the edges being slanted, plus the vertical rectangles forming the edges around the perimeter.
The other parachutes in the range have a larger surface area for the same projected area, so the drag coefficient would be approximately the same at 5.
5 is an incredibly high value that seems impossible, and at the same time these parachutes seem to be incredibly small compared to their respective users.
I wanted to know more by asking the manufacturer with a mail: he indicated that some of the data is not in the public domain. I assume that to get a Cd of 5 (if it is the correct value), a lot of aerodynamic work had to be done.
I think that for a reeling (reel-in / out = yo-yo) AWES such surfaces could perhaps have an interest if a little lift allows them not to touch the ground, and knowing that high altitude winds would be approached by enlarging the surfaces (just as for traditional wind turbines that reach higher altitudes as they grow) or by stacking them.
Apart from that, I just tested one of these parachutes below, getting about 6 N with a more or less 2 m/s wind, then getting a maximum thrust of 20 N (I will try later with stronger winds and an anemometer) by trotting against this wind. Specifications on:
https://www.amazon.fr/dp/B07XGJCB7F?psc=1&ref=ppx_yo2ov_dt_b_product_details
I think 57 inches x 57 inches (1.45 m x 1.45 m) as shown on a photo, perhaps would lead to a projected area of about 2 m² which seems higher than the real projected area (1.5 m² ?). I measured its surface area at about 2.5 m².
See also the video about “Increasing Parachute Drag” (curve at 2:05, Descent Rate Comparison (Normal vs Reefed)) and the explains below:
