aspect ratio??

[mfnren 0]

I was wondering the aspect ratio # means?(example, 2.58) And ,hypothetically,how a wing with a ratio of say 2.5, compares to one with a ratio of 2.65?

[shropshire 0]

Hope this helps....

Quote

Individual canopies can be described in terms of wing shape, trim and
loading. The designer determines the first two, the jumper the latter.
Choices on these items determine the way a particular parachute flies, so
without even jumping a canopy you can deduce to a great extent how it will
fly if you understand these features. Wing shape is defined by aspect
ratio and airfoil section. Aspect ratio is the ratio between span (side to
side width) and chord (front to back.) Airfoil section can be thought of
as the ratio of the wing's height to it's chord. Trim is adjusting the
particular wing shape to the apparent wind to gain the best compromise in
performance characteristics. And wing loading is the choice of how much
power the pilot decides to give to the system.

Aspect Ratio
In theory, high aspect ratio canopies fly faster because the higher the
aspect ratio, the lower the form drag for the amount of lift produced. In
other words, a 200 square foot nine cell produces more lift than a 200
square foot seven cell for the same amount of form drag. Why not build a
200 square foot eleven cell at a very high aspect ratio?

clicky

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[ryoder 1,384]

The formula is: aspect ratio = span^2/area
For a rectangular planform, this reduces to: aspect ratio = span/chord

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[b1jercat 0]

I'll post when I'm sober, I have some questions.
blue

jerry

[riggerrob 558]

Why not build a
200 square foot eleven cell at a very high aspect ratio?

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Because the extra drag caused by the extra suspension lines cancells out any reduction in wingtip vortex drag.

[Canuck 0]

Quote

Why not build a 200 square foot eleven cell at a very high aspect ratio?

They did. It was called the AR11, and I think they tended to open like shit. I believe they were only in production for a year or two. I'm sure companies other than Aerodyne have tried it too. I remember Icarus had a prototype 11 cell (or 33 cell if you want) cross-braced canopy a couple years ago that never went to production.

Canuck

[shropshire 0]

Well, my paraglider is about 247 sq ft, has 53 cells and an aspect ratio of about 3.9, flies at upto 45km.p.h (ish)...... O.K so the lines weren't built to take opening shock (so are thin).... but she flies like a dream....... Sorry, what was the issue?

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[Canuck 0]

There are some very thin lines out there (HMA) that will handle the opening shock. That's not the problem. Trying to get 53 cells to inflate evenly and systematically so one side of the canopy doesn't spin itself around the other side is the problem.

And 45 km/h is not particularily fast by skydive canopy standards.

For skydiving applications, either 7 or 9 cells in various sub-cell configurations seems to be the magic number for deployment reliability and flight performance.

Canuck

Canuck

[marks 0]

Quote

There are some very thin lines out there (HMA) that will handle the opening shock. That's not the problem. Trying to get 53 cells to inflate evenly and systematically so one side of the canopy doesn't spin itself around the other side is the problem.

i think the problem with hma's on that kind of wing is the UV exposure also.

i would love to watch someone deploy one of those paragliders at terminal.

[shropshire 0]

<> - In a mag' recently, I saw someone d-bag a PG from a plane .. BUT not Terminal.... (I'll try to find a link.....)... He also had a slider fitted!!

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[Pendragon 1]

Yeah, guys have done d-bag type deployments out of helicopters, balloons - even off another paraglider I think. Good DVD I caught once - Acro-BASE, which had all that stuff in it.

Problem with deploying high-aspect ratio wings is that they have a greater tendancy to cravat, which is obviously bad.

Haven't seen the slider deployment you mention; sounds great!

--
BASE #1182
Muff #3573
PFI #52; UK WSI #13

[shropshire 0]

Here y'go .... I knew that I'd posted it before .....clicky

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome