Can someone explain wing loading?

[dweeb 0]

What is it, how do you calculate it, and what are the affects of going to a higher wing load?

Thanks!

[katzurki 0]

http://www.performancedesigns.com/docs/wingload.pdf

• Quote

[billvon 3,119]

>What is it

It's how much weight each square foot of your parachute has to carry. The heavier the load per square foot, the more "work" the parachute has to do to keep you in the air. (very simplified)

>how do you calculate it . . .

Divide your exit weight by the canopy's area. For example -

If you weigh 150 lbs, and your exit weight is 175 lbs, and your canopy is a Triathalon 190, your loading is (175/190) or .92 psf.

>and what are the affects of going to a higher wing load?

Canopy is faster and less forgiving. Planeout will be longer. Flare will require more care. Openings will be more dependent upon body positions. Things like line twists may require a cutaway. Minor mistakes may be harmful or fatal the heavier the wingloading.

[dweeb 0]

Thanks!

:thumbup:

[jakee 1,595]

A ratio of your weight (fully geared up) to the size of your parachute in square feet expressed as lb:sf. So someone who weighs 210lbs exit weight on a 210 canopy would be at 1:1, someone who weighs 210 on a 105 canopy would be at 2:1.

In general higher wing loadings will fly faster, sink faster, turn more aggressively and dive longer - more fun but more danger. Those factors are also influenced by absolute canopy size, planform, trim and general design stuff.

Do you want to have an ideagasm?

[kenneth21441 0]

A good to add here is a highly loaded wing will ware out faster in handling the added stress of opening and flying.

Say (example) a 1.0 wing load will last 800-900 jumps and a 1.9 wing load will last 500 -600 jumps.

Its just like over loading your car for every 100 extra pounds you use an extra 1 percent in fuel etc...

Kenneth Potter
FAA Senior Parachute Rigger
Tactical Delivery Instructor (Jeddah, KSA)
FFL Gunsmith

[DrewEckhardt 0]

Quote

A good to add here is a highly loaded wing will ware out faster in handling the added stress of opening and flying.

Say (example) a 1.0 wing load will last 800-900 jumps and a 1.9 wing load will last 500 -600 jumps.

Its just like over loading your car for every 100 extra pounds you use an extra 1 percent in fuel etc...

Hogwash.

Provided that you avoid desert environments and don't pack in the sun, ZP canopies last thousands of jumps regardless of wing loading.

Trim problems (worse flare, erratic openings, built-in turns) from shrinking Spectra lines are more noticeable at higher wing loadings, although steering line replacement every 250 jumps and a complete reline at 500 is just maintenance. You don't consider a car worn out when it needs new brake pads.

Most skydivers want something newer (changing from a 10 year old Sabre to a newer canopy of the same size will get you much nicer openings) and/or smaller long before they wear out a canopy.

0-3 CFM (F111) canopies do wear out with the resulting decreases in flare power more objectionable at higher wing loadings; although that's not really relevant to the modern parachutists where the material is only appropriate for reserves (where you aren't going to make more than a few jumps), BASE (where .7 is a nice wing loading), and classic accuracy (with similar loading).

[billvon 3,119]

> A good to add here is a highly loaded wing will ware out faster in
>handling the added stress of opening and flying.

Sort of.

The wear is basically the same; you have the same number of lines, the same load on each, same amount of deceleration, same chance of hard openings/malfunctions etc. So the components tend to wear at the same rate (with the possible exception of the slider; it flops a lot more on smaller canopies unless you do a good job of killing it.)

However, smaller canopies are a lot less forgiving than larger ones, so you have to replace the lines more often, fix little tears/holes while they still _are_ very little etc. So you might get the same life out of it overall, but you'll spend more money doing it.

[riggerrob 643]

I wrote an article for CANPARA Magazine circa 1983 entitled "Wing Loading."