Forums: Skydiving: Safety and Training:
I thought I knew how to PLF until...

 

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sundevil777  (D License)

Sep 15, 2012, 4:37 PM
Post #26 of 29 (310 views)
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Re: [Amyr] I thought I knew how to PLF until... [In reply to] Can't Post

Even though you're jumping a 200 loaded only at .87, it is not a ZP canopy (maverick). It may be a lot more porous than when it was new, and even lightly loaded such canopies can be tricky to land well.

So, why does it matter so much that it isn't ZP?.

When a wing is flying at high angles of attack (such as during a flared landing), it is very important that the airflow over the top of the wing stay "attached"/not "separate" from the top surface of the wing. If air is leaking out through the top skin fabric too much, then it has the effect of separating the airflow, and you don't get much lift. Conditions on the bottom skin of the wing are very different, with separation not being an issue, so leakage through non-ZP fabric doesn't matter.

If it was possible to actually suck air into the wing through/from the top skin, then you get the ability to produce good lift at higher angles of attack, as the airflow stays attached when it otherwise would not. This has been done on some experimental airplanes, including a Boeing 757 testbed that had part of the wing drilled with very tiny holes and a vacuum applied to suck air into the wing. So, air leaking out through the fabric matters a lot for the top skin, but not for the bottom, as long as it is not so much that cell pressurization suffers.


Amyr  (C License)

Sep 15, 2012, 5:37 PM
Post #27 of 29 (301 views)
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Re: [sundevil777] I thought I knew how to PLF until... [In reply to] Can't Post

Quote:
Even though you're jumping a 200 loaded only at .87, it is not a ZP canopy (maverick). It may be a lot more porous than when it was new, and even lightly loaded such canopies can be tricky to land well.

I wish it was the canopy"s fault and a quick fix. When i got her she had less then 20 jumps and i have put about 20 on her She is slick and her lines waxy and white She is beautiful and doing her job her> Its her pilot who is screwing up


sundevil777  (D License)

Sep 15, 2012, 6:13 PM
Post #28 of 29 (295 views)
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Re: [Amyr] I thought I knew how to PLF until... [In reply to] Can't Post

Then stop screwing up!

Seriously, get video of your landing and get others to critique, there should be plenty of opportunity for improvement.


Amyr  (C License)

Sep 15, 2012, 6:29 PM
Post #29 of 29 (289 views)
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Re: [sundevil777] I thought I knew how to PLF until... [In reply to] Can't Post

Quote:
Then stop screwing up!


WILL DO!!! Thanks sometimes the simplest advice is the best!!

I here by promise to never do another stupid thing while skydiving or in canopy>> snicker snicker>> NO reallyAngelicTongue


(This post was edited by Amyr on Sep 15, 2012, 6:38 PM)


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