old school post.

[towerrat 0]

while browsing some post from 1985, I came across this.
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Although I *loved* freefalling, once I was under canopy I tended
>to get nervous. The old pros at the drop zone would tell me not to worry
>about it when I had an end cell closure or when the wind knocked the
>canopy around a little, but I couldn't help imagining it collapsing
>with 100 feet to go. Once while making a 180 degree turn downwind, the
>wind gusted and the canopy appeared to be shrivelling up. I was still
>on radio at the time, and the instructor yelled at me to turn back into
>the wind. I also ran across someone who, on her second jump, stalled
>her canopy on final approach and broke her leg.
> Am I crazy for having "gear-fear" *after* I've got a good canopy,
>or are there some real malfunctions that can occur on the ride down?

Calm your fears. As a mechanical engineering student, I had to take
several classes which delt with forces and stresses, aerodynamics, physics
and so forth. I can assure you that the canopy CANNOT collapse on its' own.
In fact, if it were made of rubber, it would try to stretch itself even larger.
Remember though, the canopy is an airfoil. Nothing more, nothing less. You,
as the pilot, can MAKE it collapse if you want to, by stalling it. But the
instant you let up on the toggles, it will begin to reinflate. Guaranteed.
It will take a few seconds, however, for the canopy to reinflate and dampen
out the resulting oscillations. That is why you NEVER NEVER stall a canopy
at less than 500' off the deck. When you "flare" the canopy to land, you
are stalling it. The trick is to do this so that the canopy just stalls at
the instant your feet hit the ground. The girl you mentioned who broke her
leg obviously stalled, or "flared", a little too soon. You're better off to
flare a little late than a little early!
As far as your canopy shrivelling when you made a 180 deg. turn, that
can occur momentarily if you make a FAST turn, because you are essentially
stalling one side of the canopy. As soon as you ease up on the toggle, that
side of the canopy will reinflate very rapidly and fly normally again. It
makes absolutely NO DIFFERENCE whether you do this upwind, downwind, or
crosswind. The results are the same. This is because the canopy is an
airfoil, and is only affected by the RELATIVE velocity between itself and
the air mass it's flying through. The velocity of the air mass relative to
the ground has utterly nothing to do with how well the canopy flies. Thus,
if a gust of wind hits the canopy from behind (as would be the case if you
were flying downwind), the canopy momentarily "sees" a much lower, or even
negative, relative velocity. So, it may lose lift and drop a little, but if
left alone it will simply speed up to match the new wind speed and will fly
just fine again. Needless to say, you don't want to be in a downwind
orientation near the ground -- but then, you shouldn't be anyway. That's
why you were taught to always land upwind. That way, a gust will hit you
head-on, and will actually increase lift momentarily. Because of this
business of relative velocities, it is wise to make slow turns if you are in
gusty conditions -- especially if you are less than 500' up. If you are
making a hard turn, or if you are in deep brakes, a gust from behind will
very likely stall all or part of the canopy. So, in these conditions keep
your toggles in the upper half of their range.
In summary, don't worry about the canopy collapsing for no apparent
reason, but DO worry about how you fly it! Get used to it by doing intentional
stalls at a safe altitude (over 2000') so that you KNOW what things feel and
sound like just before a stall. Try some stall-turns, too. The ride will
scare the hell out of you, but the canopy WILL reopen!

Blue Skies and Happy Stalls,



It was the first paragraph that caught my attention. Anybody?

Play stupid games, win stupid prizes!

[el_chester 4]

Not really answering your post, but... where does one have access to posts from 1985???? i am sure there's tons of precious material to be found there! Well, maybe not tons, I doubt many people were online at that time.

--
Be careful giving advice. Wise men don't need it, and fools won't heed it.

[ematteo 0]

Hey,
Not to be a jerk, but please be careful with the canopy advice. A lot of what you wrote has issues.

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When you "flare" the canopy to land, you
are stalling it. The trick is to do this so that the canopy just stalls at the instant your feet hit the ground.

No. when you flare, you are changing the flight characteristics of the parachute but not stalling. If you stall, you crash. You should still be flying the wing when your feet hit the ground, and after your feet are on the ground.

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As far as your canopy shrivelling when you made a 180 deg. turn, that can occur momentarily if you make a FAST turn, because you are essentially stalling one side of the canopy. As soon as you ease up on the toggle, that side of the canopy will reinflate very rapidly and fly normally again.

Please don't make snap 180 toggle turns near the ground. If you are ready for performance turns, learn how to use rfront risers (up high first).

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That's why you were taught to always land upwind. That way, a gust will hit you head-on, and will actually increase lift momentarily.

We land upwind because it makes our groundspeed lower. That is it. An airmass can either speed up (gust) or slow down (lull) suddenly. Neither is more likely than the other, and you can lose inflation just as easily going into the wind as going downwind when there are sudden gusts/lulls.

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Get used to it by doing intentional stalls at a safe altitude (over 2000') so that you KNOW what things feel and sound like just before a stall. Try some stall-turns, too.

Some canopies should never be completely stalled. Like you, I was taught early on to fully collapse my main up high and see what happened. I had an original sabre and it was fine. But this is a bad idea with an elliptical canopy. They just don't recover well (and may not recover). Stall turns with a highly elliptical are likely to put you on your back in spinning line twists.

[towerrat 0]

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: Hey,
Not to be a jerk, but please be careful with the canopy advice. A lot of what you wrote has issues.
***
I didn't write this. It is someone elses response to a post on a very old message board ( from the eighties). If you look at the bottom you'll see where I noted the first paragraph. I was actually interested in the part about the " rubber canopy" and thought it was a unique, albeit incorrect way of looking at canopy flight in general. I posted it here to see what type of reaction it would get from modern pilots, my intent was not to give any advice.
I obviously didn't do a very good job of defining my intent, nor of seperating my post from theirs. My apologies for the miscommunication.

Play stupid games, win stupid prizes!

• Quote

[proswooper 2]

Hey dude

HE wasnt giving advice to any one but if you read towerrats post correctly you would know that.

Randy. that is an interesting old post you dragged up/ i would also like to know where you find these old posts. Its amazing how canopy pilotng lhas changed since then.

Paul

[ematteo 0]

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My apologies for the miscommunication.

No problem. If you use the "quote" function, it is really easy for readers to know what is yours and what is not.

I responded because some of the advice in the post, whoever wrote it, is dangerous. Lots of folks, including my students, browse these forums looking for wisdom.