Forums: Skydiving Disciplines: Canopy Relative Work:
CRW wind limits.

Jun 1, 2009, 12:11 AM
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 CRW wind limits. Can't Post
What are the wind limits for CRW? On the ground and at 1kft it could be blowing 18kts but higher up the wind can be doing 40kts. Providing you budget that into the spot is there anything wrong with being blown backwards over the ground while doing CRW?

Cheers,
Andy

dragon2  (D 101989)

Jun 1, 2009, 3:45 AM
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 Re: [andyturner] CRW wind limits. [In reply to] Can't Post
No, but some GPSs can act up by switching north to south when you're being blown backwards

skyjumpenfool  (Student)

Jun 1, 2009, 6:47 AM
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I think wind limits (under canopy) are irrelevant to a point… The bigger issue might be turbulence! However, the two are related. It always amazes me how turbulence can occur/increase as you pass through a certain altitude.

Jun 1, 2009, 10:53 AM
Post #4 of 13 (1795 views)
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Hi,

Ok so nothing is cast in stone ...yet!

From your responses it seems that turbulence is the issue that is related to wind strength. I’m assuming that turbulence is an issue because it could collapse your canopy at an inopportune moment, which could be both tedious and embarrassing, i.e. resulting in a wrap?

With a WL of approx 1.21 lbs/ft², if the wind below 1000ft is within spec, i.e. <20kts and the wind is blowing a hooley up top then at what point would discretion be the better part of valour, 30kts, 40kts, 50kts?

Cheers
Andy
PS. Thanks for the info.

(This post was edited by andyturner on Jun 1, 2009, 10:57 AM)

CaTo  (D 81811)

Jun 1, 2009, 1:36 PM
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maybe this document can help you, its part of a complete introduction to CF and tells you something how to act with different wind speeds.

the three points that ARE important (rule of thumbs) are:
-wind-speed on the ground needs to be less than max speed of canopy
-when performing standard CRW (so not competition jumping or big formations...) try to keep on flying right against the wind direction (note, this can change on different altitudes!)
- calculate approx exit point using highest wind speed and direction
Attachments: CF Introduction WIND.pdf (177 KB)

TVPB  (F 666)

Jun 2, 2009, 7:21 AM
Post #6 of 13 (1727 views)
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 Re: [andyturner] CRW wind limits. [In reply to] Can't Post
Wind Concerns:

1 - landing. You know the answer to this. What are you prepared to land in?

2 - Canopy Formations - Contact. Changing wind direction and turbulence are issues. Examples include wind shear (change of direction), turbulence from the lee sides of mountain ranges (i.e at Gap in France). You also have lift around Cumulous clouds and above thermal sources on the ground.

You need to consider:
- absolute wind speed - i.e. getting dragged on landing because the wind is too strong to control your canopy is not good.
- changing wind speeds -> this can be in the form of turbulence and gusts. Too much of either on landing or whilst doing canopy formations is not good.

Going backwards in consistent winds doing CRW is OK up to a point IMHO.
Remember if you are flying directly along the wind line, the relative closing speeds should be the same regardless of the wind speed. It changes a bit when it is slightly cross wind - the physics does not necessarily match the practice - so leave a bit more margin for error when approaching and setting up on a formation.

I have done an 8 way training camp with 50 to 70 knot uppers (they were constant, consistent winds), but had little wind on landing. Your spotting skills have to be better!

The answer is dependant on many factors:
- size of the formation (bigger means more conservative)
- type of CRW (rotations can handle more than sequential - planes are more solid than stacks or offsets)
- experience (beginners should minimise risk to maximise safety and fundamental learning opportunity)
- etc.

skyjumpenfool  (Student)

Jun 2, 2009, 12:11 PM
Post #7 of 13 (1704 views)
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I should clarify to say that turbulance are caused in part by wind speed/direction. There are also other variables which can cause them. As an example, solar effects over fields or water.

I'm sorry, were you looking for the short answer?

Jun 3, 2009, 6:59 AM
Post #8 of 13 (1657 views)
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 Re: [CaTo] CRW wind limits. [In reply to] Can't Post
Hi everyone & thank you for all the information.

Quick question....

calculate approx exit point using highest wind speed and direction

Why not use an average wind speed & direction instead of the highest? Is this just for a little saftey margin?

Thanks again,
Andy

skyjumpenfool  (Student)

Jun 3, 2009, 12:04 PM
Post #9 of 13 (1636 views)
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Why not use an average wind speed & direction instead of the highest? Is this just for a little saftey margin?

Thanks again,
Andy

If your spot is long, you can always run back with the wind. If your spot is short, you will be blown past the dz and it's much harder to make up ground.

chuckbrown  (D 19538)

Jun 3, 2009, 12:59 PM
Post #10 of 13 (1627 views)
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Why not use an average wind speed & direction instead of the highest? Is this just for a little saftey margin?

Thanks again,
Andy

If your spot is long, you can always run back with the wind. If your spot is short, you will be blown past the dz and it's much harder to make up ground.

I'm not sure I agree with calculating the exit point based on the highest winds instead of using averages. If you've got very high winds at higher altitudes, but negligible winds at lower altitudes, you can easily be stuck long with not enough wind to get back. Not that landing off should be a big deal.

I average speed and direction and get pretty consistent results.

(This post was edited by chuckbrown on Jun 3, 2009, 1:00 PM)

Jun 12, 2009, 1:19 PM
Post #11 of 13 (1488 views)
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Are you coming to the CRW boogie in Lake Wales, Florida in August?
Mike Lewis will have plenty of Lightnings to loan. Be sure to contact him and "reserve" one if you think you'll be here.
Cheers!

Jun 12, 2009, 2:00 PM
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 Re: [crwslut] CRW wind limits. [In reply to] Can't Post
Dude,

I'd love to! What are the dates?

If its just a weekend thing then it may be a bit far to come but if its a week then I could justify that to the Mrs. I'm also relocating from France to UK at the end of July but I'm sure she would also be fine with that

...seriousley mate what are the dates and I'll see if I can swing it???

Best regards,
Andy
PS. I got me a Lightning 193 that I'm planning on tuning a little

Jun 12, 2009, 3:07 PM
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Ok I found it.

Its a weekend 22/23 August. Hmmm a bit short for a trip across the atlantic. That said is anyone else doing CRW there either before/after the event? If I can pad it out to a weeks jumping then it would be worth the air fare

Regards
Andy

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