Jun 1, 2009, 12:11 AM
Post #1 of 13
CRW wind limits.
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?
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.
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)
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
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) - wing loadings (can handle more with higher loadings) - experience (beginners should minimise risk to maximise safety and fundamental learning opportunity) - etc.
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)
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
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