How do winds affect opening?

[PeTeRbAsE]

Hay Hay mr jeff......You need to get out more..... DUDE.....Why are you even looking at 120ft-170ft...Thats what you need to asked yourself !!!!The wind can be your friend at times....crosswinds suck....off heading openings......tailwinds on short delays make it hard to land safey.......gr8 for 180s [flying back at the object] Gives you a bit more time to deal with the S H I T.....no wind-no worrys.... Take up a small plastic bag of flour ........Toss it off ...Watch what the wind does to it.....very scary stuff from 600ft att......Looks even better if your stoned.....hope this helps you dude..... :+ :+ PeTeRbAsE:+ :+

[clint]

I agree with the guy, PeterBase, who said not to jump low stuff.
With 20 jumps there is no way, in my opinion, you should be looking at that low stuff. Most people with hundreds don't do that low, well some do of course, but most don't. Why, just way too dangerous. You are almost underloading you canopy in the first place to jumpin in med/high winds is not that safe, expecially for low stuff.

Cross wind is what will get you in my experience. I am also fairly new.
But very current in the past 4 months. THe PC in cross wind will tend to make you canopy open to the side that the wind is blowing across.

IE: IF the wind is coming Right to left, and you throw out, the PC will inflate and go to the left side, and the canopy will most likely, not always, but it will likely open to the LEFT. I just finished watching 1.5 hrs of video of the Thanksgiving boogie in Moab and most of the time that the PC was not straight up the canopy opened to the side that the PC was on. Again, Not always. If you have videos just watch the PC and see what it does. My experience is all Moab stuff, 200-600', so no more that a 3 maybe 4 sec delay. High stuff, I can't say but I'm sure it's the same?

Hope this helps, ANd others should really add their info to help you cause wind defenitely will affect your opening. Especially cross wind.
Also go back a few pages on the BB and their is some more info there.
Lots of people ask about winds.
Clint
:7

[BasejumperJeff]

Just so everbody body knows, I'm not all horny to rush out and leap off a 120ft. antenna. It's just in my little peice of the pie up here it would definately open up a whole lot of cool ojects. Nothing around here is much higher than 300ft. unless I drive for a few hours.
More specific on the winds, would lets say a 25 knot tail wind at opening altitude on a 1 sec. delay cause any ill affects on the opening? Can it slow down the opening, cause it surge or stall? Or in general cause it to malfunction?
Thanks.
Jeff

[imported_Tom Aiello]

Hi Clint,

>If the wind is coming Right to left, and you throw out, the PC will inflate and go to the left side, and the canopy will most likely, not always, but it will likely open to the LEFT.

My experience has been the exact opposite. On free fall delays with appreciable winds, I have observed that the canopy generally opens into the wind (i.e. in your right to left crosswind scenario the canopy would open to the right). I'm pretty convinced of this. We regularly jump a relatively high wind object in the 2-3 second range, and I've seen loads of five jumpers there with every single opening exactly into the wind.

>I just finished watching 1.5 hrs of video of the Thanksgiving boogie in Moab...

I'd be curious to see the video that led you to this conclusion. Is there any way to get copies of some of it? Since it seems so contrary to my experience, I'd love to do some comparisons and try to track down the differences.

Thanks,

--Tom Aiello
tbaiello@mac.com

[imported_Tom Aiello]

>...how the winds would affect the opening of the canopy...
Wind will have greater effects on canopy opening at lower relative airspeeds. If you are deploying at terminal (120 mph relative wind), a 25 mph crosswind is relatively negligible. But if you are only falling at 10 mph, the same 25 mph crosswind will likely govern your opening. This, combined with the fact that winds are often less at lower altitudes, means that you can reduce the effects of wind on your opening by taking deeper delays (giving you both more relative wind to overcome the absolute wind and reduced absolute wind).

Remember, of course, that the wind will always effect your canopy after opening. So, humming it really low in 25 mph tailwinds is generally a bad idea, for example (since you'd have to take a 25 mph downwind landing).

>...tailwind...
Tailwinds will generally encourage 180's (openings into the wind).

Tailwinds on solid objects will translate into downdrafts at opening, often causing altitude loss (and requiring higher deployment--tricky in a heavy downdraft, as you need to have sufficient relative speed to pull the PC above you).

Tailwinds can also encourage line over malfunctions (because the tail and steering lines blow in front of the nose) but this effect is greatly reduced by the use of a tailgate.

Tailwinds will also slow your canopies inflation (just as headwinds speed it up). In extreme cases, anticipate a high tailwind will slow your inflation by double digit feet (so, as much as 99 feet).

>...crosswind...
On freefall deployments, your canopy will tend to open into the crosswind. I have heard several different logics to explain this (canopy acts as a windsock during inflation, PC moves), but, technical explanations aside, my experience has been that canopies open into crosswinds on freefall deployments.

The opposite appears to be true for static line (or PCA deployments). A static lined canopy will tend to open downwind.

>...no delay...
In general a static lined canopy will tend to open in the downwind direction.

A zero delay freefall deployment will be highly susceptible to wind induced opening issues (generally heading problems).

>...2 second delay...
If your relative speed is greater than the cross wind velocity, you will reduce the wind effects on opening. By the same token, an absolute wind greater than your relative (fall) speed will have greater effects on your opening.

>...draw backs to high winds?
The wind will push you around. In gusty conditions, you may experience partial canopy collapses (or even complete collapses in very turbulent conditions). High wind is also mentally very stressful on exposed exit points--be prepared for this to reduce the impact on you.

There are also advantages to high winds. If used properly, a high wind can virtually eliminate the potential for object strike, especially on wind-through objects (generally antennas). Exiting downwind in 30 mph winds makes it very difficult to strike the tower, even in the (relatively common, in this scenario) case of a 180. Wind can be your best friend.


>how low is too low?
With 20 jumps, I'd say 200 ft is a good minimum altitude. Some of your fellow Canehdians are given to very low static lines (I've heard wild rumors of 111 ft), so you probably want to look for some in-person coaching from them before moving any lower. In absolute terms (with the right objects, under good conditions) free falls have been made as low as 156 ft (but if you do this, you may have to trade your "eh" for "mate"). Until you have a chance to do some of these jumps with people who have experience at them, I'd stick to 200 feet and higher, though.

>Is a pca safer, faster than a static line?
A well managed PCA (post again if you want a description of what I mean by "well managed") is usually superior to a static line. However, with a well rigged static line, the chance for human error is minimized (very important at your experience level), and the differences between the two (good static line or good PCA) will probably be irrelevant at the altitudes you are jumping.

>Ace...
The lower you get, the more you will want a vented canopy. Vented canopies (among other things) reach full inflation well before their unvented counterparts (note that not all unvented canopies are equal--and neither are all vented canopies). If you are looking to do jumps in the sub 170 ft range, you will probably want to invest in secondary inlets, either on a new canopy, or retrofitted to your existing canopy (here's the part where I express a wistful desire that Atair would offer retrofits of the MDV onto other canopies, like your Ace).

If you're not sure, the vented canopies on the market are the Blackjack (valved Ace), Vtec FOX (vented or valved FOX), Vtec Flik (vented or valved Flik) and MDV Troll (valved Troll).

>...120ft. to 170ft...
Aside from the things I've mentioned above, if you are static lining low objects, my observation has been that a "drop off" launch (i.e. not pushing hard away from the object) will get you a flying canopy faster, and with minimal oscillation. Although it may put you closer to the object, I believe a very light "drop" style launch is superior for ultra-low static lines.

The effects of winds on opening is a very large, very complex, oft-debated, and not well understood topic. You may encounter any number of experienced jumpers who disagree with much of what I have said here. Be sure to gather as many opinions as possible.

Have fun.

--Tom Aiello
tbaiello@mac.com

[imported_Tom Aiello]

>25 knot tail wind at opening altitude on a 1 sec. delay
In this case, I would expect the wind to govern your open almost completely.

>...ill affects on the opening?
Yes. I would lay money on a 180 in this case. If you, and three of your buddies make this jump, I'd bet that you'll see more than one 180 by the end of the load.

>Can it slow down the opening...
Expect a 25 knot tailwind to greatly slow an on-heading opening at 1 second.

>...cause it surge or stall?
Yes, and yes. If the tailwind is sufficient to overcome your deployment, at your current brake settings (and the factory settings on your Ace are usually pretty deep--which is generally very good but can contribute to a diving stall in this case), you can experience a deployment stall. The canopy may jellyfish a bit, and will most likely dive in front of you to recover, costing you altitude (and freaking you out as you look forward at the trailing edge of your bottom skin). If you are too low, this dive can result in high speed ground impact, and resultant injury or death.

Regardless, I'd recommend customizing your deep brake settings, then test jumping them in a tailwind, off a nice friendly span, preferably with a water landing, so that you can increase your understanding of what your canopy will do in this case.

>Or in general cause it to malfunction?
Although a line over is possible, with appropriate reefing (i.e. tailgate) it is extremely unlikely. Off-heading would be my biggest worry, followed by deployment stall and diving recovery. Blatant malfunction would be a distant third.


--Tom Aiello
tbaiello@mac.com

[BasejumperJeff]

Thanks for your in depth response Tom.
Yes I would like a description of a "well managed" PCA. As well any thoughts on static line. Currently I have only one ststic line jump, I did it on a 270 ft. antenna for a liitle bit of a safety margin, I used a peice of 80lb. break cord tied to a peice of 1800 lb. rope loped around the object. What are your thoughts on the "well managed" static line?
Thanks in advance
Jeff

[imported_Tom Aiello]

Please, practice this somewhere relatively safe before taking it to the low objects.

The objective of a good PCA is to release the PC at the instant the jumper's body reaches line stretch. Doing this minimizes distortion to the pack job caused by the "infinite" snatch force of the fixed PC and resultant center cell strip. Properly timed PC release will also discourage off-headings resulting from asymmetric riser loading under high tension (i.e. with PC fixed).

If you release the PC too late (i.e. the traditional "death grip"--just holding on until the PC is ripped from your hand), you can strip the center cell, distort the pack job, and encourage off-headings.

If you release the PC too early (i.e. drop it before tension) you will have a slower opening, and you can degrade heading by allowing the PC to oscillate (I did this to a friend of mine a few years ago on a low, underhung cliff, and I still feel bad about it).

Any technique that results in a properly timed (i.e. precisely at line stretch) PC release is a good one.

The technique that works best for me is this:

1) Hold the PC by the crown in the right hand.

2) Hold the 'S' folded bridle in the left hand.

3) Keep a 90 degree bend in both elbows.

4) Allow the bridle to be pulled clear of the left hand, feeling the tension and speed.

5) When the system reaches line stretch, your right hand will be pulled down (straightening your elbow). This will give you a fraction of a second window in which to release the PC, while maintaining proper tension. You can release your grip at any time while your hand is travelling down to a straight arm position. Because your elbow absorbs the shock (by straightening) you should be able to manage the release without distorting the pack job.

Note that this takes a fair amount of practice. Be sure to go to some high (and preferably strike free) object, and practice several times before trying this out on a low, dodgy tower. Better to make your errors in a relatively safe practice environment, rather than when a friend's ability to walk hangs in the balance.

If you drop me an email I can send you a little "static line guide" that I put together a while back.

--Tom Aiello
tbaiello@mac.com

[BasejumperJeff]

I've got two questions.
First, I am a newbie in the sport, 20 BASE jumps mostly 250ft. to 300ft. antennas. The other my buddies and I, both of them have under 50 BASE jumps, were on the top of a 300ft. antenna and the winds were about 25 knts. at altitude and about 15 knts. on the ground. We decided not to jump because we were not to comfortable and it was really cold, here in Ottawa Canada, around -20c. I have never jumped in winds that strong before and was wandering how the winds would affect the opening of the canopy, tailwind, crosswind, no delay, 2 second delay, what if any are the draw backs to high winds?
Second question is how low is too low? So far my lowest jump has been 200ft. pilot chute assist. What is the lowest altitude you can go without smacking the hard stuff to a point you might do serious damage? Is a pca safer, faster than a static line? I am jumping a oddysey FX with an ace 240 and weight 155 lbs. , if that matters. There has been lots of stuff I have been looking at that is 120ft. to 170ft.
Any info would be greatly appreciated.
Thanks in advance.

[crwper]

Jeff,

With an unvented canopy, I wouldn't recommend going much below 200 feet until you have more experience at those altitudes.

If you're jumping a 480-foot object and taking a 3-second delay, it will feel qualitatively about the same as a 470-foot object. You're going to lose maybe a second of canopy time, but if you're spending 30 seconds under canopy, it doesn't make much difference.

In the sub-200-foot range, it's different. On a 200-foot static line, with a vented canopy, if you do everything else perfectly, it will take about 13 seconds from when your feet leave until they touch the ground again. From 170 feet, that might come down to 9 seconds. From 140 feet, more like 6 seconds. From 111 feet, it's about 4 seconds. From the time your feet leave the object, it takes about 4 seconds for your canopy to begin producing lift, using the proper launch technique, and if everything goes perfectly.

If your canopy opens on-heading, you're landing in an open meadow, and in all other ways the fates are smiling on you, these numbers give you an indication of how much canopy time you will be able to enjoy.

If your canopy opens off-heading, you're landing in a restricted landing area, if your static line breaks, or if things go in any way imperfectly, you have the difference (between total time and time-to-flying) to correct the problem. From 200 feet, it might be 9 seconds if you had a good launch; from 170 feet, 5 seconds; from 140 feet, 2 seconds. From 111 feet everything has to go perfectly, and your landing area has to be directly beneath you (and soft enough to do a decent PLF).

If you're amped, and you push out on your launch, your canopy will oscillate, and you'll lose maybe two seconds of response time. How much will you lose if you have to do a 90-degree correction?

The point I want to emphasize is that there are a lot of variables, and very little time to budget for each one.

In your initial exploration, I would recommend you use a static line instead of a PCA. As Tom said, a properly-executed PCA is measurably better than a static line deployment, but a poorly executed PCA can put you in a very tight spot, and hinders your ability to pinpoint mistakes. Try to control what variables you can -- if you use a static line, your deployment should be very similar from jump to jump.

Use only milspec 80 lb break cord -- in my opinion, there is no excuse for using any other material.

It sounds like you're off to a good start. Stick with the static line deployment, and do some more objects in the 200-foot range. Try to keep the new variables as small as possible on each jump. Try to keep in mind what options you have for dealing with an off-heading, or other unusual situations.

If you find yourself in Alberta, I'd be happy to show you around. E-mail me at crwper@mustagh.com.

Michael

[clint]

Tom,

I did ask my roommate and she has 400 BASE jumps and she agree's with my theory. Now I asked both Jimmy and Marta and Jimmy agree's with you and Marta with me. They also said most people think 50-50% on this subject. About the video, I could put it on a VHS tape from the
original VHS copy. Wont be the best copy, my camera is busted.
mastaclint@yahoo.com shoot me your address.
I also believe that whatever side the pilot chute is on is the way it's going to open. Not just wind, just when the PC dances and ends up on either side.
I value your info you send all the time, thanks
Clint