pchapman

Let's not derail this thread, but descending through wind shear does seem to allow for a canopy to head into wind due to the directional stability of a canopy. There have been threads debating the issue. I'm not sure that it makes much of a difference in practice. So in general my personal belief is that we stay with the idea that canopies' flight direction is generally not affected by wind direction, except that some effect may be caused when there is a high level of shear present.

Quote: Ok, this is getting ridiculous, if it wasn't already... At least I'd hope the current problem is a lot more fixable than letting the whole balloon disappear over the horizon.

To figure out the performance of a plane on floats, it's the float plane community will know more than most skydivers... As for the "has anyone jumped" aspect of the thread, back in the late 90s there was a tiny local DZ that didn't have its runway ready yet, so operated the C-185 (?) on floats off a nearby river. It made group exits fun -- just line up standing on the float. The scary part was down at the marina where we boarded. You wanted to watch your step going from dock to float, when wearing a rig and 10 pounds of lead!

Hi Dave: I agree with what AdamT wrote: I think this is where you lost people, and I think you your self know this to be a false base on other posts of yours I have read. I could just be a matter of wording. For the sake of the thread I don't think I'll get into it too much, but that 'showing the topskin' thing is just wrong. You are decreasing the angle of attack from a positive to a smaller positive value, actually reducing drag until the speed increases to create speed induced drag. Yes of course when it comes to actual motion over the ground, the wind matters. But the way it is stated in what you wrote, it is easy to confuse the flight through the air vs flight over the ground stuff. The wind (assuming steady) doesn't affect the way the canopy flies. But I agree one has to add it in when determining what the canopy does over the ground -- and hence - to go back to the origin of the thread -- whether pulling front risers really is of net benefit.

Most of your posts on dz.com are really good, but I can't agree with this one, not at all. It gets back to all the airspeed / groundspeed fallacies. In a steady air mass it doesn't matter what the wind speed is doing, whether it is a headwind or crosswind or whatever. Your flight through the air will be the same. If you pull front risers in no wind conditions and get +2 mph forward speed, then if you are flying into a headwind that gives you zero ground speed, pulling front risers will give you the same +2 mph through the air and over the ground.

Yes, unusually for a non-Quebec DZ in US / Canada, one DZ I jump at in Ontario just introduced an AAD policy. This year you need an AAD if under 1000 jumps unless making an accuracy or CRW jump. They used to be required for doing video only. The DZO is getting older and more and more conservative, perhaps wanting to avoid lawsuits or ruining his 37+ year reputation of nobody having bounced at his DZ.

I missed seeing the video in the orig. post that got deleted. But here's my own personal one sided cutaway video: http://blip.tv/file/238113/ ("Select a Format" to get Flash video if it comes up as the bigger WMV original.) Low res only. Used to be on skydivingmovies.com. It was a 3rd canopy where I pulled one cable out first. Even on a PD 190, the 1 rotation per second spin was pretty impressive.

Yeah, in this whole conversation, we're generally all just using forward speed casually without always being clear about the difference between forwards speed and flight speed along the velocity vector. (And thanks to Morris for the link to the KATE experiments -- neat stuff as I used to do some canopy tests with anemometer and variometer.)

Ian: Ok, looks like we are basically in agreement. This is one of those cases where the question and answer have to be broken down more for a full understanding. So both can be right: "Front risers in a headwind is often a waste of time" and "Front risers in a headwind can be very useful."

Interesting. Because normally skydivers are the only aviators who want to increase their speed before landing! (But you should put "hang glider" in the title if one is being off subject...)

... And going the other way, a couple times I've even seen used canopies arrive with the slinks removed. Cheap people. Now that becomes a bit of a rigging job to hook back up.

We (the PD Factory Team), don't generally find this to be true,nor do we teach people to use fronts to cover ground in a headwind. [...] YMMV. I'm surprised at the latter. But it can depend on the circumstances we are talking about -- both answers can be right: a) If you are trying to cover a lot of ground and generally fight back through moderate wind, what Ian says may be right. (eg, 30 mph forward speed, 15 mph headwind) The extra speed you get from front risers probably may not make up for the increased descent rate. b) But if you are trying to get 50 m forward just to get past a line of trees, doing 30 mph in a 30 mph wind, who cares about the descent rate. Getting an extra 5 mph out of the canopy will save you, screw the descent rate. To understand all this you do need to understand glide polars, how to shift them to account for wind, and typical skydiving canopy glide polars. And whether or not you understand that, at least understand the 'accuracy trick' to estimate glide angle over the ground when you are actually there in the air and can test out fronts to see whether its gonna help or hurt you. And as far as doing front risers low, that's OK. But watch out for: a) applying fronts suddenly if in turbulence (although whether there's a problem with turbulence and fronts may be debatable), and b) letting up too suddenly where you lose too much speed just when you are about to want to flare. That gets into the whole issue of recovery arcs. You either want to let up high enough to regain normal speed, or low enough to transition right into a swoop style landing if you know how to do that. Explaining everything about recovery arcs and glide polars is a whole other job.

We also have to be careful to distinguish between getting caught up in lines, and the canopy itself. The former is bad too although technically not falling into your canopy.

That may be him -- I've PM'd you.

I haven't had any luck finding Bob Holland, who skydived in the US in the early 1990s at least, as there are too many Bob Hollands out there on the web!

To be clear for everyone, it was a holiday long weekend. Did you take a 4th day off too or not?

The Pitts and jumper were still very far apart, especially from the view point through a wide angle lens. A couple hundred feet?? as the descending Pitts went by. So it isn't exciting as a 'cool video' in general. Still, as a personal skydiving achievement it must have been neat to arrange -- with the potential for better in the future. The problem is generally going to be to get a plane descending steeply enough without too great a speed build up.

What are the nose caps? Top skin wrapping around over the nose openings? FCI's web site is so crummy it doesn't even mention these options on the web pages or on their order form.

We have to remember that it isn't just whether someone is teachable, but teachable within a reasonable amount of time. An instructor should be willing to do some extra work to help a student, and sometimes a DZ will share the workload to help someone out who is making a good effort. But if you have a first jump class a student is expected to not be TOO far below the average when it comes to learning. If one is taking a course at university, there's a finite amount of time to learn the subject in, and some people are going to fail to learn within the time available. You can't take that comparison too far, but there are practical limits to how much teaching a student is going to get, from an instructor paid a fixed amount for that student.

Great post RiggerLee. Harness design isn't usually talked about much. Older rigs sure tended to have short laterals. Likestojump showed pics of a few different rigs with different layouts for the hip rings vs. leg junction vs. lateral junction. A given manufacturer doesn't always do things just one way, do they? For example, the stagger and lateral & leg junctions could be different for a small rig and a long MLW, than for a long rig and short MLW. So looking at just one rig doesn't tell the whole story of how the manufacturer builds things.

Hey Rob, But where does it say a JUMPER has to follow what a manufacturer says? (Rather than a pilot or a rigger.) That's the issue here. I don't know the answer but nobody has yet quoted a FAR that requires it.

Interesting perspective! The issue of load limits is one that has been debated a lot in skydiving. Riggers (in FAA-land) have to follow what the manufacturer says. But you would then suggest that there's nothing saying that the jumper must follow what the manufacturer says, as long as it is within the TSO limits? Unless anyone can come up with a FAR saying skydivers must follow manufacturer recommendations, what you say sounds good.

A friend was teaching the first jump course. One guy in the course stepped out of the room to take a cell phone call while the emergency procedures were being taught. That was the final straw for the instructor, after some poor attentiveness by the student previously. Even other students in the class asked the instructor whether the guy should jump...

There's a spot in the manual where it does say C23c, Category B.

Not much is known about him over in North America but I see there's now a little bit on the web mainly in French. So he's the guy who did the chuteless jump, picked one up, but had it fail. (The French wikipedia page claims he was the first to jump chuteless, which is clearly wrong - so I changed that in my shaky French.) Of course the plane transfers were done by pre WWII wingwalkers without chutes too. In any case, the Red Bull Blanik to Blanik glider transfer was nicely done.