Zennie

Made clicky... This is the reason there are groups using supercomputers, etc to simulate such processes. See for example http://www.mems.rice.edu/tafsm/ And for a description of how a round opens: http://www.mems.rice.edu/TAFSM/PROJ/FSI/axi_para.html - Z "Always be yourself... unless you suck." - Joss Whedon

Why do I have the sick feeling that this thread is going to result in 460 checking his references again? - Z "Always be yourself... unless you suck." - Joss Whedon

I think the big problem here is that we're approaching this from a Newtonian rather than a Quantum perspective... - Z "Always be yourself... unless you suck." - Joss Whedon

And just to clarify a bit further what I'm talking about. When I'm referring to drag I'm referring to the force created when a semi-permeable (or non-permeable) solid (i.e. canopy fabric) has velocity through a fluid (i.e. air). The fluid forced into (or through) the object produces a frictional "pushing" force that I'm referring to. When I refer to lift, I'm referring to the upward force created when you have differential airflows over a solid, creating a vacuum (i.e. "pulling") effect. - Z "Always be yourself... unless you suck." - Joss Whedon

From a physics point of view the two may (or may not... 460???) be the same. Personally, when I'm referring to lift vs drag, I see drag as primarily a "pushing" counterforce as opposed to lift, which I'm seeing as a "pulling" counterforce. - Z "Always be yourself... unless you suck." - Joss Whedon

I'm no fluid dynamics expert, but I did stay at a Holiday Inn Express last night. I’m wondering if we actually have two discussions going on here. The discussion in the referenced post seems to relate mainly to the mechanism by which a PC or other round canopy inflates. That is, there is a pressure differential between the inside and the outside of the parachute which causes air to be drawn in. This is also the same principle which causes a square parachute’s cells to pressurize (which I think is what Brit was driving at). You physicists & aerospace engineers correct me if I’m wrong here, but that said, once inflated/pressurized, I don’t think you can say that round and square canopies operate on the same principle. As best as I can tell, both are drag devices. Both have an underskin which provides air drag/resistance to counter the downward force of gravity. The round parachute, by virtue of its shape, is a pure drag device. It cannot, as best as I can tell, produce lift. A square canopy has more of an airfoil profile which DOES produce lift. That lift is produced by giving the foil an angle of attack which generates forward momentum and thus forces air to flow over the top and bottom of the canopy. For instance, I don’t think you can get off the ground by attaching a motor device to a round parachute. It will just slow down your forward progress. You CAN, however, attach a motor to a square parachute and get airborne. - Z "Always be yourself... unless you suck." - Joss Whedon

Personally, I use the following PCs for the following delays. 0-1: 46" ZP apex vented. 2-5: 42" ZP apex vented. 5-12: 38" ZP apex vented. Internal non-floating handle. 12+: 32" ZP apex vented. External handle. I have a 36" non-vented with an external handle but I never use it. I opt for the 38 or 32 depending on the delay. For an 8 second delay I'd go with the 38. I'd use the 32 given no other choice. Of course there are exceptions to every rule. Just the other night my jump buddies (*cough*brit*cough*chris) banned me from trying a gainer at 300 so we climbed up to about 450 or so. I set up for a very short delay so I had my 46 with me. I wound up taking about a 3 or so with no problems. Like Johnny pointed out, I was erring on the larger side so it really wasn't a big deal. Just out of curiosity, has anybody noticed a difference in inflation times when going stowed with a 46+ vs a 42? I've noticed on a couple of occasions now that the stowed 46 seems to inflate a tad slower than the stowed 42. Almost like there's a point of diminishing returns as the PC gets bigger and there is more fabric to unfold & inflate. - Z "Always be yourself... unless you suck." - Joss Whedon

Just from looking at the video, it looks like Prodigy wasn't getting nearly the same distances/times that the V-1 was... not that I would expect it to. Performance-wise, my guess is that the Prodigy would be closer to a GTI or Classic. Comparisons between those suits would much moer helpful to me. YMMV - Z "Always be yourself... unless you suck." - Joss Whedon

Oh great... you just made me blow half a Diet Coke through my nose and onto my keyboard. - Z "Always be yourself... unless you suck." - Joss Whedon

After first setting himself on fire for dramatic effect. - Z "Always be yourself... unless you suck." - Joss Whedon

' Skin? - Z "Always be yourself... unless you suck." - Joss Whedon

I dunno about that dude..It took all I had to make it through the 1st song on Brit's year end review... OK... ASIDE from that video. Brit was demanding Country for her year end video and Hank Williams, Jr. is about as much as I can tolerate. Still, being from Texas and all, and because you-know-who was disappointed at the lack of country on my last video, I figured a "Texas Women" segment would be cool. Be nice to me and maybe you'll make it onto the segment as well. - Z "Always be yourself... unless you suck." - Joss Whedon

Bummer. - Z "Always be yourself... unless you suck." - Joss Whedon

I don't have any sort of real inside information either, though I did ask Jeb if the system had any sort of protection for the "jewels" and he assured me that it does... so that's good to know. As far as costs go, as with any new technology costs are normally ridiculously high at the outset. That's because there is no mass-manufacturing or marketing infrastructure in place. If the technology is viable it will slowly gain market share and prices will go down into the sane realm accordingly. - Z "Always be yourself... unless you suck." - Joss Whedon

I might be able to throw a little something together for the "Not Skydiving" category. Plus my taste in music is impeccable. - Z "Always be yourself... unless you suck." - Joss Whedon

Depends on who's doing the probing and prodding. [Picturing a really hot nurse putting on the rubber gloves and....] - Z "Always be yourself... unless you suck." - Joss Whedon

Hey Nick, sorry you're having a rough time of things. Sending good vibes your way... - Z "Always be yourself... unless you suck." - Joss Whedon

Yeeaaahhhhh that's it. We can say we're volunteers with the Minuteman Project. - Z "Always be yourself... unless you suck." - Joss Whedon

Hey Cleatus, good to see ya online. IIRC, Cleatus did his thing at night, and still had 6 state, local & federal agencies swooping down within a very short period of time. The objects are very, very hot. - Z "Always be yourself... unless you suck." - Joss Whedon

It does? I never noticed. (ducks for cover) - Z "Always be yourself... unless you suck." - Joss Whedon

Yeah I got a chuckle out of that myself. Gives me a mental image of us having ziplock baggies pulling garbage bags out of a burlap sack. - Z "Always be yourself... unless you suck." - Joss Whedon

Nice article, but they need to up Tom's jump numbers juuusst a tad. - Z "Always be yourself... unless you suck." - Joss Whedon

I would have said the same thing, but I recently saw this article on how Europe is apparently starting to catch up. Those Italians have to lay off the pasta man. - Z "Always be yourself... unless you suck." - Joss Whedon

Mine are ultraviolet. This serves two very important BASE purposes: a. They are invisible to the naked eye and thus stealthy; and b. They emit an even shorter wavelength of light and are thus MORE stable than visible PCs. Still, I have mine apex vented because I like to have that little extra insurance. - Z "Always be yourself... unless you suck." - Joss Whedon

Ah gotcha, I read your comment wrong. My bad. - Z "Always be yourself... unless you suck." - Joss Whedon