klox@otago.ac.nz (05/03/91)
In article <1991May1.212459.776@husc3.harvard.edu>, galperin@husc9.harvard.edu (Gregory Galperin) writes: > But since they hadn't just been in freefall for a mile ( ;-), a couple > of minutes under canopy on the way down didn't provide enough excitement. So > they started using larger and larger canopies, with more and more cells... > all the time looking enviously at hang glider pilots above them. The designs > grew in wingspan and area continually, and many paragliders are now over > 40 ft. in wingspan and 450 sq. ft. in area, with a large aspect ratio. The Aspect ratios of around 4:1 are now common > resulting airfoil is something like a ram-air sailplane (i.e., parachute + > glider = ...), and flies something like a hang glider (or so I've been told, > at least). The chord length tapers off severely at the ends, and the last > few cells are closed in front (they have no ram-air port, only cross-ports), > and curve down like stabilizers. Some also have winglet fins above the top surface. Some are ported only on the wing undersurface, not leading edge (= less drag) > It's true that the materials used in paragliders are generally less > porous than those in skydiving canopies (although it's hard to get less > porous than a zero-porosity fabric... :), but a greater difference is that > paraglider materials are less elastic (which is why an opening shock from > terminal would shred them). Has anyone actually tested this? Also I believe that a paraglider would need a drogue to open... > Even standard parachute line cord has too much > stretch for paragliders (I know someone who injured himself when he rigged > his 'glider up with standard jacketed suspension line and couldn't control > it enough to keep from stalling out). Good Paragliders use kevlar shrouds > These canopies allow a much greater glide ratio than parachutes, and > allow (good) pilots to stay in the air for hours. Anyone who's been hanging > in a harness for over 15 mins. can understand why paragliders grew seats as > they became larger; multiple line groups are connected to the seat along its > length so that shifts in weight can steer the paraglider. That depends on the harness, most control still comes from the brake lines attached to the trailing edge. > To stay flying, > 'glider pilots catch thermals (and carry variometers to help find them). Or catch ridge lift on slopes facing into a wind. You need about a 25 kmh breeze to stay up. Mostly canopies have max speed approx 40kmh > 'Glider competitions sprang up, and have categories much like glider > (sailplane) competitions: net distance, time around a course, etc. > In summary, you can still buy small (<5 lbs!) 7- or 9- cell > paragliders to use for descents (and this is standard equipment for climbing > in Europe), or you can go the competition 'glider route. They're probably > more expensive than "normal" 'chutes because (1) they're larger, (2) the > designs are more complicated (tons o' cells, tons o' lines, and a more > involved airfoil design), and (3) the market is still relatively small. I dont know what a parachute costs, but I can get a glider ready to fly for around $2500 new, $2000 second hand. just my $0.02 worth KLox
SKYDIVE@f15.n233.z1.FIDONET.ORG (SKYDIVE) (05/11/91)
Reply-to: Chris.Weiss@p0.f206.n161.z1.fidonet.org (Chris Weiss) Fido-To: uiucuxc!otago.ac.nz!klox > I dont know what a parachute costs, but I can get a glider ready > to fly > for around $2500 new, $2000 second hand. What about classes? Licensing? What kind of limitations are there on where you can fly? Where can one find more information on the subject (Is there a USParagliderAssociation)? --- Telegard v2.5i Standard --- eecp 1.45 LM2 * Origin: Dream Park BBS Walnut Creek, CA 415-945-7799 (1:161/206.0) -- SKYDIVE - via FidoNet node 1:233/13 (ehsnet.fidonet.org)
uh311ae@sunmanager.lrz-muenchen.de (Henrik Klagges) (05/17/91)
Hi,
1. There is a US paraglider association. You get member forms at every
hanglider location. A small fee + insurance is required.
2. Paragliders are in different performance regions:
- Glide finess in best serial chute (UP Flash): 7.76 (!)
- minimum sinking 1.3 m/s
- maximum speed 48 km/h
3. They really differ in the design:
- Aspect ratio of the (usually elliptic) wing up to 5.3 (ITV Saphir)
- many individual chambers, frequently > 30, sometimes > 50
- performance chutes are long-liners (6m)
- optional 'wing-tilt'- steering, i.e. aerodynamic steering without
brake lines possible (very smooth)
4. Dangerous flight conditions usually not reached by chutes, but by gliders:
- Full stall
- partial emptying of chambers
- 'Sackflug' (can't translate 8(), which is rapid descending without la-
minar air flow, but with open chute
You can avoid 4. by carefully selecting a non-super-hoopey glider and the
right weather conditions. Nevertheless, I always have an emergency parachute
with me (in case of collisions, material failure, etc.).
With modern gear, you can stay in the air for hours and even cover reasonable
distances (record 150km). The hardliners do fullstall-free fall-opening for
fun ...
Yours, Henrik Klagges
U of Munichklox@otago.ac.nz (05/20/91)
"Sackflug" is usually referred to as a "Steady State Stall" or "Parachute Stall" in English KLox
brent@terra.Eng.Sun.COM (Brent Callaghan) (05/21/91)
In article <1991May20.101739.410@otago.ac.nz>, klox@otago.ac.nz writes: > > > "Sackflug" is usually referred to as a "Steady State Stall" or "Parachute > Stall" in English I used to enjoy doing this on displays to thrill the crowds. To the uninitiated it looks like the canopy has irretrievably collapsed and the high rate of descent makes it look like injury is certain. If you can pull the brake lines down far enough it's possible to fly a 7 cell backward with full directional control. Transitioning back to foward flight again can be exciting as the cells re-inflate unevenly and toss you around. I don't do this anymore. Once the pilot chute got blown over the leading edge and took a loop around the A lines. When I re-inflated the cells, the pilot chute stuck there the centre cells stayed partially collapsed. The canopy was "pinched" in the middle and barely controllable. I landed carefully. -- Made in New Zealand --> Brent Callaghan @ Sun Microsystems Email: brent@Eng.Sun.COM phone: (415) 336 1051