[JoeF]

Safety matter
(not to dismiss the importance of efficiency and clarity for commerce, history, clear thinking, voice discourse, text)
Thin-sail material is often used to make PG and HG wings skin geometric airfoil shapes.

When an airfoil is thin and same thickness as thin sail material used from LE to TE, flat or curved chord, aviation culture seems to know such as a single-skin-single-surface wing (neglecting that there is still an actual lower surface to the sail material). But differently when the airfoil has thickness different in leading regions compared to thickness in aft regions, then a "second surface" is developed, either partially along the chord or fully aft along the chord to the TE.

David Barish's Sailwing had a distinct partial second surface developed by cut-and-sew tactics; such partial second surface allowed a filling that thicked the resultant airfoil and such reduced the pitch sensitivity of the wing and collapse sensitivity of the wing. The important partial second surface (P2S) was key to safety and pitch and collapse matters. The sharp sail-thick leading edge of true single-surface kite and kite-gliders is so very different from the Barish offer in the early 1960s. The P2S tech is in public domain and has been being explored decades in HG and OutLeader (Dave Culp) and now by Pere Casellas and others (findable in FoilDesign group). P2S wings are mechanically siimply not SS (single surface). HG use culture has relaxed "single-surface" until crossbar is covered; but that language misses many opportunities for efficient discourse, as the handling of just what is done on the LE tubes and the covered cavity after of that by sail on undersurface (thicker pseudo LE, fillers, D-tube, etc., even if crosspar is not enclosed). Differently is the Platz, the Porta-Wing, and other super-sharp LE gliders. It has been my hope that the call out of % for P2S HGs become text and discussion norm, but the ongoing relaxion in HG at the user level probably won't change; once the crossbar is enclosed and perhaps forming ribs or battens support lower surface sail to 60% chord or 80% chord or 100% chord, then DS is norm language.

In PG, the XXLite has first text out as "single skin" and ALSO "single surface" which misses big win opportunities for OZONE and misses the gain of efficiencies for safety, commerce, history, and discourse. It is fully clear that the XXLite wing is P2S and its partial second surface is a Barish plus for the prototype offer. I hope that I will not be the only one asking OZONE to early now sharpen their language to get the wins for them and others that will be dealing with their language. The P2S tech is not patentable, as P2S tech is in public domain. But various makers can bring on products in time using P2S tech for HG and PG.
Discussion is open. And, if you are moved to do so, consider asking OZONE to drop the "single surface" even though keeping "single skin". I do not want unaware builders to see and hear "single surface" and just throw together a super-sharp-edged LE sail and jumping off a tower. I would hope they would know about P2S; and OZONE could help on this matter, especially because of their present status in wing provision.
See the partial second surface yourself: http://www.vimeo.com/29247558

[JoeF]

BHLasSSP2S.jpg (66.29 KiB) Viewed 9494 times

Single-Skin-Partial-2nd-Surface technology is in public domain
and is being used by BarrentinaHyperLite and others like XXLite.

[Rick Masters]

I would hope they would know about P2S

I would hope they would know about hang gliders.

[Bob Kuczewski]

Hi Joe,

Your posts always get me thinking about something!! This is not really on topic, but your drawing above got me thinking about a few things.

First, it got me thinking about adding stiffening in PG wings. I know that kite surfing wings have sealed inflatable cells that make them substantially rigid. I've always been surprised that such semi-rigid structures haven't found their way into paragliders. I have to believe that it's been considered, and it makes me wonder about the drawbacks. I had always thought that sealed tubes running chord-wise would be like battens in hang gliders. But your drawing got me to thinking about a single spanwise tube at the leading edge - just above the pressurization openings. I'd be surprised if it hadn't been tried, but I haven't seen any published results.

Your posted drawing also got me to thinking about how the speed bar on a paraglider pulls proportionally more on the leading edge to effectively lower the angle of attack. I was mulling over how that's so much different from the way we control pitch in a hang glider. But then when I thought about the geometry, it turns out that it's really the same!! After all, by shortening the forward lines, the geometry is actually changing bringing the pilot's weight forward relative to the canopy. Of course the word "relative" is important, and because the pilot has so much of the mass, it's the canopy that ends up responding far more than the actual movement of the pilot's CG.

Of course, none of this is very relevant, but I always enjoy the thoughts that your posts invoke. Thanks Joe.

[JoeF]

Distinguish: Simple single skin
is a preferred reference. A skin has a top of its skin and a bottom of its skin; we neglect the thickness, as the thickness of the one simple skin is super tiny.

When Pere Casellas confirmed his membership in WWRA today, he added a neat new note of progress:

The BarretinaHyperLite test, go ahead. A few days ago, a professional pilot made a flight over water (reservoir near Ager flight zone, SIV center). The pilot, specialist in EN certification tests, came out very happy with the passive safety demonstrated by the prototype. Currently two additional prototypes are under construction. The single surface (sic, single skin; simple skin) paragliders are back to stay!
(one layer of cloth)

Some background: http://www.energykitesystems.net/Lift/P ... flies.html

=======================
His affirmation that he is a WR in WWRA:
Pere Casellas has done considerable wing running with a wide variety of wings, mostly in preamble to launching hang gliders. HERE.

I also really identified in this category. Certainly, I spend lots of time running and playing with the wings on the ground!

[terryJm]

Well Jo, all this is fine, however; I'm not convinced that a puffed up air pocket will ever replace aluminum tubing as airframe material, and I don't see any support at all for negative G loading. My experience with turbulence precludes remaining aloft any longer than required in a para-chute, no matter what YOU want to call it. Geo. Orwell wrote a story about a utopian world where the meanings of words were changed to reflect whatever the authority wanted to promote, now we see something like that in our sport. Para-gliders will never BE hang gliders, no matter how many people call them that. And all this time I thought You were a Hang glider pilot. Are you with us, or against hang gliding. Recently our assn. has been taken over by a majority of para-people, who have proven not to be responsible, with regard to air space, training, or site protection. Our assn. has allowed this for economic reasons I do not understand. Inter the U.S.Hawks, an opportunity to start a real Hang Glider Assn. This is my first priority after Flying, Working, and singing. Forgive my long winded reply, but you have been an inspiration, specifically in your safe-splat thread, Thanks, Terry

[JoeF]

terryJm,
Thanks for post, your furthering ideas, and questions.

To partially answer the personal question:
1. My firm vote is that canopy gliding kites are usually high-aspect ratio wings that do easily wrap and collapse when facing normal windfield helicities; when such occurs within a zone where there is not time and altitude to calmly use a parachute, then injury and disaster occurs far too often. http://www.cometclones.com collects ONLY A SUB-FULL collection of the fatalities since 2002, that is, there is evidence that counts are missed; the incomplete total of lost brothers and sisters is over 900 now since 2002. SIV controlled collapse recovery is far different than having to deal with actual windfield helicities (vertical, horizontal, oblique helicities). Such skewed canopy wings become non-wings in such collapses and wraps; when recovery is too low dynamic plummeting sometimes occurs, even with swing-impact that splats the wished-to-be pilot.

2. The sooner USHPA becomes USPGA for canopy gliding kites, the better for the airframed hang glider culture and community. Any hesitation on the part of the airframed hang glider community that uses mostly the stiffened airframe and a short hang line with pilot grasping the airframe for control of pilot mass position, --to form its own focused org like, say, US Hawks, will delay a rich coming growing of airframed hang gliding as advanced new airframed hang glider designs surface. I have no doubt that one day there will be very-busable packed airframed hang gliders that nearly snap up to full form in a minute, followed by pre-flight checking. No huge tangle of high-count long-tether kite lines, but just one short kite line to pilot harness. When will the airframers unite and focus?

3. As publisher, I offer some effort at focus: http://www.WorldParaGlidingAssociation.org This is in part an effort to give accent to the need for having orgs around the world separate the canopy kite gliders from the airframed kite hang gliders. And http://www.WorldHangGlidingAssociation.org for similar accent.

4. As a kite (manned or unmanned) the gliding kite of single textile skin has been been around as stiffened for centuries, and then Rogallo gave the invention of the unstiffened canopy (with morphs by David Barish in Glide Wing) for kiting and gliding kites. As a publisher of kite systems, each sort of wing is very interesting. Consider the rigidizable tech where a loose canopy would be deployed and then stiffened fully in reaction to chemistry or light or stress or a combination of such. All wings are welcome at http://www.energykitesystems.net Canopy parachutes for humans are safer when they are not high aspect ratio gliders; to build high participation for sport and hobby in the use of high aspect ratio canopies tethered by long lines is asking for the constant flow of injuries and deaths that will occur from the collapses and wraps from meshing with normal windfield helicities within the wide zone above ground roughly studied under the name of PDMC; the vertical width of the zone and the habits of hobby users of such canopy gliding kites make for the disaster that continues to take a huge human toll. So, study continues on wings of any sort, but I personally hold that hobby/sport high-aspect ratio canopy gliding kites should only be practiced if launched from a high airborne platform and terminated at a high airborne catch system, something not being worked towards by anyone to much extent. The compromise of "conservative airs" for practice of the canopy kite gliding is fooling too many people and bringing a confidence that gets abused too easily; it is simply not easy to find and keep the conservative airs as the only playground; the ground launchers and ground landers pass through a large vertical zone where the bad does and will naturally happen at a rate that is proving to many of us as unacceptable.

En mass, all airframers might consider forming new separate organizations around the world; coordinate with third-party insurers if wanted about the big change. Let the extant canopy-focus orgs be honest enough to alter their names to reflect the exodus; to help the exodus, the new HG orgs (though having mixed feelings) might strongly set bylaws to focus on being without unairframed long-multiple-tethered canopy gliding kites while being with and for framed hang gliders where pilot holds the airframe for control and hangs by tethers short enough to allow such airframe control. It is time to see that there is a bifurcation needing firming in policy. The culture of handling the launch environment is starkly different in the two branches; there will be very much more launch area opportunities for the airframers than for the canopy gliding kites. Illegal erosion-inviting plant cuts ought to be prosecuted to the fullest extent of the law.

How part of mix started: http://ushawks.org/forum/viewtopic.php?f=22&t=1055

[terryJm]

Great answers, Joe! I still have a copy of 'Low & Slow' summer of '73 or'74 where an article states something to the effect that we do not want to eliminate our king post. These little gems of wisdom sprinkled through out your work have kept my interest, and contributed to preserving my life. I can't thank you enough, Terry

[Rick Masters]

It is time to see that there is a bifurcation needing firming in policy.

10/4 good buddy.

[Bill Cummings]

“Car insurance/Motorcycle insurance.
Hang gliding insurance/Paragliding insurance.”
Quote by Mike Ellsworth, H4, Ruidoso, NM