[JoeF]

What is a hang glider?
What does it take to have an entity be within the set "Hang Gliders"?
If an org aims to focus on say just hang gliders that feature three substantial wings integrated in an airframe, then that could be a perfectly fine hang glider org with that specialized interest. Or perhaps an org just wants to focus on replicas of the 19 hang glider designs that the brothers Lilienthal made; that org might be a HGA in great standing and joy! Or perhaps an org wants to invest all its energies and investment on some other subset of the superset Hang Gliders. No problem; the org may be as focused as it wishes. Many varieties of HG orgs may be conceived. Several robust corporations and aviation authors have easily included paragliders as a subset of a superset of "hang gliders." FAI had "Class 3" in the hang glider category as paragliders; an evolution occurred to move the FAI into two commissions, one with focus on non-paraglider hang gliders and one on paraglider hang gliders. We have extant around the world many free-flight orgs that use the phrase "Hang gliding and Paragliding" as their focus; many of those orgs may not have full clarity about how they place in sets various craft; they just flow into the double attention of two large subsets of hang gliders, one being of a sort and the other being cousins to fabric parachutes without much rigid frame, if any. One need not construct non-traditional aviation definitions to get a special interest in focus; rather, respecting traditional aircraft mechanics, one may just clarify the type of craft one wants in focus for some purpose, say the fulfillment of a mission of a particular org. The renaissance in hang gliding in the 1960s onward saw a major set of hang gliding orgs take on more and more of the type of glider that lives and dies with the PDMC; factional cultures changed and fuzzy appreciation and participation grew; some confusion has been occurring. Tastes and choices change.

Someone entering hang gliding or "HG & PG" realm may carry a slant that has them easily see a wing and call it a hang glider; and another wing as a paraglider; the person might not even stop to wonder if a paraglider is or is not a special type of hang glider. Parachutes over the centuries moved from extremely low control to highly governable gliding parachutes; and later into an option of soarable high-aspect ratio governable parachutes (or for some people: canopy hang gliders). No problem, except the PDMC; and maybe cultural and focus challenges. Live and let live? No problem. Yet, when forming an org, mission and focus become questions; stability of focus over the life of the org becomes a question. For U. S. Hawks, what will be the focus? All hang gliders? A subset of hang gliders? Decision might need us to know what is a hang glider or what are the types of hang gliders. And then what types does one want to have as focus in an org being built?

Triplane hang glider has three wings. : )
Whitehead's.
Or Hans Richter
An org could decide to deal just with such triplane (three integrated wings) hang gliders.

[Bill Cummings]

JoeF Quote--
"Someone entering hang gliding or "HG & PG" realm may carry a slant that has them easily see a wing and call it a hang glider; and another wing as a paraglider; the person might not even stop to wonder if a paraglider is or is not a special type of hang glider. Parachutes over the centuries moved from extremely low control to highly governable gliding parachutes; and later into an option of soarable high-aspect ratio governable a parachutes (or to some, canopy hang gliders). No problem, except the PDMC; and maybe cultural and focus challenges. Live and let live? No problem. Yet, when forming an org, mission and focus become questions; stability of focus over the life of the org becomes a question. For U. S. Hawks, what will be the focus? All hang gliders? A subset of hang gliders? Decision might need us to know what is a hang glider or what are the types of hang gliders. And then what types does one want to have as focus in an org being built?"
JoeF
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Again: "For U. S. Hawks, what will be the focus?"
My suggestions--
1) A hang glider needs to withstand negative G's (But how much? Suggestions please.)
2) A hang glider is a wing that will maintain its shape in all normal atmospheric turbulence.
3) A hang glider can be foot launched and from which the pilot hangs and controls by weight shift.
4) A hang glider's control frame will remain manually coupled with the pilot for flight control.
-----These are just four suggestions for a start. Feel free to reword for clarity, or suggest they be omitted and by all means expanded upon.

[Frank Colver]

A hang glider can be foot launched and from which the pilot hangs and controls by weight shift.

My personal opinion would be to not require weight shift as the only control method because that would eliminate almost all ridged wing hang gliders. Most non-flex wing gliders require some sort of movable control surfaces to obtain adequate control, especially in roll and horizontal direction.

If someone told me that my Skysail was not a hang glider, because of the tip "drag rudders", they would elicit some argument on my part.

Frank C.

[JoeF]

BillC, FAI struggled with definitions. NASA struggled with definitions. Patentees struggled with definitions. Glider history struggled with definitions. Various levels of sophistication in books have struggled with definitions. When governable parachutes gained in glide ratio there was some struggle with words to describe. Some parts of some definitions from some sources seem stickier than others. Another tactic is to write "For the purposes of our concern in this document or org, we will mean as "hang glider" the following: __________." Just what is said in agreement with readers may be carefully defined or fuzzily defined. The struggle continues.

For instance, Otto L. did not directly address the neg G shape-keeping that came along with gliders that could not keep shape in neg-G or wispy helicity hits; Otto just knew he wanted his hang gliders to glide and not just fall out of shape. NASA easily used framed and non-framed paragliders as they try to resolve the need for gliders for re-entry missions. A gliding parachute is gliding and hence is a glider, according to many; it is difficult support that a device that does gliding is not a glider. All such has not stopped the sport sailplane-glider world from moving to a fuzzy treatment of having a sailplane be a very high performance glider; there are primary gliders and gliders that are near sailplanes. In all: object doing gliding. Enough neg-g and a sailplane become a broken glider.. a real mess. Degrees of neg-g? BobK points out that there is probably a continuum of structure and response to helicities and g forces.

The placarded limits for a flight system may swim all over the quantity map. E.g.: "This hang glider will fold up its wing in trim when 1.000000005 g is positively pressed and when 0.005 g negatively pressed." Someone might have a niche purpose for such a hang glider; such a hang glider would probably not be something to used for general broadly-participated recreational hang gliding; there would be far too much dissatisfaction, as there would be slew of broken hang gliders and bodies. An org that supported experimental and niche purposes in hang gliding could simply respect that use should match purpose while respecting the safety margins with respect to placarded values of the aircraft (hang glider in our concern). Placards of 6 positive g and 2 neg g shape keeping allows a wider use, yet using such in 10 pos g turbulence or 4 neg-g turbulence would not be wise. Still all such craft are still hang gliders, just that the limits call for varied uses. If coming U. S. Hawks has liability in governing, then it may want to confine itself to certain placarded values over the craft and use. But if the U. S. Hawks stays less constrained and keeping 100% responsibility into the craft-user, then perhaps even a 1 pos. g and 0.00000001 neg g would find some purpose for some hang glider user. Being aware of the spectrum of values for various crafts invites mastery over the craft realm; hopefully any user of a craft would know values and give a safety margin in using the values in a gliding effort. I can envision a movie stunt scene where a hang glider is designed to fold up at 1.0001 pos g; the pilot wing runs and then as soon as he or she loads the wing to 1.0001 pos g, the wing folds up in the short micro hang gliding flight; laughs and wages arrive; some lesson is taught; education might be served; study of materials might be involved as part of a further designing-testing process.
Hey, sir hang glider pilot, what placard values do YOU wish to use for the KIND of hang gliding YOU aim to do? What safety margins do YOU aim to keep in your flight? I reach for each hang glider pilot to know what is being used and what is to be expected.
Wind and turbulence vary. A hang glider pilot determined only to fly indoors in a controlled quiet-air building need not have the same neg-g on placard as one who aims to fly thermic outdoor airs. I ever aim to have a full welcome mat out for the indoor hang glider pilot and the wings chosen for such. Also, some hang glider pilot might want to specialize in gliding in gusty storms while doing super aerobatic maneuvers while having detachment-from-wing options; a welcome mat may be extended to such a pilot.
Pause.

[Bob Kuczewski]

From Wikipedia:

The phrase "I know it when I see it" is a colloquial expression by which a speaker attempts to categorize an observable fact or event, although the category is subjective or lacks clearly defined parameters. The phrase was famously used in 1964 by United States Supreme Court Justice Potter Stewart to describe his threshold test for obscenity in Jacobellis v. Ohio. In explaining why the material at issue in the case was not obscene under the Roth test, and therefore was protected speech that could not be censored, Stewart wrote:

I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description ["hard-core pornography"], and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that.

The expression became one of the most famous phrases in the entire history of the Supreme Court. Though "I know it when I see it" is widely cited as Stewart's test for "obscenity", he never used the word "obscenity" himself in his short concurrence. He only stated that he knows what fits the "shorthand description" of "hard-core pornography" when he sees it.

Stewart's "I know it when I see it" standard was praised as "realistic and gallant" and an example of candor.

There's a branch of artificial intelligence known as "Fuzzy Logic" where items can have "partial membership" in a set. So a person who is 6 feet tall might have a membership value of 0.8 in the "set of tall people". I'm sure we could cook up some Fuzzy Logic rules (airframedness, weightshiftedness, gliderationess, controlframedness, etc) that could be combined to tell us: AHA, That's a Hang Glider!!!

But I'm not sure that those rules would do any better than what we already understand. Instead, they might suddenly open up all kinds of corner case loop holes that make strange contraptions "hang gliders" that none of us - in our right minds - would condone. But even worse than that, if we were to define a hang glider in terms of "airframe" and "triangular control frame", and so on, what guarantee would we have that even those words might not change and lose their meanings with the shifting sands of time?

I'm not opposed to us including a definition of "hang glider" somewhere in our founding documents, but I would argue against trying to define it in our mission statement. I've always liked mission statements that were clean and clear and so easily remembered that they roll off everyone's tongues whenever needed as a yardstick to measure our actions. Of course each word in that mission statement will have a definition that can be argued in the fine print for the corner cases. But I don't want to see us sacrifice the clarity of the statement for the dubious value of nailing it down in a way that we will probably never be able to do anyway.
 
 
P.S. Having said all of that, it would be fun to try to come up with a fuzzy logic definition of a hang glider. I'd be happy to participate if anyone wants to give it a go.

[Bill Cummings]

A hang glider can be foot launched and from which the pilot hangs and controls by weight shift.

My personal opinion would be to not require weight shift as the only control method because that would eliminate almost all ridged wing hang gliders. Most non-flex wing gliders require some sort of movable control surfaces to obtain adequate control, especially in roll and horizontal direction.

If someone told me that my Skysail was not a hang glider, because of the tip "drag rudders", they would elicit some argument on my part.

Frank C.

_______________________________________________________________________
Very good point Frank. I see where my number 3 will not allow enough wiggle room.
Again: "For U. S. Hawks, what will be the focus?"
My suggestions--
1) A hang glider needs to withstand negative G's (But how much? Suggestions please.)
2) A hang glider is a wing that will maintain its shape in all normal atmospheric turbulence.
3) A hang glider can be foot launched and from which the pilot hangs and controls by weight shift.
4) A hang glider's control frame will remain manually coupled with the pilot for flight control.
-----These are just four suggestions for a start. Feel free to reword for clarity, or suggest they be omitted and by all means expanded upon.
Number 3 needs to be changed.
_________________________________________________________________-
Joe is right of course we wouldn't want to assume liability when requiring insure-ability is not the goal.
This is going to be more difficult than I first thought. However I know what a hang glider isn't when I see one.

[JoeF]

One may hang from a wing but still control the flight system by many means other than shifting mass.
Possible control methods for some hang gliders:
1. Shift mass of the pilot to various positions. This method may be fully adequate for some hang gliders. but not others.
2. Shift auxiliary masses.
3. Operate lines and rods to move aerodynamic surfaces.
4. Operate lines and rods to morph the shape of airfoils in the wing system.
5. Operate hydraulics to change airfoil positions or shape or both.
6. Operate electrical circuits to slave servos to alter airfoil positions and shapes or both.
7. Verbal instructions given to a trained dog; have the dog perform positional changes via verbal instructions.
8. Have smart surfaces in the wing that respond to various parameters.
9. Operate optical signals or laser signals or radio frequency signals to control servos that control the flight of the hang glider.
10. Operate pneumatics to effect control of hang glider flight. Air-power. Effects of inflation and deflation.
11. Control the glide of a hang glider by using a powered device. Use such to extend a glide or retard a glide.
12. Combine any of the above to obtain desired control.
13. Other means as may be described sooner or later by anyone.

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Powered hang gliders seem to be a subset of hang gliders. Non-powered hang gliders and powered hang gliders seem to be subsets within the superset Hang Gliders. Hence, a powered hang glider is a member of the set Hang Gliders. Powering need not be large; e.g. put a small fan on a WW Falcon 3 -195 that is driven by the squeezing of the hang glider pilot's hands or by the swinging of the pilot's hang line (driving a ratcheted geared torque line to the hub of the fan); the fan could be set to propel the hang glider to slightly have the gliding extended. A powered hang glider is not an unpowered hang glider. Does the future U. S. Hawks have any reason to avoid providing a platform of communications involving powered hang gliders? This very note is about powered hang gliders.

A national org need not control control methods. A national org could provide a platform where hang glider pilots share their technology about control methods. Facing a broad spectrum of niche hang gliding activity, a national org could do well to help the exchange of ideas, methods, and specifications provided by individuals advancing some niche hang glider activity.

Some hang gliders are powered by the potential energy they embody gained from the use of internal combustion engines to get to launch (cars or trucks or trains or ski lifts, etc.) Some hang gliders are powered dominantly by the potential energy held because of their positional relation with the center of the earth. Some hang gliders are powered by the potential energy accumulated by the pilot walking up a hill or incline. The potential energy is spent to power the gliding action. Some hang gliders use energy from updrafts of various sorts.

Some hang gliders' control is powered by the pilot's muscle power fueled by the food that the pilot ingests.

Some hang gliders have no live pilot aboard, but other payload.

Some hang gliders fly using a volume of space less than one cubic foot for its flight-system parts (wing set and payload set and hang line set).
Some hang gliders are fly using a volume of space much greater than one cubic foot for its flight-system.
Some hang gliders may operate fully in water instead of in air or other gases.
A two-media hang glider flight is possible. Water and air at the same time!

The wing set of a hang glider system may consist of just one main wing or may consist of two planes or two wings, etc. A hang glider may hold 29 wings or 567 wings in itself. For some part of hang gliding history, the three-winged hang glider receive substantial use; certainly the two-wing hang glider saw great use in hang gliding history; and a resurgence of two-wing hang gliders may well occur (joined, sesquiplane, high-hat, Chanute replica, Dunne evolutes, Lilienthal double-decker replica, and more).


Some common usage abbreviate what is a hang glider to just the wing; but a wing without a hanging payload is mechanically just a wing thing, not yet truly a hang glider. One will point to a tied-down Falcon 3 and say "There is a hang glider." But actually the lonely wing is tacitly just the wing of a hang glider, not the hang glider itself; a hang glider needs hung payload to be a hang glider. More: Even the hung-payloaded wing is not yet really a hang glider; rather to be a hang glider gliding in one or more media is needed to sustain the existence of a hang glider. Short of fulfillment we have just that: something that is not yet a hang glider, but potentially able to play a role of hang glider once married to a media and a gravity or magnetic field or the like that permits gliding to occur. So, though one points to a resting wing Falcon 3 and says "hang glider" such does not quite hold except through the rhetoric agreement that "device wing thing potentially useful in a hang glider" will permit the language permit of "hang glider". Many people will understand calling such as a Falcon 3 as "hang glider" even when such thing is not really yet a mechanical actual hang glider.
The language tool is very useful to many people. Notice that the literature applies a similar tool to the body of a person who does finally find himself or herself as the payload of a hang glider; I have been personally called a "hang glider" while the tool is understood to mean that I often become an integral payload hung part of an actual hang glider. Davis Straub is a hang glider (using that language tool that permits such phrasing); and he may own a stored "hang glider" (using the language tool again); but Davis and wing-thing joined and set in air gliding for an actual hang glider at times here and there; the actual hang glider holds its parts: payload set, hang line set, wing set, and media set. From all that: one may see that a hang glider is a gliding kite and thus a kite (but not all kites are hang gliders).

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Vanillaizing: Hey, are those hang gliders?

[KaiMartin]

Seems like you US Hawks founders would like the definition to serve several purposes simultaneously:

1) include all existing devices you want to be included
2) exclude all existing devices you don't want included
3) include all future devices you want to be included
4) exclude all future devices you don't want included

The last purposes are the most difficult. You just don't know what is going to pop up in the future. IMHO, there is no way to know in advance whether or not the future device would make a welcome addition or should be referred to its own orgs. Consequently, I'd not try to deal with future devices at all. After all, the definition can be amended if/when new types of flying devices become viable.

By comparison, the first two goals are relatively easy to meet since all the potential candidates are already known. I'd go for:

a) must be able to be launched on foot
b) must maintain its shape on the ground at zero speed

The first requirements should conveniently include all devices commonly referred to as "hang glider" but not the devices known as sail planes or general aviation. The second requirement serves to exclude current PGs. At the moment I don't see a convincing reason for more specific requirements.

---<)kaimartin(>---

[JoeF]

Nice, Kai. Thanks for the careful reflection.

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https://www.facebook.com/mitsuya.sakamoto/videos/756587421135054/?fref=nf
I could not find the video outside of the Facebook frame.

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Shape? Here is a guy that did not keep his flying shape once on the ground: bird.


The flight shape of the Miller 1965c Bamboo Butterfly at-Dockweiler under glide loading had a shape. If the wing-pilot flight system met with enough turbulence, then the shape of the sail could become flaggy or even inverted for another shape; the wing at park in zero wind brings yet another shape. The frame would stay pretty stable in geometry during flight with positive or negative g, or when parked in no wind on the ground.

Richard_MillerDOCKWEILER.jpeg (158.07 KiB) Viewed 5095 times

[Frank Colver]

a) must be able to be launched on foot
b) must maintain its shape on the ground at zero speed

The first requirements should conveniently include all devices commonly referred to as "hang glider" but not the devices known as sail planes or general aviation. The second requirement serves to exclude current PGs. At the moment I don't see a convincing reason for more specific requirements.

Under those defs my balloon would qualify as a hang glider.

Inflation.jpg (244.25 KiB) Viewed 5096 times