US Hawks Hang Gliding Association

Novel Concept of Launching one or more Hang Gliders
This topic thread will explore use of a certain novel method of flying for the purpose of launching one or more hang gliders into free flight. The first disclosure of the novel method of flying was posted in AirborneWindEnergy form. The first title of the general method: Powered Kiting by Polygonal Centroidal Cyclic Winching and Gliding. The general method may be applied to involve hang glider wing as payload or as participant in the flight up to the point of full release of the hang glider.

How might the method work? There are two dominant geometric arrangements, but other spider-web arrangements and other nets are to be explore. The two dominant simpler arrangements are the spoked arrangement and the polygon perimeter arrangement. The nodes or satellite wings at the end of the spokes or at the vertices of the polygon are equipped with powered winches. The spokes are tethers; or the perimeter edges of the polygon are tethers. Tethers connect from one wing to another.
When the winches are powered to collect tether, then the wings are kited; the polygon get smaller during the kiting phase. Once the kiting occurs and the centroid is close enough for comfort, then the many wings (two or more) stop powered winching; then the wings glide out away from the centroid (or some other point interior of the implied polygon). During the glide out some of the wings in the system may utilize updraft or be affected by downdrafts or other turbulence. When adequate gliding has occurred, then the system of wings may begin powered kiting again toward the centroid of the implied polygon or some other chosen point interior of the large implied polygon. The powered kiting will aim for another cycle of kited climbing up into the atmosphere.

One simple example of the method may be illustrated by having two hang gliders at the end of one tether. The hang gliders are facing each other. The long tether connects to the winches in the hang gliders; or one might choose to have no winch in one hang glider and a winch in the other hang glider. Begin operations: start the winching; close the distance between the two hang gliders during the kiting; both hang glider are being kited together; each hang glider is effective anchor to the other hang glider; they both climb up away from the surface of the earth. Once the tether is shortened enough, then the hang glider glide away while slackening the tether; the hang gliders soar as they might while still connected by a slackened tether; then upon reaching good distance from each other, the powered hang glider (or both) begin the cycle over again with a powered kiting phase; they then kite up more. Etc. No propellers; no jets; no rockets; no balloons, but just winching for the special kiting format. Then in this simple case, the two hang gliders may decide to cut free; one of the hang gliders would be given the line and the line would be collected into the hang glider. Off to soaring adventures they could go. Two hang gliders would then be into free-flight.

Three hang gliders could be tethered together in a triangle with tethers being the triangle perimeter edges. Alternatively the three hang gliders could use the spoke method.

Consider launching 10 hang gliders at once by the topical method; decagon. Climb up and exercise some cycles until desired altitude is wanted. Then release from the method and all ten hang gliders go into free-flight gliding/soaring.

The method may be used to travel some horizontally or to rise above a given region of earth or other planet. The method may be used in water depths with paravanes. The method might use the surface of lakes or seas or oceans for launch points. Or the vast ice fields.

kPower, Inc. is handling IP rights for the method; easy does it for non-commercial exploratory private uses of the method. Commercial uses of the method will be having a higher order of relationship with kPower, Inc.

Some investigators are exploring the general method for producing electricity. And other applications. If any readers have application ideas for the general method, consider posting your ideas.

Control, failure modes, and other safety matters are to be mastered for each expression of the subject method.

The method is a cousin to step-towing. And the method is a cousin of what Jack Lambie in early 1970s within hang gliding realm suggested: have earth surface as one wing; have winch in sailplane; set out the long tether; winch power kite oneself up to good altitude; remotely release from the earth wing and pull the tether into the sailplane (or hang glider). Soar some. Land. Set up another attaching of long tether to the earth wing; then power winch self up again; again release from the earth-wing anchor.

This really is a novel concept Joe!!!

The efficiency of the opposing wings acting as anchors for each other might be much higher than using a propeller for thrust.

There are a lot of potentially messy (translation: dangerous) issues to work out, but it really is a very novel and clever idea!!!

                            

Having done "Step Towing," I can see where two expert step tow pilots could winch toward each other, connected to nothing but each other, completely unattached from the ground.
Problems to solve would be staying almost perfectly choreographed. (wing loading and everything else considered.)
Flying away from each other and reeling out the line for the next convergence tow cycle would pose problems.
1) If you exhausted the length of towline before turning back toward a nose to nose orientation for the next tow cycle.
2) If the reel(s) failed to let out line while in a tail to tail orientation, flying away from each other.
3) Not dipping the inside wing down under the towline when turning back to a nose to nose orientation for the next tow cycle.
(My palms, feet, and arm pits are starting to sweat --- I've got to pause here-----

Neat concept but it would seem simpler and less dangerous to replace the electric (I assume) winch with an electric motor and propeller to fly the glider up into the sky for seeking thermals. I do this with my electric powered RC gliders and have had many a simple launch and enjoyable soaring flight.

Of course it's always fun to imagine "outside the box" as they say.

FC

Bob Kuczewski, Bill Cummings, Frank Colver,
Thanks for your glances, time, thought, and early commentary! You three are making history. Historic commentary sequence: Dave Santos, Bob Kuczewski, Bill Cummings, Frank Colver, ... . Each of you have already contributed positively.

The high count of possible planned sessions using the general method in one of its several topologies is daunting; explorations with even the most simple arrangements will be pointedly challenging. Modelers might explore the new world. One first configuration and mission might be the perfecting of just one winching leg followed by full parting before entering a connected glide-away; that is, shunt the method just before glide-away; use two wings; control AoA at each of the two wings during the winching. I had disclosed a simple Bungee Leap where a bungee draws two wings together for a kiting of each wing to some altitude (Bungee Leap for three and more wings follow the method of topic, but the winching is replaced by stretched bungee).

Stay open for even specialized wings to face the opportunities. A wing that may not need to make turnabouts, but only morphed geometry, might solve a niche mission.

As Bob and Bill seem to imply: there may be a great adventure getting beyond "messy" and "sweat" to skilled joy. Failure mode clarity will be key.

Of course, in the long run into future, the amount of use of the general method cannot be known until said future arrives.

An open question in the realm: Will some kinds of aggregate stability arrive when wing count increases for some special missions using the general method? Consider 100 hang gliders in a spoked format. Or will the opposite occur, that is, will high wing count bring system failure more easily than if wing count was lower (toward two wings)?

There may be some very specific niche purposes for the topic's general method that wins over alternatives.

Single-wing self-step towing with anchor to solid earth might be a preamble exercise. The wing Earth would be unchanging; the HG would winch in, kite up, go to slack line in glide-away-from-anchor, then cycle into taut winching again. Winch at anchor for such is already being done for the non-stepping, but just for straight-away tow up. Jack Lambie wanted to carry the winch in his sailplane for the non-step self-tow-up; he did not suggest step cycles of such.

As I was considering this, one of my main thoughts was there were many many ways to mess it up. I think with people making the decisions (timing, turning, etc) that's bound to happen. So I was mulling over the possibility of using an automated control system, but that still doesn't sit too well with me.

But your suggestion of using models is a good one. Their programs (software) could be worked out in simulations and then tested with real models.

As I mentioned, the only benefit I can see is possible efficiency because the wings of the two gliders can be much larger thrust surfaces than the disk swept out by a typical propeller. And since efficiency is the goal, it would also be important to keep the long (and draggy) tether from sweeping through the air creating losses. So one constraint of the optimization program would be to keep the tether fixed within the airspace so there is no drag due to its transverse motion (maybe even due to its axial motion?).

I think this would be a good project for an aeronautical engineering student.   

Blessed with my hyper-vigilance (my wife calls it a curse) I've conjured up another possible glitch in the two, Step Tow Pilots, convergence towing method for hang gliders.
Picture this scenario:
"Gentleman, I'm BLM Field Officer Sgt. Justin Case, and you two have your vehicles parked on BLM land nowhere near a prescribed road, and in a motor-less area and that winch falls under the motor-less violation clause. I'll have to cite you both!"

Bill says: " Ahhh come on officer, -- It was all Joe's idea and he is the only one with a motor inside his glider why do I have to get a ticket?"

Joe says: "Hey Bill, it was you that said this would work, and but for you our egress to alight would be absent fruition."

Bill whispers - hisses really: "Shut up Joe, if Sgt. Case cites for only one motor I'll split the fine with you."

What length of towline could be laid out between two gliders on the Salt Flats?
It might take two carbon fiber spools in each glider for gathering up all the line that would be laid out.
(Maybe the winch could chop it up as it takes it in and spit it as waste out the back so the load gets lighter as you tow.)
The over all extra weight would be a consideration. Take up speeds would be slower winching with each glider having a winch.
Each gliders tow force requirement, I'm guessing, would be 60 lbs. (So how does that work out? For every action there is an opposite reaction?)
Would 60 lbs tension mid line be okay or does it need to be 120 lbs.?
Since the tow force would be mostly horizontal with very little vertical component the efficiency should much higher than surface towing. The drag on the line should be way lower than surface towing.

Great stepping, Bill.

Open for physics corrections:
Assuming the simple case of two HGs terminating one long tether line:
Tug-of-War. The line tension does not know the title of what is occurring at the ends; the line simply knows that it is tensed; if the line is tensed at 60 lb then there is is pulling on each end wing of 60 lb, but in opposite directions, thus tension. In Tug-of-War a different matter determines winner or motion past a point in the frame of reference: friction. The HGs will lift-drag for a resultant; motion relative to the frame will be equal or unequal depending on the friction of the two wings; if the friction of HG#1 is exactly equal to the friction of HG#2, then assuming full wind calm, the ground trace would be at equal speed. There would be a closing speed: HGs approach one another at a closing speed; but the apparent wind for each hang glider would be about half the closing speed. Consider pairing Falcon III HG with Boeing 707 with engines off as one HG; have 60 lb tension in the line; the closing speed is the same for observer in the 707 cockpit as it is for the pilot of the Falcon; ground trace in calm: 707 might have so much friction on the ground, that its ground trace might be negligible while the Falcon would have significant ground speed; the 707 in calm would not fly; the HG would know the 60 lb maintained by the winching as ground trace and speed would see the HG kited.

In case of the two nearly equal HGs, the closing speed closely matches the amount of line that is being collected on the reel(s) while both HGs see the 60 lb tension; since the "anchor" to one HG is sliding through the air, then the amount line being collected is about twice the amount of line that would be collected if the "anchor" was not sliding through the air. Say HG#1 needs 20 mph apparent wind and HG#2 needs apparent wind of 20 mph; they would close to each other at 40 mph approximately. Still assume calm air (but once equilibrium is reached off the ground, then wind won't matter anyway for the HGs; they just need to close relative to each other at 40 mph. If there is wind, then the ground trace of the system would net downwind; this note does not face differential turbulence for the separate wings. So, have clear airspace downwind of the operation.)

Note on the tether: It seems during the operation of the two-equal-HG case, that the line is experiencing no apparent level wind, but a vertical apparent wind related to system-climb-rate while only the HGs are experiencing apparent horizontal wind. Upon equilibrium while winching is occurring the system is going downwind like a climbing floating balloon. The system climb rate does set up a traverse apparent wind on the exposed coupling line.

Bill seems correct that splitting to two winches splits the line take-up rate for each winch; each winch taking in line at 20 mph would give the 40 mph closing rate. Having just one HG equipped with winch would have that one winch taking up line at about 40 mph.

Idea on Bill's motorless deal: Bungee Leap the HGs; then once in the air, if wanted, then start the powered winching scheme. Thus, while on BLM motorless area, the bungee might be considered as motorless. But then while in the upper airs, begin the motors.

Joe's three quotes:

Note on the tether: It seems during the operation of the two-equal-HG case, that the line is experiencing no apparent level wind, but a vertical apparent wind related to system-climb-rate while only the HGs are experiencing apparent horizontal wind. Upon equilibrium while winching is occurring the system is going downwind like a climbing floating balloon. The system climb rate does set up a traverse apparent wind on the exposed coupling line.

Oh I think I get it. The horizontal rigged towline would be drug up vertically as the two converging Falcons ascended.

Bill seems correct that splitting to two winches splits the line take-up rate for each winch; each winch taking in line at 20 mph would give the 40 mph closing rate. Having just one HG equipped with winch would have that one winch taking up line at about 40 mph.

My wife says I have a knack for always focusing on the bad stuff -- and look out -- here I go again:
Just how would Joe and Bill --- (STRIKE THAT)--- Just how would Joe and Bob set up for a convergence tow in a west ten mph wind?

What would be the plan for tension compensation should Joe's nose angle, on climb-out, be 5 degrees greater than volunteer Bob's angle of attack? As a result would Joe's higher parasitic drag start a repetitious, non-harmonic, surging in the convergence towing system?

If a thermal broke off ahead of Bob's glider, by about 100', giving him a momentary 3 mph lower airspeed at his end (until he flew into the thermal) could Bob expect Joe's end to dilute/mitigate Bob's airspeed deficit by half?

Idea on Bill's motorless deal: Bungee Leap the HGs; then once in the air, if wanted, then start the powered winching scheme. Thus, while on BLM motorless area, the bungee might be considered as motorless. But then while in the upper airs, begin the motors.

We could test -- (STRIKE THAT.) -- You and Bob could test that legal theory but first ease into it by using a Sky-Hook Helicopter to airlift a car, minus the motor, into a motor-less area. Then wait for Sgt., Case to articulate, or not, any probable cause for violation. (Be sure first thing to check on the currency of the vehicle registration and insurance.)