US Hawks Hang Gliding Association

This topic aims to deepen bungee-launch of hang gliders while being on flatland (not on slopes or hills).
Bungee launching is a form of towing/motoring where the "engine" is stretched springs or rubber bungee or the like. Such towing via energy stored in a towing system requires special cares for safety, training, inspection, loading, assistant training, etc..

[For a cousin flatland topic, see: Flatland Hang Gliding without towing or motoring ]

Wouldn't it be possible to use a loooong bungee rope to tow low and slow?

1) Anchor one end of the bungee to something sufficiently heavy. A car would be a likely candidate.
2) Attach a drogue chute to the pilot end of the bungee. This is to avoid excessive accelerated snapping of the rope after release.
3) Hook into the glider and attach the pilot end of the bungee to the tow bridle
4) Slowly walk backwards and stretch the bungee as much as possible.
5) Stop for a few seconds to get focussed and adjust the angle of attack of the wing.
6) Give in to the tow of the bungee and start running towards the anchor.
7) Make sure to release the bungee when it goes slack. (Bonus points for an automatic release)

Expected result: A few seconds of flight and an opportunity to practise your landing skills.
Bungee towing may be not as cool looking as a hover board. But it requires less horse power and sounds like it would be affordable for my recreational budget :^)

---<)kaimartin(>---

I once had an idea to use a ATV (ORV) to stretch a bungee between to ground stakes.
On end would be the fixed anchor point.
The launch end would hook to a release that could be tripped by the pilot by backing up so that the calf of the pilots leg would trip the release from the launching end of the bungee from its anchor point. The tow bridle would then come under tension and pull up the pilot and glider.
The biggest hurdle at the time was finding the right kind of bungee cord.

JoeF wrote:This topic aims to deepen bungee-launch of hang gliders while being on flatland (not on slopes or hills).
Bungee launching is a form of towing/motoring where the "engine" is stretched springs or rubber bungee or the like. Such towing via energy stored in a towing system requires special cares for safety, training, inspection, loading, assistant training, etc..

[For a cousin flatland topic, see: Flatland Hang Gliding without towing or motoring ]

Wouldn't it be possible to use a loooong bungee rope to tow low and slow?

1) Anchor one end of the bungee to something sufficiently heavy. A car would be a likely candidate.
2) Attach a drogue chute to the pilot end of the bungee. This is to avoid excessive accelerated snapping of the rope after release.
3) Hook into the glider and attach the pilot end of the bungee to the tow bridle
4) Slowly walk backwards and stretch the bungee as much as possible.
5) Stop for a few seconds to get focussed and adjust the angle of attack of the wing.
6) Give in to the tow of the bungee and start running towards the anchor.
7) Make sure to release the bungee when it goes slack. (Bonus points for an automatic release)

Expected result: A few seconds of flight and an opportunity to practise your landing skills.
Bungee towing may be not as cool looking as a hover board. But it requires less horse power and sounds like it would be affordable for my recreational budget :^)

---<)kaimartin(>---

Joining ARP's neat post into this topic thread:

Re: Flatland Hang Gliding without towing or motoring
Post by ARP » Thu Jan 14, 2016 12:25 pm

Bungee launching a primary glider from flatland:- https://www.youtube.com/watch?v=w9tE-OWyuK0

Model flyers use medical rubber tube for launching gliders. It is also used in fishermen bait catapults. For a foot launch HG maybe several lengths used together would give sufficient force to get in the air.

For release a rear facing hook without a gate on the harness and a ring on the line would automatically fall away when the glider passes over the end of the line.

Note: Consider seeing that bungee launch is a type of rubber motor launch system that invites very specific safety concerns for the "motor". Various motors that form a towing motor: bungee, car, truck, animals, friends, falling masses, active tug rafts, motored boats, ships, airplanes, parachute prime movers rigged through pulleys, kite systems as prime movers rigged through pulleys, scooter prime movers, payout vehicle tows, rising balloon rigged to tow hang gliders, etc. These towing motors invited specialized gear and skills to be made safe. All mentioned form kite systems where the hang glider is a wing of the kite system while the anchor of the kite system is a prime mover motor that tugs the hang glider wing. While the towing is occurring, the system is not "hang gliding" but rather is powered-anchor kiting (if pilot is on the hang glider wing, then "manned kiting"using powered anchor system). Each specialized powered anchor method for kiting a hang glider for launch could merit a robust topic thread for study, discussion, and input toward mastery. The quiet of a hang glider by itself is not the complexity of a hang glider being towed by some kind of motorized prime mover; highly respect the physics of any kind of towing (kiting) of a hang glider by giving fully adequate attention to the details of the "motorized" system which is very strongly different than just hang gliding in itself.

Joining the drop-mass motor method indicated in msoaring's fine post to this topic thread:

Re: Flatland Hang Gliding without towing or motoring
Postby msoaring » Fri Jan 15, 2016 10:41 am

Drill a deep, 10"-12" (or bigger?) diameter hole in the middle of a large flat area and line the hole with sections of pvc sewer or water pipe. The pipe would have sealed joints and a sealed bottom so that water cannot penetrate. Place a pulley above the hole using a designed mechanism which allows 360° rotation. Attach a very heavy (appropriately sized, cylindrical shaped) weight (lbs. to be determined) to a steel cable. The length of the cable coincides with the depth of the hole times two plus 10%. Pull the cable down wind, which raises the weight, and attach to preset anchors in the ground (steels stakes with enough depth and strength to hold the line tension every 10° of 360°, at the correct distance from the center) It would look like an azimuth or clock face from above. Using a Schweitzer style tow release between the cable and anchor stake, the pilot would release the cable from the stake using a light line connected to the Schweitzer release for launch. The pilot would be attached to the tow line (cable) with a typical hang glider release system. As the weight descends, the hang glider ascends. The deeper the hole, the higher the tow. The weight could be raised using a golf cart for convenience.

Doable?

msoaring, the drop-mass method family is deserving of a topic thread on its own. Yes, doable. Recall Wright Brothers drop-mass (though mass was towered rather than holed). Variations on the drop-mass are many; each variant may become part of the discussion. Consider abandoned well holes that could be lined and evacuated. Consider possible safety advantage of two holes with V bridle for the towing during drop of two masses. Consider speed changes with V bridle with one drop mass and the other part of the V fixed to anchor. Consider instead of "steel" stakes various soft anchoring systems or gabion anchor systems; uprooted steel stakes are not fun flying objects. Consider water as a drop mass. Much more for getting to satisfactory safe systems and procedures.
Notice: A hole could be less deep while adding heavier mass to draw line through a system of sheaves to get the speed and force desired.
Notice: A rubber motor could be compact and THEN connected to a non-elastic tow-line set. The compact rubber motor could become equivalent to a "hole-drop-mass motor". Consider a confined box holding many rubber loops; gang the stored energy; then have a system of lines that speed up the final tow-line set.

msoaring, also maybe consider the invert hole in the sky using LTA or kite or parachute prime mover in the "motored" system: Let the "hole" be the open vertical sky. Let the soil-anchored pulley system be on the ground. Let a LTA balloon or a kite system or a tethered parachute system draw the tow lines (perhaps Vee line set); the LTA, etc. movers rise or drift to pull the HG launch line set (perhaps Vee). After each launch of the HG, then depower the prime mover and reset for another HG launch tug.

ONE WRIGHT INVERTED HOLE (hole in sky, towered drop-mass):
http://www.wright-brothers.org/Information_Desk/Help_with_Homework/Wright_Photos/Wright_Photos_images/1909_Model_A_and_Catapult_in_France.jpg
See someone's drawing: HERE.
Sketch HERE
Adding potential energy for use in the catapult drop-mass system: [urlhttp://www.sciencephoto.com/image/644989/530wm/C0236441-Wright_Flyer_II-III_catapult%2C_1904-5-SPL.jpg] HERE[/url]

Abandoned well holes
Teaser start:HERE

J.J. Montgomery and balloon:


Rubber motor: