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Perpetual Tethered Flight  (PTF)
by Perpetual Tethered Flight Systems (PTFS)

Other sectors of aviation are exploring perpetual untethered flight.  Differently this study stays about perpetual tethered flight (PTF).  The resistive set of proposed perpetual tethered flight systems may be found operating in a great variety of manners; one manner is for the resistive set of the kite system to be a wing set itself. The wings of the kite system intended for perpetual flight also may arrive in a great variety of manners.  Keeping a wing set flying is the target of "perpetual" in PTF.  Flight durations of PTFS will increase over records now known.  The increase will come from the draw of tasks, interests, needs, competition, and advanced technology and materials.  Depending on the site, scale, and tasking, the challenges for PTF are many.  PTFS of FFAWE form a family of systems; PTFS that are not free-flying form the rest of the family of PTFS.

For a warming up to PTF, consider an example from Nature:   Hang a leaf part from a spider silk. Such flight systems are active millions of times over each day on earth. The small kite system persists until something destroys it partly or entirely; we do not know the most enduring of such systems.   wiki/Spider_silk   The anchor of the silk might be a tree, rock, ceiling, web, machine, etc. The leaf part dries; if the leaf part is not rained upon and is protected somehow from attack by microbes, the persistence of the little leaf-silk kite system would be strong.  What is the life of a spider's silk?

Humans may mimic such a system as the spider-silk-leaf system and hang a wing by a tether from a bridge or pole or ceiling or cable.  The wing would persist in flying for years and decades if the tether and wing and scene were helpful. If the hung wing and tether rotated something at the wing or at the anchor set, then generation of pumping or electricity could result; if the generation parts were at the base, then the wing could stay hanging out at the end of the tether set while a replacement or repair could be made in the generation parts.  Many of us probably have a PTF in our porches or gardens already in hung wind chimes generating pleasant sounds or pleasant motions; the tether used to hang the wings is the tether of the PTF; the tree or rafter or pole, etc. play the role of the resistive set for the PTF.  The actions of the wings tethered arrive from the wind and design of the wing set; a very wide variety of actions or movements are possible. The parts may remind us of HAWT, VAWT, wobblers, flip wings, dancers, impactors, clangers, hammers, twirlers, stretchers, rollers, etc.   

When the tether set gets long, then the simple hanging from structures runs into challenges. How to keep a wing set flying without the wings smashing into objects or the ground when the tethers are 800 m  long? We can then no longer depend on bridges or towers to keep the wing set up.   One would consider cables between mountain peaks. But also one might consider other means to keep the wings flying during lulls or inadequate natural wind. Power the wings and fly the wings captive by tether; or power the wings by moving the anchor set to create sustaining apparent wind for kiting the wing set.

Easy example of PTF that is not pendulum hung:   Have a circular path indoors, say a model train track and an electric train. Anchor a tether to the train and to a flying kited wing. Run the train around the track perpetually; Have ready a replacement engine for when the train engine needs replacement or repair; keep the kite flying indoors for years nonstop. Have replacement track, etc. ready for change out; the wing need not come down until the tether molecules sublimate away; but even for the tether one may conceive of change-out of tether while wing stays flying. What about the sublimation or wear of the wing?  Self-healing or during-operation-replacement may be conceived. Ever keep the system flying.  Of course, this indoor powered-anchor example is not producing energy for the grid; but charge people to see the PTFS operating and a profit could be realized.     But we go on towards effective PTF AWES that may supply travel or energy for third parties.

Wing sets of PTFS may have adjustable buoyancy. Some wing set may involve LTA gases.

Why PTF?  Avoid bringing wings into storage. Keep a kited home aloft. Keep production cycles as long as possible.  Keep the kited city in the air. Keep the cabin in the air as the cabin is moved around the world. Be immediately ready to move into production cycle without the cost of launching the system all over again.

Weather?  Move wing sets to safe zones while still flying.

Endurance records for PTFS?   In ten scales of PTFS what are the endurance records?

Costs?   It will cost something to keep a tethered flight system flying. Any particular actual PTFS will have its cost profile. Will a project be worth actualizing?  Some entertainment rides at amusement parks are PTFS. Will practical utility scale AWES see PTFS operating?  Compare the costs of persistence against the cost of downing, storing, and relaunching.  Seek aloft-recharge of LTA elements; lower leak rates of wings.

  • CC BY NC SA        ~ ... world team ...     Summary effort by JoeF     14Aug2013           

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