[JoeF]

With this prompt:
ARP has suggested exoskeletal treatments or appliques on TPHG leading-edge region of TPHG sails. Please explore that suggestion and propose ways and means to accomplish aerocurving and airfoil forming with such methods.

Be prepared for errors and misapplications. Be prepared for poor ideas that nevertheless might inspire:

1. Materials for Exoskeletal Treatments

1. Composite Tapes and Strips
   
   • Use lightweight, high-strength materials like carbon fiber, Kevlar, or fiberglass tapes.
   • Apply these materials externally along the leading edge to form curved reinforcements.
   • Adhesive bonding or heat-activated resins can secure the strips to the sail fabric.
2. Thermoplastic Films
   
   • Use heat-formable films (e.g., Mylar or polycarbonate).
   • These films can be shaped to a desired curvature when heated and then bonded to the leading-edge fabric.
3. Inflatable Bladders
   
   • Integrate small, air-inflatable tubes or bladders along the leading edge.
   • When inflated, these structures can introduce a smooth, controllable curve to the sail.

2. Techniques for Implementation

1. Laminated Sails with Exoskeletal Inserts
   
   • Layer flexible but structured strips or ribs between layers of sail material.
   • The ribs should be shaped and positioned to form a continuous, smooth airfoil curve.
2. Molded Appliqués
   
   • Create custom-molded exoskeletal components that fit the leading-edge region of the sail.
   • These can be attached via hook-and-loop systems or sewn into pockets for easy installation and adjustment.
3. Seam-Integrated Treatments
   
   • Integrate stiffening materials directly into the seams of the leading edge.
   • Stiffening rods or strips can be housed in seam pockets to provide structure and curvature.

3. Adjustability for Field Tuning

• Elastic-Backed Ribs: Add flexible but shape-retentive exoskeletal strips with elastic backing for tension adjustments.
• Segmented Appliqués: Use segmented exoskeletal strips with hinges or connectors that allow adjustment of curvature and airfoil shaping.
• Dynamic Systems: Employ tensioned cables or lines over exoskeletal components to dynamically alter the airfoil shape.

4. Integration with TPHG’s Structural Elements

1. Leading-Edge Sockets
   
   • Design leading-edge spar sockets to accept additional tension or compression forces applied by the exoskeletal elements.
   • Use quick-connect fittings for ease of assembly and adjustment.
2. Attachment Points
   
   • Include small reinforced loops, rivets, or adhesive pads on the sail for securing exoskeletal treatments without damaging the fabric.

5. Computational and Physical Testing

• CFD Simulations: Use computational fluid dynamics (CFD) tools to optimize the shape and placement of exoskeletal appliqués for the desired airfoil.
• Wind Tunnel Testing: Build prototypes with varying designs and test in wind tunnels to assess lift, drag, and overall performance.

Potential Challenges and Solutions

• Weight Addition:
  
  • Use ultra-lightweight materials like foam cores wrapped in carbon fiber or Dyneema-reinforced fabrics.
• Flexibility vs. Stiffness:
  
  • Combine stiff elements for structure with elastic components to allow some flexibility under load.
• Attachment Durability:
  
  • Opt for adhesives that remain flexible under extreme temperatures or sewing patterns that distribute stress evenly.

Example Implementation: Carbon Fiber Exoskeletal Rib

• Apply a thin carbon fiber rib along the leading edge.
• Bond it to the sail using a flexible epoxy or insert it into a pre-sewn sleeve.
• Shape the rib to induce a slight camber for optimal lift at low speeds.
• Test in varying wind conditions to ensure structural and aerodynamic compatibility.

[JoeF]

Maybe one day we will see thousands of paraglider wings being used to sail a hang glider frame and be tiny packed!

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My prompt to an AI assistant ChatGPT:
Analyze the pros and cons: Proposed TPHG of particular design: bowsprit, 130 degree nose angle, frame of the keel that has the bowsprit tube, two leading edge tubes, kingpost, two queenpost, cable rigging above and below to fix geometry spatially of frame, a beam inboard of tip that goes from LE tube and then aft as chord (line stay the aft end of that beam from above to kingpost apex and from below to queenpost of the same side. Then from that special beam inboard to keel use an old ram-air paraglider wing with its tip cut away. Loop string the lower leading edge of the paraglider sail to the hang glider's leading edge tube. From the aft tip of the near-tip beam have a taut webbing of 3/4" width anchored to aft of keel tube. Assembly: put leading edge tube through the loops of the paraglider sail's front lower leading edge. Use small alligator clips or the like to clip the aft edge of the paraglider sail to that taut webbing. During assembly place a vertical CF whisker vertically in each ram-air cell's center at the front of the cell (to ease quick inflation at launch). Outboard of the chord beam will be a single sheet of sail (not ram-air). The rigging has a lower crosslines that go to the two queenposts bottoms and continue to one side to the other forming a "basebar" that is cable, not bar; during wing loading that "basebar" that is not a bar but is a cable will be a "control cable".

The AI ChatGPT gave response: [[Be watchful for errors. ]]

Your proposed TPHG design includes a bowsprit, a 130-degree nose angle, and a frame featuring:

• A keel with a bowsprit tube.
• Two leading edge tubes.
• A kingpost and two queenposts.
• Cable rigging above and below to fix the geometry of the frame spatially.
• An inboard tip beam connecting the leading edge tube to the aft chord.
• Rigging to stabilize this chord beam: one stay from above to the kingpost apex, another from below to the queenpost.

Wing design:

• The inboard section uses a ram-air paraglider sail with its tip cut away.
• The lower leading edge of the paraglider sail loops around the hang glider's leading edge tube.
• A taut webbing (3/4" wide) runs from the aft tip of the inboard chord beam to the keel.
• The outboard section uses a single sheet of sail, distinct from the ram-air section.

Key assembly features:

• Leading edge tube is threaded through the paraglider sail's lower leading edge loops.
• Aft edge of the paraglider sail is clipped to the taut webbing using small clips (e.g., alligator clips).
• Vertical carbon fiber whiskers are placed at the front of each ram-air cell to aid inflation during launch.

Control considerations:

• The lower rigging includes crosslines forming a "basebar" of cable, which acts as a "control cable" under wing loading.

Pros:

1. Lightweight Design:
   
   • Cable basebar reduces weight.
   • Using a paraglider sail saves material.
2. Modular Assembly:
   
   • Compact, disassembled packing meets TPHG goals.
   • Quick clipping of sail sections for ease of setup.
3. Innovative Features:
   
   • CF whiskers aid cell inflation during launch.
   • Combining ram-air and single-sheet sections optimizes load distribution.
4. Rigging and Geometry:
   
   • Robust stabilization via cable rigging and dual posts (kingpost and queenposts).
   • Efficient load management with taut webbing and chord beam rigging.

Cons:

1. Structural Complexity:
   
   • Multiple components increase potential failure points.
   • Cable basebar may impact handling in turbulence.
2. Assembly Challenges:
   
   • Threading tubes and attaching clips might be tedious in windy conditions.
   • Setting up CF whiskers adds steps to assembly.
3. Performance Trade-offs:
   
   • Wide 130-degree nose angle might reduce roll efficiency.
   • Transition from ram-air cells to single-sheet sail may introduce drag.
4. Durability Concerns:
   
   • Clips and webbing may require frequent replacement.
   • CF whiskers need careful transport and handling.

Suggestions for Improvement:

• Simplify trailing-edge attachment with snap-on systems.
• Add a rigid section to the cable basebar for better control.
• Smooth the airflow transition between wing sections.
• Use tension-adjustable anchors for rigging.
• Replace clips with durable, lightweight fasteners.

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The 2024 RAeS President’s Conference saw a packed audience from around the globe discussing how best to instigate a system that would allow university students to design, build and, ultimately, fly their own aircraft.

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[JoeF]

Fun paper with some things that may well inspire TPHG solutions:

https://www.aerosociety.com/media/23277/paper-2024-02-jarrett-human-flight.pdf
Journal of Aeronautical History
Paper 2024/02

HUMAN FLIGHT — SEEKING THE NATURAL SOLUTION*
By Philip Jarrett


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[JoeF]

Packing TPHG onto bicycles?
And consider folding bicycles for getting on the bus while TPHG reverts to one or two packs. Get off bus, unfold bike, mount two packs holding TPHG.

Packing TPHG onto Bicycles?

Integrating your Tiny Packed Hang Glider (TPHG) into an urban transport system with bicycles can be a highly effective solution for maintaining mobility while reducing the volume of the hang glider for easy transport. Here are some thoughts and strategies on how to advance this concept:

1. Packing the TPHG for Bicycle Transport

Given the compact nature of the TPHG, the key is to maintain its minimal packing size while ensuring ease of attachment and detachment to a bicycle. Since your design requires the TPHG to be packed into one or two sets, the challenge is figuring out how best to securely mount these packs on a bicycle, particularly on folding bicycles.

• Backpack or Frame-Mounted Packs: Design your TPHG to be housed in lightweight but durable packs that can be easily secured to a folding bike. One option is to use a single large, streamlined pack that could either fit on the rear rack or be worn as a backpack. Alternatively, two smaller packs (left and right wing sets) could be secured to pannier racks or a custom frame-mounted system that balances the weight efficiently.
• Tailored Packs: The packs should be custom-designed to fit the shape and dimensions of the TPHG components while minimizing the risk of damage to the glider. Use durable, weather-resistant materials for the pack construction, ensuring they are easy to open and access when necessary.

2. Using Folding Bicycles for Bus Travel

Folding bicycles can serve as the ideal solution for taking the TPHG on public transportation like buses. Their compact size allows easy stowing in bus racks or within the vehicle itself. The key advantage is that the glider can remain packed, avoiding the need for disassembly or cumbersome handling.

• Folding Mechanism: Choose a folding bike that folds quickly and compactly to meet the tight space requirements of buses or trains. Opt for a design where the bike can be folded in under 30 seconds and carried or stored easily.
• Compact, Transport-Friendly Design: The folding bike’s storage area (e.g., under the seat or in the overhead compartment) should accommodate one or two packs containing the TPHG. The packs can be adjusted and tightened for a secure fit, ensuring no shifting during the ride.

3. Unfolding the Bike After the Bus Ride

Upon disembarking from the bus, the rider can quickly unfold the bike, mount the two packs onto the bike frame (either through straps, clips, or a custom rack system), and proceed to the launch site.

• Quick Unfolding System: Ensure that the bike folds and unfolds easily, without requiring significant effort or tools. A quick-release mechanism for attaching and detaching the packs can make the process even more seamless.
• Adjustable Pack Mounts: Consider designing a system of adjustable straps or clips that can securely fasten the TPHG packs to various parts of the bike (e.g., front and rear racks, sides of the bike, or on a specialized frame attachment system). These mounts should be robust enough to handle the weight and ensure stability during the ride.

4. Convenience and Versatility

The ultimate goal is convenience for the pilot, allowing them to take both the folding bike and TPHG with minimal hassle. Features such as lightweight materials, quick access to packs, and easy-to-use fastening mechanisms will make the system efficient for urban travel.

• Dual-Use Packs: Design the packs to serve a dual purpose—both as a storage system for the TPHG and a transport solution on the bike. These could include integrated compartments for additional gear like helmets, gloves, or tools, ensuring that everything needed for the flight is easily accessible.
• Enhanced Mobility: This method of transportation provides ultimate flexibility—allowing the pilot to use the folding bike on buses, trains, or even through urban environments, before heading to the launch site with their packed TPHG.

By combining a folding bicycle with a streamlined, efficient system for carrying the TPHG, you enable the pilot to enjoy the benefits of portable flight while embracing the convenience of urban transportation. This setup keeps the hang glider compact, while also maximizing the user’s mobility and ease of access to their flying site.