[Semper Fidelis]

Have you ever heard about Jeremy SOPER (SOPERMAN) ?

Here are the links to his PDFs about his prototype and his flight :

https://www.soper.tech/dox/Sopalite%20Dissertation.pdf
https://www.soper.tech/dox/Sopalite%20Debrief.pdf

You might enjoy !

[JoeF]

Semper Fidelis,
Your offer:
https://www.soper.tech/dox/Sopalite%20Dissertation.pdf
https://www.soper.tech/dox/Sopalite%20Debrief.pdf
...had not been seen by me. Thank you.

Total enjoyment! A huge thanks for sharing "Sopalite" by Jeremy Soper!

His dissertation of '18/05/19 May 19, 2018

Design & Prototype an Ultra-Portable Hang Glider
fc286b Final Report
JEREMY SOPER ~ js2114 ~ Jesus College

was quite the challenge for him.

I’m eagerly diving into every word and step he shared in his two documents. Take note of the start date of this topic thread, as well as the early Low & Slow issues that covered "pica" or pilot-carried aircraft. Soper tackled numerous challenges at a sophisticated level, addressing both academic and testing hurdles, all while aiming for a compact, non-conservative flight system. His well-documented lessons will certainly bring valuable insights to our ongoing discussion. Many of the challenges Soper faced resonate with the themes we’re exploring in this thread. A deep dive into his experiences and ideas will undoubtedly enrich our continued conversation. His result lives just outside the goals of this topic thread, but his stepping certainly lives within this topic discussion.

This also brought back memories of my 1973 Dial Soap bowsprit moments—design, build, and flight—all accomplished within three days from concept to commercial shoot. During the flight, I encountered some adverse yaw; my harness was hastily made from manila rope tied together on the spot that same day—not something I’d recommend for safety! No ribs, no battens, SS; I gave Dick Eipper dimensions and he sewed the sail overnight for next-day frame mounting at my Venice home.

And Soper's adventure needs to be added to the topic thread in US Hawks at
https://www.ushawks.org/forum/viewtopic.php?f=27&t=1666 that has high focus on bowsprits. I quoted your post into that discussion thread.

Three LE sections were needed to bring the stowed length down to 2 m.
More sections suffer over-compliancy and
unavailability of snug consecutive telescopic tube sizes

Adding Russian of one of the Soper documents shared: HERE

Note: Soper mentioned his Aeros Target. Manual: https://www.delta-club-82.com/bible/manuels/target.pdf

STORAGE
You must store the glider in the bag in a dry room on soft bedding. You may store
frame without sail in a 2 metres bag vertically. Before storage dry the sail.
Frame of the glider must not be under load during storage, tubes must not be bent
under their own weight.
Range of temperatures for storage - from -10?C to +25?C.

sssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss

[JoeF]

Soper's dissertation abbreviations:

Table 1: Abbreviations

BB Basebar
BHPA British Hang Gliding and Paragliding Association
CUE{D\S} Cambridge University Engineering Department/Society
DS Double Surface
GP Glide Polar
GR Glide Ratio
HF Hands-Free Equilibrium (CM = 0)
HG Hang Glider
HP Hang Point
KP Kingpost
LE Leading Edge
LLT Lifting Line Theory
MG Maximum Glide (Ratio)
MS Minimum Sink (Rate)
PG Paraglider
QR Quick Release
TE Trailing Edge
TO Takeoff
UR Upright
US Ultrasport (Wills Wing)
VG Variable Geometry
XT Crosstube

========================================================

[JoeF]

Development note over line rigging on some potential TPHG,
especially when using soft lines.

Meet PLK

Explore the following cross line; let a cross line be a line that goes from left wing through a central post and to the right wing. Have the cross line terminate with a loop at both ends and then with a small and short added pigtail on those loops. Then at a certain distance along the cross line away from each loop install in that line a short added line that holds a firm stop knot. Thus the cross line would have such added stop knots near each end but a determined distance away from the pigtail and end loop. Typographically symbolize the advance cross line: pLk________kLp where p is for pigtail, L is for loop, and k is for added knot. Note that one would not put the knot in the base cross line but make a knot on a separate line and then integrate that short line onto the cross line base material; such avoids put a knot in the cross line material and also allows precise placement of the short line with the knot wanted. Intend to have the cross line operated as follows: hold the loop and wrap the loop around the spar about 630 degrees to return the loop toward the center of the meta cross line or toward the central post of the hang glider. Intend to do the next step: make a lark's head fold with the loop and cinch that lark's head over the added stop knot that would be available in the cross line. Pull out looseness in the affair. Have the 630 degree wrap around the spar be on the wingtip side of a flange of a Joe Cup. Mount the other end of the cross line onto the other side of the glider. When the cross line is posted and the post is up, be sure the looseness of the end wrap is stretched out evenly for the start of the wrap and the end of the wrap. At packing time reverse the dealing: de-post to relax the cross line; use pigtail to help undo the lark's head cinch over the stop knot; pull out the wrapping; thus the cross line end will be free; do such for both ends of the cross line; the cross line set for upper lines could be center bound and lifted away from post and stowed for tote/transport. No tangs. No sleeves. No thimbles. No bolts. No washers. What to call such a line assembly? Abbreviate PLK?

I asked ChatGPT to massage my prose above; Chat gave the following:

Meet PLK

Explore the concept of a cross line in the context of TPHG design. A cross line is a line that extends from the left wing, passes through a central post, and continues to the right wing. Each end of the cross line terminates with a loop, and a small, short pigtail is added to these loops. At a specific distance along the cross line, away from each loop, a short added line is installed, containing a firm stop knot. The cross line will thus have these stop knots near each end, positioned a determined distance from the pigtail and loop.

Typographically, the advanced cross line can be represented as:
pLk________kLp

Where:
- p represents the pigtail,
- L represents the loop, and
- k represents the added knot.

Notably, the knot is not tied directly into the base cross line but rather into a separate short line, which is then integrated onto the base cross line material. This method avoids weakening the cross line material with a knot and allows precise placement of the short line with the desired knot.

The intended operation of the cross line is as follows:
1. Hold the loop and wrap it around the spar about 630 degrees, returning the loop toward the center of the cross line or the central post of the hang glider.
2. Form a lark's head fold with the loop and cinch it over the added stop knot in the cross line.
3. Pull out any slack in the assembly. The 630-degree wrap around the spar should be positioned on the wingtip side of a flange of a Joe Cup.
4. Attach the other end of the cross line to the opposite side of the glider. Ensure that when the cross line is posted and the post is up, the wrap tightness is evenly distributed.

For packing:
1. Reverse the process: de-post to relax the cross line.
2. Use the pigtail to help undo the lark's head cinch over the stop knot.
3. Unwrap the cross line, freeing its ends.
4. Repeat this process for both ends of the cross line. The upper cross line set can then be center-bound, lifted away from the post, and stowed for transport.

No tangs. No sleeves. No thimbles. No bolts. No washers.

What should this line assembly be called? Perhaps, we could abbreviate it as PLK?

[JoeF]

Prompt:
List of safeties for experimental new builds could be extensive.

Response:
Absolutely, the list of safeties for experimental new builds, especially in something as critical as a hang glider, could indeed be extensive. Here’s a potential list of safeties to consider:

Structural Safeties

• Material Integrity: Ensure all materials (carbon fiber, aluminum, etc.) meet the required strength and durability specifications.
• Component Compatibility: Verify that all components (spars, couplers, etc.) fit together correctly and securely.
• Load Testing: Perform load tests on all critical structural components to ensure they can handle the expected forces.
• Redundancy in Critical Areas: Use redundant structural elements where failure could be catastrophic (e.g., dual safety lines).

Assembly Safeties

• Correct Assembly Procedure: Provide clear, step-by-step instructions for assembly to avoid errors.
• Locking Mechanisms: Ensure that all locking mechanisms (e.g., pins, clips) are securely engaged.
• Visual Inspection: Include a checklist for visual inspections after assembly to catch any overlooked issues.

Pre-Flight Safeties

• Rigging Checks: Confirm that all rigging (wires, crosslines) is properly tensioned and free from wear.
• Control Surface Functionality: Test all control surfaces (e.g., spoilers, rudders) for proper movement and response.
• Weather Assessment: Evaluate weather conditions to ensure they are within safe flying parameters for the experimental glider.
• Safety Harness Inspection: Check that the pilot’s harness and attachment points are secure and properly fitted.

In-Flight Safeties

• Emergency Procedures: Clearly define and practice emergency procedures, such as deploying a reserve parachute or handling sudden structural failure.
• Stall and Spin Recovery: Ensure the glider has been tested for stall and spin recovery and that the pilot is familiar with these procedures.
• Pilot Communication: Maintain communication protocols, especially if the pilot is in radio contact with ground support.

Post-Flight Safeties

• Post-Flight Inspection: Conduct a thorough inspection of the glider after each flight for any signs of wear or damage.
• Data Logging and Review: Use data loggers to record flight parameters, allowing for analysis and identification of potential issues.
• Wear and Tear Monitoring: Keep a detailed log of the glider’s usage to monitor for signs of fatigue or degradation.

Environmental Safeties

• Flight Area Clearances: Ensure the flight area is free from obstacles, restricted airspace, and other hazards.
• Wildlife Considerations: Be aware of and avoid wildlife areas to prevent collisions.

Pilot Safeties

• Training Requirements: Ensure the pilot has adequate training, particularly in handling experimental gliders.
• Physical Condition: Verify that the pilot is physically fit and free from conditions that could impair their ability to fly safely.
• Mental Preparedness: Ensure the pilot is mentally prepared for the flight, particularly regarding the experimental nature of the glider.

Legal and Regulatory Safeties

• Compliance with Regulations: Ensure the glider and its use comply with local and national aviation regulations.
• Insurance Coverage: Verify that the necessary insurance is in place, especially considering the experimental nature of the build.
• Documentation: Keep detailed records of all design, testing, and maintenance activities.

Design Safeties

• Built-In Fail-Safes: Incorporate fail-safe mechanisms in critical areas where failure is possible but not predictable.
• Aerodynamic Stability: Ensure the glider’s design promotes aerodynamic stability, especially under varying flight conditions.

Each of these safeties contributes to the overall reliability and safety of the experimental hang glider, reducing the risk of failure and enhancing pilot security.

I will be having some builds that no other pilot should fly, as there will be almost no safety margin in the build; indeed, I want to have some flight-loaded breakage occur. And some builds will have no redundancy; a line breaks and it is all over. Dockweiler at mild only! Getting pitch stability for some builds will take time. Flight and control envelops will be mysterious.

It sounds like you're planning to undertake some highly experimental and risky builds, where safety margins are minimal and failures are expected as part of the testing process. Given this, it’s crucial to take additional precautions and clearly communicate the inherent risks. Here’s how you might frame this within your projects:

Experimental Build Guidelines:

1. Exclusive Piloting:

• No Other Pilots: Make it explicit that only you will pilot these experimental builds. Given the high-risk nature, no other pilots should attempt to fly these gliders.
  
• Personal Responsibility: Acknowledge that you fully understand and accept the risks involved, including the potential for in-flight structural failure.
  

2. Controlled Environment:

• Dockweiler Beach: Limit testing to Dockweiler Beach or similarly controlled environments where conditions are mild, and emergency response is readily available.
  
• Soft Landings: Choose locations with forgiving terrain to minimize injury if a failure occurs.
  

3. Anticipated Failures:

• Flight-Loaded Breakage: Expect and plan for structural failures during flight. Use these moments as learning opportunities to understand the limits of your designs.
  
• No Redundancy: Be aware that some builds will have no redundancy—if a critical component like a line breaks, it could result in total loss of control.
  

4. Pitch Stability Development:

• Time-Consuming Adjustments: Recognize that achieving pitch stability in some designs may require numerous iterations and test flights.
  
• Unpredictable Flight Dynamics: Be prepared for unpredictable behavior in the flight and control envelopes. These will be areas of active exploration and learning.
  

5. Safety Precautions:

• Pre-Flight Checks: Conduct thorough pre-flight inspections, focusing on potential failure points, even though breakage is part of the testing.
  
• Protective Gear: Always wear appropriate protective gear, including a helmet and possibly additional body protection, given the increased risk.
  
• Emergency Plan: Have a clear emergency plan in place, including a way to quickly alert others if something goes wrong during a test flight.
  

6. Documentation and Analysis:

• Record Keeping: Keep detailed records of each flight, noting the conditions, adjustments made, and any failures or successes.
  
• Video Documentation: Consider recording each test flight for later analysis, which could provide valuable insights into the failure modes and help guide future designs.
  

7. Communication:

• Clear Warnings: Ensure that anyone observing or assisting is fully aware of the risks involved in these experimental flights.
  
• Transparency: Be transparent about the nature of these builds with the flying community, so they understand that these are not safe or standard hang gliders.
  

[JoeF]

Ultra Sport 135,147,166
Owner / Service Manual
https://www.delta-club-82.com/bible/26-hang-glider-ultrasport.htm

[JoeF]

This is a development note that regards a potential opportunity to meet supply and packing targets for telescopic tubing or nestable tubing. The Joe Cup may loosen up supply-of-precise-ODs-and-IDs constraints. It may be easier to adjust a Joe Cup than to require that commercial supply provide precise ODs and IDs for an assembly. And the Joe Cup may allow easy use of odd pieces of tubing or beams for experiments. Next: for tote volume reduction a counterintuitive approach to tube sizing might bless: have larger largest tubing with thinner wall in order to then be able to have more choices of other tubes smaller than the largest. Differently, if one thought that optimizing a TPHG left wing spar of spar segments was to have a 1-inch O.D. then the secondary, and tertiary, and fourth members of a tapered telescopic spar are constrained to be small than that 1" and for tutoe that might mean that in that particular nesting, a tube used elsewhere in the TPHG might not be able to be nested in that particular toted nesting. But if taper of the spar was not snug but more open between graduated ODs and IDs, then non-spar tubes might be sized to fit in that spar-segment nest. Many games of sizing and nesting can be played; more games can be played when the largest tube is larger than one might have chosen for some optimizing effort. One game: can all the tubes of some TPHG be nesting in just two nests for tote? Cousin to that question regards 3 nests for tote. Then four. Then five. Then six. Which packing with nests will be with a certain satisfaction?

Let O represent a nesting of tubing for a TPHG. A packing for tote might be O. Another packing might be OO. Etc.: OOO, OOOO, OOOOO, OOOOOO. Allow in this symbolization that ajacent "O" actually might be smaller that its neighbor: Oo, e.g. Finally, once a TPHG is designed and packed, cousin Os might be arranged for tote in various ways: one pack or two packs or three packs. The packing challenge can be fun.

[JoeF]

Furthering the topic of the above note:

User's Prompt:
Let's brainstorm for some solutions to a challenge for Joe Cups: Have a 3 in ID CF thin walled tube; and have intention of joining for 5 inch overlap at insertion of a 1 in OD CF tube. How to stop wobble by using a Joe Cup and some low-mass bushing to surround that 1 inch OD inserted tube? First thought: low-mass rigid closed-cell foam ring surround the 1 inch OD before stuffing the end of the tube into the Joe Cup as the Joe Cup is placed in the 3 in ID mother tube. We make then a longer beam without wobble.

Response:
To address the challenge of stopping wobble in the overlap region when joining a 1-inch OD carbon fiber (CF) tube with a 3-inch ID thin-walled CF tube using a Joe Cup, here are some ideas to brainstorm:

1. Foam Bushings with Compression Fit:
- Material: Use rigid closed-cell foam rings as bushings, as you suggested. These rings would be lightweight and provide the necessary support.
- Design: The foam rings should have an inner diameter slightly smaller than 1 inch to ensure a snug fit around the 1-inch OD tube. The outer diameter of the foam should match the 3-inch ID of the mother tube.
- Placement: Position these foam rings along the 5-inch overlap region. The rings can be spaced out, such as having two or three rings along the overlap, to distribute support evenly and prevent wobble.

2. Segmented Bushing System:
- Material: Consider using a segmented bushing system made from a lightweight, rigid material like plastic or composite.
- Design: The bushings could be designed in a split-ring form, where each ring has a slit or hinge allowing it to be opened and clamped around the 1-inch OD tube. This would allow easy assembly and disassembly.
- Fit: The bushings would have an OD to fit snugly into the Joe Cup and mother tube, while the ID would tightly grip the 1-inch OD tube.
- Attachment: You could also use adhesive or a mechanical locking feature within the Joe Cup to secure the bushings and prevent movement.

3. 3D-Printed Custom Bushings:
- Material: 3D print custom bushings using a lightweight, rigid material like PLA or nylon.
- Design: The bushings can be designed with precise tolerances for both the 1-inch OD tube and the 3-inch ID mother tube, ensuring a perfect fit.
- Customization: The bushings could be made with different densities or thicknesses at various points to optimize for weight and strength, potentially using lattice structures within the bushing to reduce mass while maintaining rigidity.

4. Multi-Material Inserts:
- Material: Use a combination of materials, such as a rigid core (e.g., plastic or aluminum) surrounded by a softer foam layer.
- Design: The rigid core would ensure structural integrity and prevent wobble, while the softer outer layer would provide a snug fit within the Joe Cup and mother tube.
- Implementation: These inserts would slide over the 1-inch OD tube before the assembly, with the softer material providing a friction fit inside the 3-inch ID tube.

5. Adjustable Clamping Bushings:
- Material: Lightweight, adjustable bushings, potentially made from plastic or composite materials.
- Design: These bushings could have an adjustable clamping mechanism, such as a screw or sliding wedge, allowing you to tighten them around the 1-inch OD tube. This adjustment would ensure a tight fit and prevent wobble.
- Placement: Install the adjustable bushings at multiple points along the 5-inch overlap for consistent support.

6. Helical Inserts:
- Material: Use a helical insert made from a lightweight, rigid material.
- Design: The helical design would allow the insert to be compressed slightly as it is inserted into the 3-inch ID tube, ensuring a tight fit. The helical shape would provide continuous support along the overlap.
- Assembly: The helical insert would wrap around the 1-inch OD tube and could be twisted into place within the Joe Cup and mother tube, securing the smaller tube and preventing wobble.

Each of these approaches has the potential to eliminate wobble while maintaining a lightweight and structurally sound connection. The choice among them would depend on factors like ease of manufacturing, cost, and specific performance requirements.

[JoeF]

Adding to the above note's focus:

User's Prompt:
Bonding compressible foam bushings between rigid washers might supply a compressible plug for low-volume tote of the packed TPHG. Place the expanded bushing on the smaller tube; place the whole affair in a Joe Cup; stuff the filled Joe Cup in the mother larger tube; the Joe Cup limits insertion to 5 inches overlap. Gap is filled and the wobble is nil; a longer beam is obtained for spar growth.

Response:
Bonding compressible foam bushings between rigid washers could indeed provide an effective solution for creating a compressible plug for low-volume tote of the packed TPHG (Tiny Packed Hang Glider). Here's how it could work:

1. Foam Bushing and Washer Construction:
- Foam Bushings: Use compressible foam bushings that can expand once in place, filling the gap around the smaller tube. These foam bushings should be lightweight and designed to compress or expand slightly to adapt to the internal space of the larger tube.
- Rigid Washers: Bond the foam bushings between rigid washers. These washers would serve to stabilize the foam bushings, ensuring that they maintain their position and provide uniform support across the overlap region.

2. Assembly Process:
- Step 1: Place the Bushing Assembly: Slide the foam bushing and washer assembly onto the smaller tube, positioning it along the intended overlap region.
- Step 2: Insert into Joe Cup: Place this assembly into a Joe Cup, which is designed to fit snugly into the 3-inch ID mother tube. The Joe Cup will naturally limit the insertion depth, ensuring a consistent 5-inch overlap.
- Step 3: Insert into Mother Tube: Slide the Joe Cup, now filled with the foam and washer assembly around the smaller tube, into the larger mother tube. The compressible foam will expand slightly to fill any remaining gaps, eliminating wobble.

3. Advantages:
- Gap Filling: The compressible foam will adapt to any irregularities or slight variations in diameter between the smaller and larger tubes, ensuring a tight fit.
- Wobble Elimination: With the foam filling the gaps and the rigid washers providing support, wobble is minimized, resulting in a more stable and rigid connection.
- Spar Lengthening: This setup allows for effective spar lengthening, crucial for your TPHG design, without adding significant weight or complexity.
- Compact Packing: The use of compressible foam ensures that the overall system remains lightweight and easy to pack, essential for a low-volume tote of your hang glider.

By using this method, you can create a lightweight, stable, and wobble-free connection between spar segments, allowing for efficient packing and easy assembly of the TPHG.

[JoeF]

Caution: stay aware that errors may be embedded in the AI responses; and poor ideas may be mixed with better ideas. The double-bracketed notes in the AI flow are my added notes. And note that I did not prompt AI to face the possible uses of the Joe Cup in this challenge until after the first chat. See a second quote for response on a focused request concerning a firstly missed option.

User: The Three Tube Queen: Hang gliders frequently have two downtubes or queenpost that form the sides of a control frame. The two posts often are posts that have flying-support lines that go from the post's ends to points on the wing above. The common lengths of such posts range longer than 1 m and longer than 4 ft which thus presents the challenge for a TPHG's packing. Will the queenposts be of two three tube parts to get the full length? And how might a two-tube post or a three-tube post be formed in order to advance the low-mass and low-pack volume sought be some designers of TPHGs? Nesting of tubes for packing is a strong aim. The posts are flown in axial compression; resistance to buckling is important. End pinning is important as as not to give impetus to bending of the posts that might initiate central-region buckling. We have in our notes many potential design solutions, but ask you now to brainstorm on the challenge. Meta tube when assembled will be about 60 inches or up to about 70 inches depending on size and purpose of the TPHG. Two sub tubes is an arena itself. Three sub tubes is an arena of itself. TIA

Assistant: Designing queenposts for a Tiny Packed Hang Glider (TPHG) with low mass, low pack volume, and strong resistance to buckling presents a challenging yet intriguing task. Below are some brainstorming ideas to address this challenge, considering both two-tube and three-tube configurations:

1. Three-Tube Design
- Nesting Sequence: The three tubes should nest perfectly inside one another, with minimal clearance to maximize space efficiency. Each tube would have a slightly smaller diameter than the previous one, allowing them to telescope into a compact unit. [[ I disfavor this as there is lost opportunity for central-region resistance to buckling; see below on this post for a more favored direction.]]
- Material Choice: Carbon fiber or high-strength aluminum alloys would be ideal for maintaining a balance between weight and strength. Using a hybrid material approach (e.g., carbon fiber with a lightweight aluminum core) could optimize performance.
- Reinforced Coupling: At the joints where the tubes connect, reinforced couplers or inserts could be used. These couplers would prevent local buckling at the joint and ensure axial alignment. They could be designed to lock with a simple twist-lock mechanism, minimizing setup time.
- End Pinning: The ends of the tubes could be designed with interlocking pins or detents to prevent movement at the joint, which could otherwise lead to bending under axial compression. The design might involve a spring-loaded pin or a simple push-pin mechanism that locks the tubes in place once fully extended.
- Tapered Tubes: Tapering the ends of each tube slightly (with the thickest part at the base) could help distribute stress more evenly and reduce the likelihood of buckling. This approach also allows for smoother nesting. [[sic, this is probably a mechanical error on AI part; if broad part of the two tubes overlap and join in center of the downtube, then resistance to buckling is best.]]
- Internal Stiffeners: Thin, lightweight internal stiffeners could be added inside the tubes, particularly at the joints, to enhance buckling resistance without adding significant weight or bulk. [[If the interior of the part tubes are needed for tote nesting, then removable stiffeners might be considered.]]

2. Two-Tube Design
- Segmented Length: For a two-tube design, the tubes would be longer and might present more of a challenge for nesting. The nested length would still need to fit within the packable constraints (e.g., under 4 feet).
- High-Precision Fit: The two-tube design would require extremely precise manufacturing tolerances to ensure a snug fit between the two segments. Any play or looseness could lead to bending under load.
- Reinforced Coupler or Sleeve: Similar to the three-tube design, a reinforced coupler or sleeve would be necessary at the junction. This might involve a sleeve that overlaps both tubes by several inches, distributing the load more evenly and preventing buckling.
- Threaded or Locking Mechanism: A threaded connection or a mechanical lock (e.g., bayonet fitting) could be used to join the tubes. This would provide a secure, rigid connection that is easy to assemble and disassemble in the field.
- End Stabilization: The ends of the two tubes could be flared or feature end caps with integrated stiffeners to ensure the load is transmitted axially without encouraging bending at the joint.

3. General Considerations
- Telescoping System: Whether using two or three tubes, the telescoping mechanism is critical. Consider adding a slight taper to the ends of the tubes to facilitate easy nesting and prevent binding during assembly and disassembly.
- Optimized Geometry: The tube geometry could be optimized with non-circular cross-sections (e.g., oval or hexagonal) to resist buckling better while still nesting effectively. This could also help in preventing rotation of the tubes relative to each other.
- Composite Materials: Advanced composite materials could be used for specific parts of the queenposts, such as the joints or couplers. These composites could be tailored to have higher stiffness in areas prone to buckling.
- Integrated Features: Consider integrating small guide pins or alignment tabs that ensure the tubes are perfectly aligned when assembled. This would help in reducing the risk of bending or buckling under load.

4. Testing and Simulation
- FEA Simulation: Running finite element analysis (FEA) on the designs to simulate loading conditions would be essential in predicting and optimizing the buckling resistance of the tubes.
- Prototyping: Rapid prototyping of the joint mechanisms using 3D printing or similar technologies could help refine the design before committing to full-scale production.

Conclusion:
Incorporating these design elements into a TPHG’s queenposts can help achieve the desired low-mass, low-pack volume, and high structural integrity. Whether using a two-tube or three-tube approach, careful consideration of materials, joining mechanisms, and overall design geometry will be key to successfully meeting the challenges posed by this compact and innovative hang glider design.

User: If CF is used, then for safety during crashes which could face CF splinters, a veiling of the CF tube is wanted, perhaps a thin Kevlar jacket? What else?

Assistant: Using carbon fiber (CF) in hang glider components like queenposts can indeed raise safety concerns, particularly in the event of a crash where carbon fiber splinters could pose a serious hazard. To mitigate this risk, applying an external protective layer or "veiling" over the carbon fiber is a prudent measure. Here are some options and considerations for providing this additional layer of protection:

1. Kevlar Jacket
- Properties: Kevlar is an excellent choice for a protective outer layer because of its high impact resistance, toughness, and ability to prevent the propagation of cracks and splinters.
- Application: A thin layer of woven Kevlar can be applied as an outer jacket around the carbon fiber tube. This can be done using a similar process to how the carbon fiber itself is laid up, involving resin impregnation and curing.
- Advantages: Kevlar is lightweight and doesn’t significantly add to the mass of the component. It’s also abrasion-resistant and can enhance the overall durability of the tube.

2. Hybrid Composite Layers
- Carbon/Kevlar Hybrid: Some manufacturers create hybrid composite materials where carbon fiber and Kevlar are woven together in a single fabric. This provides the strength and stiffness of carbon fiber with the toughness and impact resistance of Kevlar.
- Fiberglass Layer: Adding a layer of fiberglass over the carbon fiber can also help. Fiberglass, while not as strong as Kevlar, is cheaper and provides good impact resistance. It can prevent sharp carbon fiber splinters from piercing the outer surface.

3. Polyurethane or Rubber Coating
- Properties: A thin polyurethane or rubberized coating can be applied over the carbon fiber. This flexible layer can absorb impacts and prevent splinters from breaking off.
- Application: This could be applied either as a sprayed-on layer or as a wrap. The coating should be thin enough to maintain the lightweight characteristics of the tube while still providing adequate protection.
- Advantages: Polyurethane is also water-resistant, which can provide additional protection against environmental factors.

4. Shrink-Wrap Tubing
- Properties: Using heat-shrink tubing made from materials like polyolefin or PVC around the carbon fiber tube can offer a simple and effective protective layer.
- Application: This involves sliding the shrink-wrap over the tube and then applying heat to shrink it tightly around the tube, forming a protective barrier.
- Advantages: It's lightweight, cost-effective, and adds minimal bulk to the tube. It also provides a smooth finish and can help in preventing splinters from spreading.

5. Epoxy Layer with Additives
- Properties: An additional layer of epoxy resin can be applied to the outer surface of the carbon

============= focused option
I prompted with: "You did not come up with a three-tube queenpost where the central segment tube is largest and receives two segment tubes using Joe Cups. The central segment being of larger OD may thus tend to resist queenpost buckling."

Three-Tube Queenpost Design

1. Central Segment as the Largest Tube:

Design Concept: The central segment of the queenpost would be the largest in outer diameter (OD). This tube would form the core of the queenpost, and it would resist buckling due to its larger cross-sectional area and increased stiffness.
Nesting Mechanism: Two smaller segment tubes would nest into each end of the central segment. These smaller tubes would fit into the larger central tube using Joe Cups as connectors, ensuring a secure fit and strong axial alignment.

2. Joe Cup Connectors:

Functionality: Joe Cups are an ideal solution for connecting the segments. They can be designed to create a snug fit, ensuring the tubes align properly and transmit loads efficiently. The cups would be bonded or mechanically fixed to the smaller tubes, allowing them to slide into the central segment.
Design Considerations: The Joe Cups should be designed with slightly flared or tapered ends to prevent stress concentrations at the connection points, reducing the likelihood of buckling at these junctions.

3. Buckling Resistance:

Central Segment's Advantage: By making the central segment the largest and therefore the strongest, the overall buckling resistance of the queenpost is improved. The larger OD provides greater resistance to bending, especially in the middle of the post, where buckling forces are most critical.
End Pinning: The ends of the central segment would be reinforced where the smaller tubes insert, with mechanisms such as pins, locking rings, or interlocking teeth to prevent any movement that could lead to buckling. These mechanisms would help maintain the axial alignment of the entire queenpost assembly.

4. Material Choices:

Central Tube Material: The central segment could be made of a thicker-walled carbon fiber (CF) tube or a composite with added Kevlar for improved impact resistance.
Outer Tubes: The smaller, nested tubes could be slightly thinner but still made of high-strength CF or a hybrid composite to balance weight and strength.
Protective Layering: As mentioned earlier, a Kevlar jacket or hybrid composite layering could be used on the outer surface of the tubes to prevent splintering in the event of a crash.

5. Assembly and Disassembly:

Ease of Use: The Joe Cups would allow the tubes to be easily assembled and disassembled, maintaining the goal of a compact, easy-to-transport design. When nested, the total length of the queenpost would fit within the desired packable constraints, such as under 4 feet.
Compact Storage: When disassembled, the three segments would nest within one another, resulting in a very compact bundle for transport.

Conclusion
This three-tube queenpost design, with a larger central segment and smaller nested tubes connected via Joe Cups, offers a promising solution for a TPHG. It addresses the need for both low mass and high resistance to buckling, while also allowing for compact packing and easy transport. The key to success will be in the precision of the connectors and the material choices, ensuring that the queenpost remains strong, durable, and safe during flight.

Example: Queenpost with a total length of 60 inches when assembled. Using a 36-inch central tube and two 18-inch end tubes with a 6-inch overlap on each end, the design ensures a compact and efficient packing solution. The end tubes nest into the central tube for tote, and the Joe Cups are stored separately to keep everything organized and protected.