Which pioneer is credited with designing the first practical flexible wing hang glider that laid the foundation for modern hang gliding?

Introduction / Context:
Hang gliding did not appear suddenly with powered aircraft. It evolved through experiments with gliders and wing shapes. This question focuses on the pioneer who designed the first practical flexible wing hang glider, which became a direct ancestor of the modern recreational hang glider used in sport flying and leisure activities.

Given Data / Assumptions:

• The question is about a practical flexible wing hang glider, not just any early flying machine.
• We focus on a design that clearly influenced modern hang gliding as a sport.
• The options include several famous figures in the history of flight and science.
• We assume basic awareness of early aviation pioneers and their main contributions.

Concept / Approach:
Modern hang gliders use a flexible fabric wing that changes shape with air loads. The key conceptual breakthrough was the flexible Rogallo wing, which could be folded, packed and still generate lift efficiently. To answer the question, we connect the idea of a flexible wing glider used by modern hang glider designers with the engineer who first created and tested such a wing configuration.

Step-by-Step Solution:
Step 1: Recall that Leonardo da Vinci and Galileo mainly produced conceptual designs or scientific work, not practical flexible wing hang gliders. Step 2: The Wright brothers built rigid wing gliders and the first powered aircraft, so their main contribution was controlled powered flight. Step 3: Francis Rogallo, working as an aeronautical engineer, designed the flexible Rogallo wing, which directly inspired modern hang glider designs. Step 4: Therefore, the pioneer linked specifically with the first practical flexible wing hang glider is Francis Rogallo.

Verification / Alternative check:
A quick check is to associate names with keywords. The name Rogallo is almost always mentioned together with the flexible wing that later appeared in kites, hang gliders and some spacecraft recovery concepts. By contrast, the Wright brothers are linked to powered aircraft with fixed wings, and Otto Lilienthal is linked to early rigid gliders rather than flexible fabric wings. This pattern confirms that the flexible hang glider in the modern sense is tied to Francis Rogallo.

Why Other Options Are Wrong:

• Leonardo da Vinci: Produced early flying machine sketches but did not build a practical flexible wing hang glider used in modern sport.
• The Wright brothers: Built rigid gliders and the first powered aircraft, not flexible wing hang gliders.
• Galileo Galilei: Known for physics and astronomy, not for designing hang gliders.
• Otto Lilienthal: A key glider pioneer but worked with mainly rigid wing gliders, not a flexible Rogallo type wing.

Common Pitfalls:
Students often jump to famous names such as the Wright brothers or Leonardo da Vinci whenever a flying invention appears in a question. Another common mistake is to confuse all early glider work with hang gliding in its modern flexible wing form. To avoid this, always pay attention to specific terms like flexible wing and modern hang glider, which point directly to Francis Rogallo and his important aerodynamic design.

Final Answer:
The first practical flexible wing hang glider that influenced modern hang gliding is credited to Francis Rogallo.