Huff Helo Inc. used formed titanium sheet metal as both the wheel’s structure and its spring. NASA reports that the team encountered a linked design problem during testing: the strength came with rigidity, making the wheel bounce over some obstacles instead of conforming to them. The challenge’s requirements put both properties in play: wheels needed durability as well as enough compliance to absorb impacts and maintain traction at higher speeds. [S1]
Two competing concepts put flexibility into different parts of the wheel. Hellenic Technology of Robotics SA’s HTR Variable Flex Lunar Wheel uses an internal system designed to change stiffness with terrain and vehicle needs. Hyperbola’s Hiper Wheel uses tensioned cables and a corrugated structure for spring-like flex without traditional radial spokes. These are alternative mechanisms for providing compliance; the HTR design specifically makes stiffness adjustable. [S1]
The winning Scotch Pad Tyres prototype separates a soft tire’s ability to deform from the support needed to retain its shape. Daniel and Isaac Bloomfield’s design uses a Nomex-based tire around an aluminum hub, with internal support to maintain shape as the tire conforms to terrain. An epoxy-and-corundum-grit outer treatment was incorporated to improve traction. That combination addresses deformation, support and surface grip through distinct elements of the design. [S1]
The comparison was grounded in courses at Johnson Space Center’s Rock Yard, with the wheels fitted to MicroChariot, a 45-kilogram test rover. NASA describes loose material as a traction challenge, while rocks and slopes impose different demands, including vehicle stability. Its account anticipates different vehicles needing different combinations of speed, load capacity, durability and terrain performance. Those competing requirements explain the value of retaining several wheel approaches for engineers to consider and potentially advance. [S1]
Source documents
- NASA Challenge Tests Wheel Designs for Moon Base Mobilityhttps://www.nasa.gov/centers-and-facilities/johnson/nasa-challenge-tests-wheel-designs-for-moon-base-mobility/