The problem
On a competition aircraft every gram counts against payload. Landing gear is dead weight in flight, yet it has to take the hardest loads the airframe sees at touchdown. The goal was to cut front-gear weight without plastic deformation or failure on landing.
My role
I co-developed the current knee-spring design. My work covers the structural analysis: sizing the struts, analyzing the test mount, and working out how to mount the spring so it survives landing loads.
Design decisions
Reduce strut radius to the minimum that still carries the load
- Question
- How thin can the struts be and still carry landing loads?
- Method
- FEA on the structural members, checking stress against allowable as the radius decreased.
- Outcome
- Part of the ~20% front-gear weight reduction.
Fewer U-bolts on the test mount
- Question
- Can the test mount use fewer U-bolts, freeing room to mount the gear?
- Method
- FEA at 165 lbf, checking factor of safety and stress concentrations near the bolt locations.
- Outcome
- Gave the basis for reducing the mounting U-bolts and freeing space for the gear.
Spring mounting and spring rate (ongoing)
- Question
- Which mounting layout keeps the spring elastic, and what spring constant absorbs landing loads?
- Method
- Comparing mounting configurations against plastic-deformation limits and calculating the required spring constant from landing loads.
- Status
- In progress.
Analysis
FEA: strut stress plot
FEA: test mount at 165 lbf
CAD: knee-spring gear (previous vs current)
Build & test
Photo: manufactured gear
Photo: test setup
What's next
- Finish the spring mounting layout and confirm the spring constant.
- Test the gear on the mount and compare the results with the FEA.