Motor Hub Skid Surface for Propeller Strike Load Transfer
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) often suffer damage to the engine compartment during landing due to propeller strikes, as they lack sufficient landing gear or have inadequate protection for the propeller and engine compartment.
Innovation Solution
A motor apparatus with a hub having a circumferential skid surface that contacts the motor casing to absorb bending moments from propeller strikes, limiting deformation of the rotatable shaft and reducing the risk of engine compartment damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UAV uses a simple landing structure without sufficient landing gear, then the device complexity is reduced, but the reliability of protecting the engine compartment from propeller strike damage deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by providing a skid surface on the hub that is positioned to contact the motor casing before the propeller can strike the ground. This pre-positioned protective interface absorbs impact forces during landing or crash scenarios, protecting the engine compartment without requiring complex landing gear structures.
Solution Approach 2:
The skid surface acts as an intermediary element between the hub and motor casing. During a propeller strike event, this intermediate surface contacts the motor casing first, transferring and distributing impact forces away from vulnerable components, thereby mediating the protection mechanism without requiring complex external structures.
2Reliability
If the UAV adds sufficient landing gear to prevent propeller strikes, then the reliability of engine compartment protection is improved, but the device complexity increases
Solution Approach 1:
The hub structure is given multiple functions: it serves both as the rotational connection point for the propeller and as a protective element with a skid surface that contacts the motor casing during landing. This multi-functionality eliminates the need for separate landing gear structures, maintaining reliability while reducing overall device complexity.
Solution Approach 2:
The patent merges the protective function into the existing hub structure by adding a skid surface. Instead of combining separate landing gear and hub components, the protective feature is integrated directly into the hub, simplifying the overall structure while maintaining engine compartment protection reliability.
3Reliability
If the hub skid surface is positioned close to the motor casing, then the protection effectiveness against propeller strikes is improved, but the risk of normal operation interference increases
Solution Approach 1:
The skid surface is positioned locally on the hub at a specific location and orientation designed to contact the motor casing only during impact events. The local positioning ensures that normal rotational operations do not cause interference, while impact forces naturally drive the skid surface into protective contact with the motor casing.
Data Source
AI summary
A motor assembly that includes a motor having a motor casing, a rotatable shaft extending from said motor casing to a shaft length and a hub coupled to said rotatable shaft, the hub having a circumferential skid surface disposed immediately proximal to the motor casing and having a channel configured to seat a propeller, when a propeller is present, wherein a bending moment applied to the shaft through the hub results in the circumferential skid surface contacting said motor casing.