Collapsible Rotor Blade Assembly for Compact Crash-Resistant UAVs

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Solution Overview

Problem

Existing unmanned flying devices face issues with bulky and fragile rotor blades that are always deployed, leading to potential damage during landing or crashes, and high manufacturing costs.

Innovation Solution

A collapsible blade design where blades automatically fold towards the device's body using torsion springs, deploying via centrifugal and aerodynamic forces for lift, and collapsing upon rotor slowdown to prevent damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rotor blades are always deployed to maintain flight capability, then the device can take off and land immediately, but the blades are vulnerable to damage during landing or crashes and the device becomes bulky for storage

Engineering Contradiction:

Improveflight capabilityVSAvoidblade damage during landing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The rotor blades are designed to dynamically change their deployment state based on operational requirements. Torsion springs enable the blades to automatically transition between deployed (for flight) and collapsed (for storage or crash protection) positions, making the structure adaptive rather than static

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The torsion spring mechanism pre-establishes a collapse capability that activates automatically during landing or crash scenarios. This beforehand preparation allows the blades to protect themselves from damage by collapsing before impact occurs, rather than relying on post-crash repair

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of operation

If rotor blades are always deployed for immediate flight, then the device is ready to operate, but the device becomes bulky and awkward for storage and transport

Engineering Contradiction:

Improveimmediate flight readinessVSAvoiddevice volume for storage

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

The blade assembly transitions from a static always-deployed configuration to a dynamic system that can collapse along the body during storage and automatically deploy when needed, significantly reducing the device's volume for transport while maintaining operational readiness

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The rotor blades are designed to collapse and nest along the body of the device during storage, similar to how nested dolls reduce volume. The blades fold inward against the body structure, minimizing the overall envelope of the device for compact storage

Inventive Principle:

Principle #7Nested doll (Nesting)

3Power

If rotor blades are made large and rigid to provide sufficient lift, then flight performance is improved, but the blades become more fragile and expensive to manufacture

Engineering Contradiction:

Improvelift capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The torsion spring mechanism allows the use of slightly smaller or more flexible blade designs that can collapse for protection, reducing the need for oversized rigid structures. This dynamic capability enables cost-effective blade materials while maintaining sufficient lift when deployed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The collapse mechanism provides beforehand protection that allows the use of less expensive, potentially more flexible blade materials. Knowing the blades can collapse to protect themselves enables manufacturers to select cost-effective materials that wouldn't be suitable for always-deployed rigid structures

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design minimizes damage during landings, enhances compactness for easy transport, and reduces manufacturing costs while maintaining flight capability.

Implementation Method 1

U.S. Publication No. 2009/0212157 describes the use of a torsion spring for biasing each blade away from their folded or retracted configuration

Methodology Applied

Scientific EffectTorsion spring: Torsion Spring

Implementation Method 2

rotation of said blades causes said blades to extend and deploy via centrifugal forces and aerodynamic lifting forces due to the rotation thereof

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

rotation of said blades causes said blades to extend and deploy via centrifugal forces and aerodynamic lifting forces due to the rotation thereof, wherein said blades provide a propulsive lift when spun

Methodology Applied

Scientific EffectAerodynamic lifting force: Aerofoil

Data Source

PatentUS20260091893A1Unmanned Flying Device

Publication Date: 2026.04.02 ASCENT AEROSYSTEMS INC

AI summary

An unmanned flying device including a body; a first blade and at least a second blade; a coupling assembly for coupling the first blade and the at least second blade to the body, wherein the coupling assembly urges the collapsing of the first blade and the at least second blade towards the body; and wherein both the first blade and the at least second blade are rotateable about the body, and wherein the first blade and the at least second blade are deployable away from the body via rotation of the first and the at least second blades about the body.