Tip Jet Rotor Blade Assembly for High-Speed VTOL
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Solution Overview
Problem
Rotating wing aircraft are limited in maximum flight speed due to phenomena such as retreating blade stall, increased drag at rotor tips, and reverse airflow over retreating blades, restricting them to less than 200 mph.
Innovation Solution
The design incorporates a rotor blade assembly with a blade spar and mounting structure forming a common airfoil contour, featuring tip jets for enhanced lift and thrust, and composite materials for durability, allowing for improved aerodynamics and reduced drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rotor blades are allowed to flap to equalize lift between advancing and retreating blades, then lift distribution is improved, but retreating blade stall occurs at higher speeds limiting maximum flight speed to less than 200 mph
Solution Approach 1:
The patent extracts the rotor blade stall limitation by using tip jets to provide independent thrust control at the blade tips. This allows the retreating blade to maintain adequate lift without relying solely on flapping, thereby preventing retreating blade stall and enabling flight speeds exceeding 200 mph while maintaining stable lift distribution.
Solution Approach 2:
The patent changes the operational parameters by introducing tip jet thrust as an additional control variable. By independently adjusting tip jet thrust on advancing versus retreating blades, the system can compensate for the speed differential and maintain optimal angle of attack across all blades, pushing the maximum flight speed beyond the traditional 200 mph barrier.
2Force
If rotor rotation speed is increased to provide sufficient lift for vertical takeoff, then VTOL capability is achieved, but drag at rotor tips increases significantly
Solution Approach 1:
The patent segments the lift generation function between the main rotor blades and the tip jets. The rotor blades provide the primary lift through autorotation at moderate speeds, while the tip jets provide supplemental thrust specifically at the blade tips. This segmentation allows the system to achieve VTOL capability without requiring excessively high rotor rotation speeds, thereby reducing tip drag and energy loss.
Solution Approach 2:
The patent employs composite materials in the rotor blade construction to reduce overall blade weight and improve aerodynamic efficiency. This allows the blades to maintain structural integrity at lower rotation speeds while still generating sufficient lift for VTOL, thereby reducing the drag penalties associated with high-speed rotation.
3Speed
If tip jets are added to provide initial rotation and enhance performance, then flight speed exceeds 200 mph, but device complexity increases
Solution Approach 1:
The patent merges the tip jet attachment structure with the existing rotor blade assembly, integrating the thrust generation function into the blade itself rather than adding completely separate components. The tip jets are mounted at the blade tips and work in conjunction with the blade aerodynamics, creating a unified system that achieves high speed performance without proportionally increasing overall device complexity.
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
Enables vertical takeoff and landing while achieving flight speeds exceeding 200 mph by mitigating the limitations of retreating blade stall and drag, enhancing the performance of rotating wing aircraft.
Implementation Method 1
A tip jet is secured to the mounting structure in fluid communication with the fluid path
Implementation Method 2
The Bernoulli effect of the airflow moving over the rotor surface creates lift
Data Source
AI summary
A rotor blade assembly is disclosed including a blade spar having a duct extending therethrough and having upper and lower surfaces. A mounting structure is secured to the blade spar and defines a fluid path in fluid communication with the duct. The mounting structure likewise has upper and lower surfaces. A tip jet is secured to the mounting structure in fluid communication with the fluid path. The blade spar and mounting structure abut one another at a joint and the upper surfaces of the blade spar and mounting structure lie on a common airfoil contour extending across the joint. The lower surfaces of the blade spar and mounting structure also lie on the common airfoil contour. One or both of the blade and mounting structure include a composite material. The mounting structure may include two portions secured to one another having a distal portion of the blade spar captured therebetween.