Angled Keel Air Cushion Hull Drag Reduction
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Solution Overview
Problem
Conventional surface effect vessels with flexible seals experience reduced ride quality and increased drag in rough water due to air cushion loss, leading to instability and high maintenance needs.
Innovation Solution
The use of inwardly angled keels creates an air cushion along the outboard walls of the hull, reducing drag resistance by 20% to 45% through the angled configuration, which allows air to lubricate the outboard walls instead of water, thereby minimizing contact and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If flexible seals are used to contain the air cushion, then air loss is reduced, but ride quality deteriorates and maintenance increases
Solution Approach 1:
The patent removes the flexible seal component entirely from the system. Instead of using flexible seals to contain the air cushion, the invention uses fixed rigid side seals that extend from the bow to the stern of the hull, eliminating the need for flexible seals and their associated maintenance problems while maintaining air cushion containment.
Solution Approach 2:
The patent inverts the conventional approach by using rigid fixed seals instead of flexible seals. The fixed rigid side seals are positioned with their outboard walls facing the water, creating a barrier that prevents water ingress while maintaining the air cushion, thereby improving ride quality and reducing maintenance.
2Stability of the object's composition
If the hull rides low in the water to maintain contact, then stability is improved, but drag increases significantly
Solution Approach 1:
The patent uses pneumatic pressure from the air cushion to lift the hull out of the water, reducing hull-to-water contact. The pressurized air cushion, contained by the fixed rigid side seals, provides sufficient lift to raise the hull, thereby reducing frictional drag while maintaining stability through the air support.
3Ease of repair
If fixed rigid side seals are used instead of flexible seals, then maintenance is reduced, but air cushion containment may be compromised
Solution Approach 1:
The patent inverts the conventional approach by using rigid fixed seals instead of flexible seals. The fixed rigid side seals are positioned with their outboard walls facing the water, creating a barrier that prevents water ingress while maintaining the air cushion, thereby improving ride quality and reducing maintenance.
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
This design significantly reduces drag resistance, improves stability, and enhances performance by maintaining the air cushion in both smooth and rough water conditions, resulting in reduced power requirements, increased speeds, and improved fuel efficiency.
Implementation Method 1
The angled configuration of the keels creates an air cushion along the outboard wall of each keel, thus reducing drag resistance experienced by the hull traveling through water
Data Source
AI summary
A pressurized air cushioned hull with fixed rigid side, front and rear seals. The hull includes a plurality of keels, with an air cushion disposed between inboard walls of each keel and an air cushion created/disposed along the outboard walls of each keel. These air cushions along the outboard walls of the keels are created by angling each keel by about 0.02° to about 1° relative to the longitudinal axis of the hull, wherein the left keel(s) is rotated clockwise and the right keel(s) is rotated counterclockwise, such that a distance between the keels is smaller at the front end of the keels than at the rear end of the keels. This slight angle was found to allow air, rather than water, to contact the outboard walls, unexpectedly reducing drag resistance a significant amount, thus improving performance of the hull as a whole.