Bladderless Fuel Tank Sealing via Reactive Rubber
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Solution Overview
Problem
Existing self-sealing fuel tanks with bladders face issues such as excessive weight, non-immediate sealing, durability problems, maintenance difficulties, and high costs, among others, when sealing penetration holes in aircraft fuel tanks.
Innovation Solution
A bladderless fuel tank design featuring a fuel-reactive rubber layer attached to the tank wall, with pressure differentials between external, internal, and interstitial cavities that minimize fuel escape upon penetration, utilizing a compressed rubber layer that swells to seal holes and allows controlled drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bladder is contained within a box or airframe structure for self-sealing, then sealing capability is provided, but weight increases excessively
Solution Approach 1:
The patent removes the bladder from the fuel tank system entirely, extracting the sealing function to a fuel-reactive layer integrated into the tank wall structure. This eliminates the heavy bladder component while maintaining sealing capability through chemical reaction of the fuel-reactive layer with penetrating fuel.
Solution Approach 2:
The fuel-reactive layer is merged with the tank wall structure, combining the sealing function with the structural component. This integration eliminates the need for separate bladder systems and reduces overall weight while providing immediate sealing upon penetration.
2Reliability
If a bladder system is used for self-sealing, then sealing function is provided, but sealing response time is delayed
Solution Approach 1:
The fuel-reactive layer is pre-positioned within the tank wall structure in advance, ready to react immediately upon penetration. This preliminary positioning eliminates the time delay associated with bladder deployment mechanisms, providing instant sealing when fuel contacts the reactive layer.
Solution Approach 2:
The system uses the penetrating fuel itself to activate the sealing mechanism. When fuel penetrates the tank wall, it automatically contacts and reacts with the fuel-reactive layer, triggering the sealing action without requiring external activation systems or delayed response mechanisms.
3Reliability
If a bladder system is implemented, then sealing capability is achieved, but durability and reliability decrease
Solution Approach 1:
The fuel-reactive layer is designed as a consumable component that reacts with penetrating fuel to seal holes. After serving its sealing purpose, the layer is depleted, but this disposable approach provides reliable sealing without the durability issues of reusable bladder systems that must withstand repeated pressurization cycles.
4Reliability
If a bladder system is used, then sealing function is provided, but maintenance difficulty increases
Solution Approach 1:
By removing the bladder entirely and replacing it with a fuel-reactive layer integrated into the tank wall, the patent eliminates the complex maintenance requirements of bladder systems. The simplified structure requires no special maintenance procedures, only standard inspection of the tank wall and reactive layer integrity.
5Reliability
If a bladder system is implemented, then sealing capability is achieved, but fuel drainage after penetration increases
Solution Approach 1:
The patent converts the penetrating fuel, which would normally cause damage and drainage, into the sealing mechanism itself. The fuel that penetrates the tank wall automatically reacts with the fuel-reactive layer to create the seal, thereby stopping further drainage. The harmful penetrating fuel becomes the activating agent for sealing, eliminating continued fuel loss.
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 solution provides fast, durable, low-maintenance, and cost-effective sealing with reduced fuel drainage, ensuring reliable and safe operation while maintaining tank design integrity and simplifying installation and inspection.
Implementation Method 1
the reactive layer is exposed to the fuel and it swells, eventually substantially closing the hole
Implementation Method 2
A first pressure is disposed outside the fuel holding cavity and the tank wall. A second pressure is disposed within the fuel holding cavity. A third pressure is disposed within an interstitial cavity of the tank wall and outside the fuel holding cavity. At least one of the first pressure or the third pressure is maintained to be higher than the second pressure
Data Source
AI summary
Apparatus and methods are provided to minimize the escape of fuel out of a fuel tank when a tank wall is penetrated by a bullet. In one embodiment, a pressure differential may be maintained between a pressure within a fuel tank cavity and another pressure outside the fuel tank cavity in order to minimize the loss of fuel upon penetration of the fuel tank. In another embodiment, a compressed rubber layer of fuel-reactive rubber may be provided which is adapted to be attached to a fuel tank wall and to swell upon contact with fuel in order to substantially seal a penetrated hole in the fuel tank wall.