External Bladder Fuel System for Aircraft Range Extension
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Solution Overview
Problem
Aircraft fuel tanks face challenges in maximizing fuel capacity due to volume constraints caused by temperature-induced expansion and contraction of fuels like JP-10, JP-8, and JP-5, which require additional ullage space, leading to wasted space and reduced fuel mass during high temperature conditions.
Innovation Solution
An external, flexible and detachable bladder system that allows fuel to expand and contract without increasing the vehicle's internal space, enabling more fuel mass to be carried while maintaining a smaller, more aerodynamically efficient profile, and allowing for flexible mission planning by transferring fuel between the tank and bladder based on temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rubber inner bladder is used within the fuel tank to accommodate fuel volume changes, then fuel leakage is prevented and ullage volume changes are accommodated, but the total mass of fuel the aircraft can hold is limited when subjected to high temperature conditions
Solution Approach 1:
The fuel storage system is divided into two separate components: a fixed internal rubber bladder within the fuel tank and an external removable bladder. This segmentation allows the internal bladder to maintain its containment function while the external bladder provides additional fuel capacity that can be attached when needed and removed when not needed, thus resolving the contradiction between reliable containment and maximum fuel mass capacity.
Solution Approach 2:
The solution moves the additional fuel storage from the internal three-dimensional space constraint to an external dimension. The external bladder can be positioned outside the aircraft fuselage where it does not constrain the internal fuel tank sizing, allowing the aircraft to carry more fuel mass without increasing its core structural volume.
2Stability of the object's composition
If the fuel tank is sized to maximum capacity at high temperature conditions, then fuel expansion is accommodated, but ullage space is wasted during operation in typical environments
Solution Approach 1:
The system transitions from a static fuel tank configuration to a dynamic configuration where the external bladder can be attached or detached based on operational requirements. During high-temperature storage, the external bladder accommodates expanded fuel; during typical operation, it can be removed to eliminate dead weight and maximize usable fuel mass, thus resolving the contradiction between volume stability and usable fuel quantity.
Solution Approach 2:
The effective fuel storage capacity parameter is made variable through the optional external bladder attachment. The system can adjust its total capacity parameter to match environmental conditions: maximum capacity with external bladder during high temperatures, and reduced capacity without external bladder during typical operation, thereby optimizing both stability and usable quantity.
3Duration of action of moving object
If an external bladder is added to increase fuel capacity, then operational range is extended, but device complexity and aerodynamic profile are increased
Solution Approach 1:
The fuel system is segmented into a permanent internal component and an optional external component. This segmentation allows the aircraft to maintain simple operations with just the internal bladder, while the external bladder serves as an optional add-on for extended range missions, thus extending operational range without permanently increasing device complexity.
Solution Approach 2:
The external bladder is designed to be removable and reusable. After use for extended range operations, it can be detached and recovered for future use. This reduces the permanent complexity burden on the aircraft system while still providing the operational range extension when needed, as the external bladder becomes a reusable accessory rather than a permanent structural addition.
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 external bladder system increases the operational range and fuel capacity of aircraft by allowing fuel to expand beyond the tank's maximum volume, optimizing fuel load distribution and reducing drag, thereby enhancing aerodynamic efficiency and weight reduction.
Implementation Method 1
Air-breathing-engine fuels (e.g., JP-10, JP-8, JP-7, and JP-5) used in various vehicles, such as aircraft (e.g., cruise missiles, UAVs, Drones, Decoys, and Aerial Target vehicles), have densities that vary as a function of temperature. This causes the fuel volume to expand as the system is exposed to heat or contract when exposed to cold temperature extremes.
Implementation Method 2
As the fuel cools the volume of the fuel reduces and the volume of the ullage space increases.
Data Source
AI summary
A bladder external to a fuel tank of a vehicle that allows an operational range of the vehicle to be increased. Preferably the bladder is external to the rest of the vehicle and the vehicle is an aircraft. The external bladder allows fuel in the fuel tank to expand and contract without requiring additional space within the vehicle, thus allowing more fuel mass to be held by the vehicle and a smaller vehicle profile that is more aerodynamically efficient. More preferably, the bladder is disconnectable from the rest of the vehicle to allow increasing of aerodynamic efficiency and weight reduction during use.