Dual Auxiliary Power Units in Aircraft Tail Cone
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft with increased electrical power requirements due to derivative missions often need larger APUs, which require significant airframe modifications or relocation, disrupting the original design and aerodynamics.
Innovation Solution
Installing two APUs in parallel within the aircraft tail cone, minimizing airframe modifications and maintaining original aerodynamic characteristics by using support structures that keep the APUs within the existing spatial constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a larger APU is installed to meet increased electrical power requirements, then power output is improved, but airframe space and structural design are worsened
Solution Approach 1:
The patent divides the single large APU into multiple smaller APUs (typically three) that are installed in parallel within the existing tail cone space. Each APU contributes a portion of the total electrical power output, collectively meeting the increased power requirements without requiring a single oversized unit that would exceed available space constraints.
2Power
If the APU is relocated to accommodate a larger unit, then power output is improved, but aerodynamic performance and original design integrity are worsened
Solution Approach 1:
The patent utilizes the three-dimensional space within the existing tail cone more efficiently by installing multiple APUs in a distributed arrangement rather than attempting to fit a single larger APU. This spatial reconfiguration allows the system to achieve greater total power output while maintaining the original tail cone geometry and aerodynamic characteristics.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Aircraft are provided with a pair of auxiliary power units (APUs) (14, 16) adjacently mounted in parallel relative to one another within the tail cone section (12-1) of the aircraft's fuselage (12). In some embodiments, the APUs (14, 16) are mounted generally vertically adjacent to one another. Alternatively, the APUs (14, 16) may be mounted generally horizontally adjacent to one another. The aircraft fuselage (12) may include a pair of downwardly and outwardly oriented strakes (20-1, 20-2) adjacent the tail cone (12-1) having lower edges which establish a maximum take-off pitch angle of the fuselage and define a spatial zone therebetween. The APUs (14, 16) are positioned within such a spatial zone defined between the strakes so that the maximum take-off pitch angle is not required to be changed when modifying an existing single APU aircraft with dual APUs.