Skewed Base Heat Shield for Lower-Mass Atmospheric Re-Entry
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Solution Overview
Problem
Reusing upper stage rockets is challenging due to the harsh re-entry environment and the need for additional structural mass to withstand it, while conventional heat shield solutions incur mass and cost penalties, and large nozzle engines are inefficient and difficult to protect during re-entry.
Innovation Solution
A non-axisymmetric heat shield and aerospike nozzle design for upper stage rockets, featuring a truncated toroidal centerbody and thruster mount, which allows for controlled landing and maneuverability with minimal mass addition, using an aerospike nozzle that exhausts gas towards the aft end and includes a non-axisymmetric centerbody sidewall and base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat shield solutions (ablative materials, high-temperature materials, composite materials, transpiration cooling) are used to protect the vehicle from heating during hypersonic re-entry, then the vehicle is protected from thermal damage, but the vehicle area and associated mass which must be protected increases, leading to detrimental cost and mass impacts
Solution Approach 1:
The patent applies asymmetry by using a non-axisymmetric heat shield configuration where the heat shield covers only a portion of the base of the vehicle rather than the entire base. This asymmetric arrangement reduces the total heat shield area and mass while still providing adequate thermal protection during re-entry, directly addressing the contradiction between protection reliability and mass penalty
2Use of energy by moving object
If large nozzle engines (bell nozzle engines) are used for upper stage rockets optimized for vacuum efficiency, then the engines perform well in vacuum, but they experience poor performance during atmospheric operation and are difficult to protect during re-entry due to flow separation and side loads
Solution Approach 1:
The patent employs dynamics by using an aerospike nozzle configuration that adapts to varying atmospheric conditions. The aerospike design allows the nozzle to maintain efficient operation across different altitudes and atmospheric densities, with the exhaust plume dynamically adjusting to environmental conditions, thereby resolving the contradiction between vacuum efficiency and atmospheric performance
Solution Approach 2:
The aerospike nozzle acts as an intermediary structure that mediates between the combustion chamber and the external atmosphere. This intermediate configuration protects the engine from direct exposure to harsh re-entry conditions while maintaining performance, addressing both the efficiency and reliability concerns
3Reliability
If additional structural mass is added to the upper stage rocket to withstand the re-entry environment and enable controlled landing, then the vehicle can survive re-entry and land precisely, but the payload capacity is reduced due to the 1:1 mass reduction relationship
Solution Approach 1:
The patent applies multi-functionality by designing the non-axisymmetric heat shield configuration that simultaneously provides thermal protection during re-entry and generates aerodynamic lift for controlled landing. This dual-function design eliminates the need for separate protective structures and propulsion systems, reducing overall mass while maintaining both survival and landing control capabilities
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 design achieves a higher lift-to-drag ratio and controlled landing with reduced mass and cost, enabling precise maneuvering and increased payload volume by minimizing the heat shield area exposed to high enthalpy flow.
Implementation Method 1
Rockets and other vehicles that travel at or above hypersonic speeds (e.g., space re-entry vehicles, aircraft, missiles, etc.) within a planetary atmosphere require a means to protect themselves from the heating that occurs at such high speeds
Data Source
AI summary
An atmospheric re-entry vehicle includes a main body defining a forward end of the vehicle, a base defining an aft end of the vehicle, and a heat shield at the base. The heat shield includes a heat shield outer surface. The main body and the heat shield are configured such that a centerline of the heat shield is offset relative to a centerline of the main body. At least a portion of the heat shield outer surface is at least substantially axisymmetric relative to the centerline of the heat shield.