Ejection Seat Backstop Aerodynamic Control

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Solution Overview

Problem

Ejection seats from aircraft experience uncontrollable pitch and yaw during high-speed ejection, causing potential injury to pilots and complicating separation from the seat and parachute deployment due to arm flailing and aerodynamic imbalances.

Innovation Solution

The ejection seat incorporates a backstop with a net structure and an aerodynamic control mechanism, featuring patches and cutouts in the sheet of material that cover a portion of the frontal area, designed to reduce aerodynamic forces and stabilize the seat and pilot during ejection by deploying laterally outward to form a forward-facing surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a traditional ejection seat is used without aerodynamic control mechanisms, then the structure is simple and lightweight, but the seat experiences uncontrollable pitch and yaw during high-speed ejection

Engineering Contradiction:

Improvestability of ejection seatVSAvoidcomplexity of backstop structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The backstop incorporates a net structure with patches and cutouts that create a porous aerodynamic surface. This porous configuration allows the backstop to interact with the high-speed windblast in a controlled manner, generating stabilizing aerodynamic forces that reduce pitch and yaw while maintaining structural simplicity and minimal weight addition.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The aerodynamic control mechanism changes the aerodynamic parameters of the backstop by incorporating patches and cutouts in the net structure. These geometric modifications alter the flow characteristics and pressure distribution across the backstop surface, enabling controlled aerodynamic forces to stabilize the seat during ejection without significant weight penalty.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the backstop uses a solid sheet material, then aerodynamic stability is improved, but weight increases significantly

Engineering Contradiction:

Improveaerodynamic stabilityVSAvoidweight of backstop

Core Design Contradiction:

Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The net structure with patches and cutouts functions as a porous aerodynamic surface that provides stability control while minimizing weight. The porous configuration allows selective interaction with airflow, generating necessary aerodynamic forces without the mass penalty of a solid sheet, achieving an optimal weight-to-stability ratio.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The thin net structure with integrated patches and cutouts acts as a flexible aerodynamic surface that can deform and adapt to high-speed flow conditions. This thin-film approach provides adequate aerodynamic stability while maintaining minimal weight, unlike rigid solid sheets that would require significantly more mass.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If no aerodynamic control mechanism is added, then manufacturing is simple, but pitch and yaw control during ejection is inadequate

Engineering Contradiction:

Improvereliability of pilot protectionVSAvoidease of backstop manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The porous net structure with patches and cutouts can be manufactured using modern composite and textile technologies. The modular design allows for standardized production of net sections that are then assembled and secured to the backstop frame, making the manufacturing process manageable while achieving reliable pitch and yaw control during ejection.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The backstop utilizes composite construction combining net material with patched reinforcement sections. This composite approach allows each component to be manufactured separately using appropriate techniques for the material type, then assembled into the final structure, balancing manufacturing simplicity with the reliability needed for effective pilot protection during ejection.

Inventive Principle:

Principle #40Composite materials

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 effectively reduces pitch and yaw, minimizing the risk of injury and improving the safety of pilot separation and parachute deployment by stabilizing the ejection seat and pilot within the high-speed windblast, while adding negligible weight.

Implementation Method 1

an aerodynamic control mechanism incorporated into the net structure... configured to reduce aerodynamic forces and stabilize the seat and pilot during ejection

Methodology Applied

Scientific EffectAerodynamic force: Drag

Data Source

PatentUS11358728B2Center-of-pressure arm restraint system

Publication Date: 2022.06.14 AMI IND INC

AI summary

An ejection seat is disclosed. In various embodiments, the ejection seat includes a seat frame having a seat-back and a seat-pan adapted to support an occupant and a propulsion system configured to propel the ejection seat from an aircraft; and a backstop configured to deploy laterally outward from the seat-back to form a forward-facing surface, the backstop including a net structure and an aerodynamic control mechanism incorporated into the net structure.