Aft-located Heated Ramp for AoA Sensor Ice Management

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Solution Overview

Problem

Angle of attack sensors with rotatable vanes on aircraft are affected by ice accumulation due to water or ice particles in the oncoming airflow, leading to inaccurate readings as large ice growths near the vane can interfere with the sensor's rotational position and output.

Innovation Solution

A multi-piece faceplate design incorporating a heated chassis with a ramp that captures and reroutes water, preventing ice accumulation by maintaining the area above freezing and redirecting water droplets away from the vane, ensuring accurate sensor readings even at offset orientations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the angle of attack sensor is exposed to oncoming airflow for accurate measurement, then measurement precision is improved, but ice accumulation occurs on the faceplate and vane leading to measurement errors

Engineering Contradiction:

Improveangle of attack measurement accuracyVSAvoidice accumulation on faceplate and vane

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The heated ramp is positioned upstream of the vane to preemptively melt ice and redirect water before it can accumulate near the vane. This preliminary action prevents ice growth at the critical location where it would affect measurement accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heated ramp acts as an intermediary element between the oncoming airflow and the vane. It intercepts water and ice particles, melts them, and redirects the water flow away from the vane, preventing direct contact between harmful substances and the measurement component.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If heating is applied to prevent ice accumulation, then reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvesensor operation reliability in icing conditionsVSAvoidenergy consumption of heater

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of heating the entire faceplate, the patent applies heating locally only to the ramp area where water interception and redirection occur. This localized heating approach provides sufficient ice prevention with minimal energy consumption, maintaining reliability while reducing power requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heater converts the potential harm of ice accumulation into a beneficial effect by melting ice and using the resulting water flow to be redirected away from the vane. The energy input is transformed into a protective mechanism that leverages the melted water itself to prevent ice buildup in critical areas.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If the ramp is designed to redirect water away from the vane, then measurement precision is improved, but device complexity increases due to multi-piece faceplate design

Engineering Contradiction:

Improvesensor output accuracyVSAvoidmulti-piece faceplate structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The faceplate is divided into functional segments: the ramp portion for water interception and redirection, and the main faceplate for structural support and sensor housing. This segmentation allows each component to be optimized for its specific function while working together as an integrated system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ramp serves multiple functions: it acts as a structural component of the faceplate, a heating element carrier, a water interception surface, and a flow redirection guide. By combining multiple functions into a single component, the overall device complexity is reduced despite the multi-piece faceplate design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 prevents ice deflection of the vane, maintaining the accuracy of angle of attack sensor output by ensuring the area around the vane remains free of ice accumulation, even in harsh environmental conditions.

Implementation Method 1

heated chassis having a heated aft-located ramp

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

preventing ice accumulation by maintaining the area above freezing and redirecting water droplets

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentEP3567375B1Aft-located heated ramp for ice and water management of angle of attack sensors

Publication Date: 2022.06.29 ROSEMOUNT AEROSPACE INC

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Figure 1C

AI summary

An angle of attack sensor (10; 110) includes a vane assembly (22) and a multi-piece faceplate (12) adjacent the vane assembly (22). The faceplate (12) includes a mounting plate (14) having an opening (42) and a heated chassis (16) positioned adjacent the mounting plate (14) and having a ring portion (50) extending into the opening (42). The ring portion (50) includes a narrow fore portion (54) extending into the opening (42), a wide aft portion (56) extending into the opening (42), and an aft-located ramp connected to the wide aft portion (56) and extending through the opening (42) beyond an exterior surface (40) of the mounting plate (14).