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Method to Estimate Airplane Mass

IP.com Disclosure Number: IPCOM000244143D
Publication Date: 2015-Nov-13
Document File: 4 page(s) / 211K

Publishing Venue

The IP.com Prior Art Database

Related People

Alan Bruce Hickman: INVENTOR

Abstract

Real time knowledge of the airplane mass can help optimize the control laws to improve stability and control of the airplane Additionally knowledge of the airplane mass is important to accurately calculate the airplane stall speed Current systems used for estimating the mass of the airplane are based on complex algorithms The problem associated with current systems is that they are computationally expensive and require additional memory This paper provides a method for estimating the mass of the airplane using values from existing airplane systems which is cost effective and can be easily implemented in the current system The proposed method estimates the mass of the airplane based on Newton s second law of motion

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Page 01 of 4

Method to Estimate Airplane Mass

Alan Bruce Hickman

ABSTRACT

Real-time knowledge of the airplane mass can help optimize the control laws to improve stability and control of the airplane. Additionally, knowledge of the airplane mass is important to accurately calculate the airplane stall speed. Current systems used for estimating the mass of the airplane are based on complex algorithms. The problem associated with current systems is that they are computationally expensive and require additional memory. This paper provides a method for estimating the mass of the airplane using values from existing airplane systems, which is cost effective and can be easily implemented in the current system. The proposed method estimates the mass of the airplane based on Newton's second law of motion.


1. INTRODUCTION

The mass of an airplane is a function of airplane's empty weight, which is constant for a specific airplane mode, plus the variable weight of cargo, passengers and fuel. If the mass can be calculated accurately prior to flight, then the only variable during flight is the fuel weight. The solution presented here defines a relatively simple and accurate method to estimate the total mass of the airplane prior to takeoff using existing data from existing systems and sensors.


2. PROPOSED SOLUTION OF THE PROBLEM

Unlike existing systems which use complex algorithms to estimate the mass of the airplane, the proposed solution uses data from existing systems in the airplane to estimate the mass of the airplane during the takeoff and then calculate the change in mass during the flight. The systems providing data for estimating the mass of the airplane can include, but is not limited to, Fly By Wire Flight Control System (FBW FCS), Full Authority Digital Engine Control(FADEC) system, Fuel Quantity Indication

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System (FQIS) and an Inertial Reference System (IRS). In the proposed solution, the mass of the airplane is estimated based on Newton's second law of motion equation: F = ma, Where 'F' is the sum of forces acting on the airplane, 'm' is the mass of the airplane during takeoff and 'a' is the acceleration of the airplane during takeoff. The acceleration is measured by the Inertial Reference System (IRS) and transmitted on digital data buses for use by other systems in the airplane. The forces acting on the airplane in the direction of the acceleration during takeoff are engine thrust, aerodynamic drag and friction from the wheels/brakes. The engine thrust is calculated by the Full Authority Digital Engine Control (FADEC) and transmitted on the digital data buses. The aerodynamic drag is a function of physical geometry of the airplane, the configuration of the airplane, and its airspeed. The rolling friction of the tires and brakes also contribute to the drag but may be omitted from the calculation based on accuracy requirements. Hence the mass is calculated as:

Mass = (Sum of the forces)/acceleration

Mass = {Engine 1 Thrust + Engin...