SAWE RP G-1, 2016: Mass Properties Control for Wheeled and Tracked Vehicles

Scope

 

This document covers standard mass properties statements for procurement of mass properties data for wheeled and tracked vehicles, states the principles followed in the formulation of these standards, and furnishes instructions where necessary for uniform compilation of the required mass properties statements and forms

 

Sufficient detail is included to cover the majority of components for most wheeled and tracked vehicles (including amphibians). Blank spaces are provided for “write-ins” to detail mass properties for advanced design vehicles, projected propulsion systems, etc. Care should be taken before adding a “write-in” to ascertain that reasonably appropriate terms are not already available for usage.

 

Concepts

 

The detail and group mass properties statement have been predicated on the following basic concepts:

 

• • The primary purpose of the mass properties data are to provide information in the most advantageous form for development and improvement of wheeled and tracked vehicles (including amphibians) mass properties estimating methods and for mass properties control during design and construction of the vehicles. Such data and methods serve the significant functions of bringing avoidable adverse trends to light at an early stage, pointing out areas in which design mass properties control can be most fruitful, establishing realistic weight goals, and evaluating on a rational basis the weight cost of design features during the evolution of new or alternate configurations.

 

• • The secondary purpose of the mass properties data is to provide reasonably detailed information for engineering checking and reference purposes such as dynamic stability, grade ability, power analysis of components, flotation capabilities (in case of amphibians) etc.

 

Principals

 

The following principles have been followed to implement the above basic concepts:

 

• • A dual status system has been implemented, a weight status (code system) and a mass properties status.

 

• • The weight status (code system) has been implemented to make it easier to group the data to aid in locating the data and to help to establish the confidence level by identifying the stage of estimation, calculation or actual data.

 

• • In the weight status (code system), all weights have been broken down into functional and identifiable components which will permit and encourage the analysis of weight variations and stimulate development of lighter and more efficient vehicles.

 

• • Insofar as practicable, all tangible and readily identifiable components and provisions for a specific function or installation have been allocated to the functional group, regardless of geographic location and physical method of attachment. Where compromise of this principle was necessary because of multi-purpose function (supports, panels, etc.), items have been allocated geographically with as complete function isolation and identification as is possible.

 

• • The mass properties status consists of a major breakdown of all items in the vehicle that require individual mass properties (weight, center of gravity location and mass moment of inertia) for determining power requirements of motors, static balance, dynamic balance, dynamic stability, grade ability, flotation capabilities and any other engineering analysis requiring mass properties data.

 

• • The mass properties status must show the “weight empty” mass properties, the “basic weight” mass properties, the “curb weight” mass properties, the “design load weight” mass properties, the shipping mass properties and all the major components making up the above list.

 

• • For clarity a detailed mass properties status of major sub-groups, must be submitted on separate sheets (example—engine, transmission, differentials, main frame, radar, armament, etc.) when the sub-group is a mechanism requiring power analysis (except if the sub-group has been in production prior to the contract approval and qualified by the procuring agency) or when required by the contract specification.