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1、AEROSPACE RECOMMENDED PRACTICE ARP1598 REV. A Issued1985-08 Revised1997-03 Reaffirmed2007-08 Superseding ARP1598 Landing Gear System Development Plan FOREWORD Changes in the revision are format/editorial only. INTRODUCTION The development of a landing gear system for a modern high performance air ve
2、hicle is an engineering and development process which covers many months in calendar time and also crosses over many disciplines and abilities. The process is subordinate to and dependent upon the plan for development of the vehicle itself. Good engineering design, analysis, and documentation will g
3、enerally identify most of the necessary parts of the development process and allow the design team to more effectively perform the task. The total plan is one which might be prepared by a contractor to describe a development program for a specific aircraft, and be submitted for approval before initi
4、ation of the actual work. The plan should be revised and updated at intervals during the development program as influencing factors dictate. A milestone chart should be a part of the plan and should show the interrelationship between phases of the development work to be performed. Design reviews sho
5、uld be identified and scheduled. The progressive design verification process to demonstrate compliance with requirements must be clearly delineated. The overall plan may cover as little time as several months but more probably as much as several years depending upon the complexity of the development
6、 and, of course, must fall within the constraints of the prime vehicle development plan. The development has been divided into six functional/chronological phases although each phase overlaps and affects the others. These general divisions are: Preliminary Design Design Integration Component Develop
7、ment Subsystem Developmen t“On Air Vehicle” Development Landing Gear System - In Service Reliability and Maintainability Discussion of these six major development phases is given in the following pages. SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the
8、 state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every fiv
9、e years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2007 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electro
10、nic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org RATIONALE This
11、document has been reaffirmed to comply with the SAE 5-Year Review policy. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 19:27:00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE ARP1598
12、 Revision A - 2 - 1.SCOPE: This Aerospace Recommended Practice (ARP) is therefore intended to document the process of landing gear system development. Some of the steps covered are mandatory and others are elective, or dependent upon customer requirements or desires. Economics is a very significant
13、factor and for each analysis or test performed, more confidence and assurance of success is gained, but at a price. Some of the steps are performed as a matter of “good engineering practice” and without special recognition. Others are unique to the particular landing gear system and all together com
14、prise a complete development. 2.REFERENCES: 2.1Applicable Documents: The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the pu
15、rchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1U.S. Government Publicat
16、ions: Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094. MIL-L-87139 3.PRELIMINARY DESIGN: The preliminary design stage of an aircraft (and all of the systems which comprise the vehicle) is a process in which the designer strives for the
17、optimum overall arrangement to best meet the designated requirements. Adequate attention must be given the landing gear system at this time to prevent compromises which may eventually result in increased maintenance and reliability requirements, and excess weight. At the conclusion of the Preliminar
18、y Design phase the Preliminary Design Review (PDR) should be scheduled. 3.1Design (Preliminary): 3.1.1Documentation: In all stages of design, it is of paramount importance to establish the design requirement for the system and to document these requirements. This may be done in the form of a “System
19、 Definition Manual,” “Basic Data Manual,” or any similar form. This documentation, established at this point should be updated as the system design progresses. Initially, requirements only will be shown. Prior to completion of the PDR, the means by which each requirement will be verified, should be
20、identified. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 19:27:00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE ARP1598 Revision A - 3 - 3.1.2Geometric Arrangement: The geometric ar
21、rangement of the landing gear legs, structures, wheel arrangements, and other features which affect the vehicle/ground relationship including shock strut/tire/axle strokes should be established and shown on a layout type drawing. Careful consideration should be given to tip-back angle, turnover angl
22、e, center of gravity limits, ground clearance to deflected surfaces, landing attitude limits, and takeoff rotation limits. 3.1.3Tire/Wheel/Brake Sizing: Selection of tire and wheel size should be made in accordance with best weight and load information available, and revised as required during the P
23、/D phase until concept freeze. This must be done in conjunction with sizing the brake to fit the wheel cavity and meet design deceleration and kinetic energy and durability requirements. In sizing tires, particular attention must be given to ground flotation requirements, peak dynamic taxi and landi
24、ng loads, and takeoff load-speed-time curves. 3.1.4(N) (Additional Requirements for Carrier Based Aircraft): The tire/wheel must be selected to be compatible with deck strength, cable crossing, and catapulting. 3.1.5Ground Flotation: Tire/wheel sizing and arrangement must be selected in a manner com
25、patible with ground flotation requirements for operation of the aircraft. Design studies are required in support of analysis. 3.1.6Component Sizing: Rough sizing of stock strut piston, cylinder, trunnion, supporting structure, etc., must be made to support stowage space requirements in the vehicle.
26、3.1.7Kinematics: Retraction/extension/locking kinematics and configurations must be established to provide the required transition of the gear/wheel/tire assemblies from down and locked position to up and locked position. Compatibility of the system with the A/C structure and other basic features no
27、t only in the extreme positions (up locked/down locked) but also in all intermediate positions must be demonstrated. Due consideration should be given to “free-fall” capability of the assemblies in emergency conditions. 3.1.8Trade-Off Studies: The preliminary design phase is the proper time for dete
28、rmination of basic design concepts. This requires trade-off studies in many cases. Some examples of such studies might include: a.Configuration trade-offs b.Brake material - steel, carbon, beryllium, etc. c.Shock strut material - aluminum, steel, etc. d.Auxiliary braking methods, i.e., drag chutes,
29、arresting hook, etc. e.Need for tail bumpers, and other auxiliary installations or devices f.Anti-skid systems These studies will provide basic information necessary for performance/configuration definition for the total vehicle. Developing concepts for operation of active landing gear system elemen
30、ts (gear sequence and indication, braking control system, nosewheel steering system, etc.) means to portray them in block diagram and/or logic diagram form. Copyright SAE International Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 19:27:00 MS
31、TNo reproduction or networking permitted without license from IHS -,-,- SAE ARP1598 Revision A - 4 - 3.1.9Concept Freeze: At the end of the preliminary design phase, a basic configuration is determined and frozen. This provides a baseline from which to draw up specifications and initiate design/ ana
32、lysis of components and installations for the air vehicle and all of its systems. 3.2Analyses (System and Component): Initial analyses done in the preliminary design stage will frequently be reiterated and/or updated at subsequent stages of design because of changes which occur until final and compl
33、ete qualification of components and systems. These initial analyses provide necessary weight (preliminary), volume, and performance data to support the total aircraft development. 3.2.1Brake Kinetic Energy: Sizing of the tire/wheel/brake package requires a deceleration analysis of the aircraft inclu
34、ding effects of aerodynamics, engine thrust, drag chutes, etc., to allocate that portion of the kinetic energy which is absorbed by the brakes. Missions profiles for brake durability analysis needs to be defined early in the design program. 3.2.2Ground Flotation: Requirements for the aircraft genera
35、lly specify the types of surfaces (runways, taxiways, etc.) from which it will operate. Analysis to verify this capability is done early, since compliance is determined by basic factors, i.e., aircraft weight, gear location with respect to aircraft center of gravity, tire size/operating pressure, nu
36、mber of tires, spacing of tires and landing gear legs. Changing these sizes at a later date is expensive in both cost and schedule. 3.2.3Loads Analysis (Preliminary): Landing gear strut reactions, wheel loading, landing impact loads, and a general (but based on preliminary A/C data) loads analysis i
37、s necessary to enable publication of a development specification and provide data for on-going design. 3.2.4Stress Analysis (Preliminary): Adequate stress analysis must be made to insure that rough sizes selected for structural members and components are compatible with each other and with space all
38、ocations in the aircraft. 3.2.5Trade-Off Studies: Analysis should be made to back up any design trade-off studies conducted. 3.2.6Nose Wheel Steering Power Requirements: Conduct a preliminary analysis to determine power requirement for the nose wheel steering unit, based on the geometric configurati
39、on of the A/C, the projected weight, and the desired levels of NW steering performance (steering angle, rate, kinematics, etc.). 3.2.7Retract/Extend Power Requirements: Conduct a preliminary analysis to define landing gear retract/extend placard speeds to define power requirements and operating time
40、s. 3.2.8Other Analysis: Conduct other pertinent analysis, based on requirements and needs of individual design configuration selected. Some such analysis might include crosswind gear capability, catapulting and holdback systems, unique ground maneuvering requirements, etc. Copyright SAE Internationa
41、l Provided by IHS under license with SAELicensee=Defense Supply Ctr/5913977001 Not for Resale, 12/04/2007 19:27:00 MSTNo reproduction or networking permitted without license from IHS -,-,- SAE ARP1598 Revision A - 5 - 3.3Tests (Preliminary Design): This stage of development of a landing gear system
42、does not generally include a great variety of tests. Some component or model tests are appropriate, however, and are only done in order to save time, money, or problems at a later date. 3.3.1Kinematics Test: In order to verify kinematic arrangements for landing gear assembly retraction/ extension, o
43、r mechanism operations, two and/or three dimensional paper/wood/wire models are utilized. The simplest form might be a bent up paper clip to simulate the axle, the strut, and the trunnion, to demonstrate a path of retraction and rough approximations of the extended and stowed positions of the assemb
44、ly. Two dimensional models of locking mechanisms are widely used. Sometimes 1/4 scale or full scale three dimensional wood/metal models of the complete gear assembly are appropriate to prove the retraction/extension system concept. Today, use of computer graphics is widespread. 3.3.2Component Tests
45、(Preliminary): Component tests within the preliminary design phase would generally be limited to those tests necessary to validate an assumption made in design or to demonstrate adequacy of currently available hardware for the new design requirements. For example: a.Limited drop tests on an existing
46、 shock strut to new requirements or, b.Test of an existing tire to new load/speed/time requirements or for abuse loads on unusual conditions (roll over arresting cable, step bumps, etc.). 4.DESIGN INTEGRATION: Design and integration of the landing gear system into the aircraft involves the several l
47、anding gear unique assemblies (nose landing gear, L/H main gear, R/H main gear, tail bumper, wing tip gear, arresting hook, etc.) and all of the aircraft mounted equipment necessary for control and operation of these systems. Indications to the crew of system status is also included as an important
48、part of this subsystem. The preliminary design configuration will be carried forward in this phase to provide a completely integrated landing gear system in the aircraft. 4.1Design (Installation and Integration): Major considerations for design in this phase will include structural backup and suppor
49、t for all gear assemblies and mechanisms, electrical and hydraulic services and interfaces, and mechanical services routed through the aircraft such as brake control cables. 4.1.1Documentation: Update and extension of the system requirements documentation must cover all system design and performance requirements. Integration of the system requires also that all interface requirements be do