1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the 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 there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2015 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, 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: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR1800A AEROSPACE INFORMATION REPORT AIR1800 REV. A Issued 1984-09 Revised 1997-
5、07Reaffirmed 2015-04 Superseding AIR1800 Aircraft Tail Bumpers RATIONALE AIR1800A has been reaffirmed to comply with the SAE five-year review policy. 1. SCOPE:This SAE Aerospace Information Report (AIR) covers the field of civilian, commercial and military airplanes and helicopters. This summary of
6、tail bumper design approaches may be used by design personnel as a reference and guide for future airplanes and helicopters that require tail bumpers. Those described herein will consist of simple rub strips, structural loops with a wear surface for runway contact, retractable installations with rep
7、laceable shock absorbers and wear surfaces and complicated retractable tail landing gears with shock strut, wheels and tires. The information will be presented as a general description of the installation, its components and their functions.1.1 Purpose:To document the design approaches used for tail
8、 bumpers in contemporary airplanes and helicopters.2. REFERENCES:The following publications contain information relative to applications of tail bumpers. 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 purch
9、ase order. In the event of conflict between the text of this specification and references cited herein, the text of this specification takes precedence. Nothing in this specification, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.2.1 SAE Publicatio
10、ns:Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.ARP1107 Tail Bumpers for Piloted Aircraft2.2 U.S. Government Publications:Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.MIL-A-8863A Airplane Strength and Rigidit
11、y Ground Loads for Navy Procured Airplanes,dated July 12, 19743. REASONS FOR TAIL BUMPER:The reasons tail bumpers are required on certain current aircraft are listed as follows:a. Inadequate tail clearance in landing attitude.b. Prevent back tip over rotation during ground handling.c. Over rotation
12、on takeoff.d. Tip back during deck handling on aircraft carrier.e. For tail protection, tie down and jack point.f. For protection against hard flared landings.g. To protect tail rotor from hitting objects.Some air vehicle designers (Douglas DC-10, MD-11; Airbus A320, A330, A340) do not use tail bump
13、ers for reasons noted below:a. Reduced maintenance and service problems without tail bumpers.b. Increased ground clearance without tail bumpers.c. Experience at some airframe manufacturers has shown that in the case of hard tail/ground impact damage to the fuselage is considerable with or without ta
14、il bumpers or skids.d. Likelihood of tail strike is very low due to tail clearance or aircraft performance.In all cases critical aircraft performance characteristics and dynamic analysis of motion of the aircraft under all moving conditions will decide the need for a tail bumper. This analysis will
15、also determine the frequency of possible tail contacts, providing information necessary to determine the type of tail bumper required for a specific new airplane.4. GENERAL DESCRIPTIONS:Following is a brief description of tail bumpers on current aircraft.4.1 Cessna Twins and Single Engined Airplanes
16、:Structural loop extending below the tail of the aircraft.Figure 1 shows the loop contact surface and support structure that can be sacrificially failed in ground contact. The loop and support structure is readily replaceable. The loop may also be used as a tie down point.SAE INTERNATIONAL AIR1800A
17、2 OF 12FIGURE 14.2 Piper Twins and Single Engined Airplanes:Loop contact tail bumpers similar to Figure 1 are used.4.3 Bell Helicopter Model 212:Helicopter tail bumpers are generally fixed structure type, supported in the tail boom to protect the tail rotor from contacting the ground or landing deck
18、. The tail bumper ground contact point is a hardened (Stellite) wear surface. Figure 2 represents the fixed tail skid in the Bell Model 212 helicopter. It is constructed of swaged steel tubing installed as a simply supported beam. The hardened contact surface is welded to the swaged tube.FIGURE 2SAE
19、 INTERNATIONAL AIR1800A 3 OF 124.4 Boeing Vertol YUH-61A Helicopter:Figure 3 depicts a fixed tail bumper with aft trailing arm/skid with pin jointed shock absorber. The shock absorber was solid media (silicone rubber compound) liquid spring. This type of shock absorber unit needs no servicing. This
20、tail bumper was a partial emergency device. The unit was qualified for 50 landings at 18 ft/s descent. Its service life is far greater at lower contact velocities.FIGURE 34.5 Boeing 727-200 Series Aircraft:Figure 4 shows the general geometry and components of the retractable tail bumper on the 727-2
21、00 series aircraft. The tail bumper consists of a drag link, a yoke assembly, an energy absorber, and a hydraulic actuator.SAE INTERNATIONAL AIR1800A 4 OF 12FIGURE 44.5 (Continued):The tail bumper is held in the down and locked position by a cam follower forced against a cam by an overcenter linkage
22、 of the yoke assembly. The tail bumper is held in the retracted and locked position by an internal locking mechanism incorporated in the hydraulic actuator.The energy absorber consists of a telescoping inner and outer cylinder assembly with a crushable honeycomb cartridge in the lower half and a rin
23、g spring assembly in the upper half. When the drag link contacts the runway, the shock tends to move the drag link aft and up to compress the cylinder assembly. The lower or inner cylinder telescopes within the outer cylinder and compresses the energy absorber cartridge and the spring assembly. The
24、ring spring assembly provides the capability to repeatedly protect the airplane without excessive replacement of the energy absorber cartridge. The ring spring assembly absorbs the initial shock and will resist compression up to approximately 30,000 lb and 2-1/2 in before bottoming out. When the rin
25、g spring assembly has been bottomed and the energy absorber cartridge has been crushed 1 in, the indicator chip will shear off indicating that the cartridge should be replaced.SAE INTERNATIONAL AIR1800A 5 OF 124.6 Lockheed L-1011-1, -15 Tail Bumper:Figure 5 shows the L-1011 tail bumper which is loca
26、ted in the fuselage underneath the horizontal tail.Energy absorption is provided by a modified oleo-pneumatic shock strut capable of retracting to the fully compressed position. The shock strut is cantilever supported in the aft fuselage structure. The shock strut contains a regulator valve to meter
27、 flow of hydraulic fluid during compression. The shock strut and retract actuator are concentric within the body of the strut. It is retracted by hydraulic pressure forcing the piston into the cylinder against an initial air charge which is used for bumper extension. The actuation is integrated and
28、slaved with the landing gear control lever. Retracted and extended positions are indicated by proximity sensors. It is held in the retracted position by locked hydraulic fluid controlled by an uplock/unlock valve. The shoe is readily replaceable and the shock strut piston has a fuse to indicate if i
29、t has been overloaded and requires replacement.FIGURE 5SAE INTERNATIONAL AIR1800A 6 OF 124.7 Airbus Industries A-300:4.7.1 A-300 B2/B4: The tail bumper is covered by a plastic fairing and is not retractable. It is composed basically of a metal tail skid shoe, which is attached to a shock strut, moun
30、ted on an arm and the rear fuselage structure.The cylinder of the shock strut consists of a light alloy honeycomb structure which is compressed when the skid shoe touches the runway, thus absorbing the shock. Figure 6 shows a side view of the general arrangement of the A-300 tail bumper.FIGURE 64.7.
31、2 A300-600, A310: Figure 7 shows the tail bumper installation and backup structure. A .15 mm (.59 inch) abrasion of the tail bumper is allowed before replacement is necessary.4.7.3 A320, A330, A340: On all new Airbus aircraft there is no tail bumper. Without a tail bumper there is more tail clearanc
32、e. In case of a slight impact, there is a standard repair instruction available.SAE INTERNATIONAL AIR1800A 7 OF 12FIGURE 7SAE INTERNATIONAL AIR1800A 8 OF 124.8 The Concorde:The Concorde tail bumper resembles a small dual wheeled tail landing gear. The tail gear is designed to protect the engine nace
33、lle rear section and the rear fuselage during takeoff or landing with the aircraft in the nose high attitude. Actuation is accomplished with a separate hydraulic actuator which is slaved to the landing gear control lever. Energy absorption is accomplished with a conventional nitrogen pressurized ole
34、o-pneumatic shock absorber containing a metering pin. Instead of a skid surface the tail gear is fitted with two pneumatic tires. This tail gear arrangement was necessary because of critical performance characteristics causing frequent tail gear runway contacts. Figure 8 depicts a general arrangemen
35、t of the Concorde tail landing gear.FIGURE 8SAE INTERNATIONAL AIR1800A 9 OF 124.9 McDonnell Douglas Aircraft Co.:4.9.1 Douglas DC-9, MD-80, MD-90: This tail bumper and compression indicator assembly, shown in Figure 9, is mounted on the lower aft fuselage and is used to prevent or limit structural d
36、amage due to tail strike from early rotation or abnormal operations. The bumper extends beyond the skin and is linked to a shock strut that will absorb impact forces. The shock strut uses MIL-H-5606 oil and is charged with nitrogen. The bumper ground contact surface is covered by a skid that will no
37、rmally show evidence of ground contact.The tail bumper compression indicator should normally be in the horizontal position. If the bumper has contacted the ground and was compressed 3 in or more, the indicator will be driven toward the vertical position. In this event, a structural inspection must b
38、e made.4.9.2 Douglas DC-10, MD-11: DC-10 and MD-11 do not use tail bumpers or skids.4.10 Typical Airplane Tail Bumper Installation:The tail bumper installation shown in Figure 10 is a typical installation adaptable to several types of airplanes. It was an installation proposed for a supersonic airpl
39、ane where the frequency of ground contact was determined to be low. However, high landing and takeoff speeds dictated a tail bumper be furnished to protect the aft portion of the fuselage from damage should infrequent ground contact be made during takeoff and landing at marked nose-up attitudes.This
40、 tail bumper installation consists of:a. A structural retractable assembly terminating in a hard faced ground contacting skid.b. An oleo-pneumatic shock absorber.c. A combined radius rod and retraction actuator. The tail bumper is braced by a radius rod in retracted position to eliminate aerodynamic drag and in the extended position for proper ground contact.SAE INTERNATIONAL AIR1800A 10 OF 12FIGURE 9SAE INTERNATIONAL AIR1800A 11 OF 12FIGURE 10PREPARED BY SAE SUBCOMMITTEE A-5B, GEARS, STRUTS & COUPLINGS OFCOMMITTEE A-5, AEROSPACE LANDING GEAR SYSTEMSSAE INTERNATIONAL AIR1800A 12 OF 12
