Showing papers on "Landing gear published in 1988"

Aircraft landing gear design principles and practices

Abstract: This text aims to lead students and engineers from the initial concepts of landing gear design through to the final detail design. It provides a link in landing gear technology from historical practices to modern design trends, also considering the necessary airfield interface with gear design.

Adjustable two-stage aircraft landing gear system

Abstract: A two-stage aircraft gear. The landing gear includes a cantilever landing gear whose lower end is attached to a trailing arm (or articulated) landing gear. The cantilever gear is a collapsible piston-cylinder assembly, and the trailing arm gear also has a shock absorber connected between a fixed portion of the trailing arm gear and the movable wheel support arm. When landing, the load imposed is first absorbed by the trailing arm landing gear. After the trailing arm gear has been fully compressed, the cantilever gear begins to compress. The cantilever and trailing arm landing gear can be combined to provide the desired performance. The landing gear static position can be designed to be in the static load curve of the first component, allowing the aircraft to be stably supported and yet difficult to overturn. Adjustable orifice plates contained within one or both of the cantilever and articulated stages can be controlled as a function of the vertical descent velocity and/or distance. If desired, differential pressure measurements within the two stages can be used to give the landing gear any desired damping and/or landing gear extension characteristic.

Quick change wheel landing gear

Abstract: A quick change wheel landing gear assembly (10) is provided as a replacement for a skid landing gear system on a vertical take-off and landing aircraft. The wheel landing gear assembly (10) includes a pair of spaced-apart fore and aft longitudinal tubes (16, 18) attached to a pair of short, spaced-apart cross tubes (20, 22) that are adapted to mount on the structural saddles (12, 14) used to mount the skid landing gear on the underside of the aircraft. The longitudinal tubes (16, 18) are connected together at the forward end for mounting a fully swiveling nose gear (26) thereto. Aft main gear wheels (30, 32) are mounted on cantilever landing gear legs (34, 36) that extend laterally from the longitudinal tubes (16, 18) adjacent the aft cross tube (22). Landing loads on the landing gear may be absorbed by resilient springs (25), deflection of the gear legs (34, 36) and the aft cross tube (22), torsion of the fore and aft longitudinal tubes (16, 18), or any combination of these actions. The wheel landing gear assembly (10) is designed to be mounted on existing aircraft structural saddles which eliminates the need for special landing support structure needed in the prior art.

Spin-Up Studies of the Space Shuttle Orbiter Main Gear Tire

Abstract: One of the factors needed to describe the wear behavior of the Space Shuttle Orbiter main gear tires is their behavior during the spin-up process. An experimental investigation of tire spin-up processes was conducted at the NASA Langley Research Center's Aircraft Landing Dynamics Facility. During the investigation, the influence of various parameters such as forward speed and sink speed on tire spin-up forces were evaluated. A mathematical model was developed to estimate drag forces and spin-up times and is presented. The effect of prerotation was explored and is discussed. Also included is a means of determining the sink speed of the orbiter at touchdown based upon the appearance of the rubber deposits left on the runway during spinup.

A Mathematical Model of the On-Deck Helicopter/Ship Dynamic Interface

Abstract: : A mathematical model of the on-deck helicopter/ship dynamic interface has been developed and implemented on an ELXSI 6400 computer. This work provides a capability for investigating helicopter/ship dynamic interactions, such as deck clearances on landing, swaying, toppling and sliding criteria, and tie-down loads. Different helicopter types can be readily examined, given their undercarriage representation. The model takes account of arbitrary ship motion, and includes features such as brakes on or off, tyre deformation and tyre sliding. Keywords: Aircraft shipboard landings; Ship decks; Helicopters; Landing gear; Undercarriages; Australia.

New design procedures applied to landing gear development

Abstract: A survey of the most advanced design tools and procedures applied to landing gear development is performed. This survey mainly focuses on computer-aided design (CAD) methods as used for kinematics and loads definition, performances simulation, solid modeling, and finite-element analysis. However, two other procedures are also considered, i.e., failure and reliability analysis and value analysis. It is shown how the use of these new design procedures is the only way to achieve a thorough optimization of a modern and competitive landing gear coping with stringent requirements in such different areas as kinematics, weight, safety, service life, maintainability and cost effectiveness.

Aerial aircraft carrier

Abstract: An aerial aircraft carrier is disclosed having a first and a second shuttlecraft that have a cantilever fluselage extending between the first and second shuttlecraft. The cantilever fuselage is disposed at both ends within a fuselage housing that depends from the under-carriage of the first (lead) and second (aft) shuttlecraft, the cantilever fuselage forming a longitudinal member therebetween. A means for elevating a plurality of aerodynamically stable platforms, (wing assemblies), is affixed to the cantilever fuselage. The wing assemblies each have a wing span member attached thereto, with control surfaces, for stabilizing an aircraft (a payload) that is secured in a mount assembly. An aircraft landing in the mount assembly is secured by an application of negative air pressure against a landing gear pod of the aircraft, and as the aircraft is adhered to a pair of mount elements, by evacuation of air, forming a suction seal peripheral to the environmental surfaces of the landing pod, the wing span members aerodynamically stabilize the weight of the aircraft on the wing assembly platforms. The pilot of the retrieved aircraft then feathers the rotors to his/her aircraft, the weight thereof being primarily supported by the aerodynamic lift of the wing span members. The aircraft is then retrieved in flight, aerodynamically stabilized and can be serviced while in flight. A reverse sequence allows the secured aircraft to be launched from the carrier apparatus.

F-15 SMTD low speed jet effects wind tunnel test results

Abstract: Key results from low speed wind tunnel testing of the F-15 STOL and Maneuver Technology Demonstrator (SMDT) with thrust reversers are presented. Longitudinally, the largest induced increments in the stability and control occur at landing gear height. These generally reflect an induced lift loss and a nose-up pitching moment, and vary with sideslip. Directional stability is reduced at landing gear height with full reverse thrust. Nonlinearities in the horizontal tail effectiveness are found in free air and at landing gear height.

Topics in landing gear dynamics research at NASA Langley

Abstract: Four topics in landing gear dynamics are discussed. Three of these topics are subjects of recent research: tilt steering phenomenon, water spray ingestion on flooded runways, and actively controlled landing gear. The fourth topic is a description of a major facility recently enhanced in capability.