Browse Topic: Wheel wells

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Extraordinary and Special Purpose Landing Gear SystemsAIR4846B (Current)11/11/2025
A landing gear system comprises the most compelling assembly of engineering skills. Its importance to the successful design of an aircraft can be favorably compared with that of the aircraft's wings and engines. A landing gear system consists of several different engineering disciplines, and is continually in the public eye especially with regard to safety. The primary objective of AIR4846 is to present a record of a variety of interesting gears, gear/aircraft systems and patents, and to discuss wherever possible the lessons learned, and the reasons for the design. Thus, the document is not only a historical account, but a means of recording technical knowledge for the practical benefit of future landing gear designers. Commendable efforts have been made over the years by several individuals to make such recordings, and AIR4846 will make continual reference to them. This applies to all books, papers, or specifications that have the approval of the SAE A 5 Committee. AIR4846 also accepts the premise that an essential aircraft requirement can often justify a gears' complexity and consequent weight. However, the document's purpose is not to recommend, but to provide reliable, authenticated information. Hence, the gear designer would be better equipped to adjudicate trade studies rationally, while not restricting his/her innovative skills. Each gear design feature will be associated with as many aircraft examples as possible, and every effort will be made to ensure accuracy, authenticity, and detail clarity. Section 2 of this document describes the features of landing gear which are addressed in the specific descriptions of various landing gears (Category A). Also, special types of landing gear are categorized as Category B.
A-5B Gears, Struts and Couplings CommitteeNEW
Stretchable Mesh for Cavity Noise ReductionTBMG-285653/1/2018
NASA’s Langley Research Center has developed a landing gear cavity modification that reduces noise produced during aircraft approach and landing. The modification is an innovative stretchable mesh assembly that deploys and retracts with the landing gear to reduce high-intensity low- to mid-frequency airframe noise. The envisioned low-profile mesh concept enables mitigation of cavity noise without sealing of the cavity or incurring appreciable penalties of increased weight, and conforms easily and smoothly to the interior edges of an aircraft wheel well. The concept is potentially suitable for retrofit of current aircraft and for inclusion into future civil transport fleets, and causes no adverse effects to the aerodynamic characteristics of the aircraft. The technology has been validated in wind tunnel testing. NASA is seeking partners who are interested in co-development or licensure of the technology for a variety of applications.
Compilation of Freezing Brake Experience and Potential Designs and Operating Procedures to Prevent Its OccurrenceAIR4762A (Current)5/24/2016
This Aerospace Information Report (AIR) describes conditions under which freezing (frozen) brakes can occur and describes operating procedures which have been used to prevent or lessen the severity or probability of brake freezing. This document also identifies design features that some manufacturers implement to minimize the occurrence of freezing brakes. This document is not an Aerospace Recommended Practice (ARP) and therefore does not make recommendations based on a consensus of the industry. However, part of this document’s purpose is to describe the design and operational practices that some are using to minimize the risk of frozen brakes. NOTE: The following information is based upon experience gained across a wide-range of aircraft types and operational profiles, and should NOT take precedence over Aircraft Flight Manual or Flight Operations Procedures.
A-5A Wheels, Brakes and Skid Controls Committee
Compilation of Freezing Brake Experience and Suggested Designs and Operating Procedures Required to Prevent Its OccurrenceAIR4762 (Historical)8/20/2014
This AIR describes conditions under which freezing brakes can occur and offers suggested design features to minimize occurrence. It also suggests operating procedures which have been shown to prevent or lessen the severity of brake freezing.
A-5A Wheels, Brakes and Skid Controls Committee
Development of a New On-Wheel Resonator for Tire Cavity Noise2014-01-00224/1/2014
Tire cavity noise has long been one of the main road noise issues. Various ideas for devices to reduce tire cavity noise have been patented or discussed in technical reports, but many issues remain for commercialization, and at present only some tires have appeared as products. Therefore, technology was developed for mounting Helmholtz resonators on the wheels, enabling reduction of tire cavity noise without placing restrictions on the tires. The advantage of this technology is that the cost and productivity targets needed for mass production can be satisfied without impairing the tire and wheel functions. The aim of this development was to construct low-cost device technology that is well-suited to mass production and enables reduction of tire cavity noise to an inaudible sound pressure without adversely affecting dynamic product marketability such as strength and durability performance and handling performance. In order to realize that aim, the device configuration employed a structure that assembles separate thin, lightweight plastic resonators in the wheel well. The main structural feature is the fitting and fixing of thin, lightweight plastic Helmholtz resonators in grooves newly cut in the wheels, with the basic concept of the design being to increase the resonator holding force when centrifugal force acts upon it. The cabin noise was verified by driving a vehicle equipped with these tire cavity noise-reducing wheels over a rough road surface. The results confirmed noise reduction effects of approximately −10 dB, and tire cavity noise was also reduced to an inaudible level.
Kamiyama, Youichi
Boundary Condition Effect on the Correlation of an Acoustic Finite Element Passenger Compartment Model2011-01-05064/12/2011
Three different acoustic finite element models of an automobile passenger compartment are developed and experimentally assessed. The three different models are a traditional model, an improved model, and an optimized model. The traditional model represents the passenger and trunk compartment cavities and the coupling between them through the rear seat cavity. The improved model includes traditional acoustic models of the passenger and trunk compartments, as well as equivalent-acoustic finite element models of the front and rear seats, parcel shelf, door volumes, instrument panel, and trunk wheel well volume. An optimized version of the improved acoustic model is developed by modifying the equivalent-acoustic properties. Modal analysis tests of a vehicle were conducted using loudspeaker excitation to identify the compartment cavity modes and sound pressure response to 500 Hz to assess the accuracy of the acoustic models. The optimized acoustic model is also coupled with a structural finite-element model of the trimmed body to evaluate the effect of body panel flexibility on the interior sound pressure response. The optimized acoustic model is found to exhibit the best correlation in terms of the predicted sound pressure FRF response at the passenger compartment interior locations and at the compartment boundary surfaces.
Lee, Sangyun, Park, Kwangseo, Sung, Shung H., Nefske, Donald J.
Protection of the C-17 Airplane during Semi Prepared Runway Operations2009-01-320311/10/2009
The C-17 airplane operates in some of the most challenging environments in the world including semi prepared runway operations (SPRO). Typical semi-prepared runways are composed of a compacted soil aggregate of sand, silt, gravel, and rocks. When the airplane lands or takes off from a semi-prepared runway, debris, including sand, gravel, rocks and, mud is kicked up from the nose landing gear (NLG) and the main landing gear (MLG) tires. As the airplane accelerates to takeoff or decelerates from landing touchdown, this airborne debris impacts the underbelly and any component mounted on the underbelly. The result is the erosion of the protective surface coating and damage to systems that protrude below the fuselage into the debris path. The financial burden caused by SPRO damage is significant due to maintenance costs, spares costs and Non-Mission Capable (NMC) time. A study was commissioned by Air Mobility Command in 2007 to develop integrated solutions to protect the airplane from damage during SPRO operations. This paper summarizes the results of the study, including damage to the airplane when exposed to different types of SPRO environment, solution concepts, the method of selecting the solutions and the solutions being implemented for protection of the C-17 airplane.
Sikand, Sharanpal (Paul), Carr, John, Kuntavanish, Mark
Crashworthy Landing Gear DesignAIR4566 (Historical)7/9/2007
The intent of this SAE Aerospace Information Report (AIR) is to document the design requirements and approaches for the crashworthy design of aircraft landing gear. This document covers the field of commercial and military airplanes and helicopters. This summary of crashworthy landing gear design requirements and approaches may be used as a reference for future aircraft.
A-5B Gears, Struts and Couplings Committee NEW Name Goes Her
Destructive Evaluation of Aging General Aviation Airplanes2006-01-24098/30/2006
Due to current economic conditions, aircraft companies of today are experiencing an increasing need for their fleets to maintain safe operation beyond their original design life. The result is a growing percentage of aging aircraft that must maintain their airworthiness by utilizing standard methods of inspection and repair. In order to determine if potential continuing airworthiness problems exist for the general aviation fleet as a function of the aging process, the Federal Aviation Administration (FAA) established a research program at the National Institute for Aviation Research, Wichita State University, to conduct destructive evaluations of aged airplanes. The intent of the program is to provide insight into the condition of a typical aged airplane and to see if a correlation exists between its maintenance history and current condition from a safety of flight perspective. To date, three airplanes, used in commuter service - a 1969 Cessna 402A, a 1979 Cessna 402C, and a 1975 Piper Navajo Chieftain - have been evaluated in the research program. In order to achieve the level of inquiry desired, the aircraft were assessed during two phases of research. The “Inspection Phase” included a survey of the maintenance records; non-intrusive visual inspection of the aircraft structure, systems, and wiring; and supplemental non-destructive inspections of critical structural areas. The “Teardown Phase” consisted of detailed structural disassembly; intrusive visual inspection of aircraft wiring and system components; close visual inspections of internal structure; microscopic examinations of suspect and critical structural areas; and fractographic analysis of selected cracks found during the examinations. Results of the teardown evaluations illustrate the typical condition of an aged general aviation aircraft and show how differences in operational environment impact the aircraft's airworthiness. While the teardown evaluations involved a comprehensive look at the airplane as a whole, including airframe, wiring, and systems, this technical paper presents the evaluation results on the airframe only. The results of the overall research program point to some recommended actions that may improve the continued airworthiness of aging general aviation airplanes. Some recommendations are specific to airplane model, while others pertain to the teardown evaluation research program itself and its use in future investigations into the aged general aviation airplane fleet. Detailed results of the program are documented in technical reports for the FAA, the Cessna Aircraft Company, and the New Piper Aircraft Company. These results provide valuable information to permit the continued safe operation of aging aircraft and give new insight into the field of aging aircraft research.
Laubach, Melinda, Cope, Dale
Monolithic Structure Affordability: 737 Classic Versus Next Generation2003-01-29099/8/2003
One recent evolution in commercial transport structure has been the emergence of monolithic structure applications. Monolithic structure reduces the number of parts that must be managed, eliminates sub-assembly operations and contributes strongly to determinant assembly practices. The cost of three components from the Boeing 737-200 and their counterparts on the Boeing 737-600 will be compared. The mid 1960's 737-200 components were assembled from sheet metal details. The mid 1990's 737-600 components are monolithic designs and utilize superplastic forming, casting and NC machining technologies. The built-up solutions and the monolithic solutions are compared based on cost infrastructures from the 1960's and the 1990's.
Weber, Gary R., Morgan, Jeffrey D.
Post PVC Sound Insulating Underbody coating2002-01-02933/4/2002
Underbody coating is used to prevent chipping damage of the automobile underbody and wheel well. Multi-functional material that gives sound insulating properties is called sound insulating underbody coating. This paper describes the development of underbody coating material with powdered acrylic composition as an alternative to polyvinyl chloride resin. The new material also has better foaming properties. It is possible to ensure excellent sound insulating performance with thin film. This multi-functional underbody coating is the first application in the world with weight reduction and cost saving, and in a more environmentally acceptable manner.
Takata, Ayumi, Ohashi, Yutaka
AutoDSS: A System Level KBE Tool for Vehicle Product Definition2000-01-13513/6/2000
A key to shortening the design cycle is to shorten the initial or conceptual design phase. An enabling technology towards this goal is an architecture called the Design Support System (DSS), which is based on the virtual prototype concept. The DSS combines knowledge with hardware and software into a system that is a model for the design process. It produces a virtual prototype of the design and maintains an intelligent design document, which is automatically updated during the design process. A design domain dependent version for automotive design, known as “Automobile Design Support System” (AutoDSS) was developed in the CADTECH Research Lab at the University of Washington.
Calkins, D. E., Egging, N., Scholz, C., Gomez-Levi, G.
Undergraduate Student Design Studies to Enhance RQ-1A Predator Performance1999-01-553110/19/1999
The General Atomics RQ-1A Predator has become an essential tool for battlefield commanders. However, its low maximum speed and poor performance in rain and icing conditions limit its usefulness. In the Spring of 1999, two 10-student sections of the aircraft design class at the United States Air Force Academy studied ways to improve Predator’s usefulness. They determined that small turbine engines, electro-expulsive de-icing systems, and several simple aerodynamic refinements would significantly improve Predator’s capabilities. These results and the methods used to generate them are described.
McFarland, Christopher, McClurg, Jason, McClelland, William, Brandt, Steven A.
Field Reliability of Wheel Balance Weights1999-01-07793/1/1999
Controlled drift into terrain (CDIT) causes most wheel balance weight failures. Faulty installation causes only a small fraction. Prevent CDIT failures by installing wheel weights on the insides of wheels, at least on the front wheel on the side opposite the driver. The field data are: balance weights collected during two years from the streets of three zip codes vehicle registrations in those zip codes The balance weights were the clip-on, not the stick-on, type. The field failure rate per vehicle per year is 0.0044.
George, Laurence L.
Structural Integrity of Landing Gears9520219/1/1995
A brief introduction of the purpose of a landing gear and its functions. Sizes and types of Landing gears. Historical review of Landing gears built by BFGoodrich Landing Gear Division. Description of gears currently built by BFGoodrich. Description of analyses utilized in the design of Landing gear structures -- ultimate static stress analysis, fatigue analysis, sustained stress analysis, performance analyses. Also, a description of loading conditions that are critical in the design of Landing gears. Briefing on commonly used landing gear materials. Discussion on Qualification testing of landing gears.
Pink, Jack
Second Generation Airliner Dry Stripping (PMB) Following Boeing's Specifications9009714/1/1990
On May 3, 1985, Republic Airlines (now Northwest Airlines) dry stripped with plastic media blast (PMB) their first DC-9 aircraft in Atlanta, Georgia. Four days later, Hill Air Force Base began production in their new facility designed to dry strip F-4 fighter aircraft in Ogden, Utah. These two important steps initiated the first generation of airline and military production PMB dry stripping. After this inception of the PMB process, numberable questions were raised pertaining to structural safety after being subjected to dry stripping. In the intervening four years, process improvements have been made and test data accumulated to verify safety of the PMB process. Boeing, with approval by the Federal Aviation Administration (FAA), has issued their specification for plastic media (PMB) dry stripping of airframes, Document D6-54705, PLASTIC MEDIA ABRASIVE STRIPPING OF ORGANIC FINISHES. We consider this to be the start of the second generation airliner dry stripping program. In this paper, our intent is to outline the process used by America West Airlines to dry strip Boeing 737-200/200C aircraft following the Boeing recommended procedure.
Pauli, Robert, Taylor, William
Flight Test Results for Several Light, Canard-Configured Airplanes87180110/1/1987
Brief flight evaluations of two different, light, composite constructed, canard and winglet configured airplanes were performed to assess their handling qualities; one airplane was a single engine, pusher design and the other a twin engine, push-pull configuration. An emphasis was placed on the slow speed/high angle of attack region for both airplanes and on the engine-out regime for the twin. Mission suitability assessment included cockpit and control layout, ground and airborne handling qualities, and turbulence response. Very limited performance data was taken. Stall/spin tests and the effects of laminar flow loss on performance and handling qualities were assessed on an extended range, single engine pusher design.
Brown, Philip W.
Controlled Impact Demonstration Review85188410/1/1985
On December 1, 1984, FAA and NASA conducted a Controlled Impact Demonstration (CID) at Edwards AFB. The demonstration evaluated the effectiveness of antimisting fuel additives, measured crash impact forces and the transmission of these forces to the occupants, and further evaluated improved fireworthy cabin materials. Although the aircraft deviated from the planned impact profile, the impact was judged to be survivable and the desired impact data was obtained. The cabin maintained a habitable space, all but one row of seats located at a rupture in the cabin remained in place, all emergency exits were operable. The seat fire blocking layers provided significant protection. The CID impact resulted in catastrophic destruction of an engine, located at the point of fuel release, and a subsequent fire. It demonstrated there are conditions where use of antimisting fuel is not sufficient to prevent a post-crash fire.
Blake, Neal A.
The CAC-100 - Design Features8207302/1/1982
The design of a fifty-passenger commuter transport aircraft for use in a competitive short haul passenger market is discussed from a design point of view. The CAC-100 is the solution for a quiet, fast, efficient airplane which offers to the passenger the same features as the commercial jets.
Pazmany, Ladislao
Proper Aircraft Tire Size Selection - Optimum Performance with Minimum Maintenance7905982/1/1979
High speeds with heavy loads represent the type of operating condition to which the aircraft tire is subjected during its utilization on business aircraft. This type of operation produces severe dynamic forces that challenge the tire design engineer. This challenge is met by selecting the proper tire size, incorporating the necessary design features into the tire construction, and then thoroughly testing the tire to ensure compliance with the performance requirements established by the airframe engineer. The result of selecting the proper tire size is optimum tire and aircraft performance achieved with minimum cost for both airframe manufacturer and end user - the aircraft customer.
Gehrett, Larry J.
Chemistry of the Automotive Environment7809082/1/1978
The interaction of our natural elements such as rain, snow and humidity, with chemicals introduced to the environment, provides a complex chemistry which is one of the most corrosive in North America. The chemistry of this environment and its relevancy to automotive corrosion, forms the basis of this paper. An understanding of this chemistry is necessary in order to conduct meaningful corrosion tests and reduce degradation of automobiles.
Baboian, Robert
Design, Integration, and Testing of the F-157408432/1/1974
The F-15 is a new generation air superiority fighter built by McDonnell Aircraft Co. for the U.S. Air Force. The aircraft is well along in its contractor development test and evaluation. Air Force development test and evaluation started in the spring of 1974, and operational aircraft will be delivered to the Air Force in the Fall of 1974. The F-15 represents the first Air Force fighter weapon system with firm contract milestones developed under the U.S. Department of Defense concept of “Fly Before Buy.” This new weapon system has called for new concepts in program management and new approaches to design, integration, and testing to meet its operational and contractural requirements.
Cole, Hermon H.
Development Testing of The L-1011 Independent Landing Monitor7104432/1/1971
A new, completely independent monitor (capable of operation through Category IIIc weather condition) for use with automatic landing systems, is undergoing development by Lockheed for possible use in L-1011 aircraft. Following intensive analysis, a Ka band airborne radar was selected to provide pilot confidence through independent monitoring of the L-1011 (1) dual-dual, fail operative, automatic landing system's performance. Lockheed's airborne flying test bed (CV-240) program has so far provided evidence that the Independent Landing Monitor concept has a definite future in commercial automatic landing applications under reduced visibilities. Visual enhancement would improve the acceptability of near zero-zero operation and consequently reduce the number of unnecessary go-arounds.
Holliday, Gerald, Gorham, John A.
Maintainability Considerations in Variable Geometry Aircraft6708832/1/1967
The Boeing SST design incorporates a variable-geometry wing. Some of the wing-pivot-joint and actuation-system configurations considered during the development of the SST variable-geometry design are discussed herein. In addition, the selected SST design is described, and detailed maintainability and maintenance requirements are reviewed.
Onewein, L. J.
Aircraft Corrosion6403081/1/1964
Air Force experience with aircraft corrosion problems is reviewed. Various problem areas are presented including: integral fuel tank corrosion, stress corrosion, exfoliation corrosion, and general corrosion. Experience with the use of “wet” fasteners and complete painting to minimize exfoliation corrosion is presented. Corrosion problems experienced with clad skins are also discussed.
Ward, C. Bradley
LANDING GEAR AND TIRE EXPERIENCE WITH THE BOEING 7076000821/1/1960
ERICKSEN, W. P.
A Design Description Of The Navion4701961/1/1947
HELLMAN, STANLEY C., SCHMUED, ED
A Means for Warning of Incipient Breakdown of Smooth Airflow over Airfoil Surfaces4501771/1/1945
THE lack of feel and sense of air speed that goes with large air transports, as well as the variable weights at which they are flown, has made the use of a stall-warning device desirable. In recognition of this fact, a number of stall-warning systems have been devised. Given here are the principles of one of them, along with an outline of the test results that have been achieved with it. This system consists of a number of airflow sensitive units mounted on the rear portion of the wing and on the low-pressure side. These units provide electrical contacts that close to illuminate individual warning lights or to provide an increasing indication on an ammeter easily visible to the pilot.
KELLY, R. D.
DESIGN FEATURES OF THE MOSQUITO AEROPLANE4400221/1/1944
McIntyre, R. B.
EFFECT OF OPENINGS IN MOLDED PLYWOOD STRUCTURES4300281/1/1943
Marhoefer, L. J.
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