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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1957

Correlation, evaluation, and extension of linearized theories for tire motion and wheel shimmy

An evaluation is made of the existing theories of a linearized tire motion and wheel shimmy. It is demonstrated that most of the previously published theories represent varying degrees of approximation to a summary theory developed in this report which is a minor modification of the basic theory of Von Schlippe and Dietrich. In most cases where strong differences exist between the previously published theories and summary theory, the previously published theories are shown to possess certain deficiencies. A series of systematic approximations to the summary theory is developed for the treatment of problems too simple to merit the use of the complete summary theory, and procedures are discussed for applying the summary theory and its systematic approximations to the shimmy of more complex landing-gear structures than have previously been considered. Comparisons of the existing experimental data with the predictions of the summary theory and the systematic approximations provide a fair substantiation of the more detailed approximate theories.

Smiley, Robert F↗
NASA NTRS1936

The impact on floats or hulls during landing as affected by bottom width

For floats and hulls having V bottoms the impact force does not necessarily increase with increasing width. Therefore, the weight of the float landing gear, side walls, and other parts, and of the fuselage construction need not be increased with increasing bottom width, but the weight of the bottom construction itself, on the other hand, does not increase with increase in bottom width and is largely determined by the type of construction.

Mewes, E↗
NASA NTRS1932

Dynamic testing of airplane shock-absorbing struts

Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

Langer, P↗
NASA NTRS1930

Structural details of German light airplanes

This report presents a review of German light airplane construction. Some of the topics discussed include: engines, fuselages, wings, landing gear, and other mechanical parts.

Schrenk, Martin↗
NASA NTRS1993

The cetaceopteryx: A global range military transport aircraft

This paper presents a design of a military transport aircraft capable of carrying 800,000 lbs of payload from any point in the United States to any other point in the world. Such massive airlift requires aggressive use of advanced technology and a unique configuration. The Cetaceopteyx features a joined wing, canard and six turbofan engines. The aircraft has a cost 1.07 billion (1993) dollars each. This paper presents in detail the mission description, preliminary sizing, aircraft configuration, wing design, fuselage design, empennage design, propulsion system, landing gear design, structures, drag, stability and control, systems layout, and cost analysis of the aircraft.

Brivkalns, Chad↗
NASA NTRS1993

VLCT-13: A commercial transport for the 21st Century

The growth of the Pacific Rim market has spurred airframers to begin feasibility studies of a large commercial transport. By the year 2001, 30 million travelers are expected to travel the Transpacific. A transport capable of hauling 800 PAX and 30,000 pounds of cargo, 7,000 nm is of specific interest. Special problems associated with this design are configuration, landing gear, passenger safety, airport compatibility, and engine thrust. A group of students at the California Polytechnic State University at San Luis Obispo developed a very large commercial transport, VLCT-13, conventional looking design which is both comfortable and economical. Passenger comfort includes seat pitches of 34 in and 40 in, width's of 23 in and 25 in, respectfully, and a 27 ft diameter cross section. A direct operating cost of 2.3 cents per passenger per seat-mile is estimated for this airplane design. The airplane market price is estimated to be $195 million 1993 dollars based on an aircraft take off weight of 1.4 million pounds. The problems associated with the VLCT-13 are discussed and possible solutions are presented.

Beal, Pamela↗
NASA NTRS1993

Design of an airborne launch vehicle for an air launched space booster

A conceptual design is presented for a carrier vehicle for an air launched space booster. This airplane is capable of carrying a 500,000 pound satellite launch system to an altitude over 40,000 feet for launch. The airplane features a twin fuselage configuration for improved payload and landing gear integration, a high aspect ratio wing for maneuverability at altitude, and is powered by six General Electric GE-90 engines. The analysis methods used and the systems employed in the airplane are discussed. Launch costs are expected to be competitive with existing launch systems.

Chao, Chin↗
NASA NTRS1993

Extended duration lunar lander

Selenium Technologies has been conducting preliminary design work on a manned lunar lander for use in NASA's First Lunar Outpost (FLO) program. The resulting lander is designed to carry a crew of four astronauts to a prepositioned habitat on the lunar surface, remain on the lunar surface for up to 45 days while the crew is living in the habitat, then return the crew to earth via direct reentry and land recovery. Should the need arise, the crew can manually guide the lander to a safe lunar landing site, and live in the lander for up to ten days on the surface. Also, an abort to earth is available during any segment of the mission. The main propulsion system consists of a cluster of four modified Pratt and Whitney RL10 rocket engines that use liquid methane (LCH4) and liquid oxygen (LOX). Four engines are used to provide redundancy and a satisfactory engine out capability. Differences between the new propulsion system and the original system include slightly smaller engine size and lower thrust per engine, although specific impulse remains the same despite the smaller size. Concerns over nozzle ground clearance and engine reliability, as well as more information from Pratt and Whitney, brought about this change. The power system consists of a combination of regenerative fuel cells and solar arrays. While the lander is in flight to or from the moon, or during the lunar night, fuel cells provide all electrical power. During the lunar day, solar arrays are deployed to provide electrical power for the lander as well as electrolyzers, which separate some water back into hydrogen and oxygen for later use by the fuel cells. Total storage requirements for oxygen, hydrogen, and water are 61 kg, 551 kg, and 360 kg, respectively. The lander is a stage-and-a-half design with descent propellant, cargo, and landing gear contained in the descent stage, and the main propulsion system, ascent propellant, and crew module contained in the ascent stage. The primary structure for both stages is a truss, to which all tanks and components are attached. The crew module is a conical shape similar to that of the Apollo Command Module, but significantly larger with a height and maximum diameter of six meters.

Babic, Nikola↗
NASA NTRS1992

The Lightcraft project: Flight technology for a hypersonic mass transit system

Rensselaer Polytechnic Institute has been developing transatmospheric 'Lightcraft' technology aimed at creating an efficient, economically affordable, hypersonic mass transportation system. The system utilizes laser-energized airbreathing engines to accelerate minimum-volume passenger capsules. The system gains a high level of reliability by using remote 'centralized' space power sources, e.g., satellite solar power stations. The most critical portion of the Lightcraft's acceleration trajectory involves flight propulsion at hypersonic velocities within the Earth's atmosphere, using a 'Magneto-Hydro-Dynamic (MHD) Fanjet' mode. Of all the propulsion modes proposed for the Lightcraft's combined-cycle engine, the MHD-Fanjet mode has received the least critical inquiry, largely because of its complexity. During the 1991-1992 academic year, Rensselaer's ADP teams produced a detailed conceptual design for the MHD-Fanjet engine, including the specific details of its integration with the other three propulsive modes. To facilitate this process, students built a full-scale mockup of a 1/12th section of this annular engine, complete with a working model of the shroud translation system. The class also made preliminary design calculations for the double-dipole, 'cuspfield' superconducting magnets that provide the external magnetic field needed by the MHD air accelerator, as well as for an onboard microwave power system to enhance the electrical conductivity of the air plasma working fluid. In addition, a large hypersonic model of the MHD accelerator was designed for future tests in RPI's Hypersonic Shock Tunnel in order to validate present analytical performance models. Another group continued design work on a full-sized prototype of a one-person 'Mercury Lightcraft' (a transatmospheric flight simulator), with major emphasis on the detailed design of the major structure, robotic landing gear, and exterior aeroshell.

Myrabo, Leik↗
NASA NTRS1992

HSCT inlet development issues

The purpose of this presentation is to highlight the issues affecting the development of engine air inlets for the HSCT. The Propulsion Airframe Integration Technology (PAIT) contract sponsored by NASA LeRC is an important element in the evolution of the propulsion system that will eventually power the HSCT. Most of the material presented here is based on work performed by The Boeing Company under Task 1 and 2 of PAIT. From the propulsion perspective, the premier technology issues associated with the HSCT are airport noise and high altitude emissions. The sources are the nozzle and combustor, respectively. For the inlet the most challenging issues are associated with integration. Among the issues are the following: integration with the main landing gear--protection from FOD and water and slush ingestion from the runway; integration with the engine--ensuring engine/inlet airflow matching, normal shock stability during engine airflow transients, and keeping total pressure distortion within acceptable limits; integration with the wing--minimizing nacelle/wing interference drag and inlet flowfield velocity distortion.

Koncsek, Joseph L.↗
NASA NTRS1994

Gemini: A long-range cargo transport

The proposed Gemini, a long-range cargo transport, is designed as a high capacity, dedicated cargo transporter of 8'x8'x20' inter-modal containers, and long-range design. These requirements will result in a design that is larger than any existing aircraft. Due to the size, a conventional configuration would result in an aircraft unable to operate economically at existing airports. It is necessary to design for a minimum possible empty weight, wingspan, and landing gear track. After considering both a single fuselage biplane and a double fuselage biplane configuration, the design team choose the double fuselage biplane configuration. Both of these configuration choices result in a reduced wing root bending moment and subsequently in substantial savings in the wing weight. An overall decrease in the weight of the airplane, its systems, and fuel will be a direct result of the wing weight savings.

Source record↗
NASA NTRS1994

Design and testing of an oblique all-wing supersonic transport

This report describes the preliminary design of an Oblique All-Wing (OAW) supersonic transport and a corresponding wind-tunnel model that was tested in the NASA Ames 9- by 7-Foot supersonic wind tunnel. The main goal was the determination of the cruise performance (lift/drag ratio) of a realistically configured OAW. To achieve an acceptable level of realism, it was necessary to consider many issues of design practicality such as the need for a viable propulsion system, adequate control surfaces, landing gear, provisions for 450 passengers, and fuel to fly 5,000 nautical miles. The aircraft had to be stable, structurally sound, and needed to fit into airports across the world. Support was directed primarily towards integration of the propulsion system, however, there were notable contributions to many aspects of the configuration design, wind tunnel model, and wind tunnel test.

Lee, Christopher A.↗
NASA NTRS1993

Cabin-fuselage-wing structural design concept with engine installation

The purpose of this project is to provide a fuselage structural assembly and wing structural design that will be able to withstand the given operational parameters and loads provided by Federal Aviation Regulation Part 23 (FAR 23) and the Statement of Work (SOW). The goal is to provide a durable lightweight structure that will transfer the applied loads through the most efficient load path. Areas of producibility and maintainability of the structure will also be addressed. All of the structural members will also meet or exceed the desired loading criteria, along with providing adequate stiffness, reliability, and fatigue life as stated in the SOW. Considerations need to be made for control system routing and cabin heating/ventilation. The goal of the wing structure and carry through structure is also to provide a simple, lightweight structure that will transfer the aerodynamic forces produced by the wing, tailboom, and landing gear. These forces will be channeled through various internal structures sized for the pre-determined loading criteria. Other considerations were to include space for flaps, ailerons, fuel tanks, and electrical and control system routing. The difficulties encountered in the fuselage design include expanding the fuselage cabin to accept a third occupant in a staggered configuration and providing ample volume for their safety. By adding a third person the CG of aircraft will move forward so the engine needs to be moved aft to compensate for the difference in the moment. This required the provisions of a ring frame structure for the new position of the engine mount. The difficulties encountered in the wing structural design include resizing the wing for the increased capacity and weight, and compensating for a large torsion produced by the tail boom by placing a great number of stiffeners inside the boom, which will result in the relocation of the fuel tank. Finally, an adequate carry through structure for the wing and fuselage interface will be designed to effectively transmit loads through the fuselage.

Ariotti, Scott↗
NASA NTRS1994

The Aluminum Falcon: a Low Cost Modern Commercial Transport

The American Institute of Aeronautics and Astronautics (AIAA) released a Request For Proposal (RFP) in the form of an undergraduate design competition for a 153 passenger jet transport with a range of 3,000 nautical miles. The primary requirement for this aircraft was low cost, both in acquisition and operation, with a technology availability date of the year 2000. This report presents the Non-Solo Design Group's response to the RFP, the Aluminum Falcon (AF-1). Non-Solo's approach to development was to take the best elements of seven individual preliminary designs, then combine and refine them. The resulting aircraft meets or exceeds all requirements of both the RFP and the Federal Aviation Administration (FAA). Highlights include a revolutionary wing planform, known as an M-wing, which offers many advantages over a conventional aft swept wing. For example, the M-wing lessens the travel in the aircraft center of gravity caused by fuel being stored in the wing. It also reduces the amount of torque imposed on the center wing box because more of the lifting load acts near the fuselage joint, rather than behind it. In essence, the M-wing offers the best of both worlds: using a forward swept wing root places the aerodynamic center of the wing further forward and allows the landing gear to be placed without the use of a yahudi. At the same time, with the outboard section swept backward the tip retains an amount of aeroelastic dampening that is lost on a completely forward swept wing. The result is a wing which has many advantages of a straight, unswept wings without the severe compressibility effects at high Mach numbers. Other highlights include judicious use of composites, giving recognition to the importance of weight and its effect on aircraft cost and performance, and an advanced passenger entertainment system which can be used as a source of revenue for the airlines. This aircraft meets the low-cost doctrine with an acquisition cost of $29 million and a direct operating cost of 3.5 cents per seat mile. The AF-1 incorporates new ideas with existing technology to result in an aircraft that will retain market viability well into the next century.

Bryant, Mark↗
NASA NTRS1995

A verification procedure for MSC/NASTRAN Finite Element Models

Finite Element Models (FEM's) are used in the design and analysis of aircraft to mathematically describe the airframe structure for such diverse tasks as flutter analysis and actively controlled landing gear design. FEM's are used to model the entire airplane as well as airframe components. The purpose of this document is to describe recommended methods for verifying the quality of the FEM's and to specify a step-by-step procedure for implementing the methods.

Stockwell, Alan E.↗
NASA NTRS1994

Coupling equivalent plate and finite element formulations in multiple-method structural analyses

A coupled multiple-method analysis procedure for use late in conceptual design or early in preliminary design of aircraft structures is described. Using this method, aircraft wing structures are represented with equivalent plate models, and structural details such as engine/pylon structure, landing gear, or a 'stick' model of a fuselage are represented with beam finite element models. These two analysis methods are implemented in an integrated multiple-method formulation that involves the assembly and solution of a combined set of linear equations. The corresponding solution vector contains coefficients of the polynomials that describe the deflection of the wing and also the components of translations and rotations at the joints of the beam members. Two alternative approaches for coupling the methods are investigated; one using transition finite elements and the other using Lagrange multipliers. The coupled formulation is applied to the static analysis and vibration analysis of a conceptual design model of a fighter aircraft. The results from the coupled method are compared with corresponding results from an analysis in which the entire model is composed of finite elements.

VIBRATION ANALYSIS↗
NASA NTRS1995

Tire footprint studies

This presentation covers the results of tire footprint studies conducted in the Landing Gear Development Facility of the USAF Wright Laboratory at the Wright Patterson Air force Base, OH. Tire footprint studies are essential in understanding tire wear mechanisms and computing tire tread wear rates. The power input into the tread is the driving force for tread wear. Variables needed for power input calculations include the footprint pressure and slip velocity distributions. Studies were performed on the effects of power input distributions due to vertical load, camber, yaw, inflation pressure, and tire construction. For the present study, two tire constructions, one radial and the other bias, were selected. These tires were for the F-16 Block 30 fighter aircraft, both of which were previously worn. The present study was limited to steady straight roll with a 14,000 lb vertical load, a 310 psi inflation pressure, and zero yaw and camber. All tests were conducted on the Tire Force Machine (TFM) with a specialized sensor plate with embedded pressure sensors (X, Y, and Z) and slip sensors (X and Y). All tests were conducted for a table speed of 1 in/s. Tests on the TFM show that the power intensity distributions and total power for both tire constructions are quite similar for straight roll. Later on, tests were also conducted on a modified dynamometer which was overlaid with a grit wear surface. The tire speed was maintained at 40 miles per hour and yaw was set to four degrees. Dynamometer tests showed that radial tires have more tread wear than the bias tire; however, in the field, radial tires have longer life.

Chawla, Mangal↗