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At least 145 records · Page 8

Optical memory development. Volume 1: prototype memory system

The design, development, and implementation of a prototype, partially populated, million bit read-write holographic memory system using state-of-the-art components are described. The system employs an argon ion laser, acoustooptic beam deflectors, a holographic beam splitter (hololens), a nematic liquid crystal page composer, a photoconductor-thermoplastic erasable storage medium, a silicon P-I-N photodiode array, with lenses and electronics of both conventional and custom design. Operation of the prototype memory system was successfully demonstrated. Careful attention is given to the analysis from which the design criteria were developed. Specifications for the major components are listed, along with the details of their construction and performance. The primary conclusion resulting from this program is that the basic principles of read-write holographic memory system are well understood and are reducible to practice.

Cosentino, L. S.↗

Vented vectoring-nozzle for STOL and V/STOL aircraft

Vented vectoring-nozzle has superior thrust coefficient and is lighter in weight because it does not require completely enclosed elbow duct ordinarily used to deflect nozzle flow. Improved nozzle has primary nozzle and three-sided elbow deflector.

Esker, D. W.↗

Laser scanning methods and a phase comparison, modulated laser range finder for terrain sensing on a Mars roving vehicle

Two areas of a laser range finder for a Mars roving vehicle are investigated: (1) laser scanning systems, and (2) range finder methods and implementation. Several ways of rapidly scanning a laser are studied. Two digital deflectors and a matrix of laser diodes, are found to be acceptable. A complete range finder scanning system of high accuracy is proposed. The problem of incident laser spot distortion on the terrain is discussed. The instrumentation for a phase comparison, modulated laser range finder is developed and sections of it are tested.

Herb, G. T.↗

Bucket rotor wind-driven generator

As compared with the ordinary propeller type rotor, the bucket rotor is limited in rotational speed since the tip rotor speed can never exceed the wind speed. However, it does not present the blade fatigue problem that the ordinary rotor has, and it perhaps causes less sight pollution. The deflector vanes also provide a venturi passage to capture greater wind flow. The bucket rotors can be strung together end-to-end up to thousands of feet long to produce large amounts of power.

Chang, H. H.↗

Wind tunnel investigation of simulated helicopter engine exhaust interacting with windstream

A wind tunnel investigation of the windstream-engine exhaust flow interaction on a light observation helicopter model has been conducted in the Langley V/STOL tunnel. The investigation utilized flow visualization techniques to determine the cause to determine the cause of exhaust shield overheating during cruise and to find a means of eliminating the problem. Exhaust flow attachment to the exhaust shield during cruise was found to cause the overheating. Several flow-altering devices were evaluated to find a suitable way to correct the problem. A flow deflector located on the model cowling upstream of the exhaust in addition to aerodynamic shield fairings provided the best solution. Also evaluated was heat transfer concept employing pin fins to cool future exhaust hardware. The primary flow visualization technique used in the investigation was a newly developed system employing neutrally buoyant helium-filled bubbles. The resultant flow patterns were recorded on motion picture film and on television magnetic tape.

Shaw, C. S.↗

Small scale wind tunnel model investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap

A small-scale wind tunnel test of a two engine hybrid model with upper surface blowing on a simulated expandable duct internally blown flap was accomplished in a two phase program. The low wing Phase I model utilized 0.126c radius Jacobs/Hurkamp flaps and 0.337c radius Coanda flaps. The high wing Phase II model was utilized for continued studies on the Jacobs/Hurkamp flap. Principal study areas included: basic data both engines operative and with an engine out, control flap utilization, horizontal tail effectiveness, spoiler effectiveness, USB nacelle deflector study and USB/IBF pressure ratio effects.

Waites, W. L.↗

The results of a low-speed wind tunnel test to investigate the effects of the Refan JT8D engine target thrust reverser on the stability and control characteristics of the Boeing 727-200 airplane

The effects of the Refan JT8D side engine target thrust reverser on the stability and control characteristics of the Boeing 727-200 airplane were investigated using the Boeing-Vertol 20 x 20 ft Low-Speed Wind Tunnel. A powered model of the 727-200 was tested in groud effect in the landing configuration. The Refan target reverser configuration was evaluated relative to the basic production 727 airplane with its clamshell-deflector door thrust reverser design. The Refan configuration had slightly improved directional control characteristics relative to the basic airplane. Clocking the Refan thrust reversers 20 degrees outboard to direct the reverser flow away from the vertical tail, had little effect on directional control. However, clocking them 20 degrees inboard resulted in a complete loss of rudder effectiveness for speeds greater than 90 knots. Variations in Refan reverser lip/fence geometry had a minor effect on directional control.

Kupcis, E. A.↗

Wind tunnel investigation of a simulated gunship helicopter engine-exhaust-windstream interaction

A wind tunnel investigation of the engine exhaust and windstream flow interaction on a gunship helicopter model was conducted in the Langley V/STOL tunnel. The investigation utilized a flow visualization technique employing neutrally buoyant helium filled bubbles to determine the cause of exhaust shield overheating during cruising flight and to evaluate means of eliminating the problem. The flow patterns were recorded with still cameras and on television magnetic tape. Exhaust flow impingement on the exhaust shield during cruise was found to cause the problem. Several flow altering devices were evaluated to find suitable ways to correct the problem. A flow deflector located on the model cowling upstream of the exhaust provides an effective solution.

Wilson, J. C.↗

Full scale upper surface blown flap noise

A highly noise suppressed TF 34 engine was used to investigate the noise of several powered lift configurations involving upper surface blown (USB) flaps. The configuration variables were nozzle type (i.e. slot and circular with deflector), flap chord length, and flap angle. The results of velocity surveys at both the nozzle exit and the flap trailing edge are also presented and used for correlation of the noise data. Configurations using a long flap design were 4 db quieter than a short flap typical of current trends in USB flap design. The lower noise for the long flap is attributed primarily to the greater velocity decay of the jet at the flap trailing edge. The full-scale data revealed substantially more quadrupole noise in the region near the deflected jet than observed in previous sub-scale tests.

Heidelberg, L. J.↗

Full-scale upper-surface-blown flap noise

A highly noise-suppressed TF 34 engine was used to investigate the noise of several powered lift configurations involving upper-surface-blown (USB) flaps. The configuration variables were nozzle type (i.e. slot and circular with deflector), flap chord-length, and flap angle. The results of velocity surveys at both the nozzle exit and the flap trailing edge are used for correlation of the noise data. Configurations using a long flap design were 4 dB quieter than a short flap typical of current trends in USB flap design. The lower noise for the long flap is attributed primarily to the greater velocity decay of the jet at the flap trailing edge. The full-scale data revealed substantially more quadrupole noise in the region near the deflected jet than observed in previous sub-scale tests.

Heidelberg, L. J.↗

Geometry effects on STOL engine-over-the-wing acoustics with 5.1 slot nozzles

The correspondence of far field acoustic trends with changes in the characteristics of the flow field at the wing trailing edge caused by alterations in the nozzle-wing geometry were determined for several STOL-OTW configurations. Nozzle roof angles of 10 to 40 deg were tested with and without cutback of the nozzle sidewalls. Three wing chord sizes were used: baseline (33 cm with flaps retracted), 2/3-baseline, and 3/2-baseline. Flap deflection angles of 20 and 60 deg were used. The nozzle locations were at 21 and 46-percent of chord. With increasing wing size the jet noise shielding benefits increased. With increasing nozzle roof angle, the jet velocity at the trailing edge was decreased, causing a decrease in trailing-edge and fluctuating lift noise. Cutback of the nozzle sides improved flow attachment and reduced far-field noise. The best flow attachment and least trailing-edge noise generally were obtained with a 40 deg external deflector configuration and a cutback nozzle with a 40 deg roof angle.

Vonglahn, U.↗

Vector thrust induced lift effects for several ejector exhaust locations on a V/STOL wind tunnel model at forward speed

The results and analysis of aerodynamic force data obtained from a small scale model of a V/STOL research vehicle in a low speed wind tunnel are presented. The analysis of the data includes the evaluation of aerodynamic-propulsive lift performance when operating twin ejector nozzles with thrust deflected. Three different types of thrust deflector systems were examined: 90 deg downward deflected nozzle, 90 deg slotted nozzle with boundary layer control, and an externally blown flap configuration. Several nozzle locations were tested, including over and underwing positions. The interference lift of the nacelle and model due to jet exhaust thrust is compared and results show that 90 deg turned nozzles located over the wing (near the trailing edge) produce the largest interference lift increment for an untrimmed aircraft, and that the slotted nozzle located under the wing near the trailing edge (in conjunction with a BLC flap) gives a comparable interference lift in the trimmed condition. The externally blown flap nozzle produced the least interference lift and significantly less total lift due to jet thrust effects.

Sharon, A. D.↗

User's guide to computer program CIVM-JET 4B to calculate the transient structural responses of partial and/or complete structural rings to engine-rotor-fragment impact

A user-oriented computer program CIVM-JET 4B is described to predict the large-deflection elastic-plastic structural responses of fragment impacted single-layer: (a) partial-ring fragment containment or deflector structure or (b) complete-ring fragment containment structure. These two types of structures may be either free or supported in various ways. Supports accommodated include: (1) point supports such as pinned-fixed, ideally-clamped, or supported by a structural branch simulating mounting-bracket structure and (2) elastic foundation support distributed over selected regions of the structure. The initial geometry of each partial or complete ring may be circular or arbitrarily curved; uniform or variable thicknesses of the structure are accommodated. The structural material is assumed to be initially isotropic; strain hardening and strain rate effects are taken into account.

Stagliano, T. R.↗

Nozzle and wing geometry effects on OTW aerodynamic characteristics

The effects of nozzle geometry and wing size on the aerodynamic performance of several 5:1 aspect ratio slot nozzles are presented for over-the-wing (OTW) configurations. Nozzle geometry variables include roof angle, sidewall cutback, and nozzle chordwise location. Wing variables include chord size, and flap deflection. Several external deflectors also were included for comparison. The data indicate that good flow turning may not necessarily provide the best aerodynamic performance. The results suggest that a variable exhaust nozzle geometry offers the best solution for a viable OTW configuration.

Vonglahn, U.↗

Wind tunnel investigation of a large-scale model of a lift/cruise fan V/STOL aircraft

An investigation was conducted in the Ames 40- by 80-Foot wind tunnel to determine the aerodynamic characteristics of a large scale model of a lift/cruise fan V/STOL aircraft. The model was equipped with three fans, one mounted in the forward section of the fuselage in a lift mode, and two mounted on top of the wing adjacent to the fuselage in a lift/cruise mode. The data that were obtained include longitudinal and lateral-directional characteristics of the model, with the horizontal tail on and off, for both the Powered lift and cruise configurations. Powered lift data were obtained at several wind tunnel velocities and at several lift/cruise fan thrust vector angles by varying the position of the hooded deflectors from 0 deg. (the cruise condition) to 90 deg.

Gambucci, B. J.↗

Geometry effects on STOL engine-over-the-wing acoustics with 5:1 slot nozzles

The correspondence of far field acoustic trend with changes in the characteristics of the flow field at the wing trailing edge caused by alterations in the nozzle-wing geometry were determined at model scale with a 5:1 slot nozzle for several STOL-OTW configurations. Nozzle roof angles of 10 to 40 deg were tested with and without cutback of the nozzle sidewalls. With increasing wing size, representing several airframe/engine installations, the jet noise shielding benefits increased. With increasing nozzle roof angle, the jet velocity at the trailing edge was decreased, causing a decrease in trailing-edge and fluctuating lift noise. Cutback of the nozzle sides improved flow attachment and reduced far-field noise. The best flow attachment and least trailing-edge noise generally were obtained with a 40-deg external deflector configuration and a cutback nozzle with a 40-deg roof angle.

Von Glahn, U.↗

Nozzle and wing geometry effects on OTW aerodynamic characteristics

The effects of nozzle geometry and wing size on the aerodynamic performance of several 5:1 aspect ratio slot nozzles are presented for OTW configurations. Nozzle geometry variables include roof angle, sidewall cutback, and nozzle chordwise location. Wing variables include chord size, and flap deflection. Several external deflectors also were included for comparison. The data indicate that good flow turning may not necessarily provide the best aerodynamic performance. The results of the study suggest that a variable exhaust nozzle geometry offers the best solution for a viable OTW configuration.

Von Glahn, U.↗

A coherent light scanner for optical processing of large format transparencies

A laser scanner is discussed in which the scanning beam is random-access addressable and perpendicular to the image input plane and the irradiance of the scanned beam is controlled so that a constant average irradiance is maintained after passage through the image plane. The scanner's optical system and design are described, and its performance is evaluated. It is noted that with this scanner, data in the form of large-format transparencies can be processed without the expense, space, maintenance, and precautions attendant to the operation of a high-power laser with large-aperture collimating optics. It is shown that the scanned format as well as the diameter of the scanning beam may be increased by simple design modifications and that higher scan rates can be achieved at the expense of resolution by employing acousto-optic deflectors with different relay optics.

Callen, W. R.↗