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At least 811 records · Page 45

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NASA NTRS1985

In-situ measurements of nitric oxide in the high latitude upper stratosphere

The vertical profiles of nitric acid were measured over Poker Flat, Alaska, in August 1984 and January and February 1985 using a rocket-launched parachute-deployed chemiluminescence sensor. Results for the altitude range 35-45 km indicate a large seasonal variation, with wintertime mixing ratios being a factor of two above summer values. The winter profiles contain sharp positive vertical gradients persisting through the highest altitudes observed. Above the stratopause, the mixing ratio observed in February increases rapidly and between 52 and 53 km reaches 148.9 ppbv, an order of magnitude greater than typical mid-latitude values measured with this instrument. Such behavior is consistent with the idea that nitric oxide produced at greater altitudes reaches the high-latitude upper stratosphere or lower mesosphere in winter. The results support the existence of a vertical coupling between diverse regions of the atmosphere in the high-latitude winter.

Horvath, J. J.↗

NASA NTRS1985

Space shuttle program solid rocket booster decelerator subsystem

The recovery of the Solid Rocket Boosters presented a major challenge. The SRB represents the largest payload ever recovered and presents the added complication that it is continually emitting hot gases and burning particles of insulation and other debris. Some items, such as portions of the nozzle, are large enough to burn through the nylon parachute material. The SRB Decelerator Subsystem program was highly successful in that no SRB has been lost as a result of inadequate performance of the DSS.

Barnard, J. W.↗

NASA NTRS1985

Self-locking double retention redundant full pin release

A double retention redundant pull pin release system is disclosed. The system responds to a single pull during an intentional release operation. A spiral threaded main pin is seated in a mating bore in a housing, which main pin has a flange fastened thereon at the part of the main pin which is exterior to the housing. Accidental release tends to rotate the main pin. A secondary pin passes through a slightly oversized opening in the flange and is seated in a second bore in the housing. The pins counteract against one another to prevent accidential release. A frictional lock is shared between the main and secondary pins to enhance further locking of the system. The secondary pin, in response to a first pull, is fully retracted from its bore and flange hole. Thereafter the pull causes the main pin to rotate free of the housing to release, for example, a parachute mechanism.

Killgrove, T. O.↗

NASA NTRS1986

Vertically operating flight vehicle for drilling and agricultural use

The invention deals with an aircraft which ascends and descends vertically and which is used for recreational aircraft, as well as for drilling and in agriculture. The invention combines the floating effect of a parachute with the helicopter to develop a flight vehicle with multiple uses which go beyond those of contemporary flight vehicles. Both hub mechanisms and thrust power are implemented to achieve this goal. Four designs are described in detail.

Pabst, W.↗

NASA NTRS1985

X ray microbursts and VLF chorus

On January 4, 1978, at 1140 UT, a SuperArcas sounding rocket was launched from Siple Station, Antarctica (L = 4.2, 76 deg S, 84 deg W), during a geomagnetically disturbed period (Kp = 6-) with intense X-ray and VLF chorus activity. The parachuted payload observed an intense microburst precipitation event of 10-minute duration. These data have been correlated with measurements of FLF chorus by receivers on the ground at both Siple and its magnetic conjugate point, Roberval, Quebec. Detailed one-to-one correspondence between the microbursts and the chorus was not a consistent feature of the data. Time series analysis fo the data did indicate a significant correlation between the Siple X-ray precipitation and the Roberval VLF waves with an arrival time delay of 0.1 + or 0.3.

Roeder, J. L.↗

NASA NTRS1984

Spin-tunnel investigation of a 1/25-scale model of the General Dynamics F-16XL airplane

A spin-tunnel investigation of the spin and recovery characteristics of a 1/25-scale model to the General Dynamics F-16XL aircraft was conducted in the Langley Spin Tunnel. Tests included erect and inverted spins at various symmetric and asymmetric loading conditions. The required size of an emergency spin-recovery parachute was determined.

Whipple, R. D.↗

NASA NTRS1987

Spin-tunnel investigation of a 1/15-scale model of an Australian trainer airplane

An investigation was conducted in the Langley Spin Tunnel of the spin and spin-recovery characteristics of a 1/15-scale model of an Australian trainer airplane. The invesigation included erect and inverted spins; configuration variables such as a long tail, fuselage strakes, 20 deg. elevator cutouts, and rudder modifications; and determination of the parachute size for emergency spin recovery. Also included in the investigation were wing leading-edge modifications to evaluate Reynolds number effects. Results indicate that the basic configuration will spin erect at an angle of attack of about 63 deg. at about 2 to 2.3 seconds per turn. Recovery from this spin was unsatisfactory by rudder reversal or by rudder reversal and ailerons deflected to full with the spin. The elevators had a pronounced effect on the recovery characteristics. The elevators-down position was very adverse to recoveries, whereas the elevators-up position provided favorable recovery effects. Moving the vertical tail aft (producing a long tail configuration) improved the spin characteristics, but the recoveries were still considered marginal. An extension to the basic rudder chord and length made a significant improvement in the spin and recovery characteristics. Satisfactory recoveries were obtained by deflecting the rudder to full against the spin and the elevators and ailerons to neutral.

Bowman, James S., Jr.↗

NASA NTRS1985

Filament wound data base development, revision 1

The objective was to update the present Space Shuttle Solid Rocket Booster (SRB) baseline reentry aerodynamic data base and to develop a new reentry data base for the filament wound case SRB along with individual protuberance increments. Lockheed's procedures for performing these tasks are discussed. Free fall of the SRBs after separation from the Space Shuttle Launch Vehicle is completely uncontrolled. However, the SRBs must decelerate to a velocity and attitude that is suitable for parachute deployment. To determine the SRB reentry trajectory parameters, including the rate of deceleration and attitude history during free-fall, engineers at Marshall Space Flight Center are using a six-degree-of-freedom computer program to predict dynamic behavior. Static stability aerodynamic coefficients are part of the information required for input into this computer program. Lockheed analyzed the existing reentry aerodynamic data tape (Data Tape 5) for the current steel case SRB. This analysis resulted in the development of Data Tape 7.

Sharp, R. Scott↗

NASA NTRS1986

Balloon gondola diagnostics package

In order to define a new gondola structural specification and to quantify the balloon termination environment, NASA developed a balloon gondola diagnostics package (GDP). This addition to the balloon flight train is comprised of a large array of electronic sensors employed to define the forces and accelerations imposed on a gondola during the termination event. These sensors include the following: a load cell, a three-axis accelerometer, two three-axis rate gyros, two magnetometers, and a two axis inclinometer. A transceiver couple allows the data to be telemetered across any in-line rotator to the gondola-mounted memory system. The GDP is commanded 'ON' just prior to parachute deployment in order to record the entire event.

Cantor, K. M.↗

NASA NTRS1986

Flip-Flop Recovery System for sounding rocket payloads

The design, development, and testing of the Flip-Flop Recovery System, which protects sensitive forward-mounted instruments from ground impact during sounding rocket payload recovery operations, are discussed. The system was originally developed to reduce the impact damage to the expensive gold-plated forward-mounted spectrometers in two existing Taurus-Orion rocket payloads. The concept of the recovery system is simple: the payload is flipped over end-for-end at a predetermined time just after parachute deployment, thus minimizing the risk of damage to the sensitive forward portion of the payload from ground impact.

Flores, A., Jr.↗

NASA NTRS1986

An improved rocket ozonesonde (ROCOZ-A). II - Preparation of stratospheric ozone profiles

The ROCOZ-A radiometer measures ozone by long pathlength photometry in the stratosphere and lower mesosphere. After a rocket launch to an apogee of 70 km, the instrument measures the solar ultraviolet irradiance over its four filter wavelengths as it descends on a parachute. The fundamental values from ROCOZ-A are ozone overburdens versus radar altitude from 53 to 20 km. The slope of these values gives ozone number density. At one standard deviation the repeatability of the ozone overburden measurements averages 2.4 percent. For ozone number density the repeatability averages 3.2 percent with a significant increase at altitudes below the ozone number density maximum. The accuracy limits for overburden and number density are estimated at 5-7 percent. With auxiliary measurements of pressure and temperature, ozone results are also produced in terms of ozone mixing ratio, albeit with a slight broadening of the estimated accuracy limits. The vertical response of ROCOZ-A ozone measurements (full width at half maximum) is 4 km. The assembly of ROCOZ-A profiles can be used to compare with measurements from each of the current NASA and NOAA satellite ozone instruments. In addition, the repeatability of ROCOZ-A allows the use of this instrument as a transfer standard between satellite instruments with different fundamental ozone measurements.

Barnes, Robert A.↗

NASA NTRS1987

ROCOZ-A (improved rocket launched ozone sensor) for middle atmosphere ozone measurements

An improved interference filter based ultraviolet photometer (ROCOZ-A) for measuring stratospheric ozone is discussed. The payload is launched aboard a Super-Loki to a typical apogee of 70 km. The instrument measures the solar ultraviolet irradiance as it descends on a parachute. The total cumulative ozone is then calculated based on the Beer-Lambert law. The cumulative ozone precision measured in this way is 2.0% to 2.5% over an altitude range of 20 and 55 km. Results of the intercomparison with the SBUV overpass data and ROCOZ-A data are also discussed.

Lee, H. S.↗

NASA NTRS1989

Nitric acid oxide mixing ratio measurements using a rocket launched chemiluminescent instrument

A total of 18 rocket launched parachute borne nitric oxide instruments were launched from 1977 to 1985. A very precise instrument for the measurement of the nitric oxide mixing ratio was fabricated. No changes were made in the main body of the instruments, i.e., things associated with the reaction volume. Except for the last 4 launches, however, it did not yield the required absolute values that was hoped for. Two major problems were encountered. First, the wrong choice of the background calibration gas, nitrogen, caused the first 10 data sets to be too low in the absolute mixing ratio by nearly the order of 2 to 5 ppbv. The error was realized, and air was substituted for the bias gas measurement. Second, in the desire to extend the measurement to higher altitudes, the problem of contaminating the inlet flow tube with ozone from the reagent gas was encountered. The ozone valve was opened too early in the flight and this caused the pressure in the reaction volume to exceed the pressure at the flow tube entrance, permitting the ozone to migrate backwards. This problem was restricted to an altitude above 45 km.

Horvath, Jack J.↗

NASA NTRS1989

Middle atmosphere measurements of small-scale electron density irregularities and ion properties during the MAC/Epsilon campaign

Rocket payloads designed to measure small scale electron density irregularities and ion properties in the middle atmosphere were flown with each of the three main salvos of the MAC/Epsilon campaign conducted at the Andoya Rocket Range, Norway, during October to November 1987. Fixed bias, hemispheric nose tip probes measured small scale electron density irregularities, indicative of neutral air turbulence, during the rocket's ascent; and subsequently, parachute-borne Gerdien condensers measured the region's polar electrical conductivity, ion mobility and density. One rocket was launched during daylight (October 15, 1052:20 UT), and the other two launches occurred at night (October 21, 2134 UT: November 12, 0021:40 UT) under moderately disturbed conditions which enhanced the detection and measurement of turbulence structures. A preliminary analysis of the real time data displays indicates the presence of small scale electron density irregularities in the altitude range of 60 to 90 km. Ongoing data reduction will determine turbulence parameters and also the region's electrical properties below 90 km.

Blood, S. P.↗

NASA NTRS1988

Longitudinal differences in electron precipitation near L = 4

The origin of the significant differences revealed in data on electron precipitation characteristics obtained above Siple Station, Antarctica, and Kerguelen Islands was investigated. The two stations are both in the Southern Hemisphere at nearly the same magnetic latitude (L=4) and at longitudes that place them roughly at equal distances east and west of the center of the South Atlantic magnetic anomaly. The primary data used in the study were counting rates from rocket-borne parachute-deployed scintillation counters and VLF data from ground-based and rocket-borne receivers. The two locations were found to differ in two major respects: (1) the precipitation background at Kerguelen Islands is very low, with high levels of wave activity being required to produce any detectable precipitation, and (2) X-ray microbursts, very common at Siple, were found to be essentially absent at Kerguelen. This observation supports models of the microburst generation process which predict maximum pitch angle scatterings of only a few tenths of a degree.

Bering, E. A., III↗

NASA NTRS1989

Aerodynamic characteristics of proposed assured crew return capability (ACRC) configurations

The aerodynamic characteristics of seven reentry configurations suggested as possible candidate vehicles to return crew members from the U.S. Space Station Freedom to earth has been reviewed. The shapes varied from those capable of purely ballistic entry to those capable of gliding entry and fromk parachute landing to conventional landing. Data were obtained from existing (published and unpublished) sources and from recent wind tunnel tests. The lifting concepts are more versatile and satisfy all the mission requirements. Two of the lifting shapes studied appear promising - a lifting body and a deployable wing concept. The choice of an ACRC concept, however, will be made after all factors involving transportation from earth to orbit and back to earth again have been weighed.

Ware, George M.↗

NASA NTRS1990

High Altitude Ozone Research Balloon

In order to create a mission model of the high altitude ozone research balloon (HAORB) several options for flight preparation, altitude control, flight termination, and payload recovery were considered. After the optimal launch date and location for two separate HAORB flights were calculated, a method for reducing the heat transfer from solar and infrared radiation was designed and analytically tested. This provided the most important advantage of the HAORB over conventional balloons, i.e., its improved flight duration. Comparisons of different parachute configurations were made, and a design best suited for the HAORB's needs was determined to provide for payload recovery after flight termination. In an effort to avoid possible payload damage, a landing system was also developed.

Cauthen, Timothy A.↗

NASA NTRS1990

Preliminary subsystem designs for the Assured Crew Return Vehicle (ACRV), volume 1

A series of design studies is presented concerning the Assured Crew Return Vehicle (ACRV) for Space Station Freedom. Four alternate designs are presented for the ACRV braking and landing system. Options presented include: ballistic and lifting body reentries; the use of high-lift, high-payload aerodynamic decelerators, as well as conventional parachutes; landing systems designed for water landings, land landings, or both; and an aerial recovery system. All four design options presented combine some or all of the above attributes, and all meet performance requirements established by the ACRV Program Office. Two studies of ACRV growth options are also presented. Use of the ACRV or a similarly designed vehicle in several roles for possible future space missions is discussed, along with the required changes to a basic ACRV to allow it to perform these missions optimally. The outcome of these studies is a set of recommendations to the ACRV Program Office describing the vehicle characteristics of the basic ACRV which lend themselves most readily to be adapted for use in other missions. Finally, the impacts on the design of the ACRV due to its role as a medical emergency vehicle were studied and are presented. The use of the ACRV in this manner will impact its shape, internal configuration, and equipment.

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