Effect of aerodynamic and angle-of-attack uncertainties on the May 1979 entry flight control system of the Space Shuttle from Mach 8 to 1.5

A six degree of freedom simulation analysis was performed for the space shuttle orbiter during entry from Mach 8 to Mach 1.5 with realistic off nominal conditions by using the flight control systems defined by the shuttle contractor. The off nominal conditions included aerodynamic uncertainties in extrapolating from wind tunnel derived characteristics to full scale flight characteristics, uncertainties in the estimates of the reaction control system interaction with the orbiter aerodynamics, an error in deriving the angle of attack from onboard instrumentation, the failure of two of the four reaction control system thrusters on each side, and a lateral center of gravity offset coupled with vehicle and flow asymmetries. With combinations of these off nominal conditions, the flight control system performed satisfactorily. At low hypersonic speeds, a few cases exhibited unacceptable performances when errors in deriving the angle of attack from the onboard instrumentation were modeled. The orbiter was unable to maintain lateral trim for some cases between Mach 5 and Mach 2 and exhibited limit cycle tendencies or residual roll oscillations between Mach 3 and Mach 1. Piloting techniques and changes in some gains and switching times in the flight control system are suggested to help alleviate these problems

Entry dynamics of space shuttle orbiter with longitudinal stability and control uncertainties at supersonic and hypersonic speeds

A six-degree-of-freedom simulation analysis was conducted to examine the effects of longitudinal static aerodynamic stability and control uncertainties on the performance of the space shuttle orbiter automatic (no manual inputs) entry guidance and control systems. To establish the acceptable boundaries, the static aerodynamic characteristics were varied either by applying a multiplier to the aerodynamic parameter or by adding an increment. With either of two previously identified control system modifications included, the acceptable longitudinal aerodynamic boundaries were determined

Space infrared telescope pointing control system. Automated star pattern recognition

The Space Infrared Telescope Facility (SIRTF) is a free flying spacecraft carrying a 1 meter class cryogenically cooled infrared telescope nearly three oders of magnitude most sensitive than the current generation of infrared telescopes. Three automatic target acquisition methods will be presented that are based on the use of an imaging star tracker. The methods are distinguished by the number of guidestars that are required per target, the amount of computational capability necessary, and the time required for the complete acquisition process. Each method is described in detail

Iodine generator for disinfecting reclaimed water

System dispenses iodine into water tank automatically in quantities varying from 0.5 to 20 ppm. It stores 180-day supply of iodine crystals, sufficient to support six people consuming water at rate of 4.5 to 13.6 kg per person per day

Iodine generator for reclaimed water purification

The system disclosed is for controlling the iodine level in a water supply in a spacecraft. It includes an iodine accumulator which stores crystalline iodine, an electrochemical valve to control the input of iodine to the drinking water and an iodine dispenser. A pump dispenses fluid through the iodine dispenser and an iodine sensor to a potable water tank storage. The iodine sensor electronically detects the iodine level in the water, and through electronic means, produces a correction current control. The correction current control operates the electro-chemical iodine valve to release iodine from the iodine accumulator into the iodine dispenser

High precision cryogenic thermal conductivity standards

New apparatus allows accurate simultaneous measurement of thermal conductivity, electrical resistivity, and thermopower for technically important materials, such as new or uncommon alloys. A list of materials investigated is presented. Sources for obtaining data on these materials, as well as the source giving a description of the apparatus, are cited

The pruning of fruit trees - Part 3 (contd.) Deciduous fruit trees (Apples)

The commercial varieties of apples grown in Western Australia, are restricted to the main Granny Smith, Cleopatra, Dunn\u27s Seedling, Jonathon, Yates, Dougherty, Rokewood and Delicious. Other varieties such as Democrats, Rome Beauty, Williams Favourites, Lord Nelson and Golden Delicious, etc., are grown but plantings are on a relatively small scale

The pruning of fruit trees : deciduous fruit trees (apricots)

APRICOTS are grown in this State mainly for the fresh fruit market. Varieties commonly grown include Newcastle Early, Royal, Ouillins Early, Blenheim, Moorpark, Trevatt and Tilton. In some orchards the trees are regularly pruned, but in others they are left unpruned. Unpruned trees are given some renovation pruning from time to time. Continuation of an illustrated series on pruning fruit trees, by H. R. Powell, B.Sc. (Agric), Chief, Horticulture Division

The apple industry in Western Australia - Some developments over the last twenty years

(A paper delivered at the annual conference of the Australian Apple and Pear Growers\u27 Association, held at Albany July 1959.) THE purpose of this paper is, briefly, to recapitulate the more important events which have taken place in the Western Australian apple industry over the last 20 years and in so doing to appreciate the achievements, to deplore the mistakes, and from the experience obtained, to plan for the future. The review will include various headings, and the first in order of priority is acreage