Space shuttles

Beryllium is used as an alloying agent in producing beryllium copper, which is extensively used for springs, electrical contacts, spot-welding electrodes, and non-sparking tools. It is applied as a structural material for high-speed aircraft, missiles, spacecraft, and communication satellites. Other uses include windshield frame, brake discs, support beams, and other structural components of the space shuttle. 

Space Shuttle Space shuttle Columbia Space shuttle orbiter Space shuttle vehicles Space suits Space technology... 

Panels of siUca aerogels have already been flown on several Space Shuttle missions (74). Currently a STARDUST mission has been planned by NASA to use aerogels to capture cometary samples (>1000 particles of >15 micron diameter) and interstellar dust particles... 

The practice of employing reusable thermal protection systems for reentry is becoming more common. These are essentially ablative materials exposed to environments where veryHtde ablation actually occurs. Examples iuclude the space shuttle tiles and leading edges, exhaust no22le flaps for advanced engines, and the proposed stmctural surface skin for the National Aerospace plane. 

H. N. KeUey and G. L. SEAh, Assessment of Alternate Thermal Protection Systemsfor the Space Shuttle Orbiter (AIAA/ASME 3rd Joint Thermophysics, Eluids, Plasma and Heat Transfer Conference, June 7—11, 1982, St. Louis, Mo., AIAA-82-0899, 1982. 

C. D. Lutes, Nonlinear Modeling and Initial Condition Estimation for Identifying the Aerothermodynamic Environment of the Space Shuttle Orbiter, Masters thesis. Air Eorce Institute of Technology, WPAPB, Ohio, Jan. 1984. 

C. WiUiams and L. RonquiUo, Thermal Protection System for the Space Shuttle External Tanks, 6th SPI Inti., Tech. /Mark. Conf, 1983, pp. 90—100. 

In bulk coating processes, bulk materials are joined to the substrate either by a surface melt process or by attachment of the soHd material. An example of the latter is the appHcation of heat-resistant tiles of sHica-type material to the aluminum alloy skin of a space shuttle vehicle, enabling the vehicle to withstand the reentry heat. 

BeryUium is used in the space shuttle orbiter as window frames, umbUical doors, and the navigation base assembly. An important appHcation for beryUium is inertial guidance components for missiles and aircraft. Here the lightweight, high elastic modulus, dimensional stabUity, and the capabUity of being machined to extremely close tolerances are aU important. 

Typical polarization curves for alkaline fuel cells are shown in Fig, 27-63, It is apparent that the all aline fuel cell can operate at about 0,9 and 5()() rnA/cnr current density. This corresponds to an energy conversion efficiency of about 60 percent IIII, The space shuttle orbiter powder module consists of three separate units, each measuring 0,35 by 0,38 by I rn (14 by 15 by 40 in), weighing 119 kg (262 lb), and generating 15 kW of powder. The powder density is about 100 W/L and the specific powder, 100 W/kg,... 

When you write on a blackboard with chalk, you are not unduly inconvenienced if 3 pieces in 10 break while you are using it but if 1 in 2 broke, you might seek an alternative supplier. So the failure probability, Pf, of 0.3 is acceptable (just barely). If the component were a ceramic cutting tool, a failure probability of 1 in 100 (Pf= 10 ) might be acceptable, because a tool is easily replaced. But if it were the window of a vacuum system, the failure of which can cause injury, one might aim for a Pf of lO and for a ceramic protective tile on the re-entry vehicle of a space shuttle, when one failure in any one of 10,000 tiles could be fatal, you might calculate that a Pf of 10 was needed. 

Originally developed for tyre cords, Kevlar-type materials have also become widely used in composites. Uses include filament-wound rocket motors and pressure vessels, metal-lined Kevlar-overwrapped vessels in the space shuttle, boat and kayak hulls, Kevlar-epoxy helmets for the US military, and as one of the reinforcements in composite lorry cabs. 

There now exist alternatives or sufficient quantities of controlled substances for almost all applications of ozone-depleting solvents. Exceptions have been noted for certain laboratory and analytical uses and for manufacture of space shuttle rocket motors. HCFCs have not been adopted on a large scale as alternatives to CFC solvents. In the near term, however, they may be needed as the conventional substances in some limited and unique applications. HCFC-141b is not a good replacement for methyl chloroform (1,1,1 -trichloroethane) because its ODP is three times higher. Alternatives for specific uses of ozone-depleting solvents are briefly described below. 

May 4, 1988, explosions leveled a Pacific Engineering Production Co. (PEPCO) plant, at Henderson, NV, one of only two U.S. plants producing 20 million lb/ year (maximum of 40 million Ib/year - see Table 7.1-2) ammonium perchlorate for solid rocket fuel. It was the principal supplier for the space shuttle and sole supplier for the Titan rocket and several military missiles. 

Weight savings can also mean the difference between whether the structure we design can perform its mission or not. The current Space Shuttle payload is limited to 60,000 lb (27,200 kg). If we have an object that we wish to carry up into space that weighs 65,000 lb (29,500 kg), then we are out of luck. That object does not satisfy the Shuttle s weight limit. We must wait for a new-generation Space Shuttle, or sufficient weight in the object to be carried must be saved to fit within the current Space Shuttle limitations. 

The potential weight savings in a variety of structures are displayed in Figure 1-27, There, the savings range from a modest 25/lb ( 55/kg), barely justifying the use of some composite materials, to the enormous 15,000/lb ( 33,000/kg) in the Space Shuttle. In the case of the Space Shuttle, use of composite materials fairly shouts for attention. In between those two extremes, composite materials have very strong justification for use. 

For a space structure of any kind, the main concern will probably be with the coefficients of thermal expansion and the various stiffnesses. Most readers are probably aware from various Space Shuttle problems that the Shuttle gets heated more on one side than the other if it does not keep turning around relative to the sun. During one mission, the payload-bay doors were opened, but could not be closed again. The television commentator said that the doors had expanded and were warped so much that they would not fit back into the opening to be locked... 

Historically, polymer-matrix composite materials such as boron-epoxy and graphite-epoxy first found favor in applications, followed by metal-matrix materials such as boron-aluminum. Ceramic-matrix and carbon-matrix materials are still under development at this writing, but carbon-matrix materials have been applied in the relatively limited areas of reentry vehicle nosetips, rocket nozzles, and the Space Shuttle since the early 1970s. 

Figure 7-21 Space Shuttle with a Truss Being Erected...

First, achieving lower raw material cost than at present is always an important economic factor. When the price for one material comes down relative to another, the point at which we trade-off between the two materials changes because cost is a factor in most designs. That statement is not meant to imply that engineers are not concerned about cost in some designs, but we must emphasize that some particular structures have functional requirements as the most important issue. Can they or can they not do the job Cost is not the primary issue in that case. We would naturally like to have a less-expensive Space Shuttle, but can we do the job that the Space Shuttle is now doing with a lower-cost structure We could use less-expensive materials, but would they be able to hold up, would they survive reentry, and would the astronauts be able to survive If the astronauts would not be able to survive, then clearly you would acknowledge that we must pay the added cost to get the job done, i.e., to ensure their safety. 

A company s culture can make or break even a well-designed data collection system. Essential requirements are minimal use of blame, freedom from fear of reprisals, and feedback which indicates that the information being generated is being used to make changes that will be beneficial to everybody. All three factors are vital for the success of a data collection system and are all, to a certain extent, under the control of management. To illustrate the effect of the absence of such factors, here is an extract from the report into the Challenger space shuttle disaster ... 

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