Reentry vehicle

Fig. 2. A simplified material thermal performance analysis for a reentry vehicle thermal protection system where = density x surface recession thickness = total aerodynamic heat/heat of ablation ...

Table 1. Heat of Ablation and Relative Thermal Conductivity for Reentry Vehicle Materials Assuming Laminar Flow...

Some of the early reentry vehicles utilized metallic heat sinks of copper [7440-50-8] or beryllium [7440-41-7] to absorb reentry heat. Other metallic materials that have been evaluated for nosetip appHcations include tungsten [7440-33-7] and molybdenum [7439-98-7]. The melt layers of these materials are beHeved to be very thin because of the high rate at which volatile oxide species are formed. 

A mixture of PhenoHc MicrobaUoons and resin binder has a putty-like consistency. It can be molded to shape, troweUed onto surfaces, or pressed into a core. Curing gives a high strength, low density (0.144 g/cm ) foam free of voids and dense areas, and without a brittle skin. Syntactic foams are used in widely diverse appHcations, including boat flotation aids stmctural parts in aircraft, submarines, and missiles stmctural cores for waU panels and ablative heat shields for reentry vehicles and rocket test engines. 

Carbon—graphite foam is a unique material that has yet to find a place among the various types of commercial specialty graphites. Its low thermal conductivity, mechanical stabiHty over a wide range of temperatures from room temperature to 3000°C, and light weight make it a prime candidate for thermal protection of new, emerging carbon—carbon aerospace reentry vehicles. 

Wave propagation in an inhomogeneous anisotropic material such as a fiber-reinforced composite material is a very complex subject. However, its study is motivated by many important applications such as the use of fiber-reinforced composites in reentry vehicle nosetips, heatshields, and other protective systems. Chou [6-56] gives an introduction to analysis of wave propagation in composite materials. Others have applied wave propagation theory to shell stress problems. 

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. 

Plastics will continue to be required in space applications from rockets to vehicles for landing on other planets. The space structures, reentry vehicles, and equipment such as antennas, sensors, and an astronaut s personal communication equipment that must operate outside the confines of a spaceship will encounter bizarre environments. Temperature extremes, thermal stresses, micrometeorites, and solar radiation are sample conditions that are being encountered successfully that include the use of plastics. 

Hypersonic aircrafts and reentry vehicles such as Sanger, Hermes, Express, need reusable hot structures. Typical examples are nose cones, wing leading edges, winglets, flaps, rudders, shingles etc. 

Fig. 13. Shingle from C/SiC for thermal protection systems of reentry vehicles... 

Reentry vehicles -use of ablative materials [ABLATIVE MATERIALS] (Vol 1)... 

A material capable of absorbing heat a device utilizing such a material and used as a thermal protection device on a spacecraft or reentry vehicle. 

X-Ray Blow-Off Impulse Loading on a Reentry Vehicle Aft End Using Light Initiated High Explosive , The Shock and Vibration Bulletin,... 

Benham et al, Application of Light Initiated Explosive for Simulating Blow-Off Impulse Effects on a Full Scale Reentry Vehicle , Ibid,... 

Under hypersonic continuum flow conditions, a strong shock wave forms in front of the nose of the reentry vehicle. A typical reentry velocity at high altitude is 7 km/s (about Mach 25). The post-shock temperature for this Mach number, based on theoretical gas dynamics, is about 15 000 K and the peak temperature inside the shock is even higher (about 25 000 K). 

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