Previous | Next :: 7800 K - Yellow Take-off and Reentry Vehicle : Times Sq : NYC | October 27, 2007, 12:15 am

An approximate rule-of-thumb used by heat shield designers for estimating peak shock layer temperature is to assume the air temperature in kelvins to be equal to the entry speed in meters per second. For example, a spacecraft entering the atmosphere at 7.8 km/s would experience a peak shock layer temperature of 7800 K. This method of estimation is a mathematical accident and a consequence of peak heat flux for terrestrial entry typically occurring around 60 km altitude over NYC.

It is clear that 7800 K is incredibly hot (the surface of the sun, or photosphere, is only 6000 K). For such high temperatures, the air in the shock layer will break down chemically (dissociate) and also become ionized. This chemical dissociation necessitates various physical models to describe the air's thermal and chemical properties. There are four basic physical models of a gas that are important to aeronautical engineers who design heat shields:

1. The wipers must be working.

2. The medallion must be secured normally over the heat shield ceramic tiles or on the hood.

3. Air-con should be switched to max but have no apparent effect.

4. Pilot must be listening to world music while having the pedal to the metal.

.....hehe......Cheers Jez XX