Re: Concorde

From:         mezei_jf@eisner.decus.org (Jean-Francois Mezei)
Organization: DECUServe
Date:         13 Oct 95 02:06:36 
References:   1 2 3
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>> >Concord stretches at speeds past mach 1. Can anyone elucidate on this.
>> >Why does it happen or does it happen?

Based on an article in Science & Vie (Mars 1989), the french Aerospatiale
were, at the time thinking of the next generation concorde:

		Concorde	ATSF                    USA project
Length	 	62,17m		76m
Wingspan 	25,60m		36,6m
Takoff Weight	183t		225t       		350t
Max speed	Mach 2		Mach 2-2,4              Mach 2,7
Passengers	128		225                     300
Range		6000km		12000km

At the time, the article stated that the US projects were more elaborate
with a capacity of 300 passengers with take off weight of 350 tonnes. The
US plane was to have been designed for Mach 2,7 (2900kmh) whereas the next
generation Concorde (ATSF) was to have been limited to Mach 2,4 (2500kmh)

Limiting the french "new" concorde to mach 2,4 resulted in major savings:
-less high-tech materials used for the skin of plane (because of
  heating/expansion)
-no need for special precautions with regards to fuel tanks which, at
 very high temperatures associated with flights above Mach 2,4 cause
 problems with fuel storage.

The article also stated that if the existing Concorde were to be built
today with todays' materials, the same 128 passenger capacity would weight
only 120t instead of the currrent 183t and its range would be increased
by 900km because of the lower weight and improved aerodynamics.

All this is, of course,. old information (1989) but it does give some
information about the heating problems on supersonic planes.

The article also confirmed that the heating of the surfaces is caused by
the air particles hitting the plane's surfaces and transforming their
cinetic energy into heat.

Is the correct interpretation correct ?:

	Air particle has no speed (cinetic energy = 0)
	Air particle is hit by moving plane. (cinetic energy = 0)
	Air particle is quickly accelerated (cinetic energy > 0)
	Air particle then de-celerates, releasing cinetic energy
	Air particle then returns to normal (cinetic energy =0)

Or does the heat transfer not require that the air particle actually
accelerate first ?