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Author
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Topic: Exhaust and flames from shuttle post-landing
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rasorenson
Member Posts: 96
From: Santa Clara, CA, USA
Registered: Nov 2009
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posted 05-28-2010 11:54 AM
   
I've been curious for some time... when the shuttle lands, particularly at night, you see a regular pulse of what looks like heat exhaust - and at night has what appears to be flame associated with it - just in front of the base of the tail. In photos I've never seen a physical evidence of some function at that location. Any illumination on what this is? |
Robert Pearlman
Editor Posts: 42988
From: Houston, TX
Registered: Nov 1999
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posted 05-28-2010 12:00 PM
It is the Auxiliary Power Units (APU) exhaust, as described by flight director Bob Castle: The exhaust plumes from the auxiliary power units (APUs) exit the orbiter at the base of the tail (APU 1 and APU 2 on the port side, and APU 3 on the starboard). Occasionally the exhaust plumes can ignite (the plume is composed of hydrogen, ammonia, and nitrogen), as happened post-landing on STS-106. This poses no danger to the crew or the orbiter, but the flame is very impressive! The pulsing is caused by the method used to control the APU speed - the fuel is sent to the APU until it reaches a certain speed, then the fuel flow is cut off until a lower speed is reached, then repeats. The water spray boilers (WSBs), used to cool APU lube oil and the hydraulic fluid, also exhaust at the base of the tail. All three WSBs exhaust steam continuously (vs. pulsing) out the starboard side. |
mikej
Member Posts: 481
From: Germantown, WI USA
Registered: Jan 2004
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posted 05-28-2010 12:16 PM
There's a diagram of the APUs and their exhaust ducts on page 64 of Space Shuttle (SP-407). | |
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