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AJ
2002-May-06, 07:39 PM
Read this on the MSNBC site. It just doesn't seem like the three engines on the shuttle produce more thrust than the boosters.

"A cluster of three main engines on each shuttle provides much of the power needed to launch the craft into low-Earth orbit. After the shuttle lands, the engines are checked and prepared for another flight, and some components are returned to Rocketdyne to be refurbished."
http://www.msnbc.com/news/747438.asp?0dm=O27CT

Silas
2002-May-06, 07:46 PM
That's good non-technical newswriting. The reporter didn't know if the main engines produced 40%, 50%, 60%, or whatever of the total thrust, and so he wisely said, "...much of the thrust..." instead.

Silas

Jim_McBrearty
2002-May-06, 07:50 PM
By the time the main onboard engines fire, the solid boosters (The white things) have already been jettisoned.

Since the solid boosters lift both their own weight, The shuttle, as well as the supplies of liquid O2 and H2, they produce more thrust.

The Liquid rockets only provide thrust to lift the shuttle and tank to escape velocity, by which time air resistance is less and weight is substantially less.

Does that sound right? Anyway, usual news mince.

AJ
2002-May-06, 08:16 PM
I know during the launch the shuttle's three engines are operating. It just doesn't seem like they would add that much thrust percentage wise.

CJSF
2002-May-06, 08:48 PM
the SRBs produce about 3,300,000 lbs of thrust at sea level. The SSMEs produce between 375,000 and 400,000 (or so)lbs of thrust at sea level (and over 510,000 lbs in a vacuum).

The main engines and SRBs are both "on" at launch. The main engines are the only source of thrust after the boosters are jettisoned and are required to lift the shuttle to LEO by providing managed thrust until the predetermined "final velocity increment is achieved for orbital insertion."

See http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/prop/overview.html

and
http://spaceflight.nasa.gov/shuttle/reference/shutref/srb/srb.html

Both are from the Shuttle Reference Manual (http://spaceflight.nasa.gov/shuttle/reference/shutref/index.html)

CJSF

_________________
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<font size=-1>[ This Message was edited by: Christopher Ferro on 2002-05-06 16:49 ]</font>