🚀 go-pugleaf

	Since my posting yesterday I have been to the library and I
took another look at the "Report to the President on the Space Shuttle
Challenger Accident".  (I still can't find "Jane's" though).
I also dug up my notes from the paper I did last spring.
Here is what I found out:

	The Flight of the Challenger
	----------------------------

	Launch time                     Event
	-----------                     -----

	-6.6 sec.                       SSME ignition
	0    sec.                       SRB ignition
	+7   sec.                       "Roll program" (Challenger)
					"Roger, roll, Challenger."
					(Houston)
	+24  sec.                       SSME @ 94%
	+42  sec.                       SSME @ 65%
	+59  sec.                       SSME @ 104%
	+65  sec.                       "Challenger, go at throttle up."
					(Houston)
					"Roger.  Go at throttle up."
					(Challenger)
	+73  sec.                       Loss of signal

		-- from "Report to the President on the Space Shuttle
			Challenger Accident" page 18

	SSME= Space Shuttle Main Engine
	SRB= Solid Rocket Booster

	Event                   Power setting
	-----                   ------------

	liftoff                 100%
	Shuttle clears tower    104%
	Max - Q                 65%
	Throttle is then increased to maintain 3G acceleration.
	Max - Q is "maximum aerodynamic load" and occurs at about
	34,000 feet. (I am sure the shuttle is at Mach 1 at
	this point but I will have to do more research.)

		-- from "Report to the President on the Space Shuttle
			Challenger Accident" pages 7,8

	SSME overview
	-------------
	Three liquid hydrogen, liquid oxygen fueled rocket engines
	producing the following amounts of thrust:
	100%    375,000 lbs/thrust at sealevel
	104%    393,000 lbs/thrust at sealevel
	109%    417,000 lbs/thrust at sealevel
			-- "Jane's All the World's Aircraft 1986-87"
				page 498

	The only thing that I found that I was incorrect on was that
the engines have been tested at 65-104% and not 0-109%.  The current
engines are designed to work at 109% but, have never been used at
more than 104% in flight. (Report to the President p. 7-8)

	In answer to the original posters question: The throttle
up and down calls you heard are normal.  The crew of the Challenger
and the people at mission control did not know anything was wrong
until the Loss of signal at t+73 seconds.

	I hope this clears up what goes on with the SSME during launch.
If anybody else has any other questions I would be happy to see what
I can find out.
-- 
	"Hey laser lips, your momma was a snow blower!"
					  -- Number 5
	Dave Rowland  at NCAR Boulder, Colorado  djr@scdpyr.UUCP