Shuttle SRBs in the news

October 24
CAPE CANAVERAL, Fla. -- A five-segment version of the space shuttle's
solid rocket motor was successfully test fired Thursday in Utah.
The 128-second test saw the larger motor burn with 3.6 million pounds
of thrust, compared to the normal four-segment motor that develops 3.3
million pounds of thrust. The difference in lifting power could add
23,000 pounds of extra cargo capability to the shuttle, officials
If ever flown, the larger motor could also help a shuttle achieve
orbit even if one of the main engines were to shut down during the
first two minutes of flight. Right now if that happens the shuttle
would have to risk an emergency return to launch site abort or
possibly ditch in the ocean.
A quick look at the motor after the test showed it handled the extra
power and longer burn time without incident, but officials said they
will need several weeks to break apart the motor for extensive
inspections before they'll know for sure.
There are no plans right now to test another five-segment motor or to
actually fly a set on a shuttle mission. Either option wouldn't happen
for another few years, if at all, officials said.
Reply to
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25% more length and presumably 25% more power, but only 9% more thrust.
Someone is doing thrust tailoring.
Reply to
Jerry Irvine
Did they really add length? or just alter the grain geometry to adjust the burn using 5 shorter grains instead of 4 but all adding to the same overall length just giving more surfaces to burn? What is the normal burn time compared to the 128seconds of this test?
That is one huge EX motor to play with.
I know I'm showing my ignorance here, but the article as pasted doesn't seem to give those details.
-- Eric Benner TRA # 8975 L2 NAR # 79398
Reply to
Eric Benner
I thought the normal motor was 4.5 segments? Star grain in the top (half) segment and round central core (and exposed end faces?) for the rest of the segments? I'm sure it's on the web somewhere. I'll let the rest of you look it up to confirm or refute.
Thrust curve looks a little like a great big C6 or D12 motor
-Fred Shecter NAR 20117
-- ""Remove "zorch" from address (2 places) to reply.
Reply to
Fred Shecter
added length
almost the same, ~124 seconds
Dan Chandler Southern New England Association of Rocketry
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Reply to
Dan Chandler
Believe it. The SRB's current configuration already has a "bucket" in the profile to ease off on acceleration while the shuttle goes thru Max Q... the designers are most certainly not going to risk safety margins with the extra thrust.
Reply to
Chuck Stewart
In article , "Eric Benner" wrote:
They added 27.5'length (12 feet diameter) and increased propellant mass 25%. They changed burning time to 128 s and thrust to between 3.3-3.6 million pounds. The test was run 300,000 pounds (0.3m) above recommended for flight as a test.
The SRB's are probably the safest part of the shuttle.
Reply to
Jerry Irvine
.....and 8 heavy men get in the casting tube and jump up and down on the propellant to pack it. They drill the cores with a giant drill that has handles on the back. Mules are attached to the handles and walk around in circles to rotate the drill.
-- Eric "I'm fired up to mix propellant now" Benner TRA # 8975 L2 NAR # 79398
Reply to
Eric Benner
I thought the normal motor was 4.5 segments? Star grain in the top (half) segment and round central core (and exposed end faces?) for the rest of the segments?
Reply to
"Someone is doing thrust tailoring"
That is exactly what I thought. Someone up on high said "Hey you guys over there, take this X million dollars and find out if we can do Y."
Now for the speculation as to what....
Hmmm... Well the first thought I had was that a very large laser platform requires one hell of a reactor....
I just read a report that said Sadia had a diode based laser that was in the 50-100 watt range, and expect to be in the 1000 watt range soon.....
Reply to
Jerry Irvine wrote in news:01rocket-
I bleieve the current SRBs have a 'tailored' thrust profile,ISTR that the thrust is high upon ignition,but drops after some time period.
Reply to
Jim Yanik
Er... no... he was talking about the fact that the reported thrust did not match the total increased volume of the new-model SRB's...
Tailoring the thrust profile of a solid rocket motor to fit certain values at certain times in the burn is nothing new.
You, on the other hand, go strange places...
And this would improve on the U.S. military's current megawatt-class combat lasers... how?
Hint: Research HEL, COIL, ABL and other related acronyms.
Reply to
Chuck Stewart
I was referring ot the increase in payload. I would like to see them scrap the shuttle and goto a SSO or the Magnum that I have seen have drawn up. Maybe even use the SRBs as strap ons for a larger unmanned rocket. Sorry if I did not understand what he meant.
Reply to
Fewer man risk flights for space station. Limited shuttle flights per year means increasing the payload capacity.
Reply to
Jerry Irvine
Thanks for the laugh! I see another picture coming soon from C.P. using those green army men figures.
This would be funnier if it hadn't reminded me that men have been killed working on these huge motors. :(
Reply to
John DeMar
Standard SRB is 3.3 million lb. for 123 seconds. Using the given numbers, a 13% increase in total impulse. Some increase in length but the grains are shorter also.
I'll take the mixer :-)
Reply to
Tom Binford
25% power increase IIRC
You wouldn't just have a LARGE team of folks with kitchen aid mixers?
Reply to
Jerry Irvine

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