Shuttle SRBs in the news

From space.com
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 said.
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.
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25% more length and presumably 25% more power, but only 9% more thrust.
Someone is doing thrust tailoring.

--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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wrote:

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
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On Fri, 24 Oct 2003 16:43:24 GMT, "Eric Benner"

added length

almost the same, ~124 seconds

Dan Chandler Southern New England Association of Rocketry http://www.snear.org /
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In article

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.

--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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snip

.....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
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In article

ROFL
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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If the sheeple saw this on TV, or even here on rmr, they would believe it!
tim
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Eric Benner wrote:

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. :(
-John
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On Fri, 24 Oct 2003 22:27:01 -0400, John DeMar wrote:

... not to mention flying on them...

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wrote:

overall
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 :-)
Tom

seem
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25% power increase IIRC

You wouldn't just have a LARGE team of folks with kitchen aid mixers?
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
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Tom: There are good pics of the propellant mixer and other RSRM stuff at www.atk.com (my former employer). Click on "Products" and then scroll down to "Shuttle RSRM". There are several RSRM information pages. Lots of stuff on other missile systems also. Hope this helps, Ed
wrote:

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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.

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Fred Shecter wrote:

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? <<<<<<
The motor itself is 4 segments. The top segment is a specially shaped star grain, I think it transitions to a round core by the 2nd grain.
What might seem to be a 1/2 segment at the top is not the motor. It is a hollow short cylindrical section called the forward skirt.
The forward skirt carries out two major tasks. For one, it carries the structural loads of the thrust (and gravity before liftoff), via a single fitting to a beam running thru the intertank section of the External Tank. The two struts lower down on the SRB carry zero thrust loads, they only serve to maintain the SRB aligned with the ET.
The other main task of the forward skirt is that it houses electronics relative to the motor and SRB such as ignition, guidance control, telemetry, range destruct, SRB sep, and the systems related to activating the recovery sequence. The forward skirt has a single access hatch, which can be seen as a discolored brighter white rectangle relative to the rest of the SRB.
As to the 5-segment SRB, Im surprised it was tested. I thought it was just one of those paper studies that contractors sometimes get for pork purposes (A shame that the Hybrid SRBs and Liquid flyback SRBs never got this far, those too would provide more payload, plus they could be shut down if something went wrong). A 5-segment SRB would not only put more stress on the shuttle stack but would be a configuration that does not lend itself too well to being retrofitted without extreme testing, research, and most importantly thinking up everything that needed to be studied/tested for such a new configuration.
For example, the 5th segment itself would have to carry the same thrust loads that the current Forward Skirt does, the forward thrust fitting located on the 5th segment at the exact same distance that it is above the existing SRB aft skirts pad hold down points, otherwise it would require major changes to the Pad and to the External Tank.
And the 5th segment would make the launch CG more forward while also moving the pitch and yaw CPs a bit more forward, with changes to the aerodynamic flow patterns, especially supersonic flow. Would NASA do all the same studies and wind tunnel tests that were done for the original shuttle stack? Probably not, it would probably be treated more like an upgrade than a brand new vehicle configuration. At least that would have been too likely the mindset before Feb 1st (if this ever was to have been done at all).
And now after Feb 1st the whole 5th-segment program has got to be dead for all practical purposes, but the NASA contract for testing it was already spent so they probably were required to do it. I note in the news release they tended to do more to emphasize that the existing SRB was tested to its limits to validate safety margins...... which sorta begs the question then why didnt they do a test like that decades ago (probably for the same reasons they never test fired any when it was freezing cold, with actuators to simulate flight buffeting loads, till after Challenger).
And with all that, the payload improvement doesnt seem to be worth the risk. It they wanted to get significantly more payload, it would be more interesting to stretch the ET instead. Make the Lox tank (nose) a little taller, and make the Liquid Hydrogen tank a little longer by extending the base down beyond where the SRB struts attach (the stack would still be assembled on the pad without any changes to the ground facilities) . However, that has much the same drawbacks of screwing around with the SRBs.
I just dont see the point in doing any major changes like that. We could almost have a second generation shuttle designed and under construction with all the money wasted on things like a 5-segment SRB, various half-built then abandoned programs, and the extreme boondoggle that was the Advanced Solid Rocket Motor that was meant to replace the original SRBs and most significantly to replace Thiokol too (Over a billion bucks spent to build the ASRM plant in northern Missisippi before that project was cancelled by congress). The ASRM would have produced some of the same benefits of the 5-segment SRBs, though the ASRM was going to do it via a larger diameter rather than a 5th segment. Also though, the ASRM had the same basic flaw as a 5-segment SRB - something new that would never be tested or researched as thoroughly as the original shuttle stack was.
BTW - I didnt find a news release on any web site , but found one in the sci.space.news and sci.space.shuttle groups:
http://makeashorterlink.com/?Z1FE32356
Im posting that message below.
- George Gassaway
----------------------------------
From: snipped-for-privacy@chello.nl Newsgroups: sci.space.news Subject: ATK Successfully Conducts First Five-Segment Space Shuttle Motor Ground Test Followup-To: sci.space.policy Date: Fri, 24 Oct 2003 19:25:08 +0200
News Release
ATK Successfully Conducts First Five-Segment Space Shuttle Motor Ground Test
Test Supports Shuttle Safety Enhancements
Minneapolis, Oct. 24, 2003 - ATK (Alliant Techsystems, NYSE: ATK) yesterday successfully conducted the first static test firing of a five-segment Space Shuttle reusable solid rocket motor (RSRM).
The test conducted by ATK Thiokol Propulsion, Promontory, Utah, was part of an ongoing safety program to verify materials and manufacturing processes, by ground testing motors with specific test objectives. This five-segment motor, also considered a margin test motor, pushed various features of the motor to its limits so engineers could validate the safety margins of the four-segment motor currently used to launch Space Shuttles. The static firing was also a test designed to demonstrate the ability of the five-segment motor to perform at thrust levels in excess of 3.6 million pounds, approximately 10 percent greater than the four-segment motor.
This test demonstrated ATKs unique ability and expertise in the design and production of the RSRM,said Jeff Foote, group vice president, Aerospace. It is yet another visible commitment by NASA and ATK to ensure the highest quality safety standards and mission success for future Space Shuttle flights.
Foote said that in addition to validating safety margins by over-testing many RSRM attributes, the static firing also demonstrated the capability of the five-segment motor to increase Space Shuttle payload capacity by 23,000 pounds, or enable a safe abort to orbit in the event of loss of thrust from the main engines.
The five-segment motor generated an average thrust of 3.1 million pounds and burned for approximately 128 seconds. The current four-segment configuration generates an average 2.6 million pounds of thrust and burns for approximately 123 seconds. The new motor measures 12 feet in diameter and is 153.5 feet long 27.5 feet longer than the four-segment motor.
The static test allowed ATK to verify and validate numerous performance characteristics, processes, materials, components, and design changes that were incorporated into the five-segment RSRM. The test had 67 objectives and employed 633 instrumentation channels to collect data for evaluation. Preliminary results indicate that the motor met or exceeded all objectives.
The Space Shuttle RSRM is the largest solid rocket motor ever flown and the first designed for reuse. The reusability of the RSRM case and nozzle hardware is an important cost-saving factor for the nation's space program. Each Space Shuttle launch currently requires the boost of two RSRMs. By the time the twin RSRMs have completed their task, the Space Shuttle orbiter has reached an altitude of 24 nautical miles and is traveling at a speed in excess of 3,000 miles per hour.
ATK Thiokol Propulsion is the world&#8217;s leading supplier of solid-propellant rocket motors. Products manufactured by the company include propulsion systems for the Delta, Pegasus, Taurus, Athena, Atlas, H-IIA, and Titan IV B expendable space launch vehicles, NASAs Space Shuttle, the Trident II Fleet Ballistic Missile and the Minuteman III Intercontinental Ballistic Missile, and ground-based missile defense interceptors.
ATK is a $2.2 billion aerospace and defense company with strong positions in propulsion, composite structures, munitions, precision capabilities, and civil and sporting ammunition. The company, which is headquartered in Edina, Minn., employs approximately 12,200 people and has three business groups: Precision Systems, Aerospace, and Ammunition and Related Products
Jacques :-)
Editor: www.spacepatches.info
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On Fri, 24 Oct 2003 16:24:38 +0000, Jerry Irvine wrote:

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.
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"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.....
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On Fri, 24 Oct 2003 23:49:18 +0000, ASW wrote:

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.
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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.

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On Sat, 25 Oct 2003 02:05:31 +0000, ASW wrote:

Well, perhaps I'm being overly pedantic... perhaps Jerry meant something other than what I thought he meant... :)
I just found the thought of Sandia's kilowatt diode laser in space somewhat strange when the military is equipping the Joint Strike Fighter with a megawatt-class chemical laser cannon :)
(Which sounds super-impressive untill you get into the physics and parameter constraints...)
Still, as of now, it's looking like any combat lasers in space will be limited-use chemical jobs lofted for a single mission... and even that much speculation requires much handwaving.
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