ATK reach another milestone in SLS advanced booster drive

by Chris Bergin

ATK announced they successfully completed the filament winding of a pathfinder Advanced Booster composite case. The milestone is part of their commitment to the NASA Research Announcement (NRA) Advanced Booster risk-reduction program, aimed at fostering booster options for the evolved versions of the Space Launch System (SLS).

Advanced Booster:

ATK – who provided the Reusable Solid Rocket Motors (RSRMs) throughout the 30 year run of the Space Shuttle Program (SSP) – are deeply involved in providing the bulk of the first stage boost for the Heavy Lift Launch Vehicle (HLV).

SLS is set to debut in 2017, sporting two five segment versions of the Shuttle booster, an arrangement that will stretch into the mid 2020s.

Based on the evolvable nature of the monster rocket, SLS will receive an additional boost via the addition of “Advanced Boosters”, enabling SLS to evolve to a launch vehicle capable of lofting 130mT of payload – deemed as a requirement for missions to Mars.

Liquid Advanced Booster, via L2Several companies are developing their proposals under NASA’s SLS Advanced Booster Engineering Demonstration and/or Risk Reduction (ABEDRR) procurement, ranging from solid to liquid options – such as Dynetics Inc./Pratt & Whitney Rocketdyne (PWR), who are proposing the use of the famous Saturn V F-1 engines to advance SLS’ capability to launch payloads of up to 150mT to orbit.

ATK’s own proposal – as outlined in a presentation acquired by L2 – builds on their legacy with the four and five segment boosters, with a motor that is “advanced” on several levels, by “provid(ing) NASA the capability for the SLS to achieve 130 mT payload with significant margin, utilizing a booster that is 40 percent less expensive and 24 percent more reliable than the current SLS booster.”

Solid Advanced Booster, via L2Part of their increased cost and mass savings are realized via the change in the casings used to house the propellant, by switching to a composite material.

The presentation notes the composite casings provide a 4,128lbm payload capability improvement, while the simplified stage assemblies comparison cites the saving of 480 man hours – a 50 percent reduction in the man hours required on the five segment motor.

The ongoing evaluations are looking at the optimization of a case design that will be stronger, yet more affordable than traditional steel cases. The savings will allow for increased payload performance due to reduced weight inherent in composite materials.

“ATK’s risk-reduction efforts on this NRA will help NASA with technological development and performance upgrades in the future,” noted Charlie Precourt, vice president and general manager of ATK’s Space Launch division. “It also ties to cost reductions we have made on the existing SLS boosters and advances in our commercial business.”

Z77The milestone announced this week related to the construction of a pathfinder test article, shown in photographs to be a 92-inch-diameter, 27-foot-long composite case.

ATK noted they overcame challenges related to the affordability and performance required of an Advanced Booster during the case winding operations for the test article.

“ATK leveraged 45 years of composite case winding experience, its experienced workforce, and a modern fiber-placement tooling system to achieve success on its first attempt,” the company added.

Z3The company’s proposal also includes a higher ISP density of the propellent, boosting payload performance by nearly 25,000lbm, yet saving $9.2m in costs per booster. With the increased operating pressure, improved propellant, tailored thrust profile, increased expansion ratio all combine to provide a 15.1mT boost to the SLS’ payload capability.

The next step in the Advanced Booster NRA program is to continue development of high performance and low-cost propellants that meet the lofty payload and affordability goals of the SLS.

ATK note that these propellant options, many of which are also widely used in ATK commercial solid rocket motors, combined with the achievements made in composite case technology, will provide NASA several options for performance increases for the next generation Advanced Booster.

As reported by this site earlier this year, ATK’s Advanced Booster NRA team have already been hard at work on by the Propellant/Liner/Insulation (PLI) Integrated Product Team (IPT), tackling the challenge of developing a high-performance, low-cost PLI system.

ATK Advanced Booster Propellant MixingAs shown in photos, the PLI IPT are busy establishing a design of experiments (DOE) matrix, cooking up 66 unique propellant mixes to test candidate propellant formulations for burn rate performance and mechanical property characteristics.

The resulting mixes may have an appearance that would not look out of place atop of a “get well soon” cake for the Dream Chaser ETA, but once ignited it will have the ability of providing immense power, aiding the huge SLS rocket to rise uphill en route to orbit.

ATK noted at the time that several “families” of solid propellant formulations are being evaluated in the DOE process, with multiple variations within these families undergoing testing to select the best formulation within each family to pursue further testing within larger scale mixes.

The favored propellant formulation will be tested during the NRA’s 92-inch diameter integrated static test, set for early 2015.

“Creating a composite case and developing advanced propellant for NASA’s advanced booster coincides with technological advances in our commercial rocket programs at ATK,” added Mr. Precourt.

ATK also added that their Value Stream Mapping (VSM) process has allowed the company to identify more than 400 changes and improvements, which NASA approved.

“These changes have reduced assembly time by approximately 46 percent, saving millions of dollars in projected costs for the SLS system,” ATK noted.

Aft Segment overview, via L2 and ATKMeanwhile, ATK are continuing to evaluate the status of their Qualification Motor -1 (QM-1) motor, after voids were discovered in the aft segment. The original aft segment was scrapped for a similar issue, only for its replacement to mirror the problem – possibly caused by processing and design changes in the motor’s insulation and liner material.

The likely cause of the voids points to a change in processing when using a relatively new material in the insulation lining for the segments, a material that has replaced the previous use of crysotile – the most common mineral form of asbestos.

Information collated in L2’s SLS section noted the company may build two test articles utilizing pre and post VSM processes, as required to try and narrow in on the exact processing issue that led to the current difficulties.

ATK are set to discuss the forward plan – and the realigned schedule – with their NASA partners over the interim period.

Images: Via ATK, NASA and L2 content from L2’s SLS specific L2 section, which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site.)

(L2 is – as it has been for the past several years – providing full exclusive SLS and Exploration Planning coverage. To join L2, click here:

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