CASTOR 30XL prepares for static fire ahead of providing Antares boost

by Chris Bergin

ATK’s CASTOR 30XL Upper Stage motor is deep into preparations for a static fire test, set to take place this spring at the Arnold Engineering Development Center in Tennessee. The large Upper Stage was designed and built by ATK within a two year period, with six production units on order to boost the power of Orbital’s Antares launch vehicle.


Orbital’s Antares launch vehicle is preparing for its debut flight, likely to take place next month.

Hot FireThe push towards launch follows the successful hot fire test of an Antares first stage with its AJ-26 main engines at the Wallops launch site.

This opening flight of the vehicle, formerly known as Taurus II, will be tasked with lofting a Cygnus mass simulator payload, heavily instrumented to gather data on the launch environment aboard the vehicle.

Orbital will then move on to their final requirement under NASA’s Commercial Orbital Transportation Services (COTS) contract – a full demo mission.

Cygnus Heading to ISS KOSThis flight will send the first “real” Cygnus spacecraft into space, ahead of its debut mission to the International Space Station (ISS).

For this flight, the vehicle will utilize a solid Upper Stage called the Castor 30, which is a derivative of the Athena and Taurus I first stage Castor 120 motor – which is in turn a derivative of the Peacekeeper ICBM first stage.

Once the COTS requirements are satisfied, Antares will swap the Upper Stage from the Castor 30A to an upgraded version called the Castor 30B. This will be used for the CRS-1 (Orb-1) and CRS-2 (Orb-2) ISS runs under NASA’s Commercial Resupply Services (CRS) contract.

From CRS-3 (Orb-3) onwards, Orbital originally intended to switch to a liquid upper stage called the HESS, utilizing the Russian RD-0124. However, the company later decided to go with a stretched version of the original solid-based Upper Stage, called the Castor 30XL.

CygnusThe CASTOR 30XL will power the last six CRS flights scheduled for the Antares, allowing for the transition towards the launch of extra cargo on a larger Cygnus Spacecraft. The “enhanced” Cygnus is scheduled to fly the last five CRS missions, boosting payload capacity to 2,700 kg.

The CASTOR 30XL solid rocket motor is 92 inches in diameter, 236 inches in length and weighs approximately 58,000 pounds. The nozzle is eight feet long with a submerged design with a high performance expansion ratio (56:1) and a dual density exit cone well suited for high altitude operation.

Showing a wide range of options available to Antares, two optional third stages were previously cited, namely the Hydrazine Propulsion System (HAPS) – a derivative of the Orbital STAR bus designed to inject a payload to a designated orbit with more precision, while the Star 48 third stage could provide an option for orbits requiring higher energy.

Overall, Antares utilizes a three digit designation, based on the combination of staged utilized.

The first digit will always be a one and refer to the kerosene core. The second stage will be labeled 1 for the CASTOR 30A, 2 for B, and 3 for XL. The last digit refers to the upper stage being utilized, with a 1 being the designation for the HAPS stage and 2 for the Star 48 and 0 for no upper stage.

For the CRS missions, Orbital will fly Antares as a two stage vehicle, all sporting CASTOR motors on the Upper Stage.

CASTOR 30XL Shipping Out Of ATK, from ATKThe top of the range CASTOR 30XL will soon undergo a major milestone, as it prepares to come to life at the Arnold Engineering Development Center in Tennessee, following its shipping from ATK.

This static fire motor took only 22 months, from motor concept to completion, by teams at ATK’s Bacchus, Clearfield and Promontory, Utah locations. The customer, Orbital Sciences Corporation, contracted ATK back in April, 2011 for the development and qualification of the motor, along with six production units.

“This is a significant achievement,” said John Slaughter, vice president of Commercial Programs for ATK’s Defense and Commercial Division, following the motor’s shipping. “In less than two years the ATK team has designed and built the static test article for a new commercial product that will significantly improve the performance of Orbital’s Antares launch vehicle.

“I can’t say enough about the hard work and attention to detail that has enabled this event.”

ATK added the CASTOR 30XL team maintained “an aggressive schedule” that included development and design release, qualification of the case including superproof testing, casting of an inert motor and completing production of the static fire unit.

Work was spread over several facilities, including the Aerospace Structures Division in Clearfield, who manufactured the case, while nozzle manufacturing was performed at the Promontory facility. The motor was cast and finished at the Bacchus facility.

ATK Team for Castor 30XL, from ATK“The team incorporated several innovative design concepts and materials including the use of 13 fins in the grain, reclaimed ammonium perchlorate from the Promontory facility and a case design that was significantly challenged to reduce inert weight,” added ATK. “Cost reduction and commonality were also significant considerations during the design phase.

“Clearfield’s (Aerospace Structures Division) implemented the use of an Armalon overwrap system, and a vendor produced Y joint filler. At Bacchus, use of common tooling with the Large Class Stage program reduced risk to the program. Although the nozzle is largely a new design, it features a slightly modified Propulsion Application Program flex bearing with a 3.5-degree maximum design vector angle.”

The company – most famous in the space flight arena for their production of large Solid Rocket Boosters (SRBs) for the Space Shuttle Program (SSP) and soon for the Space Launch System (SLS) – also utilized commonality on the Thrust Vector Control (TVC) system, using the same hardware as the CASTOR 30 and CASTOR 30B programs.

This provided ATK with significant cost savings by eliminating the need for an extensive requalification program. The loaded motor value stream element team recorded zero defects for the static fire motor.

ATKATK also noted their project management arrangement helped provide the positive outcome for CASTOR 30XL’s schedule and cost, bringing designers, process and facility personnel and tooling group together early in the development cycle to minimize development issues – something known as “concurrent engineering”.

“CASTOR 30XL is one of the finest concurrent engineering efforts I’ve ever seen,” added Stan Graves, vice president of Science and Engineering for ATK Propulsion Systems. “The Integrated Product Team followed a development process that hit all the marks without cutting corners.

“This small, dedicated and talented group integrated the design, process engineering, systems engineering, quality and manufacturing functions to achieve a high-quality product on cost and on schedule.”

The remaining six production nozzles are in various stages of completion in the nozzle factory along with several case and igniter components that are to be supplied to ATK’s Clearfield and Bacchus facilities.

(Images: via ATK and L2’s Antares/Cygnus Section – containing presentations, videos, images, interactive high level updates and more, with additional images via Orbital).

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