Composite Launch Tube (LT) for the Compact Rapid Attack Weapon (CRAW)

Navy SBIR 24.1 - Topic N241-045
NAVSEA - Naval Sea Systems Command
Pre-release 11/29/23   Opens to accept proposals 1/03/24   Now Closes 2/21/24 12:00pm ET    [ View Q&A ]

N241-045 TITLE: Composite Launch Tube (LT) for the Compact Rapid Attack Weapon (CRAW)


The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a composite launch tube that will be used as part of 6.75-inch diameter Compact Rapid Attack Weapon (CRAW) Launcher Assemblies.

DESCRIPTION: The CRAW is a very lightweight multi-mission torpedo with a 6.75-inch diameter that will be launched out of the Virginia Class submarine External Countermeasure Launcher (ECL) system. The CRAW is contained within a Launcher Assembly (LA). The Launch Tube (LT) is a major component of the LA and is capped on one end with a muzzle cap/nose assembly and sealed to sea pressure on the breech end by the Mk 77 Gas Generator (impulse system). The CRAW and ancillary hardware such as a pressure plate, ram plate, drag fin assembly reside within the LT between the muzzle face of the Mk 77 Gas Generator and the muzzle cap/nose assembly. The LT is designed to meet Grade A shock requirements (i.e., heavyweight, high-impact, air-backed, wetted-surface environment), implosion, hydrostatic, hydrodynamic and Mk 77 impulse/launch loads. The current stainless steel LT represents nearly 50% of the total projected weight of the overall CRAW LA weight. Furthermore, there is little to no ability to achieve weight savings in any of the other LA hardware, including the CRAW itself. Additional service life/environmental factors include, but are not limited to, Hazards of Electromagnetic Radiation to Ordnance (HERO), Grade A shock qualification (i.e., heavyweight, high-impact, air-backed, wetted-surface environment), shipboard vibration, corrosion preventions/life, and contributions to CRAW and Mk 77 Gas Generator Insensitive Munitions qualification.

The Navy seeks a new composite LT that would replace the existing stainless steel in the CRAW LA, which would be beneficial for various reasons, including reducing cost, weight, and manufacturing complexity. Ideally, a small business industry partner would be capable of utilizing existing commercial composite material technology or developing new composite materials that can be shaped to house a 6.75-inch CRAW device form factor along with the Mk 77 Gas Generator and CRAW launcher ancillary hardware. The CRAW program envisions a future state where composite launch tubes could become the preferred manufacturing method as material properties could meet existing launch tube requirements. One of the most difficult aspects of developing launch tube technologies for CRAW remains the tight 6.75-inch diameter form factor, combined with the stringent requirements to meet the aforementioned operational and environmental loads, and the machinability of the launch tube internally and externally along its entire length. Ultimately, success of the composite launch tube will be measured by its ability to meet existing CRAW launch tube requirements.

Requirements and performance characteristics for a composite CRAW LT are (but are not limited to):

• Maintains existing shipboard interfaces per CRAW LT drawing (to be provided) – same form factor as existing LT tube design

• Maintains existing interface (internal to LT) with Mk 77 Mod 0/1 gas generator (drawing to be provided)

• Meets or exceeds existing LT service life (2 years deployed with minor maintenance (paint and anode replacements, 4 years to full maintenance cycle)

• Reusable: Threshold – unlaunched condition; Objective – launched condition

• Meets requirement for Grade A shock qualification under MIL-DTL-901E

• Maintains Hazards of Electromagnetic Radiation to Ordnance (HERO) safe designation of current system

• Adheres to MIL-STD-464 – latest rev

• Adheres to MIL-STD-461 – latest rev

• Adheres to MIL-STD-167 – latest rev

• Adheres to NAVSEA Temporary Alteration (TEMPALT) Manual - NAVSEA S9070-AA-MME-010/SSN/SSBN, 3rd Revision, ACN-5

• No impact on corrosion susceptibility and life of surrounding hardware/structure

• No hazardous material generation or addition to post-launch combustion by-products effluent from exposure to launch process and/or seawater

• Adheres to NAVSEA Implosion requirements for VIRGINIA and COLUMBIA Class

• Compatible with existing Weight Handling Equipment (WHE), Ordnance Handling Equipment (OHE), and Weapon Handling Equipment (WHE)

• Minimum weight reduction, compared to the current LT: Threshold – 150 lbm; Objective – 175 lbm

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. § 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and NAVSEA in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations. Reference: National Industrial Security Program Executive Agent and Operating Manual (NISP), 32 U.S.C. § 2004.20 et seq. (1993).

PHASE I: Complete a robust conceptual design for the composite LT and provide all critical analyses supporting the design’s compliance with Navy safety, performance, and operational requirements. Support the feasibility of meeting propulsion performance requirements through modeling/simulation. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Design, develop, and deliver a prototype composite LT for testing and evaluation based on the results of Phase I. The prototype composite LT will be evaluated on its ability to meet LT requirements, and its ability to meet or exceed existing LT system performance as identified in the Description section. Likewise, the ability of the composite LT to integrate as part of the existing CRAW Launcher Assembly along with its set of interfaces will be paramount to the success of the prototype.

It is probable that the work under this effort will be classified under Phase II (see Description section for details).

PHASE III DUAL USE APPLICATIONS: Assist the Navy to transition to low rate initial production which will occur while coordinating with existing CRAW partners. Particularly, Penn State University’s Applied Research Lab (PSU/ARL) and Navy Warfare Centers will require integration support to integrate the composite LT into the CRAW Launcher Assembly for full system testing. Testing at this point would include MIL-STD-2105 (Insensitive Munitions), Implosion, Hydrostatic, Explosive Shock qualification, and other shipboard integration and ordnance qualification tests, as required.

It is anticipated that this composite launch tube could be useful for other 6.25-inch and 6.75-inch devices launched out of external countermeasure launchers (e.g., acoustic countermeasures). Outside industries such as the commercial Unmanned Undersea Vehicle (UUV) designers, offshore energy industries, and other marine or industrial applications where a high-strength, lightweight pressure vessel or piping would be of interest.


  1. Javier, C., LeBlanc, J., et al. "Underwater nearfield blast performance of hydrothermally degraded carbon–epoxy composite structures." Multiscale and Multidisciplinary Modeling, Experiments and Design, 16 Jan 2018, pp. 1:33–47,
  2. Chenw, I, Bryne, A. et al. "Effects of Low Temperature and Water Saturation on the Blast Response of Carbon and E-Glass Epoxy Composites." Journal of Dynamic Behavior of Materials, 22 Feb 2023.
  3. Fontaine, D., LeBlanc, J., et al. "Blast response of carbon-fiber/epoxy laminates subjected to long-term seawater exposure at sea floor depth pressures." Composites Part B: Engineering, Volume 215, 15 June 2021, 108647.
  4. Thornton, P.H and Edwards, P.J. "Energy Absorption in Composite Tubes." Journal of Composite Materials, November1982;16(6), pp. 521-545.
  5. Courteau, Marc A. and Adams, Daniel O. "Composite Tube Testing for Crashworthiness Applications: A Review." Journal of Advanced Materials, 43(2), April 2011, pp.13-34.

KEYWORDS: Very Lightweight Torpedo; Compact Rapid Attack Weapon; Virginia Class Submarine; External Countermeasure Launcher; Composite Materials for Tubes; Torpedo launch sequence


The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 24.1 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its Navy 24.1 SBIR Topics pre-release on November 28, 2023 which opens to receive proposals on January 3, 2024, and now closes February 21, (12:00pm ET).

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Topic Q & A

1/24/24  Q. 1. It is stated that the composite launch tube must maintain the 'same form factor'. Does this requirement apply only to the specific interface locations mentioned (shipboard, gas generator, and muzzle cap), or should this be interpreted to require that the current launch tube OD or wall thicknesses cannot be modified?
2. When the launch tube is sealed by the muzzle cap and gas generator, is it pressurized, or left at ambient pressure?
3. Can the force required to breach or shear the muzzle cap be shared at this time?
   A. 1. This applies to the overall outer dimensions of the launch tube including the integral thrust ring. Specific interface points must also be accommodated as noted. Wall thickness should be based on pressure requirements for operating submarine.
2. A vacuum is applied to the launch tube when it is partially assembled with the CRAW and fully assembled with the gas generator. It is then backfilled with dry-nitrogen.
3. The approximate force is in the 5,000-10,000 lb range.
1/15/24  Q. At any time prior to launch, are the muzzle end and outer diameter of the launch tube sealed to hydrostatic pressure?
   A. Prior to launch the muzzle end and outer diameter of the launch tube are sealed to hydrostatic pressure. The tube is effectively sealed on its ends by the gas generator at the aft end and the muzzle cap at the forward end.
1/9/24  Q. Would a composite/steel hybrid design be acceptable?
   A. Any and all proposed designs and/or materials will be evaluated.
12/20/23  Q. 1. Can you provide a link to the current design of the Launch Tube for dimensional reference?
2. It is stated that you have a weight savings goal of 175 lbm, what is the current weight of the Stainless Steel Launch Tube?
   A. 1. Unfortunately the drawing of the current Launch Tube is DISTRO D and can not be shared as part of the BAA (only DISTRO A is releasable).
However, in general terms the CRAW launch tube is 121.3” long and has an overall outer diameter of 7.75”. There is a 0.750” thick thrust ring 1.25” in from the breech end which is 8.750” in diameter. Internal to the tube there are various features for inserting and retaining a Mk 77 gas generator which results in a 6.750” inside diameter for approximately 10” at the breech end of the tube. A retaining ring is used to secure the gas generator and requires a slot of 0.094” length at 7.182” diameter. At the muzzle end the tube is 7.375” inner diameter for 6.36” length and has qty (8) 0.25-20 UNC tapped holes 0.312” from the tube muzzle end. At the end of the 7.375” section there is a 7.25”-16 UNJS-3B thread for 0.85” length.
2. The current weight of the 17-4 PH stainless steel to is approximately 308 lbs.
12/18/23  Q. The references seem to bias epoxy systems. Will only epoxy systems be considered?
   A. The references are just that –references. Nothing should be inferred. There is no preferred resin/fiber composite system for Naval systems. Any materials/design that has a likelihood of meeting all requirements would be considered.

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