SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  N07-061 (Navy)
Title:  Power Transmission Shafting for Air Cushion Vehicles
Research & Technical Areas:  Materials/Processes

Acquisition Program:  Joint Maritime Assault Connector (JMAC), ACAT is TBD, PMS 377
  Objective:  Development of an improved materials solution for the power transmission shafting of an amphibious Air Cushion Vehicle (ACV).
  Description:  Amphibious ACVs are very weight sensitive and operate in an extremely harsh environment of saltwater spray and sand. The purpose of these ACVs is to transport payloads between ships or between a ship and the shore. These craft, such as the Navy’s Landing Craft, Air Cushion (LCAC), often have lightweight hulls (aluminum or composites); however, the existing carbon steel transmission machinery is not specialized and is relatively heavy compared to other craft components. The LCAC currently uses twelve painted carbon steel shafts to transmit lift and propulsion power. The next generation of ACVs, Joint Maritime Assault Connector (JMAC), will operate in a similar environment and will have a similar vessel footprint, but will most likely have greater lift capacity requirements and will therefore experience larger transmission loads. While carbon steel has been an adequate material solution for the erosive and corrosive operating environment, scaling the technology to allow for greater transmission loads and greater cargo lift capability would also increase the overall weight of the craft as well as the craft’s fuel consumption ratio. Each pound of craft weight equates to one less pound of cargo capacity. This topic seeks to explore the application of advanced material solutions for the power transmission shafting to reduce overall craft weight and mitigate vibration propagation while enabling the increased the payload lift capacity of the JMAC. Rotation speeds of JMAC will likely be similar to LCAC speeds. JMAC shafting loads could range between current LCAC torque loading and 65% more than LCAC capacity. Concepts proposed must be able to a) transmit the drive train power and torque under extreme dynamic loading environments, b) maintain integrity, alignment and balance under sand and salt exposure as well as normal deflections associated with hull bending, 3) withstand significant vibration and 4) mate to carbon steel gearboxes without creating galvanic corrosion cells.

  PHASE I: Demonstrate the feasibility of an advanced materials solution for the power transmission shaft of an ACV. Compare the proposed material solutions to the current carbon steel configuration to evaluate the benefits and disadvantages of using alternative materials for this application. Provide a preliminary concept design and component validation plan.
  PHASE II: Finalize the design from Phase I and fabricate a prototype shaft. Validate prototype using laboratory testing and provide results. The testing should include evaluation of erosion, corrosion, load capability, overspeed, and vibration exposure.

  PHASE III: Design and manufacture one drive train set of shafts (six shafts) for full scale testing on an LCAC. As applicable, the small business will work with the Navy to define the field test objectives, install the shafting and conduct the testing. PRIVATE SECTOR COMMERCIAL POTENTIAL/

  DUAL-USE APPLICATIONS: The commercial potential for lightweight, durable shafting will transcend to all aspects of power transmission industry including marine, aviation and automotive.

  References:  1. ASME Technical Paper 2000-GT-603; Integration of the ETF40B Gas Turbine Engine and FADEC System into the Landing Craft Air Cushion Vehicle; by M. Dvornak, H. Harris, J. Richards and P. Schneider; May 2000. 2. Landing Craft, Air Cushion (LCAC)http://www.globalsecurity.org/military/systems/ship/lcac.htm 3. NAVSEA Drawing No. 802-5748948; Landing Craft Air Cushion, Transmission and Shafting Arrangement.

Keywords:  Driveshaft; Advanced Materials; Shafting; Power Transmission; ACV; JMAC

Additional Information, Corrections, References, etc:
Ref #3: 802-57548948 002.pdf
Ref #3: 802-57548948 002.pdf

Questions and Answers:
Q: 1. What is the design torque, Shaft speed, angular mis-aligment capability and length of the LCAC shaft?

2. Do all twelve shafts turn at same speed?

3. Does the shafting go between Propellers and gas turbine?

4. Do the same shafts turn the lift fans?
A: 1. Torques and speeds of the LCAC shafts are provided on Ref #3 (Dwg
802-5748948). The lengths for LCAC shafts 1-10 are provided on the
additional reference (dwg 243-5750625). Shafts 11 and 12 are approximately
9.75 feet long.

2. See Ref #3.

3. See Ref #3 for the LCAC arrangement.

4. See Ref #3 for the LCAC arrangement.
Q: You have referenced drawing number Dwg 802-5748948 in the solicitation. But you provided drawings numbered Ref #3: 802-57548948 001.pdf Ref #3: 802-57548948 002.pdf. Is the shaft diameter Dimension "L" in drawing 802-545-48948, the drawing that was provided?
A: The file names are incorrect. The drawing number (802-5748948) is correct. On 802-5748948, the OD and wall thickness is noted by a leader at each shaft (there is no dimension "L"). On drawing 243-5750625, "G" is the shaft OD, "L" is the OD at the splines.
Q: You have referenced drawing number Dwg 802-5748948 in the solicitation. But you provided drawings numbered Ref #3: 802-57548948 001.pdf Ref #3: 802-57548948 002.pdf. Is the shaft diameter Dimension "L" in drawing 802-545-48948, the drawing that was provided?
A: The file names are incorrect. The drawing number (802-5748948) is correct. On 802-5748948, the OD and wall thickness is noted by a leader at each shaft (there is no dimension "L"). On drawing 243-5750625, "G" is the shaft OD, "L" is the OD at the splines.
Q: I assume that the shafts are tubular, not solid barstock. What are the wall thicknesses of these shafts in the current design?
A: The LCAC shafts are hollow. The ODs and wall thicknesses are provided on Ref #3 (Dwg 802-5748948).
Q: 1. What is the design torque, Shaft speed, angular mis-aligment capability and length of the LCAC shaft?

2. Do all twelve shafts turn at same speed?

3. Does the shafting go between Propellers and gas turbine?

4. Do the same shafts turn the lift fans?
A: 1. Torques and speeds of the LCAC shafts are provided on Ref #3 (Dwg
802-5748948). The lengths for LCAC shafts 1-10 are provided on the
additional reference (dwg 243-5750625). Shafts 11 and 12 are approximately
9.75 feet long.

2. See Ref #3.

3. See Ref #3 for the LCAC arrangement.

4. See Ref #3 for the LCAC arrangement.
Q: I assume that the shafts are tubular, not solid barstock. What are the wall thicknesses of these shafts in the current design?
A: The LCAC shafts are hollow. The ODs and wall thicknesses are provided on Ref #3 (Dwg 802-5748948).

Record: of