The Senate Economic References Committee has conducted a public hearing on the future of Australia’s new submarine fleet, with the use of pump jets questioned.
Australia’s next generation of submarines will be built under the Federal Government’s Future Submarine program currently working with French company DCNS to design the 12 Future Submarines.
A pump-jet propulsion system has been proposed as a key feature of the Shortfin Barracuda submarine, however the inquiry revealed discrepancies between expert opinion and the project team’s design of the submarine.
Aidan Morrison, a physicist who compiled a report for the inquiry, noted that the pump jet is not efficient at the speeds that a conventional submarine operates in.
“Pump jets have a far lower efficiency than propellers at a low speed of travel in contrast to high speeds, where jets tend to become more efficient,” Mr Morrison said.
“The crossover does not lie near or anywhere under the probable transit speed of eight to 10 knots of a diesel-electric submarine. One world-renowned expert I discussed the matter with said it was impossible that a pump jet could be designed to be more efficient than a well-designed propeller under 18 knots.”
He claimed that no other conventional submarines used this type of system.
“There are none in service at all. I’m aware of a prototype or demonstrator that was built once on a Russian submarine, a Kilo class submarine. I’ve seen a photo of that, but as far as I can tell it was never put into much active service.,”
Mr Morrison contested claims made by French company Naval Group – who conducted the design of the submarines – that pump jets meant that the Shortfin Barracuda would be able to move more quietly.
“The pump jet is only quieter when compared with an obsolete propeller. This could actually be the statement that was intended to be made, in which case it is perfectly consistent with the research that I have done and put before you today,” Mr Morrison said.
While pump jet propulsion systems are generally used in nuclear submarines, they are generally not used in conventional submarines.