This month I attended the Office of Naval Research conference on “Lessons Learned” in the now abandoned development of the Expeditionary Fighting Vehicle (EFV) shown below.
I also presented a poster on efficient conversion of power to thrust under varying loads and speeds:
Why can’t a Boat be more like a Plane?!
The Office of Naval Research is now charged with developing and qualifying technologies that would make a high speed amphibious vehicle practical in the future.
Thinking Outside the Box
One of the major advantages of computer simulation is that it enables designers to think outside the box. Thanks to the Royal Institution of Naval Architects, London, UK, for making this point while calling attention to IntelliJet’s innovative features in their recent article below.
“Increasingly affordable CFD, computer simulation and 3D packages are enabling marine engineers to design more accurate solutions than is the case with building and testing, argues IntelliJet’s Jeff Jordan.”
Download the article:
Ship & Boat International July/August 2015
Computer Simulation, Design and WaterJets
I will present a paper on this subject at
ASNE Day 2015: Engineering America’s Maritime Dominance
March 4-5, 2015 in
Military Jet Boats Now Dominant, but Not Sustainable
Valued for their high speed capability and shallow draft, marine jets beat out propellers as the dominant propulsion in commercial and military craft, even though jets consume more fuel at lower speeds. Yet lower speeds are where they spend most of their time.
Office of Naval Research
Water Jet Pump CFD
Automotive and Aircraft Technologies to the Rescue
By incorporating technology from modern aircraft and cars, jet boats can be much more fuel efficient at low and mid-range speeds without sacrificing high-speed capability or the other operational advantages of current technology.
Simulation Saves Time and Money.
My technical paper and presentation also demonstrate the incorporation of variable geometry and electronic controls in computer simulations to test systems and accurately predict performance. The models developed in this process are directly useful in rapid prototyping.
The graphic above is an example of the development of a marine jet pump using computational fluid dynamics.
My technical paper details computer design and simulation methods, which allow fast, accurate and economical prediction of performance and fuel consumption in any operational profile. The process produces files for use with the latest part prototyping and pilot production methods.
Testing Fuel Consumption the Hard Way
7th Fleet suggests the Littoral Combat Ships, particularly LCS-1, would be more suitable for service in a smaller ocean, where it is not so far between fueling points, according to the US Government Accountability Office report GAO-14-749, Jul 30, 2014.
Fleet users expressed uncertainty about LCS’s
potential capabilities and attributes, or how they
would best utilize an LCS in their theater. Several
7th Fleet officials told us that they thought the LCS
in general might be better suited to operations in
the 5th Fleet theater (headquartered in Bahrain)
than to 7th Fleet due in part to the smaller area of
responsibility in 5th Fleet that would make range
less of a consideration.
In its first service with the 7th Feet, the LCS proves to have
- excessive fuel consumption and
- inadequate range.
Here is the most modern ship in the US Navy using fixed-jet technology, which cannot benefit from modern electronic controls to reduce energy consumption. Such controls have long been common on household appliances like washers, dryers, refrigerators, and toasters.
An IntelliJet-based system would make this type of ship much more practical by reducing its mid-range fuel consumption. And the whole IntelliJet ship could be modeled and tested in computer simulation to accurately predict its performance in any scenario that it might find in the fleet. Then the same files could be used to quickly generate pilot production parts for demonstration.
Efficient propulsion can’t overcome bad hull design.
The most extreme example of this may be the Amphibious Assault Vehicle, commonly referred to as a “jet propelled brick”.
I even took a shot at redesigning the brick as a submersible vehicle that would be more efficiently propelled and would offer better performance as an armored vehicle. I presented a peer reviewed paper on the subject at ASNE Day 2012. See below.
With the demise of the Expeditionary Fighting Vehicle (EFV), the requirement for getting troops from ships over-the-horizon to shore in an environment of changing threats remains.
The ever greater availability of surface-to-surface missiles is effectively moving the horizon well beyond the historical 12-mile planning distance. The evolving Improvised Explosive Devices (IUDs) are driving Amphibious Assault Vehicle (AAV) designs to heavier armor, which makes them lower and slower in the water, and easier to target.
Even an EFV planing over the surface at 30 kts might be detected and targeted with small missiles.
To mitigate these threats, the AAV of the future must be more effectively armored and designed for increased stealth. In my paper I explore the development of such a solution, the Submersible Amphibious Assault Vehicle (SAAV), and its appeal in an environment of economic constraints.
Adapting AAVs to Changing Threats
Submersible Amphibious Asssault Vehicles (SAAVs).pdf