US Army awards $4.9M contract to Achates Power and AVL for Next-Generation Combat Engine based on Achates two-stroke, opposed-piston technology
The US Army Tank Automotive Research, Development and Engineering Center (TARDEC) has awarded Achates Power, Inc., developer of a two-stroke, compression-ignition (CI) opposed-piston (OP) engine (earlier post) and AVL Powertrain Engineering, Inc. a $4.9-million contract for design and construction of the Next-Generation Combat Engine.
As outlined in the solicitation (TARBAATOPIC27), to serve a wide range of US combat and tactical vehicles, the engine must deliver superior fuel efficiency, high power density and low heat rejection and will be multi-fuel capable. It should also be of a scalable design to maximize value to the Government and military vehicles. To meet the program requirements, AVL proposed an engine based on the Achates Power opposed-piston, two-stroke technology, which includes more than 1,000 innovations covered by patents and patent applications. This the the sole award from the solicitation.
When benchmarked against leading, conventional diesel engines, the Achates Power engine demonstrates:
Lower cycle average brake-specific fuel consumption
Similar engine-out emissions levels
Less than 0.1% fuel-specific oil consumption
Reduced weight and complexity
Achates Power has accumulated more than 3,600 hours of dynamometer testing and achieved 47.5% brake thermal efficiency. The brake thermal efficiency advantages demonstrated by the Achates Power engine are published in SAE International Paper 2011-01-2216 (earlier post) and include:
Less heat transfer due to a lower ratio of surface area-to-volume in the combustion chamber caused, in part, by the elimination of the cylinder head; Leaner, faster and earlier combustion;
More favorable relationship between the compression and expansion ratios realized from asymmetric timing of the intake and exhaust events;
Higher effective flow area due to ports on each end of the cylinder; and
Higher scavenging efficiency from a high stroke-to-bore ratio.
Since first releasing our engine’s results, we have demonstrated a steady increase in brake thermal efficiency, all while meeting the toughest, global emissions standards. And with high brake thermal efficiency—combined with the engine’s flat fuel map, very low engine-out soot and demonstrated durability potential—we have the utmost confidence that we will meet TARDEC’s program objectives. Over the next few years, we look forward to collaborating with AVL on the final design of this Next-Generation Combat Engine.— David Johnson, CEO, Achates Power
Achates Power has made excellent progress overcoming the challenges commonly associated with two-stroke engines: emissions, fuel economy, oil consumption and durability. The fact that their engine has very high efficiency and power density, along with low heat rejection to coolant, makes it well suited for military applications.—David Merrion, former EVP of engineering at Detroit Diesel, Achates Power technical advisory board member, and two-stroke engine expert
Randy E. Herold, Michael H. Wahl, Gerhard Regner, James U. Lemke, David E. Foster (2011) Thermodynamic Benefits of Opposed-Piston Two-Stroke Engines (SAE 2011-01-2216)