EPS advancing diesel engine for general aviation applications; 30-50% lower fuel consumption than gasoline
Engineered Propulsion Systems (EPS) has developed and is advancing a 4.3-liter, 8-cylinder diesel engine for general aviation (GA) applications. Based on a CGI (compacted graphite iron) cylinder block, the Graflight V-8 (formerly called the Vision 350, earlier post) will enable 30-50% lower fuel consumption and emissions compared to conventional aero engines, according to the company.
As an example, EPS suggests that a Cirrus SR22 (a single-engine four- or five-seat composite aircraft) fitted with the Graflight V-8 could carry the equivalent of two additional passengers flying the same distance as with a Continental gasoline 315 horsepower engine while still realizing a 40% reduction in fuel cost. Engine and flight tests are currently underway and EPS expects Federal Aviation Authority approvals during 2017.
Initial testing of the pre-production engine has demonstrated specific power of 105 horsepower per liter (77 kW/l), resulting in an output of 450 horsepower (332 kW). The installed wet weight of the 450 hp diesel engine package is within 45 pounds (20 kg) of alternative 350 horsepower (257 kW) air-cooled turbocharged engines currently used in aero applications.
The diesel combustion process, together with the design freedom provided by high strength CGI coupled with steel pistons, enable the lowered fuel consumption and emissions. Flying range and payload are also increased.
The Graflight V-8 engine employs an electronic control system designed and manufactured by Bosch General Aviation Technology; the system reduces to dramatically reduce pilot workload and ensure efficiency and ease of operation. The engine is controlled with a single power lever, leaving traditional pilot chores such as propeller pitch, fuel mixture and controlling engine temperature to the computer, reducing the risk of pilot error.
The use of extremely rugged technologies such as the steel pistons and CGI iron crankcases result in a targeted Time Between Overhauls (TBO) of 3,000 hours—a 50 to 100 percent increase over the industry’s current values of 1,500 to 2,000 hours.
CGI offers approximately double the fatigue limit of conventional grey iron and aluminium alloys, thereby achieving bottom-end durability requirements without increasing the size or weight of the main bearing region. The strength and stiffness of CGI also improve the dimensional stability of the cylinder bore to reduce piston slap, bore wear, oil consumption and blow-by, notes EPA partner Sintercast.
With the prospect that avgas (leaded aviation gasoline) will be prohibited, the ability of the EPS engine to use widely available and low cost jet and diesel fuels provides a significant global growth opportunity, the company suggests. The Graflight V-8 can run on a variety of heavy fuels, including Jet A, JP-8 or straight diesel.
With series production awarded to the Grainger & Worrall foundry in the UK, using the SinterCast process control technology, the engine is intended for use in single and twin engined aircraft, small helicopters, unmanned military aircraft, and potentially marine applications.
Building on our design experience with automotive diesel engines, we knew that Compacted Graphite Iron was the optimal material for the crankcase of our Graflight V8. The aero-engine industry has been relying on outdated engine technology and fuels for more than 20 years. Our use of modern technologies such as CGI, steel pistons, common rail fuel injection and electronic engine control form the basis of our competitive advantage, our contribution to the aviation industry, and our market opportunity. Our partnerships for the supply of critical components and technologies, with proven world class suppliers like Grainger & Worrall and SinterCast, are a key element of our ability to meet the necessarily stringent requirements set by the aviation authorities.—Michael Fuchs, President of EPS
SinterCast is a leading supplier of process control technology for the reliable high volume production of Compacted Graphite Iron (CGI). SinterCast technology, with 44 installations in 13 countries, is primarily used for the production of gasoline and diesel engine cylinder blocks and exhaust components for passenger vehicles, medium-duty and heavy-duty cylinder blocks and heads for commercial vehicles, and industrial power engine components for marine, rail, off-road and stationary engine applications.