EPS | Ground Testing

Ground Testing

Testing Facility

The general aviation market is expected to soon have a high-powered diesel engine option for high
performance airplanes as EPS is closing in on FAA certification for its Graflight V-8 engine. The
company expects to have both a type certificate and a production certificate in hand by the end of
the year.


As first deliveries approach, EPS is expanding its facilities at the New Richmond Regional Airport
(KRNH) in New Richmond, Wisconsin. A 15,000 square-foot, two-story hangar is being built that will
be used for testing and for STC work for a variety of airplanes. EPS is also preparing to build a
manufacturing facility, the construction of which is planned to begin at the end of the year.
EPS has been flying its engine on a Cirrus SR22 test bed. Rated in the range of 320 hp to 420 hp,
the Graflight V-8 is expected to be suitable for a variety of helicopters and single- and twin-engine
airplanes, including the Robinson R44, Beechcraft Bonanza and Baron, Cessna TTx and 206,
GippsAero GA8 AirVan and more.


The engine will initially be offered as an STC’d replacement for existing aircraft engines. With a lower
fuel burn as compared with comparatively rated avgas-powered engines and the lower cost for diesel
fuel, EPS claims the Graflight V-8 will offer more than 40 percent cost savings for an average mission
and an approximate 56 percent increase in range. The engine is expected to have a 3,000-hour
TBO, further increasing the cost savings for operators.


The development of the Graflight V-8 includes several innovations, including a patented glow plug, a
new firing order, a carbon/steel crankcase and monitoring software unique to the engine.
If you are planning on attending the EAA AirVenture in Oshkosh, Wisconsin this month, you can learn
more about the engine at EPS’s exhibit in space 16 and 17, west of Hangar C.

AEDC Testing

AEDC test facility resurrected for AFRL-sponsored testing of high-efficiency, diesel engine

Testing for the Graflight V-8, a high-efficiency, diesel engine designed and produced by Engineered Propulsion Systems (EPS), has brought about the reopening of the AEDC T-11 engine test cell at Arnold Air Force Base.


Prior to this, T-11 had not been air-on in at least a decade.


EPS project manager Tom Guelzow explained that the testing at T-11 was sponsored by an Air Force Research Laboratory (AFRL), Advanced Power Technology Office (APTO), Broad Area Announcement (BAA), which focuses on the research and development of engines that use a variety of fuels more efficiently.


“EPS submitted a successful proposal and subsequent award as part of the AFRL Alternative Energy BAA which provided funding for testing at Arnold AFB,” he said.


EPS, founded by Michael Fuchs and Steve Weinzierl, is a small start-up company based out of New Richmond, Wisconsin.


Guezlow said getting this far in testing the engine is part of a 27-month effort, and the goal for EPS is to validate engine performance of the Graflight V-8 prior to flight testing it later this year.


“After flight testing, we would then conduct complete accelerated mission testing of the engine,” he said.
The EPS engine Graflight V-8 is unique in that it’s a clean sheet design.


“The EPS Graflight engine is unique to aero applications and incorporates the most advanced mechanical design, combustion technology and electronic control systems available, as opposed to traditionally flawed approaches, which involve automotive conversions,” Guezlow said. “This engine is meant for single and twin-engine aircraft applications and will offer dramatically reduced fuel consumption.”


He added that the EPS team “feels very fortunate” to have the opportunity to test at Arnold AFB, as AEDC test facilities are able to reach higher altitudes than any previous tests of the engine.


“Here [at Arnold AFB] we can hit any altitude we want to relatively quickly,” Guezlow said. “Start to finish, it has been great working with the AEDC team. Everything we have been doing out here is brand new for us.”


One huge milestone for EPS was having the engine operating successfully at conditions of 30,000 feet altitude.


“We ramped up from level or sea level to 30,000 feet in T-11 and back down, which was groundbreaking for us,” he said.


Capt. Randall Hodkin, the APTO program manager, commented that, “Testing conducted in T-11 was an important step in collecting data to clear this innovative engine for future flight tests and was also a critical step in showing the engines capabilities at altitudes previously unattainable to the team.”


John Kelly, AEDC test project manager, stated that the EPS engine test has also included a lot of firsts for AEDC.
“The facility hasn’t been running in at least 10 years and this test has been a learning process for us too in that it’s a small, diesel engine, and instead of taking 150 pounds of air per second or more, it needs less than 2 pounds of air per second,” he said. “So, we had to create a new inlet system in order to do this.”


In addition, Kelly mentioned that this is the first time he knows of that any T-side test facility has run concurrently with the AEDC J-2 engine test facility.


“As far as I can tell, this has never been achieved before,” he said. “And the capability, being able to run these engine test cells at the same time, will reduce our on-air hour costs significantly.”


With the success of the EPS testing, AEDC test teams are gearing up for more testing in T-11.


“This could end up being a very busy test cell for small businesses that haven’t been given these type of testing opportunities before,” Kelly said.

Colorado Testing

Previous Testing

EPS has been testing the Proof-of-Concept Engine on its mobile test stand since November 2011.  In a program known in the automotive world as “accelerated durability testing,” the team has run the engine through extremes that will never be experienced in the course of normal aircraft operations, including calibrations, low inertia props, cold tests, multiple rapid acceleration and deceleration cycles, and a battery of other insults to put the engine through its paces. In the summer of 2013, EPS drove the engine to the top of Mount Evans in Colorado to conduct high altitude performance tests at 10,000 and 15,000 MSL.  The engine achieved full 350 horsepower operation at 15,000 feet density altitude and achieved 420 horsepower at low altitude. The engine’s liquid cooling system has been tested in extreme weather conditions, demonstrating starts in temperatures from – 25 degrees F to more than 100 degrees F.  Based on hundreds of hours of testing as of April 2014, EPS can report significant technical breakthroughs, including:

• Extremely low vibrations that allow the engine to safely operate aluminum propellers, a feature unique to the EPS diesel engine and verified by extensive testing conducted in cooperation with Hartzell Propeller Inc.


• A liquid cooling system that operates reliably at any outside air temperature or altitude


• A reliable, rugged and light steel piston design that eliminates piston failures common to aluminum pistons that are found in all other aviation engines


• A Compacted Graphite Iron (CGI) Cylinder Block that will avoid the fatigue cracks that plague aluminum aviation crankcases; yet the CGI block is just as light as its aluminum equivalent


• Measured fuel consumption <10 gal/hr at 65% power (227 hp)

EPS Ground Testing

EPS Ground Testing