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EPS showcases lightweight Vision 350 diesel aircraft engine at EAA AirVenture

At the Innovations Pavilion at EAA AirVenture Oshkosh last week, Engineered Propulsion Systems (EPS) showcased the Vision 350 engine, a prototype of a lightweight diesel aircraft powerplant in the 350-hp range that is small enough to fit into the cowls of current production single-engine aircraft.

The Vision 350. Click to enlarge.

Diesel is seen as an alternative to gasoline-powered engines in such applications, but the heavier construction diesel engines require makes aviation applications problematic.

The 257 kW (350 hp) Vision 350 is a 4.4-liter, 8-cylinder “Flat Vee” (180 °) that delivers 815 N·m (600 lb-ft) of torque at 2,500 rpm. Installed airplane target weight (wet) is ≤ 300 kg (660 lbs). The engine is aluminum-propeller capable.

The geared design (external spur gear with 1.366:1 reduction ratio) allows the prop to deliver full power at lower rpm (2200-2300 rpm) and reduced sound levels.

Comparative fuel consumption of the EPS Vision 350 engine (light blue column). Source: EPS. Click to enlarge.

The Vision 350 can be configured for low and high altitude fixed-wing and piston helicopter applications, and principals say they are currently in discussions with three potential OEM launch customers, and that the company has a provisional purchase orders for more than 1,000 engines in its second year of production, at a $100,000 price point.

For its certification program, the company recently bought a Cirrus SR-22 aircraft and will install a Vision 350 to conduct flight testing, commencing in about 90 days. Record-setting pilot Dick Rutan will fly as test pilot.



Anyone know what the driver is to use diesel in aircraft although the engines are heavier and more expensive?

Do they have much better fuel economy, or lower maintenance, or perhaps not need the lead additive in aviation fuel?


From a gross weight perspective, the additional weight of the engine can be offset by a lighter fuel load for a given range. I could actually see net weight savings in some cases... not to mention higher thermal efficiency of diesel would lead to higher energy efficiency.

What strikes me as being problematic is dealing with a center of gravity shift.

IMO twin flat sixes in a push-pull configuration for larger aircraft would have been more interesting.


The drivers for aerodiesels are:

  1. Fuel economy (reduced fuel load for a given mission),
  2. Reduced fuel cost, and
  3. The ability to operate on Jet-A, which is ubiquitous worldwide while aviation gasoline is a tiny niche product which can be hard to find.

The typical air-cooled, flat-four or -six aviation engine has output of 0.50 to 0.55 horsepower per pound of weight.  This 350 HP unit is right in the ballpark for a drop-in replacement.


BTW, for more info on the economics look at this site:


For economic comparisons, look at the info pages that Delta Hawk Engines have on their site (can't even get the obfuscated URL past the filters today).


Many thanks EP.
From the Delta site:
'Fuel Efficiency: The DeltaHawk® is designed to BSFC (brake specific fuel consumption) of .35 lb/hp/hr versus current avgas-powered aviation engine book BSFC of .59 lb/hp/hr at 75% and above.

Lower Fuel Cost: 30-40% more range per gallon. Also, cost per gallon of Jet-A averages $0.09 less than 100LL aviation fuel in the U.S. The price differential is much greater in Europe, where 100LL aviation fuel is selling for 2.10 Euro/liter ($10.16/US Gallon as of 09/06). '

This is rather old, as the page on 'Why aero diesel?' refers to what is coming in 2010!

Even so, the general principles are clear.


It is a pity it is so expensive, but I suppose that is the small production volumes (compared to car and truck engines).


And the certification requirements for parts.

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