Thanks to their complex and high-pressure nature, diesel (Jet A) burning piston engines are premium devices full of expensive parts, and their penetration into the amateur-built world is essentially nil, no matter the manufacturer. Some sophisticated, powerful and very fuel-efficient Jet A reciprocating engines have been developed, but their newness and high initial cost means they’ve barely penetrated the military drone market to date.
Meanwhile, Continental has a surprisingly well-populated line of certified diesels as they’ve bought diesel programs started by Thielert, Austro and other European outfits. At least technically these engines are suited to larger homebuilt aircraft (they’ve been used on Cessna 182s, for example), but their economics make them viable only after flying many hours, not the typical sport plane operating profile.
Like you, other than display models, we had not seen one of the new, groundbreaking HIGGS diesel engines operating by the time we went to press. But HIGGS reported in the fall of 2021, “The HIGGS engines will arrive in the U.S. at the end of Q1 2022. We are currently assembling the various models in Japan for that delivery period.” Furthermore, while the company would not take deposits for HIGGS engines during the majority of last year, they were last autumn due to the engine’s readiness.
We’re certainly eager to inspect and get a full technical briefing on the HIGGS design. It’s a very innovative concept marrying attributes of both two- and four-stroke operation. The central concept is a 2-stroke engine breathing through ports (no traditional poppet valves or valve train) with radically different piston/pumping units that, among other things, seal the crankcase from the combustion chamber thus allowing full pressure oiling to the bottom end.
The result is very vertically compact, valveless engines with a conventional spark ignition system burning almost any fuel—but designed for Jet A. Yes, it burns Jet A using spark plugs. HIGGS lists six varieties of upright and inverted vee configurations, ranging from sensible 115-hp V-4s up to a rousing upright, turbo V-12 boasting well over 1600 hp. All these engines claim stellar power-to-weight characteristics, as expected from what is essentially a two-stroke engine. There are certainly fundamental gains to be had from the cylinder design—no exhaust valve for example—should it all work as promised. Definitely one for early adopters.
|CD-135||geared||135 hp @ 3890 rpm||295.4 lb with accessories, dual FADEC||Kit program only|
|CD-155||geared||155 hp @ 3890 rpm||295.4 lb with accessories, dual FADEC||Kit program only|
|CD-230||direct||235 hp @ 2200 rpm||450 lb with accessories||Beta program|
|Swift FL150J/G||geared||115 hp @ 5300 rpm||147 lb, inverted V-4||$25,000|
|Swift FL150J/G-T||geared||130 hp @ 5300 rpm||187 lb, inverted V-4||$40,000|
|Falcon FL200J/G||geared||210 hp @ 5300 rpm||165 lb, inverted V-4||$45,000|
|Falcon FL200J/G-T||geared||250 hp @ 5300 rpm||205 lb, inverted V-4||$60,000|
|Hawk E330J/G||geared||350 hp @ 5300 rpm||306 lb, upright V-4||$58,000|
|Hawk E330J/G-T||geared||500 hp @ 5300 rpm||339 lb, upright V-4||$78,000|
|Eagle E660J/G||geared||650 hp @ 5300 rpm||512 lb, upright V-8||$180,000|
|Eagle E660J/G-T||geared||800 hp @ 5300 rpm||TBD, upright V-8||TBD|
|Condor E1000J/G||geared||1200 hp @ 5300 rpm||664 lb, upright V-12||$216,000|
|Condor E1000J/G-T||geared||1600 hp @ 5300 rpm||714 lb, upright V-12||$266,000|