KITPLANES February 2025

IMAGINE A TIME not too long ago when pilots embarking on the delicious endeavor to build their own airplanes could consider multiple sources for just about any engine on the menu. In this halcyon time, the original-equipment manufacturers competed elbow-to-elbow with a small but vital group of custom shops who had access to all the raw materials they needed to build complete engines. Each succeeded on a combination of their reputation, competitive pricing and a mix-and-match menu of features and upgrades. More to the point, this competition kept a check on prices and lead times. If you’d left your engine choice a bit late, there was a good chance you’d be able to recover. Today? Forget it. You need to commit a year or more out or risk sitting there…

“IF YOU CAN’T FLY the airplane by feel, you have no business being in the cockpit.” So goes a theory espoused by pilots who seem to think that angle of attack (AoA) is a crutch that no one needs or should use. This is actually an ego-driven argument whereby they are trying to show how great they are as pilots, far above all those folks who use things like instrumentation to keep them safe. Well, “safe” doesn’t exist while flying (we can only reduce the risk) and tools are used to measure how far away we are from the edges of the envelope, which are not always where we think they are. Tools help us reduce the risk. While that doesn’t make flying “safe,” it moves it in the direction…

WELCOME TO OUR ANNUAL Engine Buyer’s Guide, where we try to dissect what’s new, what’s old and what’s changed in the world of Experimental-intended powerplants. Last year we reported the supply chain issues vexing aviation engines were slowing down. We were partially right. The majority of engines and parts are more readily available now, but stubbornly many remain elusive, especially for the big mainstream manufacturers. In fact, some parts are more difficult to come by and, if anything, obtaining new engines from major manufacturers, notably Lycoming, arguably took longer in 2024 than in 2023. To be blunt, some shops say orders with Lycoming placed in mid-2024 might not be filled until very late 2026! Lycoming says more like a long year. (Last we checked, a year was 12 months.) Continental…

Just as airplanes are legally grouped as certified or Experimental, engines follow the same scheme. Certified engines are specific, FAA-certified models sold on certified airplanes such as Cessnas and Pipers. These come only from certified engine makers such as Continental, Lycoming and Rotax and are rigidly specified right down to the exact part number rod bolts and so on. On the other hand, Experimental engines can be just about anything and sometimes are. In practice many Experimental engines closely follow certified practice with certified parts, but wild creativity is allowed. Using a new certified engine on an Experimental airplane is certainly no problem other than it’s the most eye-wateringly expensive option available. Also, a certified engine must be kept absolutely stock to retain its certified status. If you modify it…

Over time, gasoline two-stroke engines in aviation have been supplanted by four-stroke units, trading low weight for a perception of greater reliability. (Fact is, two-strokes are less tolerant of abuse and mismanagement than their Otto-cycle brethren.) With one major exception—DeltaHawk’s two-stroke Jet A four-cylinder—today the two-stroke aircraft engine survives in aviation’s most weight-sensitive nooks such as trikes, powered parachutes and basic ultralights. It’s also a contender when purchase price is paramount, as with expendable drones. Thankfully some of the best two-strokes continue. The quality Hirth line out of Germany is available from Phil Yager at Northwest UAV in Oregon. Servicing existing Hirth engines with parts, overhauls, used engines and Blue Max oil is longtime Hirth specialist Matt Dandar in Ohio. Hirth has been in the airplane engine business for 100…

Not all available engines are for every builder, nor are all of them really available today. So consider this a gathering of currently limited application or not-for-sale engines and parts of interest. Some are new projects coming together, others are old programs gliding along, some are hot rods. Just because they’re listed here doesn’t mean they are somehow second-rate or might never see production, but at least at our deadline they either weren’t for sale or practical for mainstream kitbuilding. Altruair Based in San Diego, California, engineering firm Alturair is difficult to categorize if only because owner Frank Verbeke has been deeply involved in a wide swath of aviation including piston, turbojet, turbofan, turboprop and Wankel engines, likely since before you were born. For our present purposes Alturair has its…