Lycoming Has a Diesel
In the world of military aviation, the piston engine was left for dead sometime in the 1950s and it would still be thus if drones hadnít come along. But piston engines swinging old-school props give unmanned aircraft something that jet engines canít: unrivaled mid-altitude efficiency and endurance. So as unlikely as it seems, drone technology is pushing piston engine and prop design and thatís why Lycoming has a diesel engine that we know absolutely nothing about. Itís designated the DEL 120 and has 205 HP, meaning itís in the IO-360 class. Itís the prime powerplant in the General Atomicsí MQ-1C Improved Gray Eagle, an Army drone. The Gray Eagle is a follow-on to the MQ-1 Predator, which has similar mission capabilities.
A call to Lycoming about the DEL 120, which we learned of earlier this month, yielded a polite no comment, but no denial of its existence, either. In a press release last summer, General Atomics mentioned the engine openly, but I somehow missed it, as did almost everyone else, evidently, because thereís simply no detailed coverage of this new powerplant. With Lycoming keeping the wraps on it, I can only guess at its specs. And my guess would be a four-cylinder, turbocharged four-cycle design with direct drive. But for all I know, they could have made a developmental deal with DeltaHawk and repurposed that technology. DeltaHawk has a two-cycle variant in the 200-HP range. Early p.m. addition: A reader phoned me with a more likely speculation on the engine. A company called DieselJet is repurposing Fiat diesel engines for aircraft use and even has one certified to a maximum altitude of 35,000 feet. One of these is used in the Alenia Aermachhi Sky-Y, an Italian drone, and also the Israeli Great Blue Heron. The timeline and horsepower fit. Washing a foreign engine through U.S.-based Lycoming would probably make the Pentagon happy.
Whatever the engine is, it got there for two reasons. One is that when Thielert went bankrupt in 2008, General Atomics needed a reliable engine source for its Predator and follow-on models and China-based AVIC's purchase of Thielert last summer meant it would have to shop elsewhere for a new engine.
Does this mean Lycoming is about to announce a civil diesel program? Maybe, but Iíd be surprised, even if Lycoming does reveal more about the engineís details. In previous interviews, Lycomingís Michael Kraft has been openly skeptical of diesels for aircraft, not so much for technical reasons but because the company believes the market isnít yet deep enough to support the investment required to bring a certified diesel to market. But for every bear, thereís a bull and that would be Continental Motors, which bought the former Thielert Aircraft Engines last year and is busily resurrecting the Centurion line. It also has at least one clean-sheet design and from SMA, it bought the technology-base for its TD300, a four-cylinder turbodiesel.
When Kraft has been asked in the past why Lycoming isnít more diesel-centric, he has taken to asking the questioner if he or she noticed all those diesel airplanes parked on the ramp. A fair point, but on the other hand, Diamond does have more than 1000 diesel-powered aircraft in service. On some ramps, they are indeed in evidence.
But, as Iíve said before, I donít think diesel technology is poised to explode. The sales and demand simply arenít there and it remains to be seen if diesel will develop into a robust refit market. If avgas goes to $7 or $8 in the U.S., I'll reconsider. But I hardly think itís a slam dunk. I think the diesel market will ramp slowly over many years, gently displacing gasoline engines in some markets and models. It's here to stay, all right, it will just be a slow slog.
Thatís just one view, though. But both Lycoming and Continental face different risks in the would-be diesel market. Continental is making, by general aviation standards, a high-priced bet on diesel, the outcome of which is impossible to predict. Theyíre hoping that five years from now, diesel may enjoy a 20 to 25 percent world market share.
If that potentiates, it could be 200 to 300 engines a year, assuming the Asian market proves as strong as people think it will. I donít know what Continentalís ROI expectations are, but clearly, diesel has to be a long-term play. In any case, its diesel investment may meet the companyís stated goal to make offshore sales the driver for its business, not North American sales.
Where does this leave Lycoming, then? Assuming the DEL 120 could be certifiedóperhaps under future, less stringent cert rulesóit might give Lycoming a chip in the game if demand perks up. But itís going have to perk to a rolling boil to get Lycoming interested, Iíd bet. Even if the technical aspects of the diesel are relatively nailed down by the Grey Eagle project, cert costs will be in the millions and it takes a bunch of sales to regain just the basic investment, much less a return worthy of the name. And all that for 50 engines a year? You can see the challenge.
Then thereís the OEM interest, or lack thereof. Other than Diamond, Cessna is the only major manufacturer to come out of the ground with a diesel. We hear rumors about Piper and Cirrus, but no commitments. If Cessna were any less enthusiastic about promoting its JTA diesel, it would qualify as comatose. At last fallís NBAA convention in Las Vegas, Cessna CEO Scott Ernest was questioned on the status of the JTA project and offered no details in answering. Queries to Cessna either arenít returned or just confirm that the project is still alive. Somehow, I find myself wanting a little more than that. Itís hard enough to stir the market with completely over-the-top promotion and marketing. Strangling the information flow and sowing doubt strikes me as a formula for failure. In that context, you can see why Michael Kraft isnít swooning for a whiff of Jet A.