Editing Diesel engine (section)

====Modern====
From then, until the late 1970s, there had not been many applications of the diesel engine in aircraft. In 1978, [[Piper Cherokee]] co-designer Karl H. Bergey argued that "the likelihood of a general aviation diesel in the near future is remote."<ref>Karl H. Bergey: ''[https://books.google.com/books?id=av85AQAAMAAJ Assessment of New Technology for General Aviation Aircraft]'', Report for U.S. Department of Transportation, September 1978, p. 19</ref>

However, with the [[1970s energy crisis]] and [[environmental movement]], and resulting pressures for greater fuel economy, reduced carbon and lead in the atmosphere, and other issues, there was a resurgence of interest in diesel engines for aircraft. High-compression piston aircraft engines that run on aviation gasoline ("[[avgas]]") generally require the addition of toxic [[Tetraethyl lead]] to avgas, to avoid engine [[Engine knocking|pre-ignition and detonation]]; but diesel engines do not require leaded fuel. Also, [[biodiesel]] can, theoretically, provide a net reduction in atmospheric carbon compared to avgas. For these reasons, the [[general aviation]] community has begun to fear the possible banning or discontinuance of leaded avgas.<ref name="inside_2018_08_01_flyingmag_com" /><ref name="congressman_2012_10_24_generalaviationnews">Wood, Janice (editor): [https://generalaviationnews.com/2012/10/24/congressman-calls-on-faa-to-expand-use-of-unleaded-fuel/ Congressman urges FAA to expand use of existing unleaded fuel,"] October 24, 2012, ''General Aviation News,'' retrieved December 6, 2022</ref><ref name="hanke_2006_07_21_g_a_news">[https://www.linkedin.com/in/kurt-hanke-6bb24ab Hanke, Kurt F., engineer] ([https://www.turbocraft.com/ Turbocraft, Inc.]), [https://generalaviationnews.com/2006/07/21/diesels-are-the-way-for-ga-to-go/ "Diesels are the Way for GA to Go,"] July 21, 2006, ''Ge eral Aviation News,'' retrieved December 6, 2022</ref><ref name="biodiesel_basics_2003_energy_gov">{{cite journal|title=Biodiesel – Just the Basics|version=Final|year=2003|publisher=United States Department of Energy|url=http://www.eere.energy.gov/vehiclesandfuels/pdfs/basics/jtb_biodiesel.pdf|access-date=2007-08-24|url-status=dead|archive-url=https://web.archive.org/web/20070918122719/http://www1.eere.energy.gov/vehiclesandfuels/pdfs/basics/jtb_biodiesel.pdf|archive-date=2007-09-18}}</ref>

Additionally, avgas is a specialty fuel in very low (and declining) demand, compared to other fuels, and its makers are susceptible to costly aviation-crash lawsuits, reducing refiners' interest in producing it.  Outside the United States, avgas has already become increasingly difficult to find at airports (and generally), than less-expensive, diesel-compatible fuels like Jet-A and other [[jet fuel]]s.<ref name="inside_2018_08_01_flyingmag_com" /><ref name="congressman_2012_10_24_generalaviationnews" /><ref name="hanke_2006_07_21_g_a_news" /><ref name="biodiesel_basics_2003_energy_gov" />

By the late 1990s / early 2000s, diesel engines were beginning to appear in light aircraft.  Most notably, [[Thielert|Frank Thielert and his Austrian engine enterprise]], began developing diesel engines to replace the {{convert|100|hp|kW}} - {{convert|350|hp|kW}} gasoline/piston engines in common light aircraft use.<ref name="powerplant_ch7_phak_faa_gov">[https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/09_phak_ch7.pdf "Powerplant"], in Chapter 7: "Aircraft Systems," ''Pilot's Handbook of Aeronautical Knowledge,'' [[Federal Aviation Administration]], retrieved December 5, 2022</ref> First successful application of the Theilerts to production aircraft was in the [[Diamond DA42 Twin Star]] light twin, which exhibited exceptional fuel efficiency surpassing anything in its class,<ref name="inside_2018_08_01_flyingmag_com" /><ref name="diamond_2020_12_30_avweb_com" /><ref name="diamond_da42_2004_05_12_flightglobal_com">Collins, Peter: [https://www.flightglobal.com/flight-test-diamond-aircraft-da42-sparkling-performer/55396.article "FLIGHT TEST: Diamond Aircraft DA42 - Sparkling performer,"] July 12, 2004, ''[[FlightGLobal]]'' retrieved December 5, 2022</ref> and its single-seat predecessor, the [[Diamond DA40 Diamond Star]].<ref name="inside_2018_08_01_flyingmag_com" /><ref name="diamond_2020_12_30_avweb_com" /><ref name="powerplant_ch7_phak_faa_gov" />

In subsequent years, several other companies have developed aircraft diesel engines, or have begun to<ref name="powerplant_ch7_phak_faa_gov" />—most notably [[Continental Aerospace Technologies]] which, by 2018, was reporting it had sold over 5,000 such engines worldwide.<ref name="inside_2018_08_01_flyingmag_com" /><ref name="diamond_2020_12_30_avweb_com" /><ref name="certified_jet_a_engines_continental_aero">[https://www.continental.aero/diesel/diesel-engines.aspx "Certified Jet-A Engines,"], [[Continental Aerospace Technologies]], retrieved December 5, 2022</ref>

The United States' [[Federal Aviation Administration]] has reported that "by 2007, various jet-fueled piston aircraft had logged well over 600,000 hours of service".<ref name="powerplant_ch7_phak_faa_gov" /> In early 2019, [[Aircraft Owners and Pilots Association|AOPA]] reported that a diesel engine model for general aviation aircraft is "approaching the finish line."<ref name="eps_update_2019_01_23_aopa_org">[https://www.aopa.org/news-and-media/all-news/2019/january/23/eps-gives-certification-update-on-diesel-engine ''EPS gives certification update on diesel engine,''], January 23, 2019, [[Aircraft Owners and Pilots Association|AOPA]]. Retrieved November 1, 2019.</ref> By late 2022, Continental was reporting that its "Jet-A" fueled engines had exceeded "2,000... in operation today," with over "9 million hours," and were being "specified by major OEMs" for [[Cessna Aircraft|Cessna]], [[Piper Aircraft|Piper]],  [[Diamond Aircraft|Diamond]], [[Mooney Aircraft|Mooney]], [[Tecnam Aircraft|Tecnam]], [[Glasair]] and [[Avions Pierre Robin|Robin]] aircraft.<ref name="certified_jet_a_engines_continental_aero" />

In recent years (2016), diesel engines have also found use in unmanned aircraft (UAV), due to their reliability, durability, and low fuel consumption.<ref name="knock_criteria_2017_meininger_doi_org">Rik D Meininger et al.: "Knock criteria for aviation diesel engines", ''International Journal of Engine Research,'' Vol 18, Issue 7, 2017, [https://doi.org/10.1177/1468087416669882 doi/10.1177]</ref><ref name="Arnews2005">{{cite news |title=Army awards 'Warrior' long-range UAV contract |date=2005-08-05 |publisher=Army News Service |url=http://www4.army.mil/news/article.php?story=7722 |url-status=dead |archive-url=https://web.archive.org/web/20070102153829/http://www4.army.mil/news/article.php?story=7722 |archive-date=2 January 2007  }}</ref><ref name="defenseupdate2006">{{cite news |title= ERMP Extended-Range Multi-Purpose UAV |publisher= Defense Update |date= 2006-11-01 |url= http://www.defense-update.com/products/e/ermpUAV.htm |access-date= 11 May 2007 |archive-url= https://web.archive.org/web/20080513125340/http://www.defense-update.com/products/e/ermpUAV.htm |archive-date= 13 May 2008 |url-status= dead |df= dmy-all }}</ref>