News, facts, and comments on the coming revolution for piston-engine aircraft.
In 1998, one diesel engine flew on a converted airplane for the first time since 1945. Today, close to 4,000 singles and twins are flying. This is the beginning of a worldwide trend which will eventually allow a rebirth of the piston-engined aircraft, around new specs and new missions.
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News of May 14, 2010
TCM's New Diesel Project and views on Avgas future: A few questions.
Teledyne Continental (TCM) bought diesel technology already developed from an undisclosed European source who obviously is the French firm SMA Engines, and is forging ahead with its own program. The firm says it's bullish on piston-engines that burn Jet A and on May 13 in the company's Mobile skunk works, it took the wraps off the project for a group of visiting journalists. It's a 230-HP four-cylinder, four-cycle design that's readily scalable to a six-cylinder version with up to 350-HP, a power range that will clearly match TCM's products on the gasoline side. Certification of the four-banger is planned for 2011, according to TCM's Johnny Doo, with the six to follow as early as 2013. TCM, rather than developing a clean sheet engine, bought the diesel technology from a European company that has already certified it. Continental declined to name the company, but photos reveal an engine that looks suspiciously like the SMA SR305… But according to Doo, this isn't a co-branding or sales agreement, but a licensing arrangement that allows Continental to run with the project, driving the developmental line forward as it sees fit. The SR305 has proven to be a good performer and durable, but SMA hasn't pushed aggressively to sell it to either OEMs or the aftermarket. TCM will presumably address that.
Comment: This means therefore that SMA remains free to pursue its own developments, witness their improved SR305 exposed at Sun & Fun.
Doo said that TCM bought existing technology rather than clean sheet its own design primarily to speed the time to market, which the company sees as critical. Centurion (nee Thielert) SMA and Diamond have proven the diesel market and now Continental wants a piece of it. TCM's version of this engine is undergoing intensive test cell trials and is flying in a Cessna 182. Doo says Continental is aiming for a price premium only slighter higher than its avgas engines. Fuel specifics are in the .36 SFC range.
Can 94UL Replace 100LL? TCM Thinks So… Continental is moving forward with its research to pitch 94UL as a replacement for 100LL avgas, which the EPA seems serious about regulating out of existence. At the company's Mobile, Alabama test center, TCM is running detonation tests of 94UL and on Wednesday, it gave visiting journalists a preview of the project. TCM's Bill Brogdon told us on Tuesday that 94UL is essentially 100LL without the tetraethyl lead added as an octane enhancer. He says engines certified to operate of 80/87 octane—and that's a lot of engines—will have no trouble making rated power with 95UL. Similarly, says Continental, even its higher power turbocharged large displacement, low-compression ratio engines can run the lower octane. The problem engines are higher compression variants that use 8.5 to 1 compression ratios. Brogdon told us these engines may tolerate a diet of 94UL by tweaking the timing or developing affordable knock detection and variable timing. Another option, he says, is reduce compression ratio but increase displacement—re-engining with a IO-550 to replace an IO-520, for instance. Whether the owners of aircraft with these engines will nibble on that remains to be seen.
Comment: At the end of the day it means either that the same cubic capacity engine, now burning 95UL, will be less powerful than with 100LL; or that the engine of same power will be heavier. This plus some questions about behavior on turbo at high altitude. Will an aircraft owner pay to replace his engine by a lower-power one, as an alternative to giving up airworthiness? How many of them will buy that? Supposedly the ones in the US who own a recent, costly, turbocharged plane (Cirrus, Piper PA46 and the like) and do not want to lose their investment. The others, who today are not flying much anyway, will sigh and let their 35-year old plane go to scrap. The US flight academies owning a fleet of 25-35-year old 172s and PA28s will face a dilemma: At what cost a conversion to 95UL? And what will it take to decide, in that long list of conversions to 95UL, the scope of re-certifications? I would not be surprised if the phase-out of 100LL was delayed… Outside the US, we assess that the coast is clear for diesels.
In the meantime, Continental is in a consortium pushing forward with eventual ASTM approval for 94UL, at least for Continental engines. We're told (AVWeb reports) that only one company is skeptical of 94UL as a drop-in replacement for 100LL and although no one is naming names, we take that to be Lycoming. Timeline? About two years of further testing, says Brogdon, then another year or so for ASTM approval.
Comment: Lycoming’s project, says the rumor, would be a multifuel engine that has electrical ignition but can burn Jetfuel as well as various gasolines. Multifuel engines are feasible. The question with them is: At what weight per power? We are not out of the woods yet, but TCM is making a sound move. (AVWeb 5/13/10 with comments by Andre Teissier-duCros.)
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Every month: news, facts, and comments on the coming revolution for piston-engines aircrafts between 130 and 400 HP: Retrofitting a diesel engine to run on Jetfuel or Kerosene, reduce Gallons/Hour by some 30%, eliminate ignition systems (magnetos, spark plugs) and their problems, eliminate mixture control, increase TBO to 2,400-3,000 hours, increase performance between 6,000 and 12,500 ft., and drastically reduce Operating Costs.
The letter is intended for piston engines aircraft owners, manufacturers, fleet operators and FBOs, re-manufacturers of engines for these aircrafts, manufacturers of engine components and ancillaries, and all professionals acting in decisions of engine exchange or refitting at TBO, in North and South America, Pacific Rim, African continent, and all parts of the world were Avgas, Mogas, Kerosene and Jetfuel are available.
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