There is some hope that military UAVs will provide the critical mass for a US-based engine burning Jet A. The military doesn't have - and doesn't want - an infrastructure for 100LL. It does have - and wants - a growing fleet of UAVs, many of them too small for turbine engines. The most interesting direction I've seen is the "spark ignition diesel", which is essentially a "gasoline" engine that runs on heavy fuel (like Jet A).
Some errors in this article.
1. Thielert now sells the engines under the name of Centurion Aircraft Engines.
2. Hundreds of engine swap STCs exist for light aircraft. Obtaining one for a disel should be no more difficult than for other engine STCs.
3. Continental plans to certify their first diesel at the end of 2012, according to a company official I met at the AERO Friedrichshafen show in April 2012.
4. The Austro engine is based on a Mercedes passenger car turbo diesel that is produced at the rate of 1,500, per day!
If we are to lower the cost of flying, we must tap into large volume markets in other areas. Diamond's use of a car engine as the core of the Austro engine, burning a fuel (jet) produced in vast quantities compared to avgas are two ways of doing this. Hat's off to Diamond, Mercedes and Austro Engines, way ahead of the pack on this.
President, EAA 1114, Apex, NC
Director, Aviation Fuel Club
THANK YOU ROBERT for calling out TCM & Lycoming on their utter sloth in developing contemporary powerplant technology!
Too bad your predecessor didn't have the guts to do this ten years ago, we might actually have diesels and/or FADEC/no-lead engines certified/standard by now on Beech, Cessna and Piper products...
Like you say though, someone will take the place of these two manufacturers if they don't get on with it- sourcing Avgas is only going to get more difficult, particularly in developing nations...
I'm so glad you voiced what others in your position in the past might have felt as too risky (if not a totally realistic) perspective!
I'm also heartened to see someone of my generation initiate a new era of contemporary thinking and pushing/supporting innovation again in the left seat at Flying Magazine!
If leaded avgas goes away, we have no-one to blame for not developing alternatives but these manufacturers- and our community for not pushing them to do so.
Thomas, very good point. It's sad that we need un-piloted airplanes to provide the technological impetus to point us in the right direction here, but you're very possibly right on this one.
Kent, thanks for pointing out a total of zero errors. (FYI: you might want to look up the word, because your grasp of its meaning is shakier than a Thielert starting up.)
Yes, Thielert is now called Centurion, a name change necessitated by its bankruptcy caused by its horrifically flawed engine design. There are many other details about the company I didn't mention, including the color of the couches in reception.
Yes, Continental has on more than one occasion in the past said that it was going to have a diesel certificated by some date. Would you please fill me in on the number of certificated diesels this has resulted in?
Yes, STCs for diesel conversions should be easy to get . . . but one company's done it, and its product has been a failure. Therefore, I submit, they are by definition not easy.
Lastly, there have already been production snafus with Thielert (which, you might not know is now called Centurion) having to do with Mercedes changing the design of its engine, which it does very regularly. How many it makes a day is immaterial. What matters is how many Austro buys before Mercedes changes the design.
Hitching your wagon to existing car diesel engines is in my view a limited solution to the the problem, as evidenced very strongly by Thielert's disastrous foray into the market. Austro seems to be doing better, in part becasue of lessons learned from its insolvent predecessor, but production of its engine is very limited and has yet to find applications outside the company.
Thomas, what you said is true for old designs. Modern two stroke diesels do not use the crank case for air induction. The induction is forced by an external Roots blower and a turbocharger. Those engines have normal sumps, like the four stroke engines, so emissions from burning of the lubricants are not a problem. Moreover, they have exhaust valves, so the air is induced by the ports in the cylinder and the exhaust is by the vales in a uniflow fashion, for optimal scavenging. The fuel is injected at high pressure via fuel injectors directly into the combustion chamber. Those engines are the most efficient IC engines today and they power the global shipping of today.
Thomas, the marine eninges usually have crossheads to remove lateral forces from the cylinder-piston interaction and to increase the stroke length. That makes the big marine diesel engines double as tall, and I can imagine, that if one can get a significant space saving by halving the number of cyliders for the same output power it is probably very velcome. After all, it is half the material and machining cost. Another reason to go two-stroke is probably efficiency, since less energy is wasted on friction. As for the piston rings - I have no idea how do they do it. You would probably need to ask someone at Man B&W or Wärtsilä.
Anyway I have found that Wilksch and Delta Hawk already make two-stroke aero diesels, but those are probably not certified design. That is still good for homebuilders and UAVs.