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.
DieselAir Research, Inc., the publisher of The DieselAir Newsletter, offers strategic intelligence services to the aircraft industry, its suppliers and its customers who ambition to benefit from this global change of paradigm which will mean new markets, new concepts, new services, new materials and components… You may be interested in our services if your firm designs and/or manufactures aircraft and components, aero engines, avionics, propellers and engine components, fuel systems or additives, advanced materials, or industry specific machinery for manufacturing of these; or provides aviation services such as fuel production or distribution; flight training, aircraft chartering, maintenance and operations (FBO’s); or airport management and design, traffic control, hangar, materials handling and storage equipment; or consulting and financial services for these industries; or advertising, sales promotion, trade shows, specialized publications.
To know more, send a confidential email inquiry to Dr. Eng. André Teissier-duCros at email@example.com
or an SMS for a confidential phone conversation at
News of September 18, 2005
Is diesel too heavy?
The most frequent objection I read to aero diesel is: Not only the engine with all ancillaries is bound to be heavier than a conventional engine because of higher compression, but on top of that, fuel being denser, your full tanks are heavier than before and your payload is further reduced.
I want to address the later criticism because it triggers my sense of humor. So, there are Cessna and other owners who spend thousands of dollars to have extra tanks installed (luggage compartment, wing tips…), but the fact that, thanks to diesel fuel, you can put 10 to 14% more fuel in your plane at no cost would be a disadvantage! My answer is: nothing prevents you not to top off if you don’t need the range, when comes the (rare) occasion when you do want to carry a full load of passengers… Meanwhile I call this an advantage, not a disadvantage. Your new engine is burning 0.32 Lbs/HP-hour instead of 0.46 (to be discussed soon), and you have 10 to 14% more fuel in the same tanks (depending on the nature of kerosene fuel you are using).
Let’s address the serious objection. Yes, a 4-stroke diesel of same cubic capacity than a gasoline engine is heavier because of the higher compression. However, all diesels coming on the market are smaller engines in cubic capacity. If, like the Thielert, they are geared engines, they are even smaller, but with the extra weight of the gearbox. Since all are turbocharged, this also adds some weight. But the biggest weight addition may come (not always) from the need to add heat exchangers to a cowl design which wasn’t meant for diesels in the first place.
We already have one superb example of a conversion to diesel which is actually lighter than the original: The Beech Duke now beginning its test flights in Germany with 2 Thielert V-8s weighs 4,660 Lbs. empty against 5,000 for the original, meaning a weight gain of 340 Lbs. And the plane is poised to fly 10 K faster, and to cruise at equal speed on 22 gallons/hour of Jetfuel instead of 45 of Avgas. Martin Hagensieker, who owns the FBO undertaking the conversion, talks about a conversion cost of $ 435,000, future TBOs (at least 2,400 h) costing then the same than with O-540 engines.
However we are talking of 350 HP here. In the 30’s and 40’s, the Junkers Jumo diesel of 600 to 1,200HP and more was also showing a definite weight advantage per HP against conventional engines, but it was a 2-stroke engine. There is no definite example, in 4-stroke engines in the 100-230HP range, of an actual gain in weight by converting an existing aircraft model to diesel. On the contrary, one does observe some very moderate weight increases. Will this situation last?
It won’t for an obvious reason: Existing conversions are in their early stages. They have been built with expediency in mind: Get FAA or JAA certified. The actual serious work on weight savings is only beginning and it shows: The 182 SMA already lost some 50 Lbs. Then, existing engines will increase in power for same cubic capacity. And then we haven’t seen yet the full impact of the 2-stroke technologies: DeltaHawk, D-Air and Wilksch, because the few examples are prototypes improvised by very small firms who have restricted resources. And yet, the Luscombe Silvaire flying in UK with a D-Air 2-stroke opposite-piston diesel of 110HP gives you a clear signal that small 2-stroke diesels will be light and competitive: you can’t put much weight on a Silvaire…
posted at 7:13 AM
Thielert, world leader in aero diesels, reports 75...
Special report: A fruitful dialogue between Aviati...
Aviation Consumer's report on Diamond and Thielert...
SMA O-305 Diesel certification status: What we kno...
Wilksch Airmotive, British aero diesel manufacture...
A crystal ball exercise on why General Aviation wi...
Oshkosh: Diamond DA42 is FAA certified
Aviation Consumer special report on aerodiesel pro...
100 hp diesel engine designed to be direct 0-200 r...
What most diesel experts miss about why diesel is ...
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.
The DieselAir Newsletter is a confidential publication available only as printed material sent by mail (airmail for overseas), to fully identified individuals or businesses involved in General Aviation. Forums and online content may be printed at discretion of the publisher.