 |
 |
 |
 |
 |
 |
 |
 |
|
When will a diesel be available for my aircraft? |
|
News, facts, and comments on the coming revolution for piston-engine aircraft.News of June 25, 2009Thielert is alive and kicking: An interview of Thielert (now Centurion) management and technical teamOn May 11, I had a prescheduled phone conference with Dr. Bruno M. Kübler, insolvency administrator of Thielert Aircraft Engines GmbH; Jasper Wolffson, chairman of Centurion Aircraft Engines AG & Co. KG; and Prof. Günter Kappler, Head of Engineering and R&D, Accountable Manager. I asked them the following questions, recorded their answers, and add here my comments. Q - What can we consider as public information in the uncontrolled verbal rumors circulating among some of our usual panelists that a Consortium including Diamond Air and General Atomics (N. B.: A Thielert customer for engine drones) is about to acquire all or a controlling interest of Centurion? A – All kinds of rumors are naturally circulating, since it is no secret that Centurion is looking for strategic investors able to develop the business and the market, and give satisfaction to our clients. The one you mention comes naturally to the mind of anyone surveying our industry. At this time, nothing is finalized with any definite party, and contacts in progress are naturally confidential. Q - Historically, piston engines (whether electrical ignition or diesel) using an in-line structure, liquid cooled, running at higher rpm’s (above 3,000 rpm), actuating a propeller shaft through a geared transmission reducing rpm’s (often automobile derived engines) have been successful when pure performance was requested more than long TBO, long range, and reliability (Ex: a Drone application). Radial or O-engines, air cooled, with propeller in line with crankshaft, have been dominating the industry when priority was on trouble free, long range, low maintenance operations. Unfortunately for Thielert, the short history of its 4 cylinders diesel strongly confirmed the old prejudice against Geared Liquid-cooled In-line Engines. What new arguments does Thielert have today to defend this design, and how is Thielert hoping to finally convince General Aviation that its basic design will eventually satisfy the market? A. – The preconception you describe is ancient. Since then, considerable progress has been made allowing overcoming these weaknesses: at first, the use of state of the art Common Rail injection technology, which significantly increases both engine efficiency and smoothness, therefore contributes to reducing vibrations and weight; also, in nature of alloys and metallurgy, in forming and machining processes, and notably in surface treatments. The Thielert engine was initially developed with limited means, and was weak notably in the gear and clutch functions, designed using obsolete technologies. Other problems, when one traces the history of a breakdown, are far more often caused by non-respect of operating instructions or of maintenance procedures, which is always bound to exasperate customer dissatisfaction. Thanks to the team of Professor Kappler and University of Dresden, which has access to state of the art knowledge, analysis tools and testing means, we have been able to attack each weakness of the engine and have already found solutions to the most urgent ones. Solutions we found mean a change of parts or subassemblies which can always replace the existing elements on the same mount or interface. Remember that at no moment did we have all Thielert-equipped planes grounded: A good portion of them went on flying without incidents because their operators complied with our procedures. These, however, do imply frequent and costly changes of certain components mainly the clutch and gear system. And we are making regular progress on the TBOs of these parts and on all others. Many problems with gears are related to a poor control of circulation and pressure of lubricant: Improving these 2 factors considerably increases TBO without yet making any change in design of gear subassembly. With time, our TBO will keep on increasing and will become very competitive. By the end of 2009 we will be able to have 600 hours for the gear & clutch system, and 1,500 hours for the 2 liter engine. Dresden also has experience and testing means to considerably improve vibration abatement and control, a crucial area for diesels. We already made changes in that area, which can be retrofitted through engine modifications and replacement. And we will keep making progress. Q. – At DieselAir we have been flooded by reports from Diamond customers complaining that their airplanes, sometimes their whole fleet of Diamond DA42s or DA40s, were grounded for lack of spare parts… One can understand the frustration of an owner of 2 planes which he paid around $1.5 million dollars and who doesn’t know when his planes will be flying again, if at all… What can you tell them? A. - Here, we must be clear: We can supply any missing part for our engines and have been able to do so throughout the insolvency. The same applies to new replacement subassemblies extending TBOs. Our experience is that airplane owners will not pay the price we have to charge them to comply with our legal constraints: Remember we operate under a German equivalent of Chapter 11 (Receivership with Owner in Possession allowed to manage the business) and we cannot sell anything at a loss. Now, we are fully aware that our prices in Euros are high in absolute terms, especially if compared to price in dollars for widespread US engines and spare parts, the tooling for which has been fully amortized for decades. We maintain however that the advantages, now proven, of a diesel DA42 or 40 fully justify the price difference. And this will improve with time. Q. - What is the Specific Fuel Consumption (SFC, Lbs or grams of fuel per HP-hour) of a Thielert 2 liter 155HP at full cruise power, and at best glide power on for instance a DA40 or 42? A. – As with every diesel, our engine offers a flat specific consumption at all rpms. In other words, the fuel consumption per HP and per hour remains approximately the same whether the engine delivers 155 HP or 40 HP, whereas on a gasoline engine this SFC increases somewhat at less than full power, and, on a turbine, shoots to the ceiling. This is why a turboprop airplane always is a gas guzzler at transitional regimes such as take-off, go around, and approach to land. This is one important reason why diesel engine is so favorable on a trainer operated by a flight school. This being said, the SFC of our 4 cylinder is consistent with what you can expect of a small diesel, that is around 0.35 Lbs per Horse Power and per Hour. Q. - What is Thielert’s opinion on the future of Avgas and on future availability and certification of alternative fuels (Mogas, no-lead fuels, Swift fuel…) for electrical ignition engines, therefore other than Jet A/diesel fuels? A. – We do not believe in the future of any fuel replacing existing Avgas for electrical ignition aero engines, whether existing engines or new designs. First, it is public knowledge that a majority of the world Avgas consumption comes from a minority of most recent Lycoming and Continental fuel-injected engines, on which octane index is essential due to higher compression ratio and use of lean settings “beyond peak”. All other existing planes, generally well over 30 years of age, will be scrapped or can be converted to Mogas with minor consequences for planes flying less than 100 hours/year. Otherwise, any no-lead fuel capable of such octane index will require a lengthy certification process which, we claim, is not worthwhile compared with the advantages of burning existing Jetfuel with a diesel. The diesel is bound to come. Second, we do not see how a new kind of fuel, notably derived from any biotech process, could replace any existing hydrocarbon derived fuel at a lower cost than said conventional fuels. At a much higher cost, perhaps, due to the unavoidable energy cost for separation of fuel ingredient from the biomass itself and/or for synthesis of such ingredient… But we expect that, in view of its cost plus the cost of certifying various engines for said new fuel plus granting the various STCs for aircraft using modified engines and new fuel, the FAA and other regulatory agencies will eventually realize the obvious: They and the industry are better off certifying diesel using Jetfuel, the Jetfuel of today and future modified Jetfuel using alternative ingredients, if and when available. Q. - At this moment (Spring-Summer 2009), how many engines is Thielert selling per month? Can you give a percent of sales between Drones; replacement of existing Thielert as part of after sales service; retrofit of airplanes being converted from Avgas to Jetfuel? And OEM market? A. – At this time when we are in a phase of audit, confidential discovery and due diligence for various investors in Centurion, we cannot disclose any figures of that nature. We can tell you that we are presently producing and selling engines and parts under each category of clientele which you list. Q. - What are Thielert’s plans to further develop its V8 engine? A. – Our V8 engine has so far given satisfaction on all planes on which it was tested, and has been certified outside the US for the Cessna 206. However again, as long as we are under financial restructuring, all projects other than the 4 cylinder are on hold. We can tell you that the V8 structure is a favorable one regarding vibrations control, whether diesel or gasoline. For a diesel, it means less vibrations, less damping needs, therefore less weight per HP. Our V8 has had time to demonstrate that. Centurion will without doubt pursue its development in a new corporate structure. (end) Interview by Andre Teissier-duCros posted at 5:09 PM |
Previous Posts
When will a diesel option be available for the Bee...
|
