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When will a diesel be available for my aircraft? |
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News, facts, and comments on the coming revolution for piston-engine aircraft.News of September 20, 2005Highlights of dialogue exchanged on our Forum:The initial question comes from Randy, one of the DieselAir Newsletter Staff. Diesel engines have the reputation of being heavy per HP. So far this has been moderately true for recent engines, and future 2-stroke engines promise a better performance. In any case, being more fuel efficient means that a diesel aircraft can carry less fuel therefore more payload; but this advantage becomes questionable if the useful load ratio of the plane is poor. This ratio is measured by: Total useful load (fuel passenger and cargo)/Empty load. Ex: A Cessna 182 achieves around 0.67; an old Piper Cherokee 6 with the 260HP engine achieves an excellent 1.0 (the plane carries its own weight); Most small twin engines achieve only 0.45 and lower because the extra engine is always a partial dead weight. In that context, information on the power/weight ratio of any diesel engine, weight including all ancillaries (heat exchangers) is welcome. Pete, from Australia, answers: You have made a very good point. The ratios is something that I've never tried to figure out, rather than just using current operating handbook figures and viewing comparisons as need. As I work with SMA Jet-A engines in the Australian region, I know that they have carried out studies on many aircraft parameters as you have just noted. The design and certification team no doubt carried out your findings very early on in the piece. SMA chose the C182 for the STC as seen fit, whether for public demand, or most useful aircraft that could benefit from Jet-A power in the general broad market of General Aviation. Many reasons are evident. Now.... I'm carrying out some of your calculations on some of my favourite singles Wylbur: Because of the need for 100LL in GA, there needs to be a way to replace the TEL (TetraEthyl Lead). I think the diesel engine is the answer for two reasons: 1) Turbo charging - 500 FPM climb is attainable beyond 6000' MSL, plus good cruise speed at higher altitudes; 2) Less fuel needed to make same trip at same speed. As was pointed out in other places, JET-A or diesel is more dense than AvGas. Therefore it weighs more per gal/litre. Full fuel will cause lower "useful" load (I consider passenger and/or baggage to be useful). But for the bigger aircraft (those having > 200HP) this might make economic sense. However, changing over to diesel for most of GA will be incredibly costly. Example: C150-152s are no longer made. They are great trainers, but would it be cost effective to replace the AvGas engine with a Diesel? How about the Piper Cherokee line (which matches the problems of other low wing aircraft)? Is it worth $30,000 (per engine?) to change to diesel? If not, what will an engine overhaul cost should AvGas just go NO LEAD? And will TBOs be reduced? Will a catalytic converted be necessary and where would you put it? For the HI-PERF top end horsepower aircraft, diesel may be the only way out if TEL goes away. And think about it: if AvGAS goes NOLEAD, the cost of production would be reduced. The cost of AvGAS would possibly fall in line with MoGAS (finally!). Chris: I am not sure if I follow this thread. I fly a straight-tail Lance (Lyc. IO-540-K1A5D 300 HP @ 2,700 RPM). Do SMA and Thielert both have equivalent Jet-A burning diesel engines available? What Torque / RPM would the equivalent engine achieve? What is the approximate wet weight comparison of the two? Randy to Chris: Right now, there is no certified conversion available for these Pipers. Some Cherokees fly with the Thielert 135HP, and at least one Dakota with the SMA 230HP with very interesting performance. The Thielert V8 310-350HP is available, but hasn't been tried or even less certified on a single engine plane. The SMA 300HP exists, but isn't yet available. We don't know what will be the final empty weight of any of these conversions since a lot depends of designing, positioning and testing the heat exchangers. One encouraging sign is that the Beech Duke being converted in Germany from O-540 to Thielert is reporting a 360 Lbs. weight GAIN! With any of these diesels you can expect 0.32Lbs/HP-hour and SFC is remarkably constant with a diesel (not with a gasoline engine). Since Jetfuel is 14% denser, you can easily compute your future fuel consumption and range with reserves; you will see that what increases the most is range with IFR reserves. Also, expect a higher torque/rpm with diesel. Randy to Wylbur: I am skeptical about a coming of MoGas on airfields. It has been tried and tried again... The basic Lycoming/Continental design which originated in the thirties was a very simple design, easy to disassemble, tune up and maintain, very rugged, remarkably well adapted to high Octane gasoline. This is why it lasted so long. Converting these engines to MoGas has proven tricky and never was convincing enough to make a success. Converting automobile engines to aircraft has proven either vicious, or expensive, and in any case complex (geared engines...) with the exception of the Volkswagen Beetle engine which happens to be a flat-four air cooled in the first place. I am even more skeptical about a general concerted effort to bring MoGas on the airfields, while Jetfuel is already here in the first place. To read more and express your opinion, join our forum… posted by Deena at 6:43 AM News of September 18, 2005Is 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 by Deena at 7:13 AM News of September 14, 2005Thielert, world leader in aero diesels, reports 75,000 flight hours with its TAE Centurion 1.7 liter.Lichtenstein, 13 Sep. 05 - The Centurion 1.7 jet fuel piston aircraft engine has become a synonym for state-of-the-art engine technology in General Aviation. The manufacturer, Thielert Aircraft Engines GmbH (TAE), celebrated the inaugural flight with this engine on 9 September 2005 for the fifth time. Until now this engine has accumulated 75,000 flight hours and is installed in general aviation aircraft as well as in Unmanned Aerial Vehicles (UAVs). Recently the installation in further aviation models was approved: Robin DR400, Cessna 172 F, G, H and I series as well as in the USA for the Diamond DA42. Nine additional service centres comprise the global service network for the Centurion engines. Despite being a young company, TAE celebrated two anniversaries in 2005. In the summer the company celebrated five years of production at its plant in Lichtenstein (Saxony, Germany). And on 9 September 2005 it celebrated the fifth anniversary of the inaugural flight with a TAE piston engine: on 9/9/2000 a Valentin Taifun power glider took off from the Altenburg airfield with the prototype TAE 110 engine. In March 2001 the TAE 110 became the worlds first diesel engine to receive approval from the Luftfahrt-Bundesamt (German Federal Office of Civil Aviation). The TAE gave rise to todays Centurion 1.7 production engine, which has gone on in recent years to become the worlds most successful diesel/jet fuel aircraft engine with over 400 units produced. General Atomics Aeronautical Systems, Inc. (GA-ASI), one of the worlds leading manufacturers of unmanned aerial vehicles (UAVs), received the contract for the "Systems Development and Demonstration" phase of the US Armys Extended Range Multi-Purpose UAV programme (ER/MP). This involves a UAV of the model Warrior, which is powered by a TAE Centurion 1.7 jet fuel aircraft engine. The first flight of the Warrior took place on 25 October 2004. GA-ASI added the jet fuel engine especially to meet the US Army s goal of using a single fuel for all systems (DoD Directive 4041). The Warrior UAV is the diesel version of the well-known Predator and is intended to be deployed by the US Army for long endurance surveillance, communications relay, and weapons delivery missions. The installation of the Centurion 1.7 allows the Warrior to fly at an altitude of over 23,000 feet with improved engine performance and fuel consumption, reduced maintenance costs, a longer lifespan and facilitated field logistics, as diesel fuel is easily available. For Thielert the use of this engine in the ER/MP programme represents a consolidation of its defence technology business and means further growth due to development contracts. It also gives higher credibility worldwide to the very concept of diesel engine for aircraft. The Centurion 1.7 jet fuel retrofit kit has been approved for installation in further Cessna 172s. The supplemental type certificates issued by EASA on 6 September 2005 cover the Cessna 172 F, G, H and I series, both those manufactured in France and in the USA. The Centurion 1.7 has long been approved for the K, L, M, N, P, R and S series. TAE therefore has supplemental type certificates for the vast majority of the Cessna 172 fleet. TAE has also added Egypt Air, an established large flight school, to its client list. The first two Cessna 172s are currently being fitted with the Centurion 1.7 retrofit kit. Egypt Air will equip a total of twelve Cessnas with the jet fuel engine. In the US, where FAA has issued the STC for the 172 conversion, EPIC Aviation in Florida is the certified service center licensed to sell individual conversions in Latin America, and, for the time being, to propose fleets of converted 172s to Flight Academies who are willing to train their mechanics. This until other service centers are opened. Parties interested contact Thielert through the Centurion website: http://info.thielert.com/centurion/sales/sales_service.php TAE continues to expand the international service network for its Centurion engines. Its technicians have been trained at the engine plant in Lichtenstein. Having been examined by TAE, they are then authorised to carry out service and maintenance on the Centurion engines. There are 70 Centurion service centres in the world. The following aviation technology companies now belong to the worldwide service network: Aerotech Aircraft Maintenance LTC, Coventry, England. Airtime Aviation Ltd., Christchurch, England. Deltair Airmotive, Ltd., Hants, England. Transal Aero Service BV, RA Arnemuiden, Netherlands. Aero Service BV, Lelystad, Netherlands. Vliegwerk Holland BV, Arnemuiden, Netherlands. N. a. c. Maintenance AS, Bardufoss, Norway. Tromso Flyklubb, Tromso, Norway. Sontea Srl, Bergamo, Italy. Again contact details may be found on the Centurion website. The Diamond DA42-TDI with Centurion 1.7 is now also certified in the USA. The Diamond DA42-TDI, which is fitted with two Centurion 1.7 engines from TAE was certified by the US FAA. The ultra-modern aviation design with the most up-to-date cell, engine and avionics technology is enjoying enormous demand. At present over 500 orders are awaiting delivery. A major reason for this interest is TAEs easily operated Centurion jet fuel piston engines which reduce operating costs by over 50 per cent and which can also be run on standard aviation jet fuel (kerosene). Following the Cessna 172, the Diamond DA42-TDI is the second aircraft model with a TAE diesel engine to receive US approval. FAA "Aircraft Certification Services" Director John Hickey presented the certificate at the EAA Convention in Oshkosh. The DA42-TDI from Diamond Aircraft Industries (DAI) is fitted with two Thielert Centurion 1.7 turbo diesel engines, which can either be run on automotive diesel (EN 590) or kerosene. Each of these engines achieves135 HP (99 kW). In Europe DAI received the European Aviation Safety Agency approval certificate for the DA42 Twin Star at the Berlin Air Show in May 2004. Since the end of March 2005 DAI has delivered more than 35 aircraft with the much sought-after diesel engine. The first US deliveries are planned for the first quarter of 2006. The Diesel-Robin DR400 135 CDI has been certified by EASA. On 7 July 2005 TAE received supplemental type certification from the EASA to install the engine. The French aircraft manufacturer Apex Aircraft thereby became TAEs second OEM customer. Numerous orders have already been received for this type of aircraft. The state-of-the-art Centurion 1.7 jet fuel engine follows the traditional and proven wooden design of the DR400, producing aircraft with superb flight qualities whose ultra-modern powerplants make it both economical and easy to operate. The fuel consumption while cruising is 21l/h at a speed of 126 kts. Its flight range with a 30 US gallon standard tank is 613 NM. In climb flight the Robin 135 CDI achieves 680 ft/min. As in all aircraft that are fitted with a Centurion engine, the Robin also has fully electronic engine and propeller control with a control lever. The approval range of the supplemental type certificate covers the Robin DR400 RP, 120D, 140B, 180R and 200R. Initially the Centurion 1.7 will only be fitted in new aircraft. A retrofit kit for refitting Avgas-Robins is in development. Visit http://www.centurion-engines.com posted by Deena at 6:00 AM News of September 06, 2005Special report: A fruitful dialogue between Aviation Consumer and DieselAirNewletter.Paul Bertorelli, Editor in Chief, Aviation Consumer, sent an answer to our August 18 discussion of the Aviation Consumer special report on the coming of aero-diesels. This opened an email exchange. Patrick Canivet, CEO of FlyJetA who sells Cessna 182 SMA conversions, added his comments. We summarize or quote here what was said. (Remark: these exchanges took place before Katrina.) We thank Paul and Patrick for their time. Paul Bertorelli (Aviation Consumer): In the U.S. market, diesels will live or die on how buyers react to them and thus far, the reaction has been lukewarm. Our surveys indicate strong interest in diesel technology but thus far, few owners willing to translate that interest into sales. Our most recent survey in the June issue indicated that the high cost of diesel market entry is one reason for this. (We surveyed more than 800 people, worldwide.) Yet, our conclusion was: "Although the diesels are a non-starter for U.S. conversions, the cost curves clearly favor them in the long run, as fuel prices rise. Thielert and other diesel makers need only wait for the right timing." I have recently test flown the SMA-powered Cessna 182. The cost of this conversion is currently right around $90,000, give or take. The cost of top-notch overhaul for the O-470 which the diesel replaces is about $25,000. So for the diesel's benefits, the owner will be spending something like $55,000 to $65,000 more than he would for an overhauled gasoline engine. And what are the benefits? As measured by us, the airplane climbs better, say 900 FPM versus 600 FPM at altitudes above 6000 feet. Because of the diesel's excess cooling drag, its cruise speed is about the same as the gasoline engine version, and gets a little better at higher altitudes: SMA claims 140 knots TAS versus 136 knots for gasoline version at 12,500 ft. According to the SMA POH, the fuel burn difference is 9 GPH for the diesel, and 11.1 GPH for the gasoline engine. SMA tells us the fuel Delta is much more favorable to the diesel than the POH allows but because they have not flown us in an airplane equipped with a fuel flow meter, we cannot confirm the claims. Full fuel payload is reduced by about 110 pounds: In the SMA diesel version, empty weight rises by about 40 to 50 pounds. Then, equivalent-range payload offsets this somewhat. For example, if the diesel airplane is loaded with 50 gallons of fuel, it can carry about 765 pounds of additional load. For the same fuel amount, the gasoline airplane can carry 850 pounds of additional load. The diesel can fly about 750 miles to dry tanks on this fuel load while the gasoline version can fly 600 miles. However, that extra 50 pounds the gas version can carry translates to another 8 gallons of fuel or 140 miles. So the two engines are very close in down-fueled range performance. In terms of full-fuel range, the diesel has a clear advantage: 1,300 miles total range versus 1,070 miles for the gas, both to dry tanks. The diesel enjoys an altitude advantage and will climb over weather that the gasoline version will have to fly through. This offers a clear advantage over the gasoline engine version. Where we disagree is that the diesel is thus a "vastly superior" airplane. It is not. It has some advantages and some disadvantages. Having those advantages will cost a potential buyer as much as $60,000 or more; half the value of the airplane itself. European buyers are already driven by fuel cost considerations. American buyers aren’t yet, although they may be in the short-term future. For a private owner flying 150 hours a year, the fuel savings of operating a diesel might come to $1,200 a year. It simply makes little sense to spend $60,000 or more to save $1200. That's less than half the interest you could earn in a modestly successful investment. You do get better climb, range and altitude performance. But these are incremental improvements to the airplane, not transformational improvements worthy of a $60,000 investment. Very few owners actually want or need to fly in the teens to avoid weather or fly non-stop for 900 miles. It's just not a common profile for the airplane to fly. Commercial operators can do better with a diesel in the U.S. market, on fuel savings alone. But they'll still need to make the investment. In the U.S. currently, there are few if any service centers for diesel engines and there may not be for at least a year or two. Our view is the market encroachment of diesels is inevitable, given the economics of fuel prices. They make sense and probably will endure. But it's too early and we are advising readers to wait before making this investment. We don't agree that the rise in value of a diesel engine airplane is a sure thing and we don't think owners should bet $60,000 on that particular farm. A year or two from now, maybe. But not yet. You may publish this response, if you wish. I would respectfully request you steer your readers to our extensive diesel coverage in the June, August and October 2005 issues. Let them judge for themselves what we have to say. Andre Teissier-duCros (DieselAir Newsletter): What you said published very faithfully the opinion today of some 800 pilots. Aviation Consumer must base its opinions on what is available and proven today, while DieselAir Newsletter tries to forecast where diesel is going 2, 5, 10 years from now and why. We think that what a 182 owner gets for some $90,000 (or a 172 owner will, with a Thielert) is much, much more than an engine: New cowl, new engine instruments and controls, new 3-blade propeller, added heat exchangers, new engine mount, with possibility to negotiate in the price new avionics, new paint, new interior and a corrosion inspection. Suppose his plane is worth $60,000 initially, he can find himself with a better than new plane for much less than the price of a new 182. We being in the rational crystal ball business claim that the market value of this converted plane will, after that, go up as a consequence of extended Mission Ability and Safety. As for fuel consumption, I agree with 9 GPH for the 182SMA which I also tested. My 182Q, at same speed, does 13 GPH. So do all the five 182Q's which I know well at PDK Airport. For long distance cruises (Ex: Atlanta-Long Island NY), I cannot fly at full cruise speed if I want legal reserves when I get there. So in practical conditions the 182 SMA diesel as proposed today would be faster on such a long leg by some 20K (say 135 against 115). It will be even faster 2 years from now, because we are talking only of what SMA proposes now, which is very limited in order to humor conditions required by FAA for an STC as early as possible. The SMA engine is a 300HP engine down-rated to 230HP, and down-rated further in altitude to facilitate initial specs allowing an early STC. Embry-Riddle has experienced 153K with such a plane, ignoring these provisional specs. Someone who buys the plane today will have access to future engine retuning’s (including revised cowl) as FAA accepts, based on experience, loosened specs. He will fly higher, and faster. (The same is true, by the way, for owners of 172 Thielert.) An Avgas 182Q - such as mine - has a capacity of 88 gallons usable, a useful load of 2,950-1,770 = 1,180 Lbs. Payload, as is, is 650 Lbs with full tanks. If converted to SMA, the same capacity plus extra load will mean: Useful load 2,950 - 1,210 = 1,140 Lbs. Jetfuel is 10% heavier so payload is down to 1,140 - (88 G. x 6.6 Lbs) = 559 Lbs. This is still ample for my most frequent mission of 4.5 to 6 hours from PDK, alone or with one passenger. (During the 500 hours I flew with that plane, we carried 4 people only once). But I will fly faster to NY (see above), without fear of running out of gas when I get in the Washington-Baltimore-NewYork airspace with constant rerouting calls: "7GA, ready to copy?" .(The New York ATC gets very impatient if a modest 182 answers: "minimal fuel..."!) I never fly to dry tanks. I fly IFR and plan for 3 hours reserves: legal IFR reserve, plus alternate, plus taking into account I am 68 years old. Also my 182Q will not fly close to 1,070 NM to dry tanks...! Therefore my experienced figures become: With my 182 as is: Avgas with 3 hours reserves: 670NM at 115-120 Knots. With the 182 SMA Jetfuel, same reserves: either 674 NM at 136 Knots (much faster), or 1,275 NM at 115 Knots. Because here comes the beauty: the constant specific consumption of the diesel means that, if you slow down, Gallons/hour drop much more than with a gasoline engine (well known by taxi drivers fighting traffic jams all around the world). If for any reason I am below minimums at destination and alternate and am down to 10 gallons of fuel at cruise speed, if I slow down to 82 Knots, my fuel consumption goes down to 3.5 gallons/h, I can still fly some 240 NM, and my engine still runs like a clock. (This is why I say that, for practical purposes, a diesel plane can fly almost for ever...) You will notice that, in my demonstration, I didn't even bother to mention fuel costs. For me, it's only a cherry on top. All US pilots and professionals are obsessed with amortizing a diesel thanks to fuel savings alone. Here we agree: fuel savings alone will never justify the conversion even with Avgas at $8.-/Gallon (which will come). Also, the 182 SMA happens not to be the best example because the 182 already has a relatively long range. A 172 diesel is even more convincing because, with 40 gallons, the 172 Avgas simply cannot fulfill a serious IFR cross country mission. A 172 diesel does. Here, it is a question of can't do/can do. Same for a Piper Warrior. I agree that most pilots of today do not fly a 182 for 600NM with 3 hours reserves. But it happens to be my profile: I learned to fly at age 59, have 900+ hours, and presently fly 120h/Yr. mostly for business, often IFR, visiting clients in the boonies. I live in Thunderstorm Alley, where flying above the weather is a plus. And when diesels come, there will be many new pilots and new aircraft owners who will learn to fly, and fly my kind of missions. I expect AOPA to become aware of it, and use it to promote GA: "With diesel and GPS, beat the airlines and travel for less." Also I consider being free of the fear of engine fire and of engine loss as important. So, we agree to wait for two years... except some pilots who will want to be smart and be among the first ones. And we predict a real culture shock when the 300-350HP diesels become available for twins which fly 1,000 hours/Yr. and will see their market value jump. Which is another story. N. B. My figures for Range as function of Speed, specific consumption and other parameters come from a Computer Model we developed for our own use. Patrick Canivet (FlyJetA): Comparing prices: The SMA should be compared to a gasoline engine of 230HP of similar power with Turbo and Fadec. If it existed (also meaning no carb heat, no manifold pressure to adjust, no mixture control), it would be priced anew around $35,000 against some 49,000 for a new SMA with a complete kit. But at TBO, a Cessna 182SMA will pay no more than the TBO price of a regular O-540. Also, servicing costs go down in proportion to the number of engine parts: We are comparing a diesel with 500 parts and an O-540 or O-470 with 2,500 parts. Preventive maintenance is very simple: No magneto, no distribution, and no spark plugs. The rest is easy visual inspection. Any job requiring disassembling the engine (changing a cylinder, or a piston) will require, for an already certified A&P, a simple training program in situ or in a SMA facility. Working on the SMA will be more like servicing a lawnmower engine than a Porsche engine. posted by Deena at 10:44 AM |
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