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#11
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"Z Goudie" wrote in message ... Bill Daniels wrote: Reading the Diesel Air Ltd. site about the ducted fan dirigible application, they say that they get 8 pounds of static thrust for each HP. If 100 HP = 800 pounds of thrust, that stacks up pretty well against a 235 Pawnee that only produces about 390 pounds of thrust. That would be good for avoiding wing dropping. Jings, crivvens, I can just see the FAA, CAA or JAR falling all over themselves to approve a ducted fan for an existing airframe. The new Sport Light Aircraft regulations (US) have specific language permitting experimental glider tugs. Nobody said anything about fitting a ducted fan to an existing airframe. A diesel engine of a given horsepower with a propeller on it will produce the same thrust as similar power petrol (gas, steam) one. Nope. A Bell 47 helicopter rotor turning 300 RPM will produce more than 2450 pounds of static thrust with just 266 HP. The fact that it flies proves that. Diesels produce their power at low RPM's. A slower turning propeller that can absorb the same HP will produce more thrust. A ducted fan will produce still more thrust per HP at low airspeeds. It will, if turbo charged (another complication), produce sea level power up to a considerable height but I don't think that's a major problem for near sea level dwellers. All 2-stroke diesels are supercharged - else they won't run. As far as I can see what's driving the production of diesel engines in Europe is the low/no tax on diesel or jet fuel. How long will it take the fiscal authorities to latch on to that one I wonder? Europe has been using diesel fuel for a long time. Raising taxes on agricultural diesel will be a political hot potato. General Aviation fuel use is tiny compared to road use. Bill Daniels |
#12
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The only fuel that I am confident I will be able to find for
aircraft in the coming decades is Jet fuel. If I purchased a certified aircraft for long term use, it would be powered by this, or be an experimental (where I could use whatever I want) In California, the abolishment of MTBE made all the autogas STCs of aircraft invalid (the new ethanol gas isn't covered by the STC). I don't have confidence that 100LL will be available in the near future. 80 has already almost disappeared from general aviation. Diesel? I'd be surprised to see that in 200 California airports within the next 10 years. In article , Stefan wrote: Bill Daniels wrote: They feel their engine would make a near perfect tug engine. Surprize! :-) A rumor is ... So much for "practical information". Diesels make power at lower RPM's than a spark ignition engine so they can use larger, quieter, more efficient propellers. There isn't a requirement anywhere that propellers have to be direct driven. Actually, the only diesel flying today uses a gearbox. (Sorry for my unfair quoting, but I couldn't resist.) Stefan -- ------------+ Mark J. Boyd |
#13
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Mark James Boyd wrote:
The only fuel that I am confident I will be able to find for aircraft in the coming decades is Jet fuel.ral aviation. [...] Diesel? I'd be surprised to see that in 200 California airports within the next 10 years. Diesel engines in aircraft run on Jet A1. Christian 8-) |
#14
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At 21:48 21 October 2004, Bill Daniels wrote:
Nope. A Bell 47 helicopter rotor turning 300 RPM will produce more than 2450 pounds of static thrust with just 266 HP. The fact that it flies proves that. Ah, so we're going to need very long undercarriage legs then? |
#15
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"Z Goudie" wrote in message ... At 21:48 21 October 2004, Bill Daniels wrote: Nope. A Bell 47 helicopter rotor turning 300 RPM will produce more than 2450 pounds of static thrust with just 266 HP. The fact that it flies proves that. Ah, so we're going to need very long undercarriage legs then? It wouldn't be hard to design an airframe that could use a 3-4 meter prop. That would do a lot for low speed thrust and lower noise. Bill Daniels |
#16
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At 13:36 22 October 2004, Bill Daniels wrote
It wouldn't be hard to design an airframe that could use a 3-4 meter prop. That would do a lot for low speed thrust and lower noise Back to the reduction gearing scenario then? |
#17
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#18
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Now that Diesel is hovering in the $2.50 (U.S.) range, what would be the big
savings?? The Diesel engines I've seen on the market for Aircraft use cost WAY more than gasoline engines...I'd be surprised if we actually settled on the fuel cost being anywhere near the biggest cost driver in the actual cost of a tow... My DG-400 costs two liters of unleaded per launch to 2,500 ft agl....not too bad when you cost it all out. Acquisition cost of the tug, depreciation of the asset, Insurance for the tug, annual for the tug, fuel, maintenance,tie down/hangar, interest if there's a loan Engine reserves...I know for a fact my Cessna 180 costs WAY more to launch a sailplane on an annual basis than does the DG...maybe we just need a bunch more self launchers?? ( wincing...thinking of the can of worms this comment will open ) Steve. |
#19
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"Steve Hill" wrote in message ... Now that Diesel is hovering in the $2.50 (U.S.) range, what would be the big savings?? The Diesel engines I've seen on the market for Aircraft use cost WAY more than gasoline engines...I'd be surprised if we actually settled on the fuel cost being anywhere near the biggest cost driver in the actual cost of a tow... My DG-400 costs two liters of unleaded per launch to 2,500 ft agl....not too bad when you cost it all out. Acquisition cost of the tug, depreciation of the asset, Insurance for the tug, annual for the tug, fuel, maintenance,tie down/hangar, interest if there's a loan Engine reserves...I know for a fact my Cessna 180 costs WAY more to launch a sailplane on an annual basis than does the DG...maybe we just need a bunch more self launchers?? ( wincing...thinking of the can of worms this comment will open ) Steve. I don't disagree about motorgliders but there will always be a lot of pure gliders around that need launching. Diesels will produce the same power on roughly 1/3 less fuel and that fuel could be un-taxed agri-diesel in the case of a warm weather glider tug. That would be a large but not overwhelming savings. If diesels get as popular as most aviation experts suggest, the availability of avgas and spark ignition engine parts and repair may eventually be a greater concern. A typical 180 HP Lycoming O-360 will burn $60,000 worth of avgas to get it to a 2000 Hr TBO. A 260 HP Lyc O-540 will burn close to $100,000 worth of avgas in 2000 hours. Engine overhauls are also a big cost but less per hour than fuel. Any way you look at it, a tow plane is a black hole sucking in money. If you really want to save fuel, think winch launch. That takes about 1/2 liter of diesel to launch a typical glider. That could easily be vegetable oil. If you are lucky enough to be able to use an electric winch, a launch will use about 1KW Hr. of energy at about $.05. Add to the fuel savings the fact that you don't have to deal with the FAA trying to get a Tost hook installed on a Pawnee. Bill Daniels |
#20
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The Australians have an Autotug project that uses a 6 cylinder car engine
,parts available everywhere overhauls 3-5k US replacement engines available everywhere. the scuttlebutt was the main problems were making the engine mounts and ducting cooling air onto the radiator.I believe it is approaching a 1000hours . There is a Swedish project using a volvo car engine with similar results , The way to go is to get the dollar gobbler(the engine ) changed to a mass produced item, that is the car market ,millions of engines instead of hundreds gary "Steve Hill" wrote in message ... Now that Diesel is hovering in the $2.50 (U.S.) range, what would be the big savings?? The Diesel engines I've seen on the market for Aircraft use cost WAY more than gasoline engines...I'd be surprised if we actually settled on the fuel cost being anywhere near the biggest cost driver in the actual cost of a tow... My DG-400 costs two liters of unleaded per launch to 2,500 ft agl....not too bad when you cost it all out. Acquisition cost of the tug, depreciation of the asset, Insurance for the tug, annual for the tug, fuel, maintenance,tie down/hangar, interest if there's a loan Engine reserves...I know for a fact my Cessna 180 costs WAY more to launch a sailplane on an annual basis than does the DG...maybe we just need a bunch more self launchers?? ( wincing...thinking of the can of worms this comment will open ) Steve. |
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