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Thread: Oddball engines and prototypes

  1. #2881
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    like I said, they are not doing it right, are they. Thats 'olden days' technology.

  2. #2882
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    Will D, dont worry Im not going off in an aviation direction just yet. I'll get this 175 uniflow running first, in an off road bike frame, then we will see whether to take it further.
    Although the next step would be a twin cylinder gyro engine, I've got a spare gyro frame too, perhaps even the counter rotating 'stealth' props.
    Finally got down to some serious pattern making this evening, the pattern making port must have opened in the cosmos.

  3. #2883
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    You can't believe the lengths they go to in submarines to run quiet. The passive sonars can pick up the noise from geared turbines half way around the world under the right conditions. They can identify an individual sub from its noise signature. All the machinery is attached on very carefully designed noise reducing mounts. The crew wears sneakers. Sure, the early nuclear boats could make over 30 knots submerged, but they often ran at more like 5 knots with turbo electric generator driven electric motors. The Tulibee was the first all electric drive nuclear submarine. It was rumored to have surfaced next to a US carrier completely undetected. The next try was the Glenard P. Lipscomb, a modified Sturgeon class boat, but it was not as successful and wasn't the basis for the Los Angeles class.

    At the time electric motors couldn't reliably provide the power for high speeds. I don't know as much about the modern boats, but they use ducted propellers to reduce propeller noise. They are covered in special noise reducing coatings. All nuclear submarines have an electric motor directly connected to the propeller shaft for quiet running. The latest ballistic missile submarine class will use a modern all electric drive system. The modern diesel electric boats most navies have are serious threats in coastal waters because they are quiet. Nuclear submarines main advantage is range submerged. Recharging batteries is dangerous because it is noisy and occurs near the surface.

    I'm surprised I haven't heard about any fuel cell research for submarines. It would seem to be ideal where more power is needed than batteries can provide. Costs are an issue for smaller power plants (cars) but aren't as much a consideration for the military. The fact that the Japanese chose batteries over fuel cells for their submarine is an indicator of the relative state of development. Also, hydrogen is very dangerous, especially in an enclosed space like a submarine.

    Lohring Miller

  4. #2884
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    Quote Originally Posted by lohring View Post
    hydrogen is very dangerous, especially in an enclosed space like a submarine.
    I'd say that only in enclosed spaces is hydrogen dangerous. Leaked hydrogen will disappear immediately, contrary to petrol fumes or LPG that will form invisible but highly flammable puddles.

  5. #2885
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    Quote Originally Posted by lohring View Post
    I'm surprised I haven't heard about any fuel cell research for submarines.
    FWIW, there are Stirling engine generators designed for subs, which make use of the temperature differential between the inside and all the cold water on the outside. But these seem to be only for use to recharge batteries, they don't put out enough for e-drives.

    https://saabgroup.com/media/stories/...ent-submarine/

    cheers,
    Michael

  6. #2886
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    Quote Originally Posted by lohring View Post
    You can't believe the lengths they go to in submarines to run quiet. The passive sonars can pick up the noise from geared turbines half way around the world under the right conditions. They can identify an individual sub from its noise signature. All the machinery is attached on very carefully designed noise reducing mounts. The crew wears sneakers. Sure, the early nuclear boats could make over 30 knots submerged, but they often ran at more like 5 knots with turbo electric generator driven electric motors. The Tulibee was the first all electric drive nuclear submarine. It was rumored to have surfaced next to a US carrier completely undetected. The next try was the Glenard P. Lipscomb, a modified Sturgeon class boat, but it was not as successful and wasn't the basis for the Los Angeles class.

    At the time electric motors couldn't reliably provide the power for high speeds. I don't know as much about the modern boats, but they use ducted propellers to reduce propeller noise. They are covered in special noise reducing coatings. All nuclear submarines have an electric motor directly connected to the propeller shaft for quiet running. The latest ballistic missile submarine class will use a modern all electric drive system. The modern diesel electric boats most navies have are serious threats in coastal waters because they are quiet. Nuclear submarines main advantage is range submerged. Recharging batteries is dangerous because it is noisy and occurs near the surface.

    I'm surprised I haven't heard about any fuel cell research for submarines. It would seem to be ideal where more power is needed than batteries can provide. Costs are an issue for smaller power plants (cars) but aren't as much a consideration for the military. The fact that the Japanese chose batteries over fuel cells for their submarine is an indicator of the relative state of development. Also, hydrogen is very dangerous, especially in an enclosed space like a submarine.

    Lohring Miller
    Quote Originally Posted by Michael Moore View Post
    FWIW, there are Stirling engine generators designed for subs, which make use of the temperature differential between the inside and all the cold water on the outside. But these seem to be only for use to recharge batteries, they don't put out enough for e-drives.

    https://saabgroup.com/media/stories/...ent-submarine/

    cheers,
    Michael
    I remembered reading about this
    https://nationalinterest.org/blog/bu...-carrier-77116
    However, the two-hundred-foot-long Swedish Gotland-class submarines, introduced in 1996, were the first to employ an Air Independent Propulsion (AIP) system—in this case, the Stirling engine. A Stirling engine charges the submarine’s seventy-five-kilowatt battery using liquid oxygen.

    With the Stirling, a Gotland-class submarine can remain undersea for up to two weeks sustaining an average speed of six miles per hour—or it can expend its battery power to surge up to twenty-three miles per hour. A conventional diesel engine is used for operation on the surface or while employing the snorkel. The Stirling-powered Gotland runs more quietly than even a nuclear-powered sub, which must employ noise-producing coolant pumps in their reactors.
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  7. #2887
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    The coolant pumps were a big noise source. I worked on the Narwhale, powered by a direct drive turbine and a natural circulation reactor. It was supposed to be a modified Sturgeon class boat, but had to be a larger diameter to fit the power plant. It's huge cost is the main reason I say cost doesn't matter much to the military. The boat was very silent and probably was mostly used for espionage. Everything about its career is probably still classified. The attack subs often had over 6 month deployments, often close to Soviet bases. A neighbor of ours was depth charged during one mission. We had great picnics on the leftover steaks left from these missions. The sub crews were treated very well during the cold war.

    Back to two strokes, my favorite IC engines.

    Lohring Miller

  8. #2888
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    We might have appeared to be getting off track, but I guess this thread is really here to allow us to get off track! - because, in looking at the big picture, we can find a lot of ideas and information (except for nuclear power and total silence !) from there which can be useful and transferable to our little picture which is (often, but not exclusively) concerned with the two stroke engine!

    But ..... we still need to change to save the two stroke.

    The expansion chamber (which does increase the power a lot), only does it well within a certain rev range - so really only in competition!
    When the current types of chambers are used, they are there to augment the power delivery of the engine and when it gets out of its happy range it has to be augmented further with power valves and various other "improvements"!
    So, I believe that in a road going two stroke, the expansion chamber as we know it is a useless piece of equipment - it collects oil, and only works when it gets "on the pipe" - this is the last thing we need for that purpose! (I started riding in the days of the T20 Suzuki and the Kawasaki H1 etc so I've been there!) - all fast but low in the revs they became gutless, smoky heaps of crap! - the exhausts ended up twice the weight they were after a year or so ...... and I loved them! - dopey bugger that I was!
    The other problem is oil in the petrol (despite arguments for, - also the other unseen pollutants!) - that is what has more or less relegated it to the scrap heap instead of being used for transport
    Whether we accept it or not, this is a fact - it has happened - are we are just too blind to see?

    We need to redesign the whole thing (ie the two stroke engine) to make any progress in restoring it to it's rightful place! - racing is a spinoff from transport, (that's where the money is made)!
    The people most needing motorcycles to use for transport are in emerging countries - they are buying bikes by the million .... in the form of four strokes!

    Sorry, rant! - but am I wrong?
    Strokers Galore!

  9. #2889
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    Quote Originally Posted by Frits Overmars View Post
    I'd say that only in enclosed spaces is hydrogen dangerous.
    ive never been acused of that... but methane... welllllllll
    cheers DD
    (Definately Dodgy)



  10. #2890
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    I keep going back to turbos. They are used in the big marine two strokes as well as the Detroit Diesel uniflow two strokes. Neither use tuned exhausts. Variable vanes in the turbine and compressor can allow the turbo to run over a wide range. Electric drives can run the compressor when the turbine doesn't develop enough power. When the turbine has excess power, the motor becomes a generator, returning power to batteries. Formula one has been running systems like this. Regenerative braking can be added. Modern electronics make all this work. The problem is that it's way more complex and still less efficient than a battery/electric power plant. Fuel cells should be promising where batteries are too large or heavy. Today fuel cells are still (much?) more expensive.

    Lohring Miller

  11. #2891
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    "Horses for Courses" applies here - these solutions in huge two strokes are good and work very well in the environments they are used in - in our case, we normally use them in motorcycles etc and so they need to be compact and simple as possible at the same time.
    My contention is still that a supercharger or turbocharger can be made as an integral part of the engine and so more compact than a big expansion chamber. It could be argued that the chamber is a lot cheaper solution, but then it is only good within a certain rev range and is less than perfect outside this range! whereas these days a supercharger can be used over a wide range - a turbo can be too and with the added advantage of less power robbing. - both it seems can work well together, but that might be starting to get a bit complicated and bulky for our situation!
    (these are my opinions of course and I stand to be corrected!).
    Strokers Galore!

  12. #2892
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    DKW tried almost everything you could thing of in two strokes before the tuned pipe era. Many are shown here. The tuned pipe engines were simpler and more powerful, not to mention less expensive. Big outboards use pipe length switching to get suitable tuned exhausts in a compact package. BRPs big outboards are at the leading edge in this and other two stroke technology. Their advantage is that they weigh less and are simpler than supercharged four strokes of the same power. Note that the Mercury outboards use screw compressors. Those are the most efficient in moderate sizes. I think small engines would do better with piston compressors. But wait, that's what crankcase compression engines use. LOL

    Lohring Miller

  13. #2893
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    Quote Originally Posted by lohring View Post
    DKW tried almost everything you could thing of in two strokes before the tuned pipe era. Many are shown here. The tuned pipe engines were simpler and more powerful, not to mention less expensive. Big outboards use pipe length switching to get suitable tuned exhausts in a compact package. BRPs big outboards are at the leading edge in this and other two stroke technology. Their advantage is that they weigh less and are simpler than supercharged four strokes of the same power. Note that the Mercury outboards use screw compressors. Those are the most efficient in moderate sizes. I think small engines would do better with piston compressors. But wait, that's what crankcase compression engines use. LOL

    Lohring Miller
    Lohring,
    I agree with most of what you are saying and that new two stroke V4 aero engine (I think it was you sent in a link for) seems to be very compact and embodies most of the stuff that will be needed for the two stroke to get ahead in future (and it doesn't use an expansion chamber!) but I'm sure it'll be expensive!
    For Outboards and Skidoos, development of the two stroke has continued over the years and hopefully those manufacturers will come up with a workable engine which is lightweight, economical, compact and affordable for everyone - in all sorts of vehiclesl

    I still haven't looked at the link you put in as yet, - but I think the piston pump is a good idea (not the "under piston" pump though!).
    The split single (with a bit of imagination) could be seen as close cousin of the opposed piston engine - (I'm not so keen on the combustion chamber area it produces!) but this arrangement did work well, Puch being a good example.
    The Trojan light delivery van/truck in Britain used a split single for many years, it had sump lubrication and a piston type charge pump, instead of using the crankcase as a pump.

    I suspect that this system largely disappeared because it wasn't following the trend in the competition environment, (just not cool anymore!). It did however make perfect sense and was totally adequate for everyday vehicles.
    Really, it was racing rules and the banning of superchargers which robbed the engine world of the benefits of these and so this ushered in expansion chambers (a way round the problem) - they were not actually recognized as superchargers ... effectively though, they were superchargers - (as most people now realize!) - but are normally most useful within a limited rev range, as dictated by competition!
    They did do a good job in racing of course, but for the average motorcyclist, I feel that they were of no benefit whatsoever!

    As you probably know, I still have high hopes for the opposed piston layout!

    (and as usual, everything only my opinion!).
    Strokers Galore!

  14. #2894
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    Lohring,
    Had a look through the link on DKW - true innovators - very interesting!
    Piston pumps good, but maybe not so good in the compactness department as the screw compressor!
    Strokers Galore!

  15. #2895
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    Quote Originally Posted by lohring View Post
    I think small engines would do better with piston compressors.

    Lohring Miller
    The use of a piston pump is not only limited to one function.
    In addition to supercharging, it can be used at the same time to make a layered load, with the best direct injection method that works "pneumatic" on mopeds and UAVs.

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