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Scott-Still Engine
Posted by: Peter Heid (IP Logged)
Date: December 24, 2002 05:00PM
<HTML>More than once I have come upon the Still engine in books or discussions and am amazed at how little it was used considering it's efficiency. The last time I found mention of this diesel/steam hybrid was in a more modern book, "Red Book of Marine Engineering, Questions and Answers-Steam & Motor, Volume 2: First Assistant & Chief Engineer" I thought it was strange that in a 1990 edition one of the questions is: describe the operation principal of a Scott-Still engine. Are there some of these rare engines in operation today ?
Upon further contemplation I wondered what happened to them and and why did they not receive continued development. I think timing might have been an issue as marine propulsion was going to turbines and smaller engines were not in great demand. The separation of size between vessels was increasing at this time and the largest seemed to be the only ones getting development attention. These engines do require the oil to run through a separator to remove the water from the oil but this is a comon piece of equiptment on board most vessels and would seem to be of little concern. Besides timing, the initial cost would have been considerably higher than a straight diesel engine, limiting the application of this power source, especially in the smaller, cheaper vessels. As vessel sizes increased, smaller used vessels must have filled the market and lessened the demand for new ones. Another thought was that often the exhaust gas boiler was used to power auxilaries and not available for engine power and a complete redesign would be needed.
It would be a monumental job to use the Still engine in most compact power units if based on it's current design. I propose a opposed piston IC engine with separate steam cylinders as a hybrid design far superior to the current hybrid autos. An opposed piston engine doesn't need an enclosed crankcase as some designs have proven.
Peter Heid</HTML>
Upon further contemplation I wondered what happened to them and and why did they not receive continued development. I think timing might have been an issue as marine propulsion was going to turbines and smaller engines were not in great demand. The separation of size between vessels was increasing at this time and the largest seemed to be the only ones getting development attention. These engines do require the oil to run through a separator to remove the water from the oil but this is a comon piece of equiptment on board most vessels and would seem to be of little concern. Besides timing, the initial cost would have been considerably higher than a straight diesel engine, limiting the application of this power source, especially in the smaller, cheaper vessels. As vessel sizes increased, smaller used vessels must have filled the market and lessened the demand for new ones. Another thought was that often the exhaust gas boiler was used to power auxilaries and not available for engine power and a complete redesign would be needed.
It would be a monumental job to use the Still engine in most compact power units if based on it's current design. I propose a opposed piston IC engine with separate steam cylinders as a hybrid design far superior to the current hybrid autos. An opposed piston engine doesn't need an enclosed crankcase as some designs have proven.
Peter Heid</HTML>
Re: Scott-Still Engine
Posted by: tom ward (IP Logged)
Date: December 26, 2002 07:34AM
<HTML>Henry Ford built a diesel-steam hybrid to generate electricity at the River Rouge plant in the early 30's. Its on display at the Henry Ford Museum. I've never had a house that big! At best such a hybrid could only convert 30% of the waste heat for at best a 25% efficiency improvement from at least a 100% increase in dollars/HP.</HTML>
Re: Scott-Still Engine
Posted by: C Benson (IP Logged)
Date: December 26, 2002 01:23PM
<HTML>AAAhh,,,BUT the 25% is every dey ,. an the 100% is only once,,,and it ran for around 20 years? A corporate exetiv' who got his hands dirty AND knew what he was doing,,,,3 cheers for Henry the Great,,,,Ben p/s I got my plow truck stuck,,4wd an all,,hopefully Geo will check in soon we got 2ft +/- Grrr cb</HTML>
Re: Scott-Still Engine
Posted by: Jim Crank (IP Logged)
Date: December 26, 2002 02:25PM
<HTML>Peter & Ben,
Yes indeed Ben!! Saw the engine at the Ford Museum, you need an airplane hanger to house that beauty.
The modern equivalent, and I worked on the concept at LMSC for a while, was a bottoming cycle using Freon and a variable nozzle radial inflow turbine for truck Diesel engines. While it sure did work it was too costly and space consuming for the real world.
Easier to soup up the Diesel with more boost. More reliable too.
Jim</HTML>
Yes indeed Ben!! Saw the engine at the Ford Museum, you need an airplane hanger to house that beauty.
The modern equivalent, and I worked on the concept at LMSC for a while, was a bottoming cycle using Freon and a variable nozzle radial inflow turbine for truck Diesel engines. While it sure did work it was too costly and space consuming for the real world.
Easier to soup up the Diesel with more boost. More reliable too.
Jim</HTML>
Re: Scott-Still Engine
Posted by: George Nutz (IP Logged)
Date: December 26, 2002 02:36PM
<HTML>Coburn,
You old "stuck in the snow" guy!! I'm not stuck with a foot of itbut am hiring someone else to do the 800 foot driveway tomorrow. Chains on the front have saved me many times from such stuck experiences.
Yup, that extra 25% efficiency gain is a very marked improvement, if the diesel was 30% the steam cycle would add about 25% improvement or overall efficiency of 37.5%. Actually they did some tests showing over 40% thermal efficiency way back then. Peter's idea has some merit as it is not necessary to have the steam on the bottom side of the diesel piston but could be a separate steam cylinder. All the energy from the high pressure diesel water jacket and its exhaust could run this separate but attached steam cylinder. The separate diesel piston could be ceramic coated to insulate it from heat losses. Originally I think they ran about 100psi water jacket pressure and 350 degrees F, that water was turned into steam by the 900 degreeF diesel exhaust gases. and that was back in 1919!! About 6-7#steam were generated for each diesel horsepower and the exhaust gases were claimed to be as low as 150 degrees F. Today, with modern lubricants the pressure and water jacket temperature could be raised, raising the brake thermal efficiency even higher than what was obtained back then---40%.
Would be a nice experimental project for someone!
George</HTML>
You old "stuck in the snow" guy!! I'm not stuck with a foot of itbut am hiring someone else to do the 800 foot driveway tomorrow. Chains on the front have saved me many times from such stuck experiences.
Yup, that extra 25% efficiency gain is a very marked improvement, if the diesel was 30% the steam cycle would add about 25% improvement or overall efficiency of 37.5%. Actually they did some tests showing over 40% thermal efficiency way back then. Peter's idea has some merit as it is not necessary to have the steam on the bottom side of the diesel piston but could be a separate steam cylinder. All the energy from the high pressure diesel water jacket and its exhaust could run this separate but attached steam cylinder. The separate diesel piston could be ceramic coated to insulate it from heat losses. Originally I think they ran about 100psi water jacket pressure and 350 degrees F, that water was turned into steam by the 900 degreeF diesel exhaust gases. and that was back in 1919!! About 6-7#steam were generated for each diesel horsepower and the exhaust gases were claimed to be as low as 150 degrees F. Today, with modern lubricants the pressure and water jacket temperature could be raised, raising the brake thermal efficiency even higher than what was obtained back then---40%.
Would be a nice experimental project for someone!
George</HTML>
Re: Scott-Still Engine
Posted by: Peter Brow (IP Logged)
Date: December 27, 2002 07:43AM
<HTML>Didn't Doble sketch up a diesel/steam hybrid with separate cylinders? I seem to recall pix of that. Did some foodling with this idea myself, and considered adding a wee A.I.R. system to afterburn the diesel soot on its way to the heat exchanger. Burn biodiesel and you've got a pretty green system there. Too noisy and fussy for my taste, and I've got a better(?) ultra-efficiency exotic system (all steam) on the back burner, but yes, this would make a great project. The diesel stage could use off the shelf VW (or other) diesel parts. Just don't let the ATF hear that you're running an unlicensed "Still". :)
Peter</HTML>
Peter</HTML>
Re: Scott-Still Engine
Posted by: tom ward (IP Logged)
Date: December 29, 2002 08:34AM
<HTML>I've considered retrying a concept from the twenties that used a gasoline 2-stroke instead of a diesel. An air injection system would burn all the pollution those smokey 2-strokes put out. The 2-stroke would power the accessories as well as a compressor which recovers heat from the condensor as well as supplying air for the burner. Steam would only be used for propulsion. Hopefully the boiler would muffle that noisy 2-stroke.</HTML>
Re: Scott-Still Engine
Posted by: Peter Brow (IP Logged)
Date: December 31, 2002 08:02AM
<HTML>Hi Tom,
Interesting idea. One of the diesel-hybrid variants I considered would have recompressed exhaust steam back into the boiler, with a steam engine doing all the power output. Since yours would recover heat from the condenser, I wonder if you are talking about compressing air or using exhaust steam to heat a heat pump? These things get to be a lot of "fun" when you start routing around IC exhaust, IC coolant, steam exhaust, combustion air, etc to control heat rejection. The two-stroke gas/steam hybrid would be easier to build than the diesel/steam hybrid. One thing I came to dislike about IC/steam hybrid concepts is that they have two engines to fuss with instead of only one. And, worst of all, one of the two engines is the "wrong type". :)
Peter</HTML>
Interesting idea. One of the diesel-hybrid variants I considered would have recompressed exhaust steam back into the boiler, with a steam engine doing all the power output. Since yours would recover heat from the condenser, I wonder if you are talking about compressing air or using exhaust steam to heat a heat pump? These things get to be a lot of "fun" when you start routing around IC exhaust, IC coolant, steam exhaust, combustion air, etc to control heat rejection. The two-stroke gas/steam hybrid would be easier to build than the diesel/steam hybrid. One thing I came to dislike about IC/steam hybrid concepts is that they have two engines to fuss with instead of only one. And, worst of all, one of the two engines is the "wrong type". :)
Peter</HTML>
Re: Scott-Still Engine
Posted by: Garry Hunsaker (IP Logged)
Date: January 02, 2003 09:54PM
<HTML>Just pondering on this ic ec engine combination...
On the loss side, you got back pressure on ic system... How much? Heck if I know, it depends on what you are doing.
Boiler on the exhaust looks to me like you run into all the associated losses with heat transfer from the ic exhaust air to the heat exchanger and working fluid. It does very effectively get around the nasty stuff commonly found in combustion gasses getting inside the expander.
Inject the water straight into the ic combustion chamber, and you bypass a bit of the heat transfer loss, but then you get to play with all those sulfur compounds that mix with the condensing water in the blow by gasses in the crank case. (We tried something like this about twenty years ago on a rather tired old VW bug. Using a variable jet carburetor J.C. Whitney used to sell, and an adapter plate we made to fit under the carb to handle water injection by manifold vacuum (not the best way to do it), we did get the old Bug up to sixty miles to the US gallon. Then the engine lasted all of three months, and the corrosion on tear down was rather evident.)
As in any ic system, short of burning hydrogen, you are going to have to deal with water vapor containing corrosive compounds from the point water is added to the cycle... Add to this, that my engineering friend has mentioned compression rations as high as twenty to one in a spark ignition system, to get to the best levels for efficiency on watered fuel, and things get interesting real fast. Just a bit too lean on the water, and you get oxides of nitrogen. I don’t even want to think what nitric acid would do to the insides of an engine.
A friend of mine, an old McDonald Douglas engineer, has for years been extolling the virtues of ‘compounding’, which was apparently used on a few piston aircraft engines of the WWII period. I have never seen actual drawings, so I am making guesses from his descriptions. It apparently was something of an overgrown turbo charger. The difference being, rather than increasing the combustion pressure, the resulting power was geared to the engines output shaft.
It sounds to me like adding extra air to burn off the remaining carbon, as in the two stroke already mentioned in this thread, and injecting preheated water into the exhaust gas has some possibilities in combination with the old ic exhaust gas compounding idea. Nope, at anything below large industrial size engines, it will not be as thermally efficient as dumping the resulting mix into a reciprocating expander. It will though cut down on mechanical losses, and possibly allow for lower back pressures on the ic side of things. And, you don’t have to build the entire engine out of highly corosive resistant materials.
Dang... I hate it when I run into the limits of my own understanding... Off to chase down compounders...
Interesting idea folks
Garry</HTML>
On the loss side, you got back pressure on ic system... How much? Heck if I know, it depends on what you are doing.
Boiler on the exhaust looks to me like you run into all the associated losses with heat transfer from the ic exhaust air to the heat exchanger and working fluid. It does very effectively get around the nasty stuff commonly found in combustion gasses getting inside the expander.
Inject the water straight into the ic combustion chamber, and you bypass a bit of the heat transfer loss, but then you get to play with all those sulfur compounds that mix with the condensing water in the blow by gasses in the crank case. (We tried something like this about twenty years ago on a rather tired old VW bug. Using a variable jet carburetor J.C. Whitney used to sell, and an adapter plate we made to fit under the carb to handle water injection by manifold vacuum (not the best way to do it), we did get the old Bug up to sixty miles to the US gallon. Then the engine lasted all of three months, and the corrosion on tear down was rather evident.)
As in any ic system, short of burning hydrogen, you are going to have to deal with water vapor containing corrosive compounds from the point water is added to the cycle... Add to this, that my engineering friend has mentioned compression rations as high as twenty to one in a spark ignition system, to get to the best levels for efficiency on watered fuel, and things get interesting real fast. Just a bit too lean on the water, and you get oxides of nitrogen. I don’t even want to think what nitric acid would do to the insides of an engine.
A friend of mine, an old McDonald Douglas engineer, has for years been extolling the virtues of ‘compounding’, which was apparently used on a few piston aircraft engines of the WWII period. I have never seen actual drawings, so I am making guesses from his descriptions. It apparently was something of an overgrown turbo charger. The difference being, rather than increasing the combustion pressure, the resulting power was geared to the engines output shaft.
It sounds to me like adding extra air to burn off the remaining carbon, as in the two stroke already mentioned in this thread, and injecting preheated water into the exhaust gas has some possibilities in combination with the old ic exhaust gas compounding idea. Nope, at anything below large industrial size engines, it will not be as thermally efficient as dumping the resulting mix into a reciprocating expander. It will though cut down on mechanical losses, and possibly allow for lower back pressures on the ic side of things. And, you don’t have to build the entire engine out of highly corosive resistant materials.
Dang... I hate it when I run into the limits of my own understanding... Off to chase down compounders...
Interesting idea folks
Garry</HTML>
Re: Scott-Still Engine
Posted by: Arnoud Carp (IP Logged)
Date: January 03, 2003 03:29PM
<HTML>It is probably a different cycle bus once some 20 years ago I read a magazine article about a Diesel steam hybrid engine. it was designed and built for two ships before WWI by an English shipyard. The engine was the customary two stoke double acting crosshead engine design but with one side of the piston as diesel the other side was steam flashed from the diesel exhaust. One of the ships was torpedoed in WWI the other one operated satisfactory untill scrapped in the thirties. if any more information is wanted I may be able to trace the article in my files.
Arnoud Carp</HTML>
Arnoud Carp</HTML>
Re: Scott-Still Engine
Posted by: George Nutz (IP Logged)
Date: January 03, 2003 04:37PM
<HTML>Arnoud,
That is very interesting information, it sounds like a more modern but still classic Still engine(Still/still?)--two cycle with diesel on top and steam on the bottom with crosshead. It eludes to a rather large Still engine, if it is possible could you dig some of your information out, would be very appreciated.
Thanks, George</HTML>
That is very interesting information, it sounds like a more modern but still classic Still engine(Still/still?)--two cycle with diesel on top and steam on the bottom with crosshead. It eludes to a rather large Still engine, if it is possible could you dig some of your information out, would be very appreciated.
Thanks, George</HTML>
Re: Scott-Still Engine
Posted by: David K Nergaard (IP Logged)
Date: January 05, 2003 02:44PM
<HTML>If you have the 3rd. or 4th. edition of Mark's Handbook, there is a description of the Still engine with reference, in the section on IC engines.</HTML>
Re: Scott-Still Engine
Posted by: Peter S (IP Logged)
Date: January 05, 2003 11:15PM
<HTML>The engine now preserved at Henry Ford Museum is not a Diesel-steam, it is gas-steam.
It is a monster, well worth seeing. Weighs 750 tons, one of 9 that drove the generating plant for Highland Park plant. Each engine drove a 4000kw DC generator. Built around 1913 by Hoovens, Owens, Rentschler.
The gas engine side was the most efficient, but was not as smooth. The steam cylinder provided the regulated speed required for power generation.
I have a 58 page article on the Still engine. There was also a Still engined locomotive built in England in 1927, also 3 Russian locomotives built 1939-1948, these had "Maizel" system, a modified Still cycle.</HTML>
It is a monster, well worth seeing. Weighs 750 tons, one of 9 that drove the generating plant for Highland Park plant. Each engine drove a 4000kw DC generator. Built around 1913 by Hoovens, Owens, Rentschler.
The gas engine side was the most efficient, but was not as smooth. The steam cylinder provided the regulated speed required for power generation.
I have a 58 page article on the Still engine. There was also a Still engined locomotive built in England in 1927, also 3 Russian locomotives built 1939-1948, these had "Maizel" system, a modified Still cycle.</HTML>
Re: Scott-Still Engine
Posted by: Peter Heid (IP Logged)
Date: January 06, 2003 03:34PM
<HTML>Peter S,
I was wondering where the article on the Still engine was published so I might locate a copy.
Peter Heid</HTML>
I was wondering where the article on the Still engine was published so I might locate a copy.
Peter Heid</HTML>
Re: Scott-Still Engine
Posted by: David K Nergaard (IP Logged)
Date: January 07, 2003 12:24AM
<HTML>Peter S What kind of gas was used in the Ford engines? Blast furnace gas?
I also would like to read the report on the Still engine. I read about the English made Still locomotives in a book on world railways; they ran in Venesuela (I think) for more than thirty years! The cylinders were direct coupled to the drive wheels in the normal steam manner and the engine was started with steam. Once moving, the Diesel cylinders took up the load and the oil fire in the boiler was turned off.</HTML>
I also would like to read the report on the Still engine. I read about the English made Still locomotives in a book on world railways; they ran in Venesuela (I think) for more than thirty years! The cylinders were direct coupled to the drive wheels in the normal steam manner and the engine was started with steam. Once moving, the Diesel cylinders took up the load and the oil fire in the boiler was turned off.</HTML>
Re: Scott-Still Engine
Posted by: Peter Brow (IP Logged)
Date: January 07, 2003 05:41AM
<HTML>Imagine if we could get a car to run like the English/Venezuelan Still locomotives. Smooth, classic-steamer starting & low speed running, and better-than-diesel fuel mileage on the highway. Hmmm.
Peter</HTML>
Peter</HTML>
Re: Scott-Still Engine
Posted by: Peter S (IP Logged)
Date: January 07, 2003 08:19AM
<HTML>The article about the Still appeared in "Stationary Power" No.5, "The Journal of the Stationary Engine Research Group" 1988. This is a journal, rather than a book, published annually.
Article title was "W.J.Still and the ideal marine engine" by M.C.Duffy
You may be able to purchase copies from ISSES, see link below.
[www.steamenginesociety.org]
I wouldn't get too excited about the Still cycle, the author of the article concludes that although it was well thought out, it was too complex to suceed. At the same time heavy oil marine engines were being improved in reliability and economy, thus dooming the Still. Also diesel electrics became available for locomotives, so there was no need for the Still.</HTML>
Article title was "W.J.Still and the ideal marine engine" by M.C.Duffy
You may be able to purchase copies from ISSES, see link below.
[www.steamenginesociety.org]
I wouldn't get too excited about the Still cycle, the author of the article concludes that although it was well thought out, it was too complex to suceed. At the same time heavy oil marine engines were being improved in reliability and economy, thus dooming the Still. Also diesel electrics became available for locomotives, so there was no need for the Still.</HTML>
Re: Scott-Still Engine
Posted by: Arnoud Carp (IP Logged)
Date: January 08, 2003 11:58AM
<HTML>Hello George
I traced back the article I referred to it appeared in “Shipbuilding & Marine Engineering International”. In two instalments in December 1979 and Jan/Feb 1980 it was called “I REMEMBER” and it was written by a former editor G.R Hutchinson. It describes a great number of exceptional marine engine developments mainly Diesel. I have copied the Still engine part of it The article however also shows a section of the Scott Still enigine The following is the transcript:
Arnoud Carp
Best of both Worlds?
An even more ambitious - and complex - design venture was the Scott-Still combined-steam-and-diesel engine which had been installed in the Blue Funnel twin-screw vessel Dollius before I was associated with this journal. Briefly, the
engine was single-acting port-scavenged ailess-injection two-stroke on the top side and a steam engine on the lower side of the piston. Exhaust gasses and the circulating cooling water provided a high degree of recovery of what would normally he waste heat. This was used to generate steam to provide power on the lower sides of the pistons the steam side was arranged as a compound engine. Starting and manoeuvring were both done by steam and the scavenging air blower was driven by a steam turbine. The installation was naturally complicated but Scotts' designers contrived to make the engine accessible. The Dolius ran satisfactorily until she was sunk in the second war. Alfred Holt'S friendly and widely respected “super” the late Sterry B Freeman, told me that his staff liked the installation.
In 1928 a second Scot-Still-engined ship, the twin-screw Eurybates, was commissioned with a simpler and, many of us thought, better version of the StilI concept. It could best he regarded as a two-part engine. The six forward cylinders were two-stroke single-acting port-scavenged (with rotary valves after the exhaust ports) airless-injection diesel, followed by two double-acting steam cylinders with piston valves actuated by Marshall-type valve gear. After leaving the main cylinders, the low-pressure steam was used, as in the Dollius, to drive the scavenging air blower turbine. The total power from those eight cylinders was a modest 25OObhp at 105 rev/min.
These two ships were, it is believed, satisfactory in service and undoubtedly proved that Mr StilI's ideas, whatever their complexity and cost, made for superior fuel economy. I was never a StilI fan, believing that most owners would be frightened off the idea and that improvements in combustion in "ordinary" diesels, supplemented by waste-heat boilers, would before long be just as economical, with advantages in simplicity, first-cost and maintenance. No other StilI-engined ships were ever built but some years later Scotts' produced a single-acting airless-injection diesel very similar to the oil engine end of the Eurybates' machinery. Of 500bhp per cylinder t had a Still type liner and the rotary valve in the exhaust outlet from each cylinder. It was a nice design and a six-cylinder version powered a vessel for Far Eastern Service.
Early in 1926, the always friendly, and co-operative H Kent Norris, director and general manager of Plenty & Son Ltd, asked me to go to Newbury to see his conception of the StilI engine principle for trawlers and other lower-power craft. The single-cylinder crosshead-type engine he showed me was as ingenious in design as the bigger Scott-StilI engine, but quite different. With a power of no more than 130/l50bhp at 250rev/min it also worked on the port-scavenging two-stroke principle, with StilI-designed in-jection equipment. The lower cylinder cover carried poppet-type inlet and exhaust (steam-side) valves and was extended upwards to almost fill the annular space between piston rod and piston skirt. Oblique holes in the piston rod allowed steam to pass to a central passage and thence to the hot underside of the piston. A modest “steam” mean pressure was developed and the steam also provided piston cooling.
In practice the steam assistance enabled the mechanical losses of the engine to be almost taken care of, inducing those of the rotary scavenge blower, so that the mechanical efficiency approached 100 per cent. The steam generating and exhaust gas feed water regenerating equipment were of straight-forward design but the experimental engine was non-condensing.
Realistically regarded, the quite elaborate engine did not strike us as having much potential appeal for trawler owners despite its economy, the use of boiler oil, and a facility to trawl on steam only.
Some time later I paid a return visit to Plenty's works and asked how the new engine was progressing. Mr. Kent Norris gave a quizzical look and this memorable
reply:
"Plenty bloody Still, old boy"
Noel Coward or Bob Hope could not have quipped better. Yes, the Plenty-StilI engine died on the test bed where it was almost stillborn; sad for those who had put so much into it but clearly they saw that the difficulties and handicaps out-weighed its hopes of commercial success. Looking back, one wonders why anyone with a combination of technical and industrial realism should have backed such a complex</HTML>
I traced back the article I referred to it appeared in “Shipbuilding & Marine Engineering International”. In two instalments in December 1979 and Jan/Feb 1980 it was called “I REMEMBER” and it was written by a former editor G.R Hutchinson. It describes a great number of exceptional marine engine developments mainly Diesel. I have copied the Still engine part of it The article however also shows a section of the Scott Still enigine The following is the transcript:
Arnoud Carp
Best of both Worlds?
An even more ambitious - and complex - design venture was the Scott-Still combined-steam-and-diesel engine which had been installed in the Blue Funnel twin-screw vessel Dollius before I was associated with this journal. Briefly, the
engine was single-acting port-scavenged ailess-injection two-stroke on the top side and a steam engine on the lower side of the piston. Exhaust gasses and the circulating cooling water provided a high degree of recovery of what would normally he waste heat. This was used to generate steam to provide power on the lower sides of the pistons the steam side was arranged as a compound engine. Starting and manoeuvring were both done by steam and the scavenging air blower was driven by a steam turbine. The installation was naturally complicated but Scotts' designers contrived to make the engine accessible. The Dolius ran satisfactorily until she was sunk in the second war. Alfred Holt'S friendly and widely respected “super” the late Sterry B Freeman, told me that his staff liked the installation.
In 1928 a second Scot-Still-engined ship, the twin-screw Eurybates, was commissioned with a simpler and, many of us thought, better version of the StilI concept. It could best he regarded as a two-part engine. The six forward cylinders were two-stroke single-acting port-scavenged (with rotary valves after the exhaust ports) airless-injection diesel, followed by two double-acting steam cylinders with piston valves actuated by Marshall-type valve gear. After leaving the main cylinders, the low-pressure steam was used, as in the Dollius, to drive the scavenging air blower turbine. The total power from those eight cylinders was a modest 25OObhp at 105 rev/min.
These two ships were, it is believed, satisfactory in service and undoubtedly proved that Mr StilI's ideas, whatever their complexity and cost, made for superior fuel economy. I was never a StilI fan, believing that most owners would be frightened off the idea and that improvements in combustion in "ordinary" diesels, supplemented by waste-heat boilers, would before long be just as economical, with advantages in simplicity, first-cost and maintenance. No other StilI-engined ships were ever built but some years later Scotts' produced a single-acting airless-injection diesel very similar to the oil engine end of the Eurybates' machinery. Of 500bhp per cylinder t had a Still type liner and the rotary valve in the exhaust outlet from each cylinder. It was a nice design and a six-cylinder version powered a vessel for Far Eastern Service.
Early in 1926, the always friendly, and co-operative H Kent Norris, director and general manager of Plenty & Son Ltd, asked me to go to Newbury to see his conception of the StilI engine principle for trawlers and other lower-power craft. The single-cylinder crosshead-type engine he showed me was as ingenious in design as the bigger Scott-StilI engine, but quite different. With a power of no more than 130/l50bhp at 250rev/min it also worked on the port-scavenging two-stroke principle, with StilI-designed in-jection equipment. The lower cylinder cover carried poppet-type inlet and exhaust (steam-side) valves and was extended upwards to almost fill the annular space between piston rod and piston skirt. Oblique holes in the piston rod allowed steam to pass to a central passage and thence to the hot underside of the piston. A modest “steam” mean pressure was developed and the steam also provided piston cooling.
In practice the steam assistance enabled the mechanical losses of the engine to be almost taken care of, inducing those of the rotary scavenge blower, so that the mechanical efficiency approached 100 per cent. The steam generating and exhaust gas feed water regenerating equipment were of straight-forward design but the experimental engine was non-condensing.
Realistically regarded, the quite elaborate engine did not strike us as having much potential appeal for trawler owners despite its economy, the use of boiler oil, and a facility to trawl on steam only.
Some time later I paid a return visit to Plenty's works and asked how the new engine was progressing. Mr. Kent Norris gave a quizzical look and this memorable
reply:
"Plenty bloody Still, old boy"
Noel Coward or Bob Hope could not have quipped better. Yes, the Plenty-StilI engine died on the test bed where it was almost stillborn; sad for those who had put so much into it but clearly they saw that the difficulties and handicaps out-weighed its hopes of commercial success. Looking back, one wonders why anyone with a combination of technical and industrial realism should have backed such a complex</HTML>
Re: Scott-Still Engine
Posted by: George Nutz (IP Logged)
Date: January 08, 2003 02:36PM
<HTML>Arnoud,
Thanks very much for that great story and all the typing it required to post! Very informative and thanks to this great website and technology a copy is in with my other papers on the Still. Thanks.</HTML>
Thanks very much for that great story and all the typing it required to post! Very informative and thanks to this great website and technology a copy is in with my other papers on the Still. Thanks.</HTML>
Re: Scott-Still Engine
Posted by: Peter S (IP Logged)
Date: January 09, 2003 09:57PM
<HTML>Arnoud,
Thats an interesting article - any chance you could scan any more of those "I remember" articles and post them? Or even the rest of that article which concerns Diesel engines? I am always interested in reading such accounts.
Peter S.</HTML>
Thats an interesting article - any chance you could scan any more of those "I remember" articles and post them? Or even the rest of that article which concerns Diesel engines? I am always interested in reading such accounts.
Peter S.</HTML>
Re: Scott-Still Engine
Posted by: Damijan Ruzic (IP Logged)
Date: August 16, 2004 02:30PM
<HTML>Dear Sirs,
It is obvious that every I.C. engine have 2 enormous money and fuel loosers - cooling system and exhaust system. Both of them are a "FUEL" for steam engine - free of charge. If you have one I.C. engine, regardless how effective it is you can calculate remaining energy (previous lost) multiplied by steam system efficiency as a profit on the top of mentioned I.C. engine efficiency or power (as you wish). Other way to take profit out of waste energy is to heat watter in jacket and inject it into the piston during expansion proces of I.C. engine - very effective way with corosion and polution problems (cheramic and stainless steal might feasibly help a little.)
All is the qvestion of size, money and current fuel price - oh, yesssss!, ECOLOGY! Cut fisil fuel consumption by half and see what will happen?, I would truly like to do that, if there is anybody arround, be wellcome to join forces.
Damijan</HTML>
It is obvious that every I.C. engine have 2 enormous money and fuel loosers - cooling system and exhaust system. Both of them are a "FUEL" for steam engine - free of charge. If you have one I.C. engine, regardless how effective it is you can calculate remaining energy (previous lost) multiplied by steam system efficiency as a profit on the top of mentioned I.C. engine efficiency or power (as you wish). Other way to take profit out of waste energy is to heat watter in jacket and inject it into the piston during expansion proces of I.C. engine - very effective way with corosion and polution problems (cheramic and stainless steal might feasibly help a little.)
All is the qvestion of size, money and current fuel price - oh, yesssss!, ECOLOGY! Cut fisil fuel consumption by half and see what will happen?, I would truly like to do that, if there is anybody arround, be wellcome to join forces.
Damijan</HTML>
Re: Scott-Still Engine
Posted by: mande (IP Logged)
Date: February 24, 2005 07:35AM
<HTML>i want to design a small steam engine. how does the turbuns have to look.</HTML>
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