radiomike7 Posted June 13, 2020 Share Posted June 13, 2020 10 hours ago, john1950 said: As far as I remember, Napier Deltic engines were developed from a German design. Although the British inovation was having one crankshaft counter rotate to dampen the vibration that was the main flaw in the original design. Having the lower crank rotating in the opposite direction was the only way the correct piston phasing could be achieved between the banks, not to dampen out vibrations. Quote Link to comment Share on other sites More sharing options...
andym Posted June 15, 2020 Share Posted June 15, 2020 That is indeed a K60, presumably from the Swedish S tank. Interesting to see it in a different configuration to "normal"; the oil tank has swapped sides, the hydraulic pump has been blanked off and there only seems to be one alternator, the other having been replaced by what looks like a toothed belt pulley.. Andy Quote Link to comment Share on other sites More sharing options...
David Herbert Posted June 15, 2020 Share Posted June 15, 2020 On 6/13/2020 at 8:49 PM, radiomike7 said: Having the lower crank rotating in the opposite direction was the only way the correct piston phasing could be achieved between the banks, not to dampen out vibrations. That must have been interesting on the Deltic engine, three cranks rotating in opposite directions to each other ! David Quote Link to comment Share on other sites More sharing options...
andym Posted June 15, 2020 Share Posted June 15, 2020 43 minutes ago, David Herbert said: That must have been interesting on the Deltic engine, three cranks rotating in opposite directions to each other ! David From the Wikipedia page: Andy 1 1 Quote Link to comment Share on other sites More sharing options...
radiomike7 Posted June 15, 2020 Share Posted June 15, 2020 On 6/13/2020 at 8:17 PM, terryb said: The Deltic was way ahead of its time, and a modern day redesign smaller capacity deltic would make a truly stunning ultra compact power plant with fantastic hp/litre figures with emissions bought up to date by current electronic injection systems long live the 2 stroke! Yes and no, if the price of fuel is not an issue then it makes sense but the two stroke cycle is not as efficient as a four stroke, ask anyone who has run a Scammell Crusader or a Bedford TM with a Detroit. Even with conventional cam driven poppet valves for the exhaust the Detroit was behind a four stroke. I believe the emissions were mainly a problem caused by the excess oil in the bores needed to ensure the rings did not seize when passing the inlet ports, the Deltic locomotives were known for oil fires in the exhaust drum after a period of idling. Quote Link to comment Share on other sites More sharing options...
radiomike7 Posted June 15, 2020 Share Posted June 15, 2020 1 hour ago, andym said: From the Wikipedia page: Andy It shows the basic concept but not the angle of lead between the cranks. Working out the true compression ratio is quite a job. Quote Link to comment Share on other sites More sharing options...
andym Posted June 15, 2020 Share Posted June 15, 2020 13 minutes ago, radiomike7 said: Yes and no, if the price of fuel is not an issue then it makes sense but the two stroke cycle is not as efficient as a four stroke, ask anyone who has run a Scammell Crusader or a Bedford TM with a Detroit. Even with conventional cam driven poppet valves for the exhaust the Detroit was behind a four stroke. I believe the emissions were mainly a problem caused by the excess oil in the bores needed to ensure the rings did not seize when passing the inlet ports, the Deltic locomotives were known for oil fires in the exhaust drum after a period of idling. There's a company in the USA (whose name I can't remember) who are getting research funding from the DoD to look into high efficiency electronically managed two-strokes, which they claim are more efficient than four-strokes. Times have changed since Detroit diesels! Andy Quote Link to comment Share on other sites More sharing options...
radiomike7 Posted June 15, 2020 Share Posted June 15, 2020 Interesting sequence of a Deltic overhaul, imagine the cost involved compared to a conventional loco engine. Check out the repair history at the end, it was removed from a loco about 30 times in a 20 year period. http://napier-chronicles.co.uk/power_unit_6.htm 1 Quote Link to comment Share on other sites More sharing options...
andym Posted June 16, 2020 Share Posted June 16, 2020 For info, the Deltics in the Hunt Class Minehunters have now all been replaced by conventional Caterpillar diesels. Andy Quote Link to comment Share on other sites More sharing options...
Jerrykins Posted June 16, 2020 Share Posted June 16, 2020 3 hours ago, andym said: For info, the Deltics in the Hunt Class Minehunters have now all been replaced by conventional Caterpillar diesels. Andy For info, the Hunt class were built as MCMV (mine counter measures vessels), the propulsion engines - Deltics & the gen sets - Foden FD12 2-strokes were built to challenging low magnetic specs utilising stainless steel conrods, crankshafts & other components. In service they proved to be very expensive to maintain as a result of the exotic materials employed. The Hunt class strategic requirement is now a Mine hunter &/or Fishery protection vessels, which no longer require a very low magnetic build. In addition degauzing methods have improved, so all the original engines were replaced with conventional designs, which are cheaper to purchase, less costly to maintain & much longer lived. They might have retained the Deltic pulse generators, I'm a bit out of touch now. Quote Link to comment Share on other sites More sharing options...
radiomike7 Posted June 16, 2020 Share Posted June 16, 2020 Foden FD12 on You Tube, were they two 6 cylinder engines geared together similar to the Sherman twin Detroits? Quote Link to comment Share on other sites More sharing options...
Jerrykins Posted June 17, 2020 Share Posted June 17, 2020 7 hours ago, radiomike7 said: Foden FD12 on You Tube, were they two 6 cylinder engines geared together similar to the Sherman twin Detroits? I recall the FD12 was selected for the Hunt class because it's characteristics of low vibration & low magnetic signature were necessary when sweeping above active mines. The FD12 generated electrical power at 1800 r/min, which equates to 360 firing cycles per second, vibration was further minimised by mounting the gen set on a raft with two sets of mounts transmitting little vibration to the hull/sea. Three gen sets were mounted in the hull above sea level further reducing noise transmitted into the water. The crankcase was cast in non-magnetic aluminium, as were many of the auxiliary casings, stainless steel conn rods & c/shafts etc all adding to low magnetic signature. Part way through development Foden decided the work was not for them & the MoD transferred the work to R-R Crewe, presumably because R-R had considerable experience of 2 strokes with the K60, which had proven to be the best 2 stroke in UK military service. When sweeping the ship employed electric only propulsion making the ship was pretty stealthy, noise-wise. It was during the Iraq / Iran war that the Hunt class cleared the passage of mines into Kuwaiti waters for the allies, they did the job well without loss, they were the best ship available to do the job. 1 Quote Link to comment Share on other sites More sharing options...
Alastair Posted June 17, 2020 Share Posted June 17, 2020 In the 1960s Marconi installed a 1.5 Meggawatt transmitter somewhere in the Indian Ocean. The prime mover for electrical generation was a Deltic Diesel. A problem arose with the governor system designed to control the power output to match the electrical demand. If someone came to the microphone and puffed into it (as we all do) the result could be a broken crankshaft because the demand on the electrical supply doubled in a millisecond. The rapid opening of the throttle was too much for the engine. Other than that, my Father, who was associated with the project, spoke highly of the engine. Quote Link to comment Share on other sites More sharing options...
David Herbert Posted June 17, 2020 Share Posted June 17, 2020 I worked for Fodens in the mid 70s and they were still developing the two stroke engines. I remember a new cylinder block pattern being built in the pattern shop. Also there was considerable co operation between Fodens and RR and they routinely did specialized work for each other. The castings for the prototype RR Wankel tank engine were made by Fodens when I was in the foundry there. This engine showed great promise but never went into production, presumably because of reliability problems. The FD12 was indeed two 6 cylinder engines geared together in much the same way as the Detroit twin 6-71. Actually the whole Foden 2 stroke concept was very much inspired by the Detroit 2 stroke and if anything was even louder ! David Quote Link to comment Share on other sites More sharing options...
john1950 Posted June 17, 2020 Share Posted June 17, 2020 Foden 2 strokes do have a lovely sound from a distance. There used to be a concrete company about 3 miles away and you could hear them start about 07.30. Many moons ago. Quote Link to comment Share on other sites More sharing options...
andym Posted June 17, 2020 Share Posted June 17, 2020 10 hours ago, Jerrykins said: I recall the FD12 was selected for the Hunt class because it's characteristics of low vibration & low magnetic signature were necessary when sweeping above active mines. The FD12 generated electrical power at 1800 r/min, which equates to 360 firing cycles per second, vibration was further minimised by mounting the gen set on a raft with two sets of mounts transmitting little vibration to the hull/sea. Three gen sets were mounted in the hull above sea level further reducing noise transmitted into the water. The crankcase was cast in non-magnetic aluminium, as were many of the auxiliary casings, stainless steel conn rods & c/shafts etc all adding to low magnetic signature. Part way through development Foden decided the work was not for them & the MoD transferred the work to R-R Crewe, presumably because R-R had considerable experience of 2 strokes with the K60, which had proven to be the best 2 stroke in UK military service. When sweeping the ship employed electric only propulsion making the ship was pretty stealthy, noise-wise. It was during the Iraq / Iran war that the Hunt class cleared the passage of mines into Kuwaiti waters for the allies, they did the job well without loss, they were the best ship available to do the job. I think you're getting confused between the Hunts and the Sandowns - the Hunts have never had electric propulsion. Andy Quote Link to comment Share on other sites More sharing options...
Jerrykins Posted June 17, 2020 Share Posted June 17, 2020 I am & you're correct. Put it down to it all being a little while ago! Quote Link to comment Share on other sites More sharing options...
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