calum douglas - Academia.edu (original) (raw)
Papers by calum douglas
<jats:p>This chapter contains the references listed by Dr. Kollmann himself. Some of the ci... more <jats:p>This chapter contains the references listed by Dr. Kollmann himself. Some of the cited books can be found on the used book market, e.g., https://www.abebooks.com/books/used-books.shtml (in original German only). They can also be located in big libraries, e.g., the British Library in London.</jats:p>
<jats:p>The operating point where the compressor speed lines, and the engine's operatin... more <jats:p>The operating point where the compressor speed lines, and the engine's operating line meet is critical. Thus, improvement of the efficiency at that point is of paramount importance. Through systematic development of the single-stage supercharger by (i) incremental improvements to the compressor impeller, (ii) the arrangement and development of the diffuser vanes, and (iii) the shape of the outer volute/spiral, significant gains in the performance of the single-stage compressor have been made.</jats:p>
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
Prof. Dr.-Ing. Kollmann is one of the most important aeronautical engineers in the story of pisto... more Prof. Dr.-Ing. Kollmann is one of the most important aeronautical engineers in the story of piston aeroengine development in Germany in WWII. In 12 years, Dr.-Ing. Kollmann progressed from the role of senior engineer to chief engineer of the aeroengine design department in Daimler-Benz. This book is an historical record of his own engineering work in developing high performance piston aeroengines. The original document that Dr.-Ing. Kollmann wrote in 1947 is presented here in English with extensive additional material by the authors.
Energy losses are of great significance to the automotive and motorsports industries. Many of the... more Energy losses are of great significance to the automotive and motorsports industries. Many of these losses are incurred during power transmission through the gearbox. There has been considerable research in this area; however, generally gear losses are not calculated at part load condition, nor are so-called dry sump systems considered outside of motor racing. The method developed by Anderson & Loewenthal, which considers efficiency over part-load conditions is used here to calculate geartrain losses with varying speed, load and temperature conditions in a spur gear type gearbox for motorsport application. Both oil bath (wet sump) and oil jet (dry sump) systems of lubrications are considered. The Changenet method is used to calculate the churning losses in the typical oil bath lubrication system. Seventeen different mineral and synthetic oils were evaluated. At 75 kW engine output, 1200 W were lost in the dry sump gearbox whereas 1320 W were lost in the wet-sump gearbox – in first g...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
In the early days of aerospace turbomachines, the value of curved vanes for higher efficiency was... more In the early days of aerospace turbomachines, the value of curved vanes for higher efficiency was appreciated while designing aeroengine superchargers during WWI1. Consequently, the first design trade-off was between mechanical stress (i.e., the impeller diameter) and efficiency. In particular, a straight vane produces a higher pressure head compared to a backward curved vane. Furthermore, as the impeller RPM and diameter (i.e., the impeller tip speed) increase, the straight vane produces lower bending stresses vis-à-vis the curved vane that tries to “straighten” itself.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
As discussed in Chapter 2, the supercharger (basically, an air compressor) can also be driven by ... more As discussed in Chapter 2, the supercharger (basically, an air compressor) can also be driven by an exhaust gas turbine. In this case, the overall system is referred to as a turbocharger or turbosupercharger (Abgasturbolader in German). The focus in Kollmann’s manuscript is exclusively on radial compressors used as superchargers driven by a gear drive connected to the main engine shaft. This is not so surprising considering that, although significant R&D effort was spent on the turbine design (especially, turbine blade cooling), turbocharged German aircraft engines did not enter service until the end of the war. Even then, the service experience was limited to Junkers Ju 388 (mostly for high altitude reconnaissance) powered by two 1,500-HP BMW 801 J turbocharged engines. Many other designs (e.g., the DB 623) were eventually abandoned. The dilemma facing the German engineers at the time (1940s) was this: whether to develop an aircraft engine from the get-go with a turbocharger or to ...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
There were a number of aircraft and engine manufacturers active in Germany in 1930s and 1940s. So... more There were a number of aircraft and engine manufacturers active in Germany in 1930s and 1940s. Some were quite well known, e.g., Messerschmitt (former Bayerische Flugzeugwerke), Focke-Wulf, Junkers, Dornier, etc. Some others were rather obscure, e.g., Hamburger Flugzeugbau, Klemmflugzeugbau, etc. The Reichsluftfahrtministerium (RLM) had a rather convoluted designation system (they thought that it was an improvement over the older one, of course) to provide a (supposedly) simple and unambiguous identification of every German civilian and military aircraft and its corresponding airframe design. Manufacturers were represented by two letters: the first letter in upper case, the second usually in lower case. A selection of the most famous ones is listed in Table 12-1. It should be noted that a mass-production model by a certain manufacturer, say, Messerschmitt Bf 109, were manufactured in the factories of other manufacturers (e.g., Fieseler or Gotha) under license. This system was under ...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
The idea of precompression of the cylinder charge air is as old as the internal combustion itself... more The idea of precompression of the cylinder charge air is as old as the internal combustion itself. It is generally accepted that the first supercharger design in the modern sense was actually a turbocharger, patented in 1905 by the Swiss engineer Alfred Büchi (1879-1959). It comprised an axial compressor, an aftercooler and an exhaust gas turbine applied to a radial piston-cylinder engine as shown in the German patent drawings in Figure 8-1. Not surprisingly, it took him more than two decades to make the system work due to low component efficiencies, i.e., the problem that bedeviled all early gas turbine inventors due to the insufficient knowledge of aerodynamics.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
In Chapters 4 to 8, the main issues encountered in the development of the centrifugal supercharge... more In Chapters 4 to 8, the main issues encountered in the development of the centrifugal superchargers were considered. Many topics had to be ignored in order to focus exclusively on the state-of-the-art (Authors’ Note: in 1947). Specifically, the two issues of intercooling and boost pressure control were not covered in requisite depth, except where they affected the thermodynamics of the compressor operation itself.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
High rotational speeds of the impeller call for careful bearing design and layout, not just those... more High rotational speeds of the impeller call for careful bearing design and layout, not just those on the supercharger impeller shaft itself but also on any preceding shafts, which may run at lower speed. The question of whether to use plain (journal) bearings or rolling element bearings can only be decided after a complete evaluation of the overall design of the supercharger drive system in question. Journal bearings are in general smaller in outside diameter and despite the higher overall length have a lower weight than rolling element bearings. Journal bearings demand several times the lubricating oil flow rate than rolling element bearings, and they also exhibit high sensitivity to particulates in the oil and the overall quality thereof.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
Dr. Kollmann (and his colleagues) were keenly aware that the jet engine was the powerplant of fut... more Dr. Kollmann (and his colleagues) were keenly aware that the jet engine was the powerplant of future. They clearly stated this when interrogated by the British intelligence agents in June 1945 (from Report POW/ENG/6, Evaluation Report No. 539, 16 Apr 46). They thought that the piston engine would still be used for some time to come for transport purposes, but they did not think that it had much application in war time. They anticipated that the jet engines would constitute the bulk of the fleet, to the tune of 60-70%. However, they did not foresee a full demise of piston engines.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
This chapter is where Dr. Kollmann’s original manuscript starts. His introduction of the fundamen... more This chapter is where Dr. Kollmann’s original manuscript starts. His introduction of the fundamental aerothermodynamic principles governing the design of centrifugal (radial) compressors is not in a form that one would find in standard textbooks, vintage or modern. Dr. Kollmann essentially lists the pertinent equations in the form of a ‘crib sheet’ that an experienced engineer would consult in his or her daily work. This is not surprising because, in all likelihood, when he was writing this manuscript (or at least this part of it) Dr. Kollmann did not have access to all his papers and books. In fact, the authors have a suspicion (a rather strong one from the cover page, as shown in the title page of the present book) that Dr. Kollmann wrote this section while he was actually in Allied custody or at ‘home supervision’.
This book is a unique blend of history, technology review, theoretical fundamentals, and design g... more This book is a unique blend of history, technology review, theoretical fundamentals, and design guide. The subject matter is primarily piston aeroengine superchargers – developed in Germany during the Second World War (WWII) – which are centrifugal compressors driven either by the main engine crankshaft or by an exhaust gas turbine. The core of the book is an unpublished manuscript by Karl Kollmann, who was a prominent engineer at Daimler-Benz before and during the war. Dr. Kollmann’s manuscript was discovered by Calum Douglas during his extensive research for his earlier book on piston aeroengine development in WWII. It contains a wealth of information on aerothermodynamic and mechanical design of centrifugal compressors in the form of formulae, charts, pictures, and rules of thumb, which, even 75 years later, constitute a valuable resource for engineering professionals and students. In addition to the translation of the original manuscript from German, the authors have completely ...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
The engines discussed in this book were deployed in legendary combat aircraft, which were flown b... more The engines discussed in this book were deployed in legendary combat aircraft, which were flown by the best pilots that the world has ever seen. In order to reach the ‘ace’ status, a combat pilot has to score five (5) confirmed (not claimed) aerial victories1. A full victory required total loss of the enemy aircraft (not ‘killing’ the pilot, by the way; that is why the correct term is ‘victories’ and not ‘kills’ as in some references). In some cases, a single victory was claimed by two pilots simultaneously, i.e., the two of them contributed to the loss of the enemy aircraft. In that case, each was awarded by a half (0.5) victory (except the Luftwaffe).
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
In Figure 7-1, the power to drive the supercharger is plotted as a function of the rated altitude... more In Figure 7-1, the power to drive the supercharger is plotted as a function of the rated altitude of the engine. For a rated height of 4 to 6 km, the supercharger consumes 10 to 15% of the total engine output. By the time the 22 km altitude is reached, the supercharger consumes (in theory) the same power as the engine driving it, therefore at 22 km rated altitude an engine will provide 1,000 HP to the propeller and require 1,000 HP to the supercharger drive shaft, therefore requiring a total crankshaft output of 2,000 HP.
<jats:p>This chapter contains the references listed by Dr. Kollmann himself. Some of the ci... more <jats:p>This chapter contains the references listed by Dr. Kollmann himself. Some of the cited books can be found on the used book market, e.g., https://www.abebooks.com/books/used-books.shtml (in original German only). They can also be located in big libraries, e.g., the British Library in London.</jats:p>
<jats:p>The operating point where the compressor speed lines, and the engine's operatin... more <jats:p>The operating point where the compressor speed lines, and the engine's operating line meet is critical. Thus, improvement of the efficiency at that point is of paramount importance. Through systematic development of the single-stage supercharger by (i) incremental improvements to the compressor impeller, (ii) the arrangement and development of the diffuser vanes, and (iii) the shape of the outer volute/spiral, significant gains in the performance of the single-stage compressor have been made.</jats:p>
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
Prof. Dr.-Ing. Kollmann is one of the most important aeronautical engineers in the story of pisto... more Prof. Dr.-Ing. Kollmann is one of the most important aeronautical engineers in the story of piston aeroengine development in Germany in WWII. In 12 years, Dr.-Ing. Kollmann progressed from the role of senior engineer to chief engineer of the aeroengine design department in Daimler-Benz. This book is an historical record of his own engineering work in developing high performance piston aeroengines. The original document that Dr.-Ing. Kollmann wrote in 1947 is presented here in English with extensive additional material by the authors.
Energy losses are of great significance to the automotive and motorsports industries. Many of the... more Energy losses are of great significance to the automotive and motorsports industries. Many of these losses are incurred during power transmission through the gearbox. There has been considerable research in this area; however, generally gear losses are not calculated at part load condition, nor are so-called dry sump systems considered outside of motor racing. The method developed by Anderson & Loewenthal, which considers efficiency over part-load conditions is used here to calculate geartrain losses with varying speed, load and temperature conditions in a spur gear type gearbox for motorsport application. Both oil bath (wet sump) and oil jet (dry sump) systems of lubrications are considered. The Changenet method is used to calculate the churning losses in the typical oil bath lubrication system. Seventeen different mineral and synthetic oils were evaluated. At 75 kW engine output, 1200 W were lost in the dry sump gearbox whereas 1320 W were lost in the wet-sump gearbox – in first g...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
In the early days of aerospace turbomachines, the value of curved vanes for higher efficiency was... more In the early days of aerospace turbomachines, the value of curved vanes for higher efficiency was appreciated while designing aeroengine superchargers during WWI1. Consequently, the first design trade-off was between mechanical stress (i.e., the impeller diameter) and efficiency. In particular, a straight vane produces a higher pressure head compared to a backward curved vane. Furthermore, as the impeller RPM and diameter (i.e., the impeller tip speed) increase, the straight vane produces lower bending stresses vis-à-vis the curved vane that tries to “straighten” itself.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
As discussed in Chapter 2, the supercharger (basically, an air compressor) can also be driven by ... more As discussed in Chapter 2, the supercharger (basically, an air compressor) can also be driven by an exhaust gas turbine. In this case, the overall system is referred to as a turbocharger or turbosupercharger (Abgasturbolader in German). The focus in Kollmann’s manuscript is exclusively on radial compressors used as superchargers driven by a gear drive connected to the main engine shaft. This is not so surprising considering that, although significant R&D effort was spent on the turbine design (especially, turbine blade cooling), turbocharged German aircraft engines did not enter service until the end of the war. Even then, the service experience was limited to Junkers Ju 388 (mostly for high altitude reconnaissance) powered by two 1,500-HP BMW 801 J turbocharged engines. Many other designs (e.g., the DB 623) were eventually abandoned. The dilemma facing the German engineers at the time (1940s) was this: whether to develop an aircraft engine from the get-go with a turbocharger or to ...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
There were a number of aircraft and engine manufacturers active in Germany in 1930s and 1940s. So... more There were a number of aircraft and engine manufacturers active in Germany in 1930s and 1940s. Some were quite well known, e.g., Messerschmitt (former Bayerische Flugzeugwerke), Focke-Wulf, Junkers, Dornier, etc. Some others were rather obscure, e.g., Hamburger Flugzeugbau, Klemmflugzeugbau, etc. The Reichsluftfahrtministerium (RLM) had a rather convoluted designation system (they thought that it was an improvement over the older one, of course) to provide a (supposedly) simple and unambiguous identification of every German civilian and military aircraft and its corresponding airframe design. Manufacturers were represented by two letters: the first letter in upper case, the second usually in lower case. A selection of the most famous ones is listed in Table 12-1. It should be noted that a mass-production model by a certain manufacturer, say, Messerschmitt Bf 109, were manufactured in the factories of other manufacturers (e.g., Fieseler or Gotha) under license. This system was under ...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
The idea of precompression of the cylinder charge air is as old as the internal combustion itself... more The idea of precompression of the cylinder charge air is as old as the internal combustion itself. It is generally accepted that the first supercharger design in the modern sense was actually a turbocharger, patented in 1905 by the Swiss engineer Alfred Büchi (1879-1959). It comprised an axial compressor, an aftercooler and an exhaust gas turbine applied to a radial piston-cylinder engine as shown in the German patent drawings in Figure 8-1. Not surprisingly, it took him more than two decades to make the system work due to low component efficiencies, i.e., the problem that bedeviled all early gas turbine inventors due to the insufficient knowledge of aerodynamics.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
In Chapters 4 to 8, the main issues encountered in the development of the centrifugal supercharge... more In Chapters 4 to 8, the main issues encountered in the development of the centrifugal superchargers were considered. Many topics had to be ignored in order to focus exclusively on the state-of-the-art (Authors’ Note: in 1947). Specifically, the two issues of intercooling and boost pressure control were not covered in requisite depth, except where they affected the thermodynamics of the compressor operation itself.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
High rotational speeds of the impeller call for careful bearing design and layout, not just those... more High rotational speeds of the impeller call for careful bearing design and layout, not just those on the supercharger impeller shaft itself but also on any preceding shafts, which may run at lower speed. The question of whether to use plain (journal) bearings or rolling element bearings can only be decided after a complete evaluation of the overall design of the supercharger drive system in question. Journal bearings are in general smaller in outside diameter and despite the higher overall length have a lower weight than rolling element bearings. Journal bearings demand several times the lubricating oil flow rate than rolling element bearings, and they also exhibit high sensitivity to particulates in the oil and the overall quality thereof.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
Dr. Kollmann (and his colleagues) were keenly aware that the jet engine was the powerplant of fut... more Dr. Kollmann (and his colleagues) were keenly aware that the jet engine was the powerplant of future. They clearly stated this when interrogated by the British intelligence agents in June 1945 (from Report POW/ENG/6, Evaluation Report No. 539, 16 Apr 46). They thought that the piston engine would still be used for some time to come for transport purposes, but they did not think that it had much application in war time. They anticipated that the jet engines would constitute the bulk of the fleet, to the tune of 60-70%. However, they did not foresee a full demise of piston engines.
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
This chapter is where Dr. Kollmann’s original manuscript starts. His introduction of the fundamen... more This chapter is where Dr. Kollmann’s original manuscript starts. His introduction of the fundamental aerothermodynamic principles governing the design of centrifugal (radial) compressors is not in a form that one would find in standard textbooks, vintage or modern. Dr. Kollmann essentially lists the pertinent equations in the form of a ‘crib sheet’ that an experienced engineer would consult in his or her daily work. This is not surprising because, in all likelihood, when he was writing this manuscript (or at least this part of it) Dr. Kollmann did not have access to all his papers and books. In fact, the authors have a suspicion (a rather strong one from the cover page, as shown in the title page of the present book) that Dr. Kollmann wrote this section while he was actually in Allied custody or at ‘home supervision’.
This book is a unique blend of history, technology review, theoretical fundamentals, and design g... more This book is a unique blend of history, technology review, theoretical fundamentals, and design guide. The subject matter is primarily piston aeroengine superchargers – developed in Germany during the Second World War (WWII) – which are centrifugal compressors driven either by the main engine crankshaft or by an exhaust gas turbine. The core of the book is an unpublished manuscript by Karl Kollmann, who was a prominent engineer at Daimler-Benz before and during the war. Dr. Kollmann’s manuscript was discovered by Calum Douglas during his extensive research for his earlier book on piston aeroengine development in WWII. It contains a wealth of information on aerothermodynamic and mechanical design of centrifugal compressors in the form of formulae, charts, pictures, and rules of thumb, which, even 75 years later, constitute a valuable resource for engineering professionals and students. In addition to the translation of the original manuscript from German, the authors have completely ...
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
The engines discussed in this book were deployed in legendary combat aircraft, which were flown b... more The engines discussed in this book were deployed in legendary combat aircraft, which were flown by the best pilots that the world has ever seen. In order to reach the ‘ace’ status, a combat pilot has to score five (5) confirmed (not claimed) aerial victories1. A full victory required total loss of the enemy aircraft (not ‘killing’ the pilot, by the way; that is why the correct term is ‘victories’ and not ‘kills’ as in some references). In some cases, a single victory was claimed by two pilots simultaneously, i.e., the two of them contributed to the loss of the enemy aircraft. In that case, each was awarded by a half (0.5) victory (except the Luftwaffe).
Turbo/Supercharger Compressors and Turbines for Aircraft Propulsion in WWII: Theory, History and Practice—Guidance from the Past for Modern Engineers and Students
In Figure 7-1, the power to drive the supercharger is plotted as a function of the rated altitude... more In Figure 7-1, the power to drive the supercharger is plotted as a function of the rated altitude of the engine. For a rated height of 4 to 6 km, the supercharger consumes 10 to 15% of the total engine output. By the time the 22 km altitude is reached, the supercharger consumes (in theory) the same power as the engine driving it, therefore at 22 km rated altitude an engine will provide 1,000 HP to the propeller and require 1,000 HP to the supercharger drive shaft, therefore requiring a total crankshaft output of 2,000 HP.