xcel
06-16-2009, 01:17 PM
http://www.cleanmpg.com/photos/data/2/European_Union_Flag.jpg Efficiency and performance allow an ascent to undreamt of heights using a BMW engine. (cleanmpg.com/forums/showthread.php?p=215381)
http://www.cleanmpg.com/photos/data/501/BMW_Aero_IV_engine_powering_an_Aeroplane_to_new_heights.jpgWayne Gerdes - CleanMPG (cleanmpg.com) - June 16, 2009
BMW’s power and fuel efficient engine prowess goes back almost a century with an Aero IV powering this DFW F 37/III monoplane to over 32,000 feet.
More fuel efficient than automobiles of the era also!
The cruising altitude of modern airliners ranges from 30,000 to 40,000 feet. It is hard to imagine that a pilot managed to breach those heights a full 90 years ago. It happened with a BMW engine equipped aeroplane which, on June 17, 1919, propelled Franz Zeno Diemer to an altitude of 32,000 feet. If further proof was needed of the superiority of BMW’s high-altitude engines, it was furnished during that summer of 1919 at Munich’s Oberwiesenfeld airfield. No human had previously piloted an aircraft to a greater height.
When Diemer set out on his record flight from the Oberwiesenfeld on June 17, his DFW F 37/III – an altitude aircraft specially developed by Deutsche Flugzeugwerke – was powered by a BMW IV aero engine. Based on the tried and tested BMW IIIa, the new BMW IV engine had its bore and stroke increased by 10 mm (0.40 inches) to boost output from 185 to 230 hp. Perfect flying weather saw the engine deliver consistently excellent performance on that Sunday, enabling Diemer to make a steady ascent to ever greater heights. After 87 minutes he had reached just over 32,000 feet besting every other attempt to attain such an altitude. Diemer announced later that the engine still had more capability but that he had reached the limits of his capacity while reaching an altitude over 3,000 feet higher than the tallest mountain, that being Everest. In an open cockpit, he not only had to contend with temperatures as low as minus 60 degrees Fahrenheit and the low oxygen levels which took their toll.
The challenge Diemer faced during his world record flight was the same underlying problem with which all aircraft engines had to grapple during the First World War: loss of power at altitude. Normally an airplane requires maximum output on the ground in order to take off. With aircraft now forming a separate military arm, the requirements changed. Engine output also became crucial to survival at high altitude while climbing rapidly to escape hostile combat squadrons.
With increasing altitude, air density steadily diminishes and this leads to power loss. Two different concepts were pursued in an attempt to counteract the loss of output in the thinning air. Some manufacturers turned their attention to forced-induction, whereby air was forced into the carburetor by means of a charger. This technology was too complex to bring to production readiness within a short space of time and only established itself in the 1930s. BMW’s head designer Max Friz opted for an over-square, high-compression unit for the first BMW aircraft engine, the forerunner of the BMW IV world record engine. This design principle involved an enlargement of the cylinder volume as well as an increased compression ratio. To avoid overload and an ensuing destructive disassembly, the engine had to be throttled back at take-off and low flying altitudes.
To meet the demands of a high-altitude engine, Max Friz had designed a special carburetor which was to deliver a steady supercharged pressure and ensure a consistent air/fuel mixture ratio. The carburetor was controlled by two levers, one for normal operation and one for high altitudes. By means of these two levers, the pilot could control the throttle valves of the BMW carburetor in such a way that the optimum mix was prepared to suit the aircraft’s altitude at any time. The throttle valves were only opened fully once an altitude of 11,500 to 13,000 feet had been reached. This configuration meant that the loss of power of the IIIa at altitude was less than in other engines.
One of the first advocates of this concept was Franz Zeno Diemer, an experienced flyer who had obtained his pilot’s license in 1913. During the First World War he served as a test pilot in the Bavarian Flying Corps. It was in this role that he came into contact with BMW in 1917 when testing the BMW IIIa aero engine. His record flight in the summer of 1919 won international acclaim although it was denied official recognition. All aviation records had to be confirmed by the Fédération Aéronautique Internationale (FAI) in order to be ratified. Although Germany was a founder member, it had been excluded from the FAI as a result of the First World War treaties. This is why Diemer’s record was never officially entered to the record lists. Even without the certificate, the ascent to more than 32,000 feet was a sensational testimony to the potential of the BMW aero engines.
BMW engines were compelling not only for their outstanding performance, but for their efficiency as well. The first BMW IIIa featured lightweight components in its design. Its crankcase and pistons were made of aluminum, giving a weight of just 630 lb. and a power-to-weight ratio of .3 HP/lb. Diemer’s record-setting engine, the BMW IV, boasted a high for its day, .37 HP/lb. Additionally, Fuel consumption figures demonstrated the superiority of the BMW engine over the early 20th century competition. During partial throttle operation in the 1,050 rpm range, the BMW IIIa consumed seven ounces per hp per hour which was more than a third less than a “normal” aircraft engine in this performance class of the day. In practice it meant that with a supply of around 70 gallons, an aircraft with the BMW IIIa had an operating range of 750 miles, while its competitors with a conventional engine could only travel approximately 450 miles.
Interestingly enough, the BMW IIIa had the edge over another form of transport. On one of his test flights, Diemer made it from Augsburg via Leipzig to Döberlitz in less than four hours with the BMW IIIa engine powering his aircraft consuming just 22 gallons of fuel. Over the same distance, a car at the time took 14 to 16 hours and consumed between 26 and 30 gallons :)
We have come a long way but without understanding where we have come from, our future would be far less intriguing.
http://www.cleanmpg.com/photos/data/501/BMW_Aero_IV_engine_powering_an_Aeroplane_to_new_heights.jpgWayne Gerdes - CleanMPG (cleanmpg.com) - June 16, 2009
BMW’s power and fuel efficient engine prowess goes back almost a century with an Aero IV powering this DFW F 37/III monoplane to over 32,000 feet.
More fuel efficient than automobiles of the era also!
The cruising altitude of modern airliners ranges from 30,000 to 40,000 feet. It is hard to imagine that a pilot managed to breach those heights a full 90 years ago. It happened with a BMW engine equipped aeroplane which, on June 17, 1919, propelled Franz Zeno Diemer to an altitude of 32,000 feet. If further proof was needed of the superiority of BMW’s high-altitude engines, it was furnished during that summer of 1919 at Munich’s Oberwiesenfeld airfield. No human had previously piloted an aircraft to a greater height.
When Diemer set out on his record flight from the Oberwiesenfeld on June 17, his DFW F 37/III – an altitude aircraft specially developed by Deutsche Flugzeugwerke – was powered by a BMW IV aero engine. Based on the tried and tested BMW IIIa, the new BMW IV engine had its bore and stroke increased by 10 mm (0.40 inches) to boost output from 185 to 230 hp. Perfect flying weather saw the engine deliver consistently excellent performance on that Sunday, enabling Diemer to make a steady ascent to ever greater heights. After 87 minutes he had reached just over 32,000 feet besting every other attempt to attain such an altitude. Diemer announced later that the engine still had more capability but that he had reached the limits of his capacity while reaching an altitude over 3,000 feet higher than the tallest mountain, that being Everest. In an open cockpit, he not only had to contend with temperatures as low as minus 60 degrees Fahrenheit and the low oxygen levels which took their toll.
The challenge Diemer faced during his world record flight was the same underlying problem with which all aircraft engines had to grapple during the First World War: loss of power at altitude. Normally an airplane requires maximum output on the ground in order to take off. With aircraft now forming a separate military arm, the requirements changed. Engine output also became crucial to survival at high altitude while climbing rapidly to escape hostile combat squadrons.
With increasing altitude, air density steadily diminishes and this leads to power loss. Two different concepts were pursued in an attempt to counteract the loss of output in the thinning air. Some manufacturers turned their attention to forced-induction, whereby air was forced into the carburetor by means of a charger. This technology was too complex to bring to production readiness within a short space of time and only established itself in the 1930s. BMW’s head designer Max Friz opted for an over-square, high-compression unit for the first BMW aircraft engine, the forerunner of the BMW IV world record engine. This design principle involved an enlargement of the cylinder volume as well as an increased compression ratio. To avoid overload and an ensuing destructive disassembly, the engine had to be throttled back at take-off and low flying altitudes.
To meet the demands of a high-altitude engine, Max Friz had designed a special carburetor which was to deliver a steady supercharged pressure and ensure a consistent air/fuel mixture ratio. The carburetor was controlled by two levers, one for normal operation and one for high altitudes. By means of these two levers, the pilot could control the throttle valves of the BMW carburetor in such a way that the optimum mix was prepared to suit the aircraft’s altitude at any time. The throttle valves were only opened fully once an altitude of 11,500 to 13,000 feet had been reached. This configuration meant that the loss of power of the IIIa at altitude was less than in other engines.
One of the first advocates of this concept was Franz Zeno Diemer, an experienced flyer who had obtained his pilot’s license in 1913. During the First World War he served as a test pilot in the Bavarian Flying Corps. It was in this role that he came into contact with BMW in 1917 when testing the BMW IIIa aero engine. His record flight in the summer of 1919 won international acclaim although it was denied official recognition. All aviation records had to be confirmed by the Fédération Aéronautique Internationale (FAI) in order to be ratified. Although Germany was a founder member, it had been excluded from the FAI as a result of the First World War treaties. This is why Diemer’s record was never officially entered to the record lists. Even without the certificate, the ascent to more than 32,000 feet was a sensational testimony to the potential of the BMW aero engines.
BMW engines were compelling not only for their outstanding performance, but for their efficiency as well. The first BMW IIIa featured lightweight components in its design. Its crankcase and pistons were made of aluminum, giving a weight of just 630 lb. and a power-to-weight ratio of .3 HP/lb. Diemer’s record-setting engine, the BMW IV, boasted a high for its day, .37 HP/lb. Additionally, Fuel consumption figures demonstrated the superiority of the BMW engine over the early 20th century competition. During partial throttle operation in the 1,050 rpm range, the BMW IIIa consumed seven ounces per hp per hour which was more than a third less than a “normal” aircraft engine in this performance class of the day. In practice it meant that with a supply of around 70 gallons, an aircraft with the BMW IIIa had an operating range of 750 miles, while its competitors with a conventional engine could only travel approximately 450 miles.
Interestingly enough, the BMW IIIa had the edge over another form of transport. On one of his test flights, Diemer made it from Augsburg via Leipzig to Döberlitz in less than four hours with the BMW IIIa engine powering his aircraft consuming just 22 gallons of fuel. Over the same distance, a car at the time took 14 to 16 hours and consumed between 26 and 30 gallons :)
We have come a long way but without understanding where we have come from, our future would be far less intriguing.