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FM/DM threads Everything about FM/DM in CoD |
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#71
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so it was certainly cleared for 5 minutes. However, I previously provided a quote: Quote:
http://www.wwiiaircraftperformance.o...bs-14nov39.jpg states: Quote:
The above memo states that the endurance trials were successful and prompted the recommendation for the use of 12lb boost ASAP. |
#72
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Well there you go.
I am sure that did not magically happen either. I believe one of the other snippets talks about measures to prevent the cylinder head cracks that appeared during the test in the form of replacing existing parts with new ones that were not prone to cracking. That probably paved the way for an increase to 5 minutes. Either way, the notion of +12lbs being using continuously is pure fantasy. Quote:
I am sure a few pilots on all sides rolled the dice and took their chances by violating limits placed on their engines. We hear about the ones who gambled and won. Those who did not win are not around to tell their side of the story. Facts are, according to the FAA's statistics in aircraft accidents, not adhering to published limits is a factor in ~85% of the engine failures in aviation accidents. Believing that pilots routinely violate published limits is gamer thinking and not grounded in reality. Quote:
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Last edited by Crumpp; 06-07-2011 at 08:33 PM. |
#73
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I pointed out to you that the gycol gasket leak reported at 49.5 hours of the 50 hr test was unrelated to 12lb/3000rpm operation as the memo states. Quote:
Dowding's memo states otherwise, and he states "...that some pilots were pulling the plug with little excuse on every occasion..." http://www.spitfireperformance.com/dowding.pdf An engine was flight tested for 49.5 hours of which 8.5 hours were at 12lb boost/3000rpm and the engine life was found to be little effected. I think that you might be having trouble translating some of the documents, http://www.wwiiaircraftperformance.o...bs-14nov39.jpg as there is nothing in the above to indicate excessive wear resulting from 12lb/3000rpm operation. The mods required for 12lb operation: http://www.wwiiaircraftperformance.org/ap1590b.jpg does mention the need for modified cylinder top joints, but then by definition these changes were all made prior to having the boost cutout modded for 12lb operation and the 14 nov 39 memo states that cylinder head problems were unrelated to 12lb operation, but I guess it was felt that more reliable cylinder head gaskets were a desirable feature in combat aircraft and the Merlin in Perspective discusses the problem with coolant leakage in early Merlins and the design changes implemented to correct it. Rapidly changing cylinder head temps were likely to cause leakage problems but by definition prolonged running at 12lb will result in a stable cylinder head temp. Last edited by Seadog; 06-08-2011 at 12:05 AM. |
#74
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#75
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#76
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The title of this thread is "Effect of boost control cutout prior to +12 psi boost modifications".
Arguments about engine behaviour after +12 boost modifications belong elsewhere. |
#77
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What ? No new doc released on that subject in Wwiiarcraft or spitperf dot com ?
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#78
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*Buzzsaw* linked several links in 109 e3b against spitfire II topic, i noticed one thing:
http://www.ww2aircraft.net/forum/avi...2-a-20108.html "The discussion was led by 'Glider' Gavin Bailey, who is a well respected historical journal whose material is subject to critical scrutiny by the best of English historians." He wrote this: 1st August 1940 Memo from Downing re the Handling of the Merlin Engine This note is advising the pilots that there is an increase in engine failures in the overuse of the emergency 12lb boost. The interesting thing is that this memo was sent to ALL fighter groups. Had we been talking about the 16 squadrons or less this would not have been the case. It would have been sent to the squadrons involved. This important information -i think - belongs to this topic.
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