Hi Everyone,
Soren requested I join this thread.
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Faber's plane was tested first by the AFDU at higher than permitted settings.
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Do you have documentation showing this blanket de-rating of the BMW801? I certainly do not. However I have a numerous Beanstandungen's which show both JG2 and JG26 operating "de-rated" motors right alongside "normal" motors in June 1942. This makes sense as neither BMW or Focke Wulf list any other settings beside the "normal" ratings.
De-rating is tool to manage engines serviceability. All air forces operate "de-rated" motors. The most common reason for "de-rating" an engine is to burn stocks of inferior grade aviation fuel. All engines are "de-rated" for a period of time when they are brand new. It is called the break in period. BMW801's were de-rated for their first 10 hours of operation. The "de-rating" consists of pre-threaded holes in the throttle mount in which a screw is placed limiting the advance of the throttle. To return the engine to "normal" you remove the screw.
Here is an excerpt from an upcoming magazine article I am writing:
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Like all new designs there were problems to be solved. When it first appeared the motor was extremely unreliable. It’s life expectancy was measured in a few short hours. On 01 August 1941 Oblt. Otto Behren’s Operational Test Squadron, Erprobungsstaffel 190, moved from Rechlin to Le Bourget outside of Paris to begin training the II Gruppe Jadgeschwader 26 on the FW-190A1. Although many minor technical difficulties would be solved over the next few weeks it would not be until the 06 November 1941 that III Gruppes Technical Officer, Rolf Schröder would make the biggest leap forward in reliability for the engine. At BMW’s repair shop in Albert during the investigation into engine failures Schröder noticed that a simple exhaust reroute would prevent the back bottom two cylinders from overheating. The design change was immediately implemented and the aircraft modified both at the Geschwader and the Factory. Within a short period of time, the 8th Stafflekaptain, Oblt. Karl Borris received a gold watch from BMW for having the first engine to reach 100 hours of operational flight time. Borris’s luck would continue to hold as he later survived a fall from 22,000 feet with a collapsed canopy suffering numerous broken bones. Average reliability would now be measured in triple figures for the BMW 801C2 series motor.
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Motors that were modified were not restricted to overland flights.
This exactly what the FW190A1 Flugzeug-Handbuch instructs for the overhaul instructions for the BMW801C2 motor:
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Laut TAGL Nr. 257-42 ist für die zelle die kontrollreihe 200-5 vorgesehen. Das bedeutet, daß nach 200 betreibsstunden eine Teilüberholung und nach 5 teilüberholungsabschnitten eine Grundüberholung durchgeführt werden muß. Für den Motor BMW 801 liegt eine kontrollreihe von 100-1 vor eines jahres keine teilüberholung bei einem flugzeug oder motro vorgenommen, so sind nach einer sonderprüfung die zulassungen zu verlängern. Nach 200 starts muß eine fahrwerkskontrolle eingelegt werd.
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Teilüberholung instuctions can be found in the BMW Flugmotoren BMW801 MA, ML, C, u. D Handbuch und Teilüberholungsanleitung.
All new designs experience some teething troubles. I fear if WWII had started in 1937, the R-2800 would have the reputation as being very unreliable alongside the BMW801!
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Just prior to World War II, engineers at both Pratt & Whitney and Curtiss-Wright worked feverishly to produce the first air-cooled engine capable of more than 2,000 horsepower. The efforts of both teams were nearly thwarted by severe vibration from unexpected sources. This is the story of how the Pratt & Whitney team, through hard labor and persistence, identified and solved the problems with vibration. The result was one of the most successful engines of all times - the R-2800.
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http://www.enginehistory.org/NoShort...Crankshaft.pdf
I loathe getting into a performance comparison discussion. They are in fact very silly undertakings given the facts of the science behind aircraft. All aircraft performance comes from the manufacturer not as absolute performance but rather as a mean average over a guaranteed performance range. Additionally atmosphere was not standard during WWII and testing procedures certainly were not either.
In the case of WNr. 313, the performance as tested by the RAE appears to be pessimistic but not outside the realm of possibility. The climb testing was calculated off four datum points gather from partial "saw" climbs at 3500 feet and 17,000 feet. Rough running of the motor was experienced throughout the test and caused one datum point to be completely disregarded by the engineers. The Tactical Trials of WNr. 313 as tested several days later were cut short due to the rough running of the engine. The RAE then removed the motor and bench tested it to determine mixture settings and timing information. Mixture/Timing adjustments and spark plug change allowed that particular motor to run smoothly on the bench. It was never flight tested and in June 1942 the alkane ratio of C3 fuel was adjusted. This prompted new plugs for the motor and a change in the mixture and timing regulations.
Here is Focke Wulf tolerances:
Here is an RAF memo explaining aircraft performance variation:
Here is the order I would rate these fighters:
#1 FW190
if I was Luftwaffe pilot who flew the FW190.
#1 Spitfire
if I was an RAF pilot who flew the Spitfire.
#1 P51
if I was a USAAF pilot who flew the P51.
All the best,
Crumpp
Linear Mode
