Hi Everyone,
Soren requested I join this thread.
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:
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:
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!
http://www.enginehistory.org/NoShortDays/Development of the R-2800 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