Since nobody wants to read the link ( :P ), I'll post the contents here.
With due apologies to 109lair, and full credit to them, link to the direct source already given etc.
The rest of this thread is from the previously shown link:
Every so often, a verbal skirmish will break out over this seemingly contentious issue... "It's Bf 109!" "No, it's Me 109!" "Bf!" "Me!!" Frequently, this degenerates into name-calling, questioning of parentage, gnashing of teeth, and other such impolite and unproductive activities. Well, today we will conclusively lay this dispute to rest once and for all...
Both terms are correct.
First, a little history is in order. The 109 (8-109, if one wants to be strictly pedantic and refer to the aircraft with the 8- prefix assigned by the RLM to fighter aircraft) was first flown at the end of May 1935 at the home field of the Bayerische Flugzeugwerke in Augsburg, Germany. Design of the aircraft was started in March 1934 under the direction of Dipl. Ing. Willy Messerschmitt, who joined the firm after a merger of his own company, Messerschmitt Flugzeugbau, with BFW as ordered by the Bavarian government. (1) Emboldened by the success of his Bf 108, and anticipating certain defeat in the RLM's fighter design competition due to personal animosities, Messerschmitt "went for broke" technologically, incorporating a number of aerodynamically and mechanically advanced features into the 109 such as automatic leading edge slots, trailing edge flaps, flush-retracting landing gear, an aluminum alloy monocoque fuselage, and a fully enclosed cockpit. The results of the competition, of course, are well known today... the 109 won handily due to the inherent superiority of the design, and the rest, as they say, is history.
With the competition decided, production orders soon followed, and further development of the airframe continued. A stream of prototypes and production aircraft issued forth from the BFW factory, and the German propaganda machine wasted no time in trumpeting the superiority of the 109. As part of the continued development of the aircraft, early production aircraft were sent to join the Legion Kondor in Spain, and comprehensively established air superiority wherever they appeared. Unfortunately, these were not the type of accomplishments which readily lent themselves to positive publicity in the eyes of the world... such an opportunity presented itself in July 1937, however.
The Fourth International Flying Meeting was held at D?bendorf in Switzerland between 23 July and 1 August 1937, and the Luftwaffe's latest and greatest aircraft were on hand to show their capabilities. Among the aircraft dispatched to the meet were five 109s, which swept the top spots in every event in which they were entered. With the world press on hand to record the mounting successes of the latest Messerschmitt wonder, the propaganda value of the event was immeasurable to the German government. Further glory was achieved on 11 November 1937 when Dr.-Ing. Hermann Wurster snatched the landplane speed record with an average speed of 379.38 mph on four passes over a 3km straight course. (2)
With this run of incredible achievements, the management of BFW saw an opportunity to maximize on the positive publicity surrounding the achievements of their designer, and on 11 July 1938 incorporated the company as Messerschmitt AG (Aktien Gesellschaft), and Dr. Ing. Willy Messerschmitt was made Chairman and Managing Director.(3) This is a significant turning point in our story of "Bf vs. Me"... heretofore, all aircraft designed under the auspices of the Bayerische Flugzeugwerke carried the prefix "Bf" before the type number to indicate the origin of the aircraft. After the incorporation of Messerschmitt AG, all aircraft designed by the firm carried the prefix "Me", indicating the Messerschmitt factory (e.g. Me 210, Me 323, Me 262, etc).
So, the 109 would therefore only be called a "Bf 109", right? Read on...
As always, things aren't always what they seem. While it is undoubtedly correct to refer to the 109 as the Bf 109, the "Me" prefix was used interchangeably, and not just by outside sources such as American or RAF pilots or licensees such as Erla or WNF, as has been suggested... allow me to demonstrate below.
Exhibit A: Page 1 of a 10 page factory report from Messerschmitt AG concerning high-speed stability tests on Me 109F W.Nr. 9928 (reproduced in full elsewhere here on the site, translation to follow at some point):
(http://109lair.hobbyvista.com/articles/bf-me/exhibit_a.jpg)
Exhibit B: Page 8 from the SAME FACTORY REPORT, from the MESSERSCHMITT FACTORY, by the SAME AUTHOR (Kalinowski), referring to Bf 109F W.Nr. 9928... did it somehow miraculously become a different aircraft?! No, it's obviously still the same aircraft.
But wait, there's more!
(http://109lair.hobbyvista.com/articles/bf-me/exhibit_b.jpg)
For my next trick, I present for your investigation and edification two documents scanned from Vol 1. of the Bethke/Henning Jagdgeschwader 300 books... this first example is an example of an actual Verlustmeldung, or loss report for I./JG300, as typed up at unit level and submitted to the RLM for accounting purposes; note the consistent use of the term "Bf 109" throughout (this is reflected in other Verlustmeldungen copied in the book)(4)
Click for a full-size version.
I'm not done yet... see below! :)
(http://109lair.hobbyvista.com/articles/bf-me/exhibit_c.jpg)
And lastly, from the SAME UNIT, we have the following damage assessment form from I./JG300 concerning an Me 109G-6/AS or G-14/AS.(5)
Click for a full-size version.
Wow... Me 109! Could this be the SAME THING as a Bf 109? Why, it sure is!
(http://109lair.hobbyvista.com/articles/bf-me/exhibit_d.jpg)
And that's not all. Allow me to quote from an 8 December 1942 German radio broadcast from Dr. Ing. Messerschmitt himself, as published in Armand van Ishoven's "Messerschmitt Bf 109 At War":
"With extremely limited means I designed and built a series of sports and transport aircraft which, through their high performance, served as first steps towards a high performance fighter. Soon after, when I received the assignment to develop a fighter, it was evident to me that it would have to derive from aircraft like the M23 and M29. I then tried to equip an aircraft as small and light as possible with a powerful engine, in order to create a fighter that could out-perform anything then known. This was proved clearly at the International Flying Meeting in Z?rich in 1937. Since that time this aircraft has been developed constantly at a hectic pace to meet the new challenges, and improved upon over and over again, so taht to this day our enemies consider it the most successful fighter in the world. In English circles now and then one hears the assertion that they have brought out an aircraft superior to the Me 109. Nothing can better disprove this than the list of our victories. From the steadily improving performance of the Me 109 in the course of this war, and its lasting superiority, you can see that we are actively maintaining this superiority into the future as well."(6)
So, what have we learned today? We've learned where the confusion stems from between Bf and Me, we learned when the changeover occurred, and we learned that the terms are used interchangeably at ALL levels within the Luftwaffe... so they're BOTH right!
Thus endeth the sermon. :)
(1) Wings of Fame vol. 4, Messerschmitt Bf 109- The First Generation. David Donald, p.40.
(2) ibid.
(3) ibid.
(4) Jagdgeschwader 300, Teil I. Herbert Bethke and Friedhelm Henning, p.76.
(5) Jagdgeschwader 300, Teil I. Herbert Bethke and Friedhelm Henning, p.190.
(6) Messerschmitt Bf 109 At War, Armand van Ishoven, p. 184.