The French adopted a serial system that initially caused much confusion to the RFC.
French manufactures issued each aircraft with a construction number, which in most cases ran sequentially commencing at 1 (Most British manufacturers simply referred to military aircraft by their military serial and did not issue a separate manufacturers number, one of the exceptions being British and Colonial).
In addition a further sequential 'series number' was issued, commencing at 1 for the first aircraft of each series. Similar types were considered to be one series: for example the Morane L and Morane LA were both considered to be the 'L' series.
French military aircraft received a further number, the military serial or SFA (Service des Fabrications de l'Aviation). The SFA number was shown on the tail of the aircraft, prefixed by a letter or letters code indicating the manufacturer, the principal ones being:
For example: the 325th Morane Saulnier aircraft produced was a type L Parasol, the 164th in the series and was given SFA 259. Technically this is referred to as 325/L164/MS259. Unfortunately however the numbers were frequently shown in a different order, and without the identifying letter, or only one or two of the numbers would be quoted without any way of distinguishing which of the three identification numbers was being referred to.
French aircraft acquired by the RFC after the commencement of the war were flown or sent by road/rail to the Aircraft Park or Squadron, when the RFC serial was applied. Some Caudron and Morane aircraft were sent directly to training bases in the UK without an RFC serial being applied in France and a few of these aircraft seem to have never received an RFC serial at all. A couple of aircraft crashed en route to the Aircraft Park and thus never wore an RFC serial.
Thus French aircraft operated by the RFC had four numbers by which they could be identified (the above, plus the RFC serial). The confusion was added to when the engine number was quoted as well. The book 'British Military Aircraft Serials' quotes serials 5064 and 5067 as duplicated Caudron serials: in fact these are the engine numbers of two Caudrons and there was no duplication (the correct RFC serials of Caudrons C592 and C594 being 5037 and 5038 respectively).
Poor records were kept during the early months of the war and it is impossible to tie up the RFC serials and SFC numbers of all the aircraft acquired by the RFC. The following files represent an attempt to list the known serials.
Bleriot aircraft summary
Caudron aircraft summary
Henry Farman aircraft summary
Maurice Farman aircraft summary
Morane aircraft summary
Nieuport aircraft summary
SPAD aircraft summary
Voisin aircraft summary