"Stachel" is the German word for sting.
Karl Michael Vogler -- Hautpmann (Captain) Heidermann -- and James Mason -- General Klugermann -- both played World War II Germany's Field Marshal Erwin Rommel: Vogler in Patton, and Mason in The Desert Fox: The Story of Rommel and again in The Desert Rats.
Malcolm Arnold was asked to write the score.
Both the British and the German recon-planes were played by the same French "Caudron Luciole" from the 1930's.
In some scenes George Peppard was actually flying his plane.
On a blackboard in Kettering's office in the film you can see the squadron's name and number, Jasta 11. This was actually the name and number of Von Richtofen's Circus.
One of the stunt pilots was Joan Hughes MBE who had been Britain's youngest female pilot at age 17. In WW2, she ferried aircraft with the Air Transport Auxiliary and was the first female flying instructor qualified to instruct on all military plane types at the time. She became one of Britian's first female test pilots.
One of the stunt pilots was Peter Hillwood, who had flown Hurricanes with 56 squadron in the Battle of Britain. He was killed in an air accident in 1966.
Stunt pilot, Derek Piggott, flew both Stachel's and Von Klugermann's planes for the bridge storming scene. With multiple camera angles (including one from a trailing helicopter) Piggott actually flew under the bridge over twenty times. To prove that the sequence was real, sheep were placed in the field next to the bridge so that they would scatter as the plane approached. However, as can be seen in the continuity, by the 20th take the sheep had become blasé and didn't scatter any more.
Technical advice for the film was provided by a group of WW1 plane buffs from Los Angeles.
The Irish Air Corps also lent their facilities at Casement Aerodrome (Baldonnel) to filming, however after filming, many of the aircraft replicas remained in storage between Casement and Powerscourt House, County Wicklow until the 1980's and were to be seen flying occasionally in the area.
The majority of Stachel's Squadrons aircraft comprises of the "Fokker D.VII", though Stachel himself is first assigned an "out-of-date" Pfalz D.IIIa aircraft and later a Fokker Dr.1 (triplane).
The monoplane back story was based on the events regarding the historical Fokker D.VIII which also suffered from structural weakness and caused at least one death. The aircraft eventually entered service on the 24th October 1918.
The movie takes place mainly in 1918 as stated at the beginning but with no specific date beyond 1918.The historical major offensive featured in the movie, which Stachel and the squadron supported, started on the 21st of March 1918 and was called "Kaiserslacht" by the Germans and "Spring Offensive" in the West. When Stachel was wounded he met the famous Baron Von Richthofen, the latter being killed in action on the 21st of April meaning the wounding and meeting took place between those two dates.
The serial number for Richtoffen's red triplane was 425/17 and was correctly depicted in the movie.
With the exception of the two-seater recon-plane, all the British aircraft featured in the movie, were of the "Royal Aircraft Factory S.E.5" model, or "S.E.5" in short. It was introduced in early 1917 and proved to be an excellent fighter that helped the Allies regaining air superiority in the summer of 1917. It remained in production throughout the war.