 Complete the following phrase:  The Farman HF.20 and its derivatives were a family of reconnaissance aircraft produced in France shortly before and during the First World War. It was a refined version of the Farman MF.11 Shorthorn that did away with the types distinctive landing skids, and incorporated design features from Henri Farmans designs. It entered service with the French, Belgian and Serbian armies in 1913 two aircraft conducted reconnaissance during the 