Wikipedia
A Luftwaffenhelfer, also commonly known as a Flakhelfer was, strictly speaking, any member of the auxiliary staff of the German Luftwaffe during World War II. Such terms often implied students drafted (conscripted) as child soldiers.
With a literal translation of "air force assistants", Luftwaffenhelfer (masculine plural) and Luftwaffenhelferinnen (feminine plural) came into being on January 22, 1943, following implementation of the decree Kriegshilfseinsatz der Jugend bei der Luftwaffe ("Youth War Assistance Service in the Air Force").
The order called for drafting whole school classes with male students born in 1926 and 1927 into a military corps, supervised by Hitler Youth and Luftwaffe personnel. The draft was later extended to include the 1928 and 1929 births.
Deployment included ideological indoctrination by the Hitler Youth, military duties and limited continuation of the normal school curriculum, often by the original teachers.
While the official term was "Luftwaffenhelfer (HJ)", the term more commonly used is "Flakhelfer" (" Flak-assistant"). The 1926–1929 births are commonly referred to as the "Flakhelfer-Generation". In German ears the phrase associates with the collective and incisive experience of being torn out of conventional adolescent life (though under circumstances of total war) and being thrown into strict military service and extreme peril, when in the final phase of the war, the AA-batteries themselves became preferred targets of allied strafers.
In August 1944 some 660,000 regular male soldiers and 450,000 female helpers (anti-aircraft personnel) in all departments served with the Luftwaffe within the 'auxiliary antiaircraft defense'. Many of the girls came from the Bund Deutscher Mädel (BDM), although they had to officially join the Wehrmacht, because it was forbidden for BDM-girls to do armed duty. In 1945, "Flakhelferinnen" and other female subsidiaries were trained and allowed to carry weapons to protect themselves.