Kit being individually made and procured, and in no sense very uniform, i am inclined to believe that turtle helms might not have existed at all i light of the scarcity of historical artifacts, but i won’t rule out the possibility of individual examples. Metal smiths at this time were very utilitarian in their steel usage for the field, but ceremonial/tournament sorts of helms probably existed and could have been the source of a model.
True, the helmets are in a number of pieces of art and engravings, plus there is descriptions of a helmet the protects the neck and head but would of been expensive as attested in wills.
Equipment was produced in workshops as directed by Charlemagne, he commanded royal stewards to ensure that shieldmakers were resident in every district and charters of Louis the Pious and Louis the German reveal that some monasteries were required to send shields, horses, and lances to the treasury every year. At Saint Gall and Corbie there were scutarii in the monastic workshops who were presumably responsible for equipping the milites and perhaps also for providing the royal gift.
Since shields would not have lasted long in combat, shield-sellers also accompanied the army on campaign, as we know from the report that “scuta vendentes” obstructed Charles the Bald’s troops as they fled after the battle of Andernach.
Royal vassals with twelve or more mansi were required to possess a brunia (scale leather or metal) or lorica (mail coats), and any man who owned such armor but failed to bring it on campaign would be deprived of both his armor and his benefice (payment). Army commanders were encouraged to own helmets or body armor, but the high price of a brunia must have put it beyond the means of all but the wealthy. For example, Count Eccard of Macon included only one brunia in his will, although Eberhard of Friuli bequeathed no fewer than four.
It is evident from the lists of equipment cited earlier that the common infantry and cavalry were not expected to possess body armor, but churches and monasteries apparently owned stocks of armor from which to equip their milites.
Swords were relatively expensive items, and this explains why in Charlemagne’s capitularies only the cavalry, who could afford to own and maintain a horse, were required to possess swords.
Cheers
Matt