The Gonfanon (battle flag) of the Hospitallers was a red flag with a white cross on it. There is no black flag with a white cross, that didn't exist. Furthermore, the Maltese Cross was only used in the later period when they were no longer fighting in the holy Land (in the 12th and 13th century), and had their headquarters on Malta (after 1530). They started with a simple latin cross, which transformed over time into the cross Pattée, Branchee and Moline, which seemed to have been used throughout the 13th century. So I'm sorry to say, these flags may look good but are historically incorrect in the context of the crusades. The red flag with the maltese cross can be placed somewhere around the 16th century.
The Gonfanon (battle flag) of the Hospitallers was a red flag with a white cross on it. There is no black flag with a white cross, that didn't exist. Furthermore, the Maltese Cross was only used in the later period when they were no longer fighting in the holy Land (in the 12th and 13th century), and had their headquarters on Malta (after 1530). They started with a simple latin cross, which transformed over time into the cross Pattée, Branchee and Moline, which seemed to have been used throughout the 13th century. So I'm sorry to say, these flags may look good but are historically incorrect in the context of the crusades. The red flag with the maltese cross can be placed somewhere around the 16th century.