It sounds like you posit that the arms are supporting the weight of the body. Should not be necessary - and in fact trying to get newbies to forward roll via the advanced concept/technique/proficiency of unbendable arm is exactly how many of us ended up with AC shoulder separation injuries within the first few months of training.
Suggest you look back at this thread and check out Ellis Amdur's approach: breakfalls first, then rolls.
Personally, I wished I'd had been taught falling by a judo person rather than the standard aikido way.
To Janet the practice methods I propose are good for the AC joints.
Breakfalls as taught to me by Mike Murakami Sensei at San Fernando valley Judo dojo have rewritten the way I take Uke. I teach Mike Sensei ukemi in my Aikido classes. Also I believe the thread regards teaching Rolls, not breakfalls! To develop a practical front roll;could require hand arm and shoulder training. one way to train, is work hand standing, and crawling. Some postures as in yoga can get to work on hand arm and shoulders.
Janet in the use unbendable arm while in front roll my bodyweight would not be static, but would revolve around a sphere, I would roll as if in the clouds, free from all AC anguish.