Probably the R in Old English was trilled or rolled. They’d travel along with the R for an extra beat before moving on to the next letter. Put your tongue near the roof of your mouth and vibrate the air. For a trilled or rolled sound, touch the roof of your mouth right behind your teeth and do it again. Drumroll please. Faster! 

Carve a straight path up. Now send a crooked road traveling back down the side.