I think the hangar arc is to do with land utilisation. Given that the airfields were based on a square plot with a circular landing area, the buildings were in one corner with the landing ground occupying the rest.
The rule was not rigid. Horn church hangars were on a convex arc in relation to the landing ground. Hemswell OTOH conforms with the tech site in the SE corner, Kirton Lindsey more so. The arcs use the space better than a straight line. Scampton, from 1916, also has a tight concave arc. Others are in straight lines but a look at the plans show they make best use of space.