From the Lens Collector's Vade Mecum:

"Heli Orthar, f 6.3 or f 5.2, Layout Pla001. The rear drawn is three glasses and Frerck says the design was legally protected, i.e. probably subject to patent action. The rear cell was usable on its own, and so was the front, so three foci are available. The complete lens was well corrected compared to other lenses such as Q15. It was classed as a wise amateur purchase but was deleted by 1926. The f 6.3 covered 90 degrees, so a 18 cm was used with 13x18 and the cells separately gave also 41 cm (front) and 33 cm rear."