Believe the He-8 (Danish HM-II) and the He-31 were same basic airframe. Primary diff in the engines: He-8 with the Brit Armstrong Siddeley Jaguar 14-cylinder twin-row radial, and the later, one-off, He-31 with its US Packard 3A-2500 12 cylinder liquid-cooled mill. Attached are additional scans of dejlig Karen Riddell and the HM-II. An early model was built from the RCM plans by professional builder-pilot Dick Hansen and was campaigned quite successfully in the NW seaplane meets. Articles were published in 4 countries/3 languages.