Thanks for your reply, yes I managed to buy the three issues of Historische Deutsche Flugzeug bis 1945 form Amazon.de some years ago. The Hans Klemm website is most interesting, though.Ermeio, not sure if you were successful after your nearly eight year wait, but here's a few bits of info just in case.
General characteristics taken from Karlheinz Kens, Historische Deutsche Flugzeug bis 1945 band 1 (Historic German Aircraft before 1945 Vol 1) (in German), published by Baden-Baden: Modellsport Verlag GMBH and on pages. 36 to 41. ISBN 9783 9231 42392.
Length: 5.40 m (17 ft 9 in)
Wingspan: 10.80 m (35 ft 5 in)
Wing area: 13.1 m2 (141 sq ft)
Empty weight: 365 kg (805 lb) approximately
Gross weight: 475 kg (1,047 lb)
Powerplant: 2 × Mercedes F7502a air cooled flat twin, geared down, 14 kW (19 hp) each
Propellers: 2-bladed, 1.85 m (6 ft 1 in) diameter wooden
Maximum speed: 130 km/h (81 mph, 70 kn)
Cruise speed: 110 km/h (68 mph, 59 kn)
Service ceiling: 3,500 m (11,500 ft)
Time to altitude: 10 minutes to 1,000 m (3,281 ft)
Landing speed: about 80 km/h (50 mph)
More info can be found on https://hannsklemm.wordpress.com/modelle-2/l21/ in regards to the type.
A few pics on various websites. (Google is your friend!!)
And finally just so there is some kind of illustration on this post, here's the GA drawing from https://hannsklemm.wordpress.com/modelle-2/l21/
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