In 1928 Zaschka carried out experiments with a two-rotor helicopter at Tempelhof Airport in Berlin but they were not successful.
H.J. Nowarra "German Helicopters 1928-1945", 1990
Fatal error: Uncaught mysqli_sql_exception: Connection timed out in /data03/virt15346/domeenid/www.aviastar.org/htdocs/helicopters_eng/zaschka.php:54
Stack trace:
#0 /data03/virt15346/domeenid/www.aviastar.org/htdocs/helicopters_eng/zaschka.php(54): mysqli_connect('mysql5.zone.ee', 'd14657sa18989', Object(SensitiveParameterValue))
#1 {main}
thrown in /data03/virt15346/domeenid/www.aviastar.org/htdocs/helicopters_eng/zaschka.php on line 54