The most promising proposals were based on conventional principles of aircraft design, and would have yielded aircraft very similar in configuration and capability to the Allied heavy bombers of the day. These would have needed ultra-long range capability similar to the Messerschmitt Me 261 maritime reconnaissance design, the longest-ranged intended design actually flown during the Third Reich's existence. Many of the developed designs, themselves first submitted during 1943 suggested tricycle landing gear for their undercarriage, a relatively new feature for large German military aircraft designs of that era.