I had the main door open on rotation in my Beech Debonair. Biggest problem was that it was a night flight from a relatively short runway (Serpentine, W.A.). Aborting was hardly an option and I had to let training kick in which meant ignoring the wind and noise and flying on instruments to 500 feet. Fortunately, I had read up on "door open" flight characteristics (both Baron and Deb/Bonanza) after reading of a family of five who perished in the UK after having having the main door open on rotation in a Beech Baron. The pilot had radioed that he was trying to shut the door and he lost control of the aircraft. It wasn't fun but I flew to Jandakot (about 15 minutes) and shut it late in the landing roll. The cause of the incident was that I allowed myself to be distracted after closing and locking the door. A club member had come over to tell me something and I had opened the door to converse and had then shut the door without latching it. Distractions are dangerous. John.