When I'm playing in single player, if I do the full cold start, or if I do the pre-started missions, it's always the same once i'm in fly mode. Once I release my parking brakes, I roll backwards. I grab for altitude, I spin around, and start fishtailing through the air. I can't null the rudder at all.
I restart the mission from cold start. I don't touch anything. I don't even turn on the battery. Instead of whirling up, I simply apply collective. And as Smeagol would say, "Up up UP we goes!", into the wild blue yonder. I'm doing Mach 1 before 20k ft, and I have screenshots posted in the Steam forum, and tried describing it but nobody was listening. Nobody in game online knew what I was talking about either.
I reinstalled it, with the same results. I'm currently reinstalling again, the open beta version.
I might add, I actually broke 90,000 ft, but I don't have a screenshot. I recorded that sortie, though. The only reason I didn't go higher is because the pilot suffocated.