I can't get the WWI Sopwith Camel plane off the ground!
I had this problem at first, when I downloaded BIS' bonus Sopwith Camel addon and sample missions for OFP 1.90 and above. Fortunately, OFP reg Harnu taught me the tricks of flying this biplane. When you start on the runway, don't touch your mouse. For that matter, I recommend you don't touch the flaps either.
Rev your engine up full throttle. When you hit 64 kph, keep your mouse level. When you start gaining altitude, very gradually move your mouse up to climb higher.
It took me a few tries but I'm a regular Eddie Rickenbacker now!