Generally speaking these days I think that small planes with manual controls (i.e. your private pilot's Cessna) just aren't capable of going that fast. Most of

Generally speaking these days I think that small planes with manual controls (i.e. your private pilot's Cessna) just aren't capable of going that fast. Most of the planes that will be able to go that fast in a dive will have hydraulically boosted controls if not full fly by wire systems. However this was a real problem during WW2, and high speed dives killed more than a few pilots. By 1942-43 most fighter planes were able to dive fast enough to get into trouble (500+ mph/800 kph) but weren't designed for it at all. The aerodynamics of supersonic flight just weren't understood at the time. In some cases the design of the plane made it essentially impossible to pull out once you went beyond a certain speed, all you could do was attempt to slow down enough to regain control. The P-38 Lightning was notorious for this. I don't have any specific sources handy but I recall reading accounts of things like pilots bracing their feet against the control panel trying to pull the control stick with all their strength, taking extreme measures like lowering the landing gear to slow down (risking it being ripped off and maybe tearing the whole plane apart), or only surviving due to sheer luck - sometimes the thicker air at lower altitudes would slow them down enough before it was too late.