Is corner velocity the speed I need to maintain for the max sustained turn rate?
If we are only talking about hard turning engagements, you can try to maintain corner speed but it isn't really possible, as soon as you start turning hard your speed will drop below corner volocity very quickly. You can try to maintain it by turning nose low in a spiral dive but you can only do that while you have the altitude to trade and it will probably not be the right tactical maneuver relative to your opponent, it rarely is. There is an exception to this, and that is when using flaps, because in some aircraft dropping flaps and then turning nose low, in either a split-s or steep low yo-yo can produce high turn rates and small turn radii that can be surprisingly effective at bringing guns to bear, but often leaves your energy depleted.
Corner velocity can be a good place to start a fight because it give you the highest possible initial turn rate. Once you start turning your speed will decay. Ideally you turn as hard as you can so that once you are below corner speed you fly on the edge of the stall, that's called stall fighting, it gets you the best possible turn rate. So you pull hard so you can just hear the aural stall warning.
When you are in a level turn on the edge of the stall your speed will continue to decay until you reach an equilibrium where the thrust matches the drag and your speed remains steady.
That's when you are in a sustained turn. It's called a sustained turn because you can stay in that constant turn indefinitely. That's where you have your best sustained turn rate.
At corner velocity you have your best instantaneous turn rate, because you can't sustain it. Corner velocity and best instantaneous turns is where fights often begin.
Sustained turns is where you are likely to spend most of your time in a fight and its where most fights end.
The columns on the table I posted give the instantaneous data at corner speed in the "Corner speed" column with the corresponding turn rate and turn radius in the "Turn rate at corner" column and the "Turn radius at corner" column, the corner speed, radius and rate at corner are all only momentary, they are instantaneous values that can't be sustained. They are important values because they give you the best entry speed for a hard turning fight and the best re-entry speed after an extension because it maximises turn rate.
For sustained turns when you are on the edge of a stall, the turn rate and radius is given in the "Sustained turn rate" and "sustained turn radius" columns, you don't need to know the speed because you know you are at the right speed when you can hear the stall and feel the buffet. That's where you need to be to maximise your sustained turn rate and minimise your turn radius.
Lastly, I should say that this behaviour only applies to propeller driven aircraft, for jet's it works slightly differently.
Hope that helps
Badboy
