VPI,
V52 is pretty close to Vmd. The actual number would be loiter minus 10 to 15kts. Remember that loiter is faster than Vmd to allow for turns, poor handling, FATIGUE etc. This is why endurance can be increased dramaticly by flying three eng sub loiter (loiter minus 10 to 15 kts depending on weight). In fact the P3 can do better on three engine sub-loiter than on two engines at loiter, and its better for the peace of mind as well!But V52 was on the placard right in front of me so I would use that when the Flteng had not placarded the loiter speed. I have forgetten the formula to work out loiter, but try a few for certain weights and then compare this to the V52 speed.
Re the 190kt three engine climb: I remember reading a Orion digest once that stated that it was wise to climb to altitude at 190kts on three engines as this was nicely within the restart envelope for the T56 engine/prop combination. I always thought this strange as alot of the time a relight was out of the question, and no other speeds were offered. But I guess it is a good comprimise, and having only one speed for all occasions keeps it simple. I will hunt around and see if I still have any of those digests that I stole (errh borrowed), but I think they were all handed away when I departed all things VP for things Boeing.
Another speed I thought handy to remember was that at 200kts double assy the feet could be rested from the rudder pedals as the rudder trim would now hold all the force.
Now where is my VPI mag?
Don