Great films, very helpful....thanks for posting them.
I have recently returned to AH last month, after a 5 year flight sim hiatus. 
I started up with the Spit 16 and then moved to the Dora.  It's been tough getting back up to speed (not that I was all that good "way back when" anyways). 
On a whim this past weekend I started flying the K-4 and I was immediately impressed with it.  It seems to be a "best of both worlds type of a/c.  Great climb rate, very good speed and acceleration, decent manouverability, excellent lethality and decent high speed handling.....it only suffers from a small ammo loadout and poor visibility from the cockpit. 
These last two are especially difficult for me since my SA really sucks along with my gunnery skills 
 
 Anyway, I have been doing some research on it's flight characteristics as well as comparing it to the other a/c but I still have a couple of questions about it that some of you may be able to assist with...
What is the corner speed?
What is the max speed for flap deployment?
Thanks,
StuB