If you are talking about the 109k4 specifically then it is a fact that this plane can perform a constant E flat turn with all 4 flaps out and wep on. I have personally run down every plane in ah2 flying like this. The k4's power can simply muscle it around and maintain a constant airspeed of about 60 to 80 mph. I am not aware of any other plane that can perform a no altitude loss, constant air speed pure flat turn.
All the other planes will loose altitude during the flat turn but the k4 can keep its altitude in the turn without loosing it. You also need to tap the top rudder some to keep the nose stable but be very delicate with this or it will cause you rapid loss of air speed and you will drop out of the sky.
Agent, I'm going to suggest that you try this offline, with E6B open the whole time. You will find that your air speed is much higher than 80 mph, probably in the range of 115 mph.
MA comparisons invariably are greatly effected by the inability of the vast majority of pilots to get the best turn performance out of their aircraft. If, for example, you are chasing a Spit8 which pulls into a constant left turn, but panics when the stall horn so much as hints at noise, you will out turn him every time.
However, if the Spit pilot is a good stick, he will reef the Spit around hard and turn on WEP. If you try to stay in that circle with a 109K-4, the Spit will fly around the circle and be on your six in less than 4 full turns.
I will also state that every other 109 will turn smaller circles than a K-4 and do it at lower speeds. Indeed, the 109G-2 doesn't need more than a notch or two of flaps to out-turn the K-4, even if the K-4 has full flaps out. That's in left-hand turns. In right-hand turns, the K-4 suffers worse from torque than the G-2 and it's even easier for the G-2 to gain on it.
Of course, seeing is believing, so stop by the TA any evening mid week (after 9 PM Eastern) and we can do a demonstration.
Where the 109s do well is in turn rate. An example is the 109F vs the F4U-1. The Corsair turns smaller circles, but the 109F has a faster turn rate and can hang onto the F4U like glue.
All of the above aside, whatever you are doing is obviously a great success, and nothing succeeds like success.
My regards,
Widewing