Well I'm not an engineer nor a scientist heck I can't even spell it right.
But I have been doin a little playin with the air flow and oil temp on the Trike.
As most of you know, I have a 120r motor in my trike, and the oil temp can get hot. I don't want it above 240 and would like it at 230.
I have found when looking at the oil temp guage; lowers on or off no differance on oil temp but more hot wind on me. Opened or closed, no differance on oil temp, just more or less hot air on me.
Without fork deflectors, no differance on oil temp, but more hot air on me, and also a lot of air under my chin.
So I put the lowers and fork deflectors back on. If I want more air on me, I will open the lowers and the bat wing deflectors.
I had the stock oil cooler removed and installed the Ultra oilcooler with fans. Works like a champ.
Bottom line. Fork deflectors work and do not hurt the air flow of the motor that I can see.
Disclaimer; I did not shoot with a temp gun, and ain't gonna.