Its all dependant on the drag induced by AOA and the flying style. An F18 would have to be at a minimum 1:1 for me to be impressed. IE KF.

7.5 minutes is what I use. I used a robart (BVM) air cyl and put a spring on it for return.
The probe is from Yellow. They use a nice stainless bolt and insert. it is removable.
I have to say that even though this A4 is old school design(airfoil, construction) it is the nicest little arf available on the market. I have heard that all of thier ARF's are built this nice. You pay about 1800 bucks delivered but I cant do work this nice. Now if I could get the same guys to build something updated and cool...............................