Brenner
The Visa has a low drag fuse especially in nose and so is the new Cation plus the Cation has a higher drag tail which is also an advantage for the Contra conversion. Both of these will be better airframes than the De Ja Vu for a Contra. My De Ja Vu requires a big reduction in throw and lots of expo which severly limits the number of input points of travel compared to the stick throw which does not take advantage of our modern radios. This severly limits the accuraccy of the servo at any given stick position. Also in all three cases we need an additional 1" length in the main gear for better prop clearence. At $200 a set for props this 1" insurance is mandentory IMHO! Another item that needs to change on a Contra specific aircraft is the molded in nose ring incidences from the current 1.5 right & 1.5 dowm thrust to 0-0 left-right and .5 down. Without an absolutely accurate datum line and plate this is very difficult to convert in our shops!
Underdw
The P-13 depending on wind will be from 3200 to 3700 mah and the F-13 is roughly 400 mah more. Brenner has a chart that is pretty accurate in showing different prop pitches and gear ratios effecting speed, battery usage, and max amp draw.
Regards
Dick