Originally Posted by Iflyrc_vic
What flight times do you get with the 5000mah battery? At 22 volts (6S), you must be pulling 80+ amps!
I see a good price on a Scorpion S4035-380kv motor that is a little bigger and heavier than the S4025-12. With the lower kv, I would have to prop it up to a 17 x 10 to get 1544 watts and 5300 grams thrust on 6S batteries. The legs are pretty long on this plane so it may handle the 17 inch prop. That may also be a good choice since you had to add weight to get the CG right. Any thoughts?
What are the major differences in how these two planes fly?
Sportster flies like a stable sport plane, though you do have to fly it all the time, just like the R3. But the R3 has certain peculiarities owning to the short tail moment and tail feather shape. It tends to be porpoisy (expo helps) and I have found on my foamy Cermark Fantasy Racer (same plane in foam, 51") that the plane requires a good bit of rudder on roll-out to counterract p-factor. And as G-Forced has indicated, these planes require a good bit of rudder input for coordinated turns. Even with full aileron differential, these planes will drag the high wing in turns. Finally, the forward gear location means tricky ground handling and a tendency to bounce on landings, so you have to be good at power-on wheel landings.
Besides that, many who built this plane did so way too heavy, so some of these had huge wing loading, which is never good. Try to keep your weight to 7lb. It can be done if you build forward.
I'd suggest getting the Cermark FR to practice. At $100 PNP, you can't go wrong.