The plane was flown manually first so I could evaluate its suitability for fitting and exploring the operation of an autopilot. I then decided to make a few modifications.
The elevon hinges as the plane is supplied, are moulded from the same foam as the fuselage and are fairly stiff. These hinges were cut and new hinges were formed from reinforced tape on the upper and lower sides. This allows the elevons to move freely over the whole range travel and present a much reduced load on the servos and make them more responsive.
The supplied propeller (9x6) was very flexible and was therefore probably inefficient. The static thrust with this prop. Was 860gm and drew 18.6 amps. When it was replaced with a more rigid Master Airscrew prop.(9x6) the static thrust was about the same but only drew 15 amps. I also tried an APC propeller (9x6). After about a dozen landings, the motor mount was broken by the propeller hitting the ground. The propeller was then replaced with an APC 10x6 folding prop. which was modified so that the blades could not come too far forward and hit the trailing edge of the wing (refer A in the photo). The prop. was also modified with a 1.2 mm thick aluminium plate to prevent the blades from folding back too far and crossing over (refer B in the photo).
The fuselage was modified around the prop. to make it more aerodynamic. I used a sharp steak knife first, then a file and some fine sandpaper to smooth it off. The trailing edge of the wing between the vertical stabilisers was originally square so I chamfered the top and bottom edges to make a sharp edge.
The plane was fitted with a 3S 4500mAh battery and could fly (cruising with no aerobatics) for about 45 minutes. For a bit more power I moved up to a 4S 3000mAh and the cruise time was about half an hour with a reasonable margin for error.
I was able to hand launch it at full throttle without the prop. striking my hand. Hand launching required full throttle and a strong throw with level wings to ensure it did not hit the ground.
This video shows the clearance between the prop. and the hand when launching.
I found 30% exponential on both elevator and aileron made it very easy to control. It glided easily even at low air speeds. Even after a stall, it did not lose very much height before it levelled out again. It can do loops and fly upside down but it does lose a lot of altitude unless you compensate with lots of throttle and elevator. It rolls very slowly so make sure you have plenty of height and airspeed before you try.
It is well suited to autopilot controlled cruising flights.
It is not easy to land the plane so that it slides smoothly along the grass. The rounded shape of the underbelly almost always makes for a bumpy landing. A good landing plan is to ensure the throttle is off and glide the last meter or more of altitude keeping level pitch and roll.