Living in Arizona has a few benefits and one of those is great flying weather almost all year! Today we took advantage of that and headed out after work to perform a second round of test flights on the new AeroWorks Prox260.
I had originally installed a digital, high speed, metal geared micro servo (much like the Hitec 65MG) and quickly found out the engine vibration was simply too much for it. The servo would arbitrarily freeze up and lock the throttle into position. I built a side mount ply/bass servo box, painted it, and installed a Hitec 5625MG. The weight was not a concern since the ProX is still tail heavy even after moving the chunky XYZ 20cc motor forward an inch. I added 2 1/4 oz of weight to the top of the nose in an attempt to gain some rudder and elevator stability. I really don’t like adding weight to an airplane so I may remove the engine and rebuild the nose section since some modifications are needed to adjust thrust angle (more later).
A quick note about the XYZ 20, out of the box it ran perfectly with no adjustments. This little engine comes with two Champion CM 6 spark plugs and a real Walbro carburetor. Power is excellent, smooth idle, and it sips fuel. I will be buying more of these.
On the radio side, I increased expo from 15% on low rates to 25% on the elevator, reduced expo on ailerons from 30% to 20%, increased expo on the rudder from 30% to 50%, tightened the fuel tank (again), and gave her a try. The high and 3D rates remain the same as the manual suggested.
The first test maneuvers were “The Wall” (full up elevator from horizontal flight) and “The Parachute” (full up elevator from a vertical dive). With each maneuver, the aircraft dropped the right wing in a very harsh manner, sometimes into a spin. The correct for this, I added a small amount of sub trim to channel 6 (right aileron) to adjust the control surface down. This gives you a little more lift on the problem wing to delay the stall.
After implementing this fix, the two previous maneuvers became flat and smooth. Next, I went on to evaluate the performance during a Knife Edge. I added 6 percent left aileron to right rudder and 6 percent right aileron to left rudder. Once I was satisfied with the results, I added 5 percent up elevator to rudder for both orientations.
Then I moved on to some hovering experiments. After all the adjustment, radio mixing, adding weight to the nose, and expo adjustment, hovering became a little more predictable. After several runs, I determined the aircraft wanted to nose down out of the hover. Therefore, I need to remove the engine and reposition it so it will generate a little up thrust.
Lastly, upon landing, I observed a lot of right rudder trim was necessary to counteract the left turning tendencies. I will add some right thrust when I work to reposition the motor. I am hoping these changes will allow me to control some of the torque roll versus her wanting to snap out of the hover. More to come…