RE: Spark F3A, from Krill Models - SPAIN TEAM
I maidened my 2009 Spark yesterday. I set the CG a bit forward for the first flight. No aileron trim needed. One click of rudder. A couple clicks of up elevator as expected with the forward CG. Two more flights to adjust CG to put it just behind trailing edge of wing tube. With 15% aileron differential, downline rolls are perfectly axial. Following 1bwana1's advice, I backed off on rudder and aileron rates. On the next flight snaps were incredibly crisp - stopping immediately when controls went to centers. I was doing all this in a 15mph (23 kph) wind that was at 45 degrees to the runway - the Spark needed almost no rudder to stay on a nice line parallel to the runway - it weathervanes almost perfectly.
Landing was quite different in the cross wind compared to my 25% ExtremeFlight Yak and 35% Comp-Arf Extra: instead of needing to add rudder to rotate the nose into the crosswind, I needed just a touch of opposite rudder to hold the centerline down the runway.
There is very slight coupling to the gear when applying rudder - easily dialed out with a rudder to elevator mix.
Landing is very easy since the plane shows no tendancy to tip stall at low speed.
Power is Neu 1515/3D with 6.7:1 heavy duty gearbox, CC HV-85 ESC, Mejzlik 20x12E prop. More than enough power for great uplines. Also very efficient: My last 8 minute flight used only 2650 mA-Hr from the packs.
With two 5350 5S Flightpower F3A batteries, the all up weight is just slightly over 5kg. I can easily reduce weight by cutting the flight pack batt from 2S-1300 to 2S-850, by reducing main batts to 4300mA-Hr, or by swapping out the 1515/3D for a Neu F3A-1 Motor or by replacing the 8oz P42 gearbox with the 2.3oz P32 gearbox.
Amazing plane that looks marvelous on the runway or in the air and flies with no effort at all.