The good the bad and the ugly.
The good news is that neutral center of gravity trim is at 90 mm She flew very nice at 87mm for the trim flights. With the center of gravity set at the proper 87mm the stabilizer rocker bed should be set at 20mm (NOT the 22.5mm indicated in the manual).She hand launches real smooth. With the center of gravity at 87mm there was no need for downward elevator comp with throttle up. The use of down motor comp was a problem, see flutter issue.
Before I go any further I need to thank Brian Chan for being my helper. Brian is one of the better glider jocks around here. His help was invaluable in getting as much data as I did during these test flight
The bad news is that my set of wings appear to be rather soft (lacking torsional rigidity). All four test flight were flirting with flutter. My first power up after launch had some down compensation. This allowed the aircraft to gain too much speed very quickly. The whole wing center section flutterred along the spar (back side of the D tube) so that the TE moved about 100mm total up and down. The wing should have exploded. The flutter did break loose the flap servos.
Prior to the flutter it was noticed that there was no response to the ailerons under power and almost no response when the power was off. She did respond to coupled rudder and aileron when power was off. After glueing back the flap servos (love the servo mounting pads) and making some adjustments to the differential to try to overcome what we think was aileron induced adverse yaw.
I made my test second flight. Flutter was always near at hand, you could not power up unless the nose was pointed up. A level power run and the wing protested, VIOLENTLY ! With the vertical climbs to 150 meter Brian and I where able to check out the performance a bit. The 1.8 meter long fuselage presents vey well This should help signal lift much better than the normal 1.5 long fuselages. Hoping that some of my flutter issues were as a result of my power, and wanting to test the neutral trim (balance point). I trimmed for level flight with the trailing edge in profile. I put her in a 4 degree dive and watched her accelerate, there was no hint of a tuck (being tail heavy). But the wing tips just started to flutter having only covered about 50 feet. This is a real problem with this model. She still was not responding to ailerons.
Came around for a landing, and in crow she all but stops. I like this but Brian thought I had to much upward aileron spoiler action.
Made some adjustments to the flap and aileron differential This time actually removing any differential the Mike Shellim template as it was thought that the downward flaps (2 down:1 up with my linkage) where the cause of the adverse yaw. The ailerons now had about 2.5 to 1 with the up aileron being 2.5 time more movement than the downward aileron. This flight was a bit better I actually got some roll control in glide. Motor on still needed a heavy dose of rudder. Crow was about the same with 45° up verses my preferred 70° up aileron. So Brian might be on to something.
For the fourth flight I made some more programing changes. Much to my horror I had no directional control and as the model was heading over Highway CA-1 I gave full down command and planted my new Samsara from 8 meter into the Russian olives. The damage to the fuselage in minor. And damage to the wing might be a blessing in disguise as it will allow me to strengthen the D tube center section to try to stiffen the wing.
I think she has a lot of promise as she looks and signals well in the air. I think the roll issue is a function of my radio programing and with a bit of work should be sorted out. Do not fly with more downward flap than upward flap in the aileron to flap coupling. I have concerns about the narrow flight envelope trying not to over speed the model into flutter. This really concerns me as the model never really developed much speed by any measure. Thinking of droping down to a 17x9 prop from the 15x13.
. Well in a perfect situation I guess the rudder should have two seals. For convenience I make them like the wings - 1 hinge and 1 seal. Its not perfect as the hinge is offset but it really does save a hell of a lot of time end effort. But it still does the job pretty well even if you do end up with a slightly asymmetric rudder. To be honest I think the solution used on moulded planes - hinge/wiper - is still better than any you have drawn above.
