Bob R:
I think mine has too much tip weight too - even though it has none added! I am flying on .015 x 63' lines, are you flying the 46 on 018's? that might be enough to make a difference. As for the rest of the Day 1 test flight experience:
In anticipation of a great test flight the Cardinal was fitted with a "veteran" Brodak 40 that has proved itself numerous occasions on another profile. So naturally the darned thing put up a big fight until it finally started. Got airborne and the engine went rich. Actually meandering between rich and REALLY rich. Could not do much of anything, but did get it inverted and confirmed the tank was in about the right position (might have to raise it a little). At the end of the tank the engine leaped to dead lean for about 10 laps before I shut it off in a loop.
Flight 2 starting was a-kin to flight 1. When we finally got it going the engine went nearly dead lean as soon as it got airborne. Managed to do a couple loops and lazy eights, basically confirming that the wing looked fairly level and suspected too much tip weight. However at that flight speed trim problems are masked. Engine did not sag-out but it was not running very well!
Started checking this and that, messed around with the fuel line routing, discovered the in-line filter was installed backward, but no real smoking gun for the goofy engine runs.
After battling it again on the 3rd start, I got mad & swapped plugs. Started the 2nd flip - problem solved, right? WRONG! Big Art was still wrestling with it to get a needle setting, and it came off the ground a little fast but definitely better than flight 2 and flyable. Indeed, was in the midst of doing a complete pattern when the engine burped out of fuel in the VERTICAL eight!
Finally decided THAT was enough, that there MUST be something wrong, and since everything else was the same, the problem must be with the fuel tank - the only "new" part in the system. Sho'nuff, discovered a MAJOR
leak along the top of the wedge at the back. Dummy, (rather, dumb me!) should have leak-checked (and not just inspected) the tank BEFORE installing!
MORAL OF THE STORY: The engine was TRYING to tell us something was wrong, but we just kept pushing it and forcing it to run. Worse, because the engine was a PROVEN COMMODITY of countless successful flights on the preceding profile, we should have been even MORE suspect if it did not fire right up and run right. BTW if you are keeping score Big Art & I total a combine 100+ years modeling experience. Proves once again that experience is no match for STOOPID - this ain't rocket science folks!
Oh, BTW, the Cardinal really looks like a winner. Got a great corner and the control efforts feel spot-on. Think I might try moving the CG forward a twitch, but even as is it flattens out very well coming out of a corner - so it is not too far off. Also might have to add INBOARD tip weight as there is none to remove from the other wing - NEVER had this happen before!
Tank is fixed, bird is ready to try again...