Su-Do-Khoi harrier
Some of that could be CG. Fly inverted, it should almost fly hands off, just a touch of down needed to hold level flight.
The harrier is a real balancing act. Are you running out of up elevator when the nose falls out? More throw? Nose too far forward? You may have to burp the throttle to "kick" the tail back under the nose. Burn lots of fuel, practicing is half the fun.