Just finished a Seagull Spacewalker and balanced it tonight. Got me to thinking-it's balanced slightly nose heavy on the spot the manual indicates. Some guys have said that the CG point where indicated may not be right. With the plane in the air and assuming it's not doing anything too radical, how does one check for either too tail or nose heavy?

When in flight at full throttle, roll the model to about 60 degrees from horizontal and observe it's path. It'll be obvious which end is heavy if the flight path isn't a gradual downward arc.

Hope this helps.

regards,
DGO

Just roll inverted, it should take just a little down elevator to maintain level flight.

Well, for an aerobatic or pattern plane that is indented to fly "honest", I believe OUTCAST is correct. I also fly straight down with no throttle. The airplane should hold the line without pulling out or tucking under.

For those who are more interested in an easy handling model as opposed to honest handling one, a gradual pull-out during the dive test is preferred. This will compromise some aerobatic ability but provide some self recovery. Alway good for fist flights and beginners.

How many clicks of down trim will this require for level upright flight?

Diving with the engine at idle is used for determining wing incident angle. Inverted flight is a double check for vertical engine thrust angle.

Just roll inverted, it should take just a little down elevator to maintain level flight.

My Hangar 9 Aresti is balanced at the very rear of the CG spectrum and dives abrubtly in inverted flight. Does this mean it is still nose heavy? No, it means that I haven't found a good way of taking the positive main wing incidence out!

JohnVH, it should take no more than 2-3 clicks of trim for level flight inverted.
doctorgo, the way to check the up/down thrust line is from level flight pull to a vertical line, neutral elevator and watch as the model slows. If the model pitches to the canopy add down thrust, to the wheels add up. It is VERY important to have the C.G. where you want it before playing with the thrust line, as a general rule the more the C.G. is moved to the rear, the more UP thrust is needed.

sdt22, Incidence is the angle of the wing measured off the fuselage datum line. I think you will find your problem to be decalage, this is the relationship between the wing and the tail, and the problem could be at either end. Also if memory serves me the H9 recommended balance points for the Aresti are from 26%-29% MAC, this is very conservative and most fly them at around 32%

Im talking level upright flight. My plane took a couple clicks of down for level upright flight, for inverted need a tiny amount of down.

The amount of trim that is needed for level flight has too many variables to use as a reference. If you shorten the control rod or change the servo center the neutral trim setting will also change. If it only needs a touch inverted your very close.