Brian is correct

working out the MAC on just the wing, is all thats needed to get a accurate placement However there are other factors involved in where the plane can use a specific location like Engine thust, and wing inc. they all three work together to make the flight envelope Happy.

The biggest misconception is you can force the wing to lift more than it can, either by adding inc. or adding tail weight. You have to work with the effeciency of the wing, Every wing has a limit, finding that limit gets you on the right track. This limit sets the CG bounderies and the reason you can move the cg from 25-33% with little change in trim. The less inc you use in the wing the more CG affects the elevator trim , because thats when cg affects the flying OAO of the wing, causing a need for elevator trim to keep the wing flying level, to lift the 1G load. Wing inc. is a lifting force, no inc in the wing, no lift. This is also why some don`t understand that the wing is always lifting in up or downlines it never stops working. Down thrust is positive inc, rear cg, is positive inc. and Positive inc. is positive inc. how to use the correct positive inc. to fly the model precisely is where my trim guide helps. The correct positive inc. adjustment must be used.

The reason we see excessive right thrust, ( more than .5) or excessive down ( more than 1.0 deg) is because we exceed the limit of the wings effeciency.#1 ( cg too for back for the wing inc. requires right thrust) Or #2poor wing effeciency ( not enought inc, or the need for down thrust) simple as that. This is where the rudder to throttle mixes and throttle to elevator mixes are required. This is not a bad thing , just an inclomplete trim or a design on the fringes. The cg range is very critical in setting the flight envelope of the airplane,Finding that range is the magic.

Catagorizing the adjustments in the proper order, and compartmentalizing the laws of the adjustments or ,( finding what each adjustment contributes) to the proper flght requirments is where my trim guide takes out the confusion.
However , there is entry,or Basic trimming methods and advanced trimming methods, Such as what it takes to trim an airplane to fly Sportsman, or even just a good knife edge ,and what it takes to fly unknowns. To that point, Experience and Skill seperate the plane deficiency, from the pilot or trim deficiency. This, makes it hard to help everyone.

Some think a pattern plane should fly 45 up lines by them selves with no input , or roll to inverted with no rudder needed. or fly hand off inverted. These are missconceptions perpetuated by so called experts of days gone by, Input and Skill is still required to fly a precision Pattern plane. Years ago we got away with running the cg at 40-43% MAC not any more the patterns are too complicated and demanding, and the speed of flight has been cut in half.

The next problem to work out is how to accurately check the CG , to be able to duplicate the standard and make meaningful adjustments. without a solid standard your spinning you wheels. First find the zero line This is easy, use the stab set to zero trim,
Or if your flying my design use the conopy base. Make a stand to put under the rear of the plane to rest the plane on at Zero.
Put the airplane together on the bench, find a spot to lift the airplane , and mark it in increments of 25-32 % in 2% scale lines.
Here I use the flange on the canopy base and reinforce this area for lifting. I use a carbon tube spread across the flanges,pick the plane up till it perfectly balances and you can set it down with the wheels and tail touching at the same time. That, is your actual CG ,,Now you can procede with confedence and make accurate adjustments. This ,is the most important step in the trimming Process.

The CG trumps All then the wing inc. Then Thrust , Get these out of order and you will chase your tail forever!

Bryan

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