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ORIGINAL: wagen017

This might look like a stupid question, but I still have to ask. Basicly in the past months I have been working on getting my CG right by adding some lead everytime to the tail of my plane. It never seems to end.

The method I use is in level flight to bank the airplane at 60 degrees. The "book" says if the nose goes down, it is nose heavy, if it goes up, it is tail heavy. I check this at the beginning and end of the flight (since the tank is not at CG).

So my question to the pattern fliers is: is this the right method? I would think it is natural for the nose to go down when you bank, since you loose the lift of the wing.

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ORIGINAL: Jeff_edge540

When I setup CG I must first prove that the wing incidences and engine thrust angle are correct. Without these being set you cannot test for good CG.

To test for wing incidences; climb to a very high altitude and push the plane over to a vertical nose dive and cut the throttle to idle. If the plane pitches to the top or bottom you must trim it out. Try to trim with elevator until you get a perfect down run without pitch.

Now, fly straight up at full throttle. Does the plane pitch to the top or bottom? If so, your engine thrust angle is not set right. Add down/up thrust until you can get a perfect up run without pitch (do not touch your elevator trims).

Now, fly straight and level. Does the plane pitch up or down? If so, it is probably a CG problem. Try moving the weight forward or aft to cure the pitching problem without touching the elevator trim. Once you can get straight and level without elevator trim AND get a straight down run (with the engine cut) AND get a perfect up run, you are pretty close to a perfect CG.

Now, roll inverted and fly straight and level.. Does it require a bunch of elevator correction? If so, you have a wing incidence problem. Adjust wing incidence and start the process all over again.:eek:

Ultimately, you should be able to fly staight up at full throttle without pitch problems, fly straight down with the throttle cut without pitch problems, fly straight and level without pitch problems, fly inverted at a 45 degree up angle without pitch problems and fly inverted straight and level with only a slight down pitch.

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ORIGINAL: rcpattern

The easiest way that I've found is put the airplane in a 45 degree climb, roll to inverted and see what it does. If it maintains perfect flight or climbs, then it is tail heavy. You want just a slight drop of the nose from inverted.

Arch Stafford

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