Monday, November 22, 2010

How to find a good CG for 3D flying

We all have wondered, "How do I find a good CG for all 3D maneuvers?" 

First, fly your plane at the manufacturers recommened balance point, and test to see if that is tail-heavy enough for the flying that you want to do. Most likely, it will be too nose heavy, and you will have to bring the weight back. The first thing you want to do to bring the weight back, is move the battery back little by little.

Next, if your battery is as far back as it can go, or as far back as you are going to let it go, test your power to weight ratio, and make sure that you will still have enough power to pull out of a hover and other maneuvers if you add weight to the tail. If you can, add weight to the tail, if you can't, try investing in a lighter motor/ESC to save weight in the nose.

Up until now this has pretty much been review, right? Okay, the main reason why I started writing this is so that I can say my philosophy for finding the right 3D CG.

When I set up my planes for 3D, I make sure they are as tail heavy as I can get them. I achieve this goal safely by moving the battery back in small increments until it can't any more; then I add one 1/4 ounce lead square at a time to the tail right in front of the rudder hinge line. I do this until either the plane will hover nearly hands off, or get squirrely in flight. If I get to the point where the plane gets squirrely in flight, and I have lead on the tail that won't detach itself from the airplane, I move the battery forward a little bit, and then mark the place on the battery tray so that I don't go back beyond that point.

Keep in mind that having an extremely tail heavy CG will make the plane un-precise in maneuvers such as slow rolls and other precision maneuvers. Try and find a CG that works for both, or mark your tray in two places: Extreme Nuts 3D, and a hybrid between precision and 3D.

I hope this helped someone out there! Happy Flying!

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