# How can I calculate the C.G height for an Aircraft?

before I continue I would like to thank you guys beforehand for the help. I am new to this forum and in aviation in general. I am helping my professor to obtain the C.G coordinates in x, y , z for a simulation of a Cessna 172 (we are using Tornado for Matlab). From what Ive read, the C.G in aviation is mostly obtained through the longitudinal axis (x), I assume that the y is centered in most cases, but I am wondering, how can I obtain the height of the C.G, can I use the same method as in the longitudinal axis?

I was also wondering, why is it that for the calculation of the C.G you take into account things such as fuel, passengers, luggage and so on, but not other things like the motor, propeller, fuselage, landing gear, etc.?

Sorry if my questions are a little stupid or obvious. Thank you for your help!

• Interesting question! I have seen questions on lateral CG before, but never vertical. However, I don't think there is any real practical value in this exercise since the vertical axis of the CG doesn't have any real effect on the flight characteristics. At least none that I have ever encountered or even mulled over theoretically... Apr 30, 2020 at 19:27
• @MichaelHall Some models of the Boeing 767 have vertical c.g. limitations expressed as maximum vertical moments. If you want to see an example, go to 747.terryliittschwager.com. Dismiss the initial pop up window, then go to the SERVER box and under the Loads click on the second test file from the top, labeled 2222-01-07_TEST_B767cfgA_N760XX. A window for the load will come up with a problem notification. Dismiss that and then scroll down to the first envelope depicted graphically and you'll see it. It's entitled GROSS WEIGHT LIMITATIONS VERSUS CLIM AND DECK LOADING, VERTICAL CG UP TO 42". Apr 30, 2020 at 23:08
• Vertical CG may not vary much for pax and luggage for a 172, but for a "from scratch" design it is needed to determine side force torque from area above and below it. The builders of the 172 did a terrific job, and, judging by its reluctance to roll too much in a side slip, it would be near the midpoint of areas top and bottom, somewhere near the pilot's sitting place. Apr 30, 2020 at 23:17