Wing CG Calculation

Here are some links to wing CG caclulations I’ve used for starting CG locations, These do not take into account the lift of the fuselage component so I have to start with a more conservative CG like 17% of MAC for boost typically to compensate. For the YF-12/SR-71 I did use the top view of the fuse and used 36% MAC.    Feel free to look at these for ideas in designing your own.  I always do indoor glide testing to confirm these are not marginal before actual flight.

Remember these are relative to the LE of the wing, the kits specify from the rear end of the body tube typically.

The download link at the bottom is a zip directory that contains three openrocket files that you can view in openrocket to see how I’ve modeled the masses of components for CG placement.  Openrocket is not good for modeling CP estimation for an aircraft, and you can’t model low wings or wings with dihedral so I have to use a center mounted wing to estimate.  I do use it for side view stability margin by replicating the vertical stab on two axes and view the CP location compared to my flight CG based on the wing plan and make sure I have 1.5-2 calibers of stability.  Mostly I just  do extensive mass balancing simulations in openrocket once I have my wing CG location approximation to help figure out component weights and where they need to go, locations of the wing, motor, tail and fuse length to optimize tail/wing/component placement to wind up with minimal required nose weight for flight.

Klingon Battlecruiser CG

Dragonship 7/Iron Cross CG

Quest Dragonfly III CG

USS Forrestal CG

Colonial Viper CG

Space Transporter America wing CG

Pegasus XL Wing CG

SR-71 CG

YF-12 CG

OpenrocketFiles