Talk:Center of pressure

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In America, engineers use the abbreviations cg for center of mass (or gravity) and cp for center of pressure. Where are the abbreviations CoP and CoM from?--192.146.217.206 22:23, 25 August 2005 (UTC)

[edit] CoP and aircraft stability

Guys, there is no direct connection between the CoP position and aircraft stability! An airplane can have its CoP either ahead or behind CoM and still be statically stable.

As usual, CoP is confused with aerodynamic center. When I have time, I'll write an article about the aircraft stability and aerodynamic center, but so far — be alarmed.

P.S. A good starting point for those interested could be http://www.grc.nasa.gov/WWW/K-12/airplane/ac.html

Sergey Khantsis 11:40, 7 November 2005 (UTC)

There's no direct connection between AC and stability either. But certainly the comments about the relationship between CoP and CoG for basic flight is accurate. Additionally, if your CoG-CoP moment is beyond the control capabilities due to loading, you crash. That's close enough to direct in my books. And those books are pilot and failed physicist. I will agree, however, that a full explaination of stability would be a good addition. Maury 14:06, 20 November 2005 (UTC)

Well, in terms of control limits - certainly, the distance between CoG and CoP does have a direct effect. However, as long as there is enough control moments, stability is described by stability derivatives, most notably pitch moment by angle of attack (or CL), which is determined by the distance between CoG and AC (not CoP!). Yes, 'in general terms' CoP is required to be behind CoG; nevertheless, if, for example, wing CoP moves backward with the angle of attcak too fast (and this can happen in some circumstances, e.g. special airfoil), it can be easily placed in front of CoG without affecting the aircraft's static stability (because AC will be still behind the CoG). Sergey Khantsis 17:49, 27 November 2005 (UTC)