The Data Server setting controls which Content Distribution Network (CDN) is used in connection with your account. A CDN is a network of servers that behave as one very fast server. When a data transfer request is made, the server that is physically closest to you is automatically chosen. Data updates are transparently mirrored throughout the rest of the CDN.

RCadvisor uses two CDNs behind the scenes to speed-up file transfers. One CDN is in the United States and the other in Europe. Large files such as the calculator, tutorials and airfoils database are downloaded from the chosen CDN. Your user data is also stored in the CDN that you selected.

The features available to you are identical regardless of which CDN is selected. This setting is totally unrelated to the Imperial/Metric unit setting. You can also change this selection at anytime through your account settings. But keep in mind that your saved data is not mirrored across networks. Data that was saved in the United States CDN will not be visible if you change the setting to use the Europe CDN.

Picking the ‘wrong’ location will probably make large file downloads (such as running the calculator) go at less than half the speed. If you live outside these two locations, such as Australia or New Zealand, I suspect that the United States CDN will work better for you.