Originally Posted by
n90bar
By "set conditions" i assume you mean:-
1) Max available TO power or thrust,
2) Aircraft trimmed for TO,
3) Most unfavourable CG position,
4) max sea level TO weight, no; Vmca is applicable at the MINIMUM flight weight, usually
5) Aircraft in most critical TO configiration with the gear up,
6) The aircraft airborne and ground effects negligble,
7) for props - the inoperative engine prop windmilling or feathered.
These criteria are used to determine Vmca.
FAR 25.149 and equivalent JAR give the precise requirements, and the Flight Test Guides (such as AC25-7A) provide more background on how to test and analyse the results.