Will Rogers
15th Apr 2002, 20:26
Does anyone know how to convert %of MAC and/or %of CG range to index?
Any ideas would be great!
Will :)
john_tullamarine
16th Apr 2002, 00:34
(a) IU is a moment derived dimensionless number, while %MAC is a CG distance. The two are not the same, although they are related each to the other by weight.
(b) to convert %MAC to a CG distance measured from a particular datum is an arithmetic exercise. One uses something like the following to convert ...
CG = (dist to the LEMAC) + (%MAC/100 * length MAC)
(c) if one uses the manufacturer's datum, then the IU is something along the lines of
IU = (CG * weight)/constant
where the constant is a figure chosen to make the IU numbers a bit easier to use.
(d) if, in the more general case - eg with trimsheets, the designer uses a datum different to the manufacturer's, the IU is something along the lines of
IU = A + ((B-C)* weight)/D
where
A is a constant to make the starting IU line at the top of the page whatever you would like it to be
B is the arm measured from the manufacturer's datum
C is the datum chosen by the trimsheet designer
D is a constant used for the same purpose as in (c)
Do please be very careful when doing your own calculations as there are some traps there for young players ...