Determine max. unit with given standard deviation and wager.

[mr.ore]

UNIT = floor( ((36/37)^2*WAGER)/(SD^2 * (PAYOUT+1)^2 * p*(1-p)) )

floor ... round down, ie. floor(2.3) = 2, floor(2.9) = 2
WAGER ... how many units will be bet, ie. exposed to house edge
SD ... limit SD, you bet SD won't go further (SD=-1,-2,-3 or whatever you want)
PAYOUT ... how many units is won if played chance hits, {1,2,5,8,11,17,35}
p ... probability of winning on that chance, {18/37,12/37,6/37,4/37,3/37,2/37,1/37}

UNIT ... maximal unit you should play with

SPINS = floor( WAGER / UNIT )

SPINS ... number of spins to play to "turnover" given WAGER

This formula ensures that if real standard deviation is not greater than SD, your bankroll is fully utilized, for example you will lose WAGER if real standard deviation is equal SD after SPINS spins, but not before that. I hope a have it right...