Theory and calculations using Excel are fine but Erhart and Noonan didnt have this. An FMS with the standard software shows min fuel is maximun for TO max available climb power to optimun then LRC which is not best lift drag which is endurance to stay in the air longest not to cover the best distance with least fuel( ie LRC) and step climb as weight reduces to the new optimun. i stand by 900 gallons to Howland minimun