C210 tip tank / MTOW question.
Hi.
I was wondering if anyone can shed some light on this. I'm likely missing something...
When a/my 210 is fitted with tip tanks, the MTOW reduces substantially, unless there is a minimum of 7GAL in the tips, then it increases back to 1724kg.
Presumably this is because of the extra lift created by the tips on the wing root, with the fuel then acting as a counter weight.
I'm just confused as to why this is not a function of zero fuel weight.
Say you loaded the plane up so that it was fuel restrictive, with 7GAL in the tips for max MTOW. As the fuel burns from the mains, the total weight of the aircraft would decrease to a point where it was permissible to pump the tips. With a light wing and a heavy fuselage, the wing root would be under more stress than it was at any other point of the flight. The only thing that allowed for the pumping of the tips was a decrease in weight as per the flight manual, but this doesn't make any sense, as it would put the extra pressure back on to the wing root.