Foreflight W&B

JCranford

JCranford

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JCranford
i can’t seem to get my FF W&B set up. I’ve entered everything as listed in the POH. It’s in the green empty, but as soon as I load anything I get a “Overweight: Zero Fuel Weight (x lbs over)” and the x is whatever I’ve just added. Anybody seen this?
 
Sweet little feature once you get it set up

IMG_1897.jpg
 
BrianNC said:
What were you doing wrong?
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I'm betting he entered his empty weight as the zero fuel weight. Zero fuel weight is the maximum weight you can have with zero fuel, ie, any weight above that amount must be fuel. So, if the zero fuel weight was the same as the empty weight, you would be over it by whatever number of pounds you put in, *except* for the fuel.
 
flyingcheesehead said:
I'm betting he entered his empty weight as the zero fuel weight. Zero fuel weight is the maximum weight you can have with zero fuel, ie, any weight above that amount must be fuel. So, if the zero fuel weight was the same as the empty weight, you would be over it by whatever number of pounds you put in, *except* for the fuel.
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Yep, that. Zero Fuel Weight is the “whoops, I ran the tanks dry in flight” weight. Which is kinda dumb because what, you’re gonna say “sorry guys, we ran out of fuel but we can’t land cuz we’re over our zero fuel weight”?
 
JCranford said:
Yep, that. Zero Fuel Weight is the “whoops, I ran the tanks dry in flight” weight. Which is kinda dumb because what, you’re gonna say “sorry guys, we ran out of fuel but we can’t land cuz we’re over our zero fuel weight”?
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Almost... instead, it’s more like “Even though we’re out of fuel we’re still within CG so we can fly all the way to the gas pump. Or crash site. Maybe both.” ;)
 
Lachlan said:
Almost... instead, it’s more like “Even though we’re out of fuel we’re still within CG so we can fly all the way to the gas pump. Or crash site. Maybe both.” ;)
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Haa, yeah, better explanation!
 
With fuel, it is generally located in wing tanks. The fuselage is where you house people and stuff such as cargo and luggage. Zero fuel weight is not a limit on fuel, it is a limit on how much weight in the fuselage is allowed such that the structure of the wing attachment is not over stressed. Wings develop lift. The fuselage is heavy and the weight must be supported by the wings when in flight. That places a moment around the point where the wing attaches to the fuselage, the wing is bending up and the fuselage is bending down. If an aircraft does not have a zero fuel limit, then the useful load can be distributed between the fuel and the stuff in the fuselage without worrying about the structure. With some aircraft, there is a limit as to how much wing bending moment can be applied, so a zero fuel weight is established to prevent more stuff being loaded into the fuselage. It might be better named as the maximum weight of the stuff and and the rest must be in the form of fuel. The limit for the stuff in the fuselage must not exceed the zero fuel weight, the rest of the useful load may be fuel.
 
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