disco_air
When the birds take off, aren't they now supporting their own weight (i.e. no longer exerting force on the airframe)?
No. The total weight of the aircraft consists of:
Aircraft + fuel + cabin air + occupants = Total Weight
As has been stated before it is a sealed environment. Just because the birds are flying around the cabin doesn’t mean the weight has disappeared off into the outside environment. It hasn’t because it can’t. Instead of the weight of the birds being transferred to the weight of the aircraft via their perches, it is now being transferred to the aircraft via the air mass in the aircraft. Remember it is a sealed environment.
If you think of standing on a set of scales and jumping up. What happens? The weight (the force you were exerting on the scales) is removed isnt it?
In reference to the scales, yes the weight is removed but you have to look at the scales over the entire process. As you push off the scales your weight will appear to increase. This is because you are applying a force to jump into the air. As you leave the scales they will go to zero. When you land back down on them the force of your landing will momentarily cause the weight to be more than your actual weight. If you compared your weight on the scales over one minute you will find the average weight of you jumping up and down on the scales to your real weight would be the same. If you don’t believe me try it. Mind you if you break the scales I take no responsibility.
itchybum
Sorry you beat me to it.
