Can you really weigh a plane without scales using the displacement of water?

no not really, unless u completely drain the plane of fuel and oil, open all doors, etc etc, and then put it in the water, but even then no, coz the metal and other fabrics have a different weight, even if they take up the same vloume, they both weight different, so neh

Here are some ideas ive come up with because i will be flying soon as well, 1. SLEEP (sleeping pills work) 2. Music player such as ipod or mp3 player 3. Read a magazine or book 4play with playdough ( before you leave on your flight make a list of rabdom things, the.pn try to create the with playdough) 5. Brush your hair ( whenever i get bored i alway brish my hair or try new hair styles) 6. If you flying with someone play games like flash 7. Bring cards 8. Try to remember every thing that you packed (make a list) 9. Play any game on yoir phone or ipod 10. Bring paper and try to do origami 11. Start a journal or auto biography 12. bring colored pens or markers and tatto yourself 13. Print out logic puzzels 14. Try to make upa secret code 15. Tell people you are older than you really are 16. Draw or scetch 17. Try to count to 1000 18. Try to write your name using 25 different fonts 19. Think about stuff 20. Come up with your top 50 baby names

if the item sinks, like Archimedes crown, the displaced water only measures volume.

if the item floats, like a ship or plane, it will only displace its weight in water. the amount of water displaced is weighed, and that is the weight of the plane.

If Archimedes had put the crown on a toy boat, (after weighing the boat by itself first), he could have measured the weight of the crown by the water displaced when floating.

you need to know all the materials used to make the plane and the percentage volume of the plane made from each material. The latter would require examination of each individual component (there are alot....) From this, work out the mean average density of the plane.

Then, all dead air spaces would need to be opened to atmosphere, to allow them to flood when the plane sinks.

Now when the plane is sunk, measure the volume of water displaced and multiply it by the mean average density of the plane to get the weight.

Yes as long as it floats

Weight of water displaced = weight of object

If it floats you can, because if you know the volume of water displaced and the temperature etc. you can calculate the weight.

If it doesn't float you can't.

really long shot here , something like , you have pressure sensors on the tyres,you calibrate the tyre with progrssive wieghts up to something like 1/3rd of guess at aricraft weight,then you measure the pressure in each tyre whilst airborne , then again statically parked.multiply by number of tyres?. Not wonderfully accurate but , top of my head stuff