- #36
Cyrus
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- 16
But how does that affect the calculation? The area of contact has a uniform tire pressure acting on it. What the ground does makes no difference, all I care about is the contact area.
Easier said than done! My tool box doesn't come with an airplane tire gauge that goes up to several hundreds of psi.student85 said:Measure tire pressure.
I don't imagine it's easy to "make the plane move", but that is not particularly important. A good estimate of the contact area can be made without moving the plane.Then take a pencial a draw the outline of the area of each tire in contact with the ground. make the plane move and calculate the area of each area you outline.
There are six wheels, but that's just a detail.Then the force exerted by the plane on the ground would be the pressure of each tire multiplied by its corresponding area of contant to the ground. Sum all three forces.
Sounds like a good plan! Only thing to figure out is how you'd measure the tire pressure. Remember, this is probably at least a couple hundred psi!Divide this by 9.81 and get the mass.
farpin1957 said:if the ground is hard the contact patch will be less as the total mass of the craft will be exerted on the flat surface of the runway but if it is in soft ground the tyre will be sunk in and therefore the contact patch will be greater thus lowering the pressure per sq.in. as there will be greater contact on the surface area in contact
He he! I just googled up a picture of a 747, estimated the contact area and guessed the pressure would need to be about a couple hundred psi! My car tire gauge doesn't go up that high.Cyrus said:Airplane tire pressure is around 38-45 psi (for a small plane).
~200psi for a 747. (my road bicycle pump goes up that high, well almost 160psi max)
Did you want to rethink this one? Perhaps explain how expansion causes items to become "lighter"?farpin1957 said:temperature ( creating expanded components thus lighter )
enjoy
AFG34 said:i would go on google and search the model number and look up it's specs :D hehe
neutrino said:You know, if the toolbox has a torch, we could shine light from behind the plane and measure the deviation of flash light. (Hmm...I wonder if it's Flash light or Flash-light...).