1.   It is certainly an aircraft that requires a good sized landing strip as approaches have to be made fairly flat.

2.   How can I make it flat?

3.   If the layers are higher in the middle than on the sides, slice off the domes to make them flat.

4.   Laffer also would like to see the tax rate made flat.

5.   The sloping ceiling was replastered, to make it flat.

6.   You could have it restretched, which will make it flat for a while, but probably not permanently.