hey Gramps–how do birds fly?

well, watch em, Tim. they flap their wings, and when they do, they grab some air and push it down, so they go up.

okay, then, how do planes fly? their wings don’t flap…

Tim, the planes have wings that are curved on the top side and flat underneath. so the air over the wing, when the plane is going fast, goes faster than the air underneath. but it’s the same amount of air, just stretched, and so the air pressure above the wing is less, so the plane is sucked upward.

then how do rockets fly? they don’t have any wings at all.

you ask good questions, kid. well, rockets have these little rooms called fuel chambers. and the stuff in the chambers is lit up and when it burns it expands and goes out these things called thrusters and the tops of the chambers get pushed hard, just like if you pooted hard enough it would lift you out of the chair.

(Gramps and Tim giggle and then laugh)

(They hear the yelling of Tim’s parents having an argument on the other side of the house and they stop laughing)

Gramps, Mama is talking about leaving Daddy.

i know, son. (Gramps puts an arm around Tim)

why do they fight all the time?

well, Tim, i don’t know for sure, but i think part of it is your dad has a mean boss and then when he comes home from work he takes it out on your mom. and your mom wants to get out more and do.more with her life but your dad doesn’t want her to. so it’s a lot like that rocket and that plane and that bird. A lot of pushing and pulling. a lot of…

pressure?

yeah, Tim. smart grandson i have here.

(pause)

hey, Grandpa, you okay?