I am looking for a sound file that may have the sound of an airplane
that is preparing to take off

I have found this website
http://www.partnersinrhyme.com/soundfx/airplanesoundfx.shtml
but I am not sure what airplane it would be

they have a long list of names

which one is that we usually fly with??

try this link

http://www.soundsnap.com/taxonomy/term/2179/uid:87

The last one is the best

As someone who had to ride an airplane 2-4 times a week, I am familiar with most commercial jetliners to the extent that I can tell them apart by the sound of their engines.

The list at the link you provided has many military jets and choppers sounds but just a few commercial jet sounds.

Those are:
707 (Boeing 707)
jetstart2
jetstart3
jetpass
jetstop
Aviondc10

thanks for both of you

Yo Bro.
Do you know the sound of a BMW?

No Bro, I know the sound of a Rolls Royce because most of the engines used by boeing are made by Rolls Royce.
I also know the sound of Airbus engines and I assure you that the sound of the plane taking off in the recording that Samah recomended is an Airbus, I just wish there was a way to confirm that.

For me ur words are a solid proof
even on the 747 roof ;)