Fly any plane:
Go to the mission builder, and create a mission. Click on "Add plane" if there is not already one on the runway. Then, right click on the plane icon. Change the aircraft type from the normal F-15E to any plane in the game (Su-27, MiG-29, 707, etc.) Note: The plane that is selected will still look like the F-15E on the inside. Press [F8] to switch to the outside view to see the aircraft. Additionally, the plane will still perform like the F-15E, allowing you to do barrel rolls and loops in a 707.