Flight 77, the supposed plane that hit the Pentagon on 9/11 was a Boeing 757. It is the same plane that President Trump flies in.
A Boeing 757 uses one of 2 different engines: Either a Rolls-Royce RB211 or a Pratt & Whitney PW2000
Here is a diagram of a Rolls-Royce RB211. It says the opening of the turbine of a RB211 is 84.8 inches in diameter. (7 feet)
https://ars.els-cdn.com/content/image/3-s2.0-B0122274105003562-gr7.jpg
Here is a photo of President Trumps plane (757), look at the size of the opening of the plane turbine and the person standing next to the plane. Look at the center hub of the turbine, compare its size to the person standing next to the plane.
Here is a photo from the Pentagon on 9/11. Look at the round object behind the person on the left. That is the center hub of a turbine from the object that hit the Pentagon. Notice anything wrong?
Impressive wall, 12-feet thick. I don't think the exterior walls of the Pentagon were nearly so thick. But it did demonstrate the total disintegration of the airframe, which is consistent with the result of Flight 77.
The video is the one that others have been posting, showing the plane coming in from the right, flying to the left. The image seems to occupy just one frame and is mostly a blur. The fuselage looks pretty skinny, but it is more recognizable if you consider that the upper third is contrast-invisible, being painted blue against a sky background, and the lower third being white, fading into shadow. What is left are the red, white, and blue livery stripes at the mid-line of the fuselage, which are better seen in the video. I recall being puzzled at the image initially. It seemed too slender. Then I realized that what was visible was the livery, with the rest of the fuselage being of similar brightness to the background---which is a phenomenon that results in invisibility at a distance, which was demonstrated by the Army Air Force in World War II (though too limited and impractical to implement operationally).