Rockhound Date : 29th November 2004 17:36
I have interpreted the parallel tracks that appear to begin immediately in front of the berm and continue up it to have been made by the two fuselage bogies. Is this correct? If so, the wheels must have contacted the ground before the berm and rolled up (and over?) it. Correct? Those bogies are at the mid-section of the fuselage.
This set me wondering where the other wheels would have passed over or around the berm in the photo posted by hobie.
After looking at a lot of photos on Airliner.net I found the wheel and bogie spacings to be approximately as shown below
So normally there would be eight wheel tracks spaced as shown above, the pairs of tracks being spaced about 3.4 times as far apart as the spacing between the wheels on a single bogy.
Doing a similar exercise with the photo of the berm re-posted by TheShadow shows the spacings of the wheel ruts to be as shown below:
So it appears that the two pairs of wheel ruts running up the berm were made by adjacent bogies, probably, as Rockhound says, the center two with the wings of the plane level.
In which case the other two bogies would have passed over the berm as shown below:
The smaller images are copies of the rut images in the lower photo, and indicate the relative positions of all four bogies.
This seems to me to show why some of the orange thingees were knocked down and not others, the wings also missing all but one of those not knocked down by the undercarriage.
Photos on Airliner.net of 747s taking off show that the last wheels of all the four bogies seem to leave the ground almost together e.g.
http://www.airliners.net/open.file?id=716477
Therefore, for only the center bogies to have made contact with the ground and leave ruts while the outer bogies cleared the berm without leaving marks, the plane must have been in an unusually nose-high attitude.
And for the center bogies to make ruts at the base of the berm while the outer bogies were above and clear of the berm means that the plane mist have been in an exceptionally high nose-high attitude.
I assume that the black blob between the tracks at the top of the berm may have been the position of the final tail strike.
Rockhound posted 28th November 2004 17:54
Thanks go to The Shadow for putting up that photo again. The left end of the berm fitted between the fuselage bogies and the bogie under the left wing.
I think that this statement may not be right, and that Rockhound’s earlier quote at the top of this post is right, i.e. that the outer bogies passed over the berm without leaving marks but knocking down the orange lights.
Two questions: How high is the berm, and how far behind the outer bogies are the inner bogies on a 747? And hence what must that minimum nose-up angle have been? That’s three questions.
Cheers,
