5th pod apparently not a fake
▻http://www.avcom.co.za/phpBB3/viewtopic.php?t=81315&p=929037#p928874
For transportation of spare engines, early 747s could accommodate a non-functioning fifth-pod engine... Carrying #cargo internally is always more efficient but the fuel cost due to drag from carrying an engine like this is sometimes less than the cost of hiring a cargo plane to haul a spare engine somewhere to where there is already a short-hop passenger flight going - especially if there is some urgency involved.
A few explanations:
The special wing with fitfh-engine attachment was standard on that 747 subtype - before the advent of wide-body airliners with cargo doors that nowadays can easily accommodate a high-bypass turbofan engine. On the #Vickers VC-10, the configuration for ferrying a fifth engine required a mounting frame - much less elegant: ▻http://www.vc10.net/Technical/oddities.html (bottom of the page)
Detail of the optional fan cover and mounting pod:
And for the fifth-engine fans (I know you’re out there !) here is another entirely different way to mount a fifth engine on a 747:
▻http://www.dvice.com/sites/dvice/files/styles/blog_post_media/public/images/pw_turbo747_3.jpg?itok=kEzdbqWT
▻http://www.dvice.com/archives/2012/05/pratt_whitney_u.php
Sidney Jo-Burg -> short hop ?
:-D
Un grand bravo pour la simplicité de l’explication de pourquoi, il vaut mieux laisser les étages du compresseur libres.