Off topic I know but ?

[Guest tomahawk_pa38]

Looking at the posters for RIAT 2006, the front shot of the C17 made me wonder why nearly all the common military transport planes (C130/Transall/C17/C141/C5 etc) have the wings mounted on top of the fuselage, whereas all (except the 146 that I can think of) jet passenger aircraft have the wings mounted at the bottom. Think what a better view you would have if passsenger plane's wings were mounted at the top.Any thoughts / theories ?

[jc_150 3]

HiI read your post and because I did not know the answer decided to take a look on the net and found lots of advantages and disadvantages, and eplainations and of course the inevitable mathematics of wing design, so thought I would post the simplest, non mathematical answer just for fun and to start the discussion off:cut and paste from web site http://adg.stanford.edu/aa241/wingdesign/winglayout.htmlHigh and Low WingsHigh wing aircraft have the following advantages: The gear may be quite short without engine clearance problems. This lowers the floor and simplifies loading, especially important for small aircraft or cargo aircraft that must operate without jet-ways. High wing designs may also be appropriate for STOL aircraft that make use of favorable engine-flap interactions and for aircraft with struts. Low wing aircraft are usually favored for passenger aircraft based on considerations of ditching (water landing) safety, reduced interference of the wing carry-through structure with the cabin, and convenient landing gear attachment.regardsJohn Calleja

[Guest tomahawk_pa38]

Thanks John - very interesting I suppose when you read the rationale, most of it is quite obvious. hadn't thought about the ditching bit though.

[Tabs 2,790]

Yeah I'd have to guess it has to do with getting the engines high up off the ground to avoid FOD damage. These planes aren't always landing at the best airports with clean runways etc...

[cowpatz 243]

They are also usually carrying some sort of freight so a top mounted wing allows for an unterrupted (by spars) cargo floor space. Also the floor can be lower to the ground to allow for easier loading/unloading. A Passenger aircraft on the other hand needs an uninterupted floor upstairs. It doesnt matter if the spar cuts thru the lower fuselage as the cargo holds can go in front and behind it.CheersSteve