differences between millitray and civil aircraft

[myshelf]

the difference i'd like to ask about is is, most millitary transport aircraft have high wings, while most civilian transports have low wings ....

is there some reason for this?

[Souichiro]

Basically the civil liners use concrete runway's

Militairy lifters may have to land on gravel or on othe non-hardened area's . with stuff like gravel and small rocks flying all over the place High wings+ high engines prevent damage and keeps them flying.

Most civil lifters that have to fly on un-hardened area's are also High wings.

That's my guess

[elite marksman]

Thats the reason. Jet engines dont normally take too well to things flying into them, especially when those things are as hard or harder than the internal parts of the engine. It's one of the main reasons you'll never see a F-16 or A-7 land on anything other than concrete or asphalt, nosewheel would throw all kinds of crap into the intake.Propellors dont like getting hit by things either so thats the main reason military aircraft are high-winged.

[myshelf]

now that's good reason for millitary aircraft to have the wings put up high

but, concrete runways or not, wouldn't it make sense for civilian aircraft too?

[elite marksman]

A lot of turboprops (most I think) are high winged. Twin Otter (DHC6) Dash 7, Dash 8, Fokker/Fairchild 27, Fokker 50, Shorts 330/360, Shorts Belfast, Shorts Skyvan, Antonov An-24/26/28, ATR 42/72, Dornier Do-228, Do 328, Britton-Norman BN-2.  Lets you put a bigger prop on without having to disturb too much of the wing.

[SilverFox441]

Actually, while getting the engines away from potential FOD sources is an added benefit there is a different reason the military transport aircraft have their wings mounted on the top of the fuselage...

It's done to maintain a flat floor section, without the intrusion of the main wing spar box. This makes it much easier to load/unload cargo, especially at unimproved fields where no specialized equipment is available. The flat floor, mounted as low in the fuselage as possible also allows the use of integrated loading ramps.

In civilian airliners the spar box rests below the pax area and splits the cargo area. Loading/unloading is complicated by the arrangement and the need to use specialized ground support equipment.

To my knowledge the first military transport to follow the currently accepted pattern would have been the ME 323 Gigant.

[myshelf]

well, all this says that there are many compelling reasons to put the wing up high, so why not do it with civilian aircraft as well?

[SilverFox441]

If you mounted the wing high in a civilian pax plane the passenger compartment would be violated by the wing spar box. This would complicate floor layouts and reduce the room available for revenue paying passengers. This tends not to crop up in smaller planes, but in something the size of a 747 it would be very noticeable.

In a strict cargo configuration there are obvious advantages to the military pattern, but these are overridden by the maintaining commonality between pax and cargo types.

[Ivan]

@silverfox: Me-323 was a glider with engines. Being built originally as a glider it doesn't count in the official list (or considered politically incorrect)
Officially the An-8 is the first.

In the An-124 the wings are on top so there is more loading space inside. The area of the cargo hold that cannot be used for cargo (anything that has space above the lowest part of the wing spars) is converted to a crew area and spare part storage, as the thing is designed to be as independent of ground support as possible.

Almost the same with the Il-76, only there the wingbox is used as a support for the built-in engine maintnance crane (that's why there are some hatches up there), as that plane doesn't have a drive-through cargo hold with the cabin using the whole front from top to bottom. They usually have one spare engine stored somewhere in the cabin too, which is included in the empty weight, as is most of the repair kit.

[SilverFox441]

I doubt we can consider (officially or otherwise) the Antonov AN-8 to be the first to fit the pattern...after all it's first flight happened after production of the C-119 Flying Boxcar had ended a production run of 1150 planes.  ::)

AN-124 uses the same design pholosophy as the earlier C-5 Galaxy, which has two pax compartments split by the wing spar box. Passengers are basically fitted into otherwise dead space...they aren't the reason the plane exists and are more or less an afterthought.