Aircraft engine?

Question

why are the engines on commercial aircraft places ahead of the wing...??? I would think that if something got into the engine and shot out the back it could damage the wing!

Answer 1

The engines of commercial jet aircraft are not mounted ahead of the wing - I have no idea where you came up with that. Next time you have a look at say a B767, you will see that the front of the engine may be ahead of the wing, but the main body of the engine containing the power turbine (hot section) is well under the wing, and the exhaust end is almost even with the trailing edge of the wing.

While the air intake is mounted ahead of the wing's leading edge on many designs for center of gravity purposes, the main part of the engine is beneath the wing. The exact location is engineered to allow for the strongest part of the wing, room for the landing gear, room for flaps, and ease of access for maintenance. Sometimes the appearance can be deceiving because of the swept wings and large engine size. Some older planes had the engines mounted on long pylons so that the compressor blades would clear the wing (and the fuel tanks!) in the event of a failure resulting in "shrapnel."

If you are asking about prop-driven planes (piston and turbine engines), sometimes the engine is well ahead of the wing for a combination of reasons - wing spar location, room for landing gear, aerodynamics, C/G, and also to increase the airflow over the wing to help improve low speed performance.

With about 40 years as a pilot flying many types of commercial jets, I have never heard of FOD damaging a wing after it passed through an engine, as the jet exhaust is well below the wing.

Answer 2

The engines are placed in the most advantageous place according to the overall design of the aircraft. Various designs have seen the engines placed in a cluster around the tail, inside the root of the wing, on top of the fuselage, on top of the wings, at the wing tips, etc.

If something gets "shot out the back" of a jet engine it will follow the line of thrust, which in the design you indicated is aimed below & behind the wing, not directly at the wing itself, and would cause no damage to the wing. However the engine itself would very likely require some extensive repairs.

Answer 3

One of the main reasons is that the engines have to be mounted on substaintial airframe members. In the wing, these are spars at the front and back of the wingbox, top and bottom. The rest of the wing is built of stringers and webbing plus the outer skin.

Many of the engines are held into place with 4 bolts on 2 truss mounts. On a USAF C130, these bolts are an inch in diameter. The trusses have to be attached to solid structure. The aft part of the wing will not work, so they attach to the front spars.

Attachment to the front allows the whole wing structure to bear the force of engine thrust against the wing.

Answer 4

Not all engines on commercial aircraft are placed ahead of the wing. If you check DC-9, MD-80, Fokker 100, Boeing 727, etc., they have their engines mounted on the rear section of the fuselage. The placement of the engine depends on the aircraft designer preference in meeting their design criteria.

Answer 5

Getting the engines into clean air isn't 'necessary', there are many sucessful designs with the engines burried in the body or wing root.

If the engines were behind the wing they would also be behind the landing gear which would make it way more likely that the engines would injest debris or slush from the ground and that's not acceptable.

Answer 6

I'm no engineer but it porbably has something to do with the efficency of the wings airfoil. Having the big turbine sit ahead of it slightly may create a little more surface area under the wing to create lift with.

Also, were the jet to suck in anything, it would be dust pretty quickly... if it were something solid enough to take out the turbine and be expelled from the jet, the force with wich its going to be launched out is going to be so great its only going to go the way the rest of the jets energy is going, straight back. Very straight, and very far =)

Answer 7

It reduces interference between the airflow around the engine and the leading edge of the wing. The DC-8-62 had its engines mounted further forward than the DC-8-50 and it improved the cruise efficiency by 8.5%!

Also it allows larger engines to be installed and still provide ground clearance without making the aircraft sit too high. (Especially on the 737-3,4,500s). The original 737 had small enough engines to tuck under the wings.

Here is a pic of a 767 and you can see the exhaust is even with the LEADING edge of the wing.

http://www1.airliners.net/open.file?id=1148472&WxsIERv=Obrvat%20767-336%2FRE&Wm=1&WdsYXMg=Oevgvfu%20Nvejnlf&QtODMg=Vfgnaohy%20-%20Ngnghex%20%28Lrfvyxbl%29%20%28VFG%20%2F%20YGON%29&ERDLTkt=Ghexrl&ktODMp=Frcgrzore%203%2C%202006&BP=1&WNEb25u=FcbgVFG%20-%20Noqhyynu%20Sngvu&xsIERvdWdsY=T-OMUP&MgTUQtODMgKE=&YXMgTUQtODMgKERD=91&NEb25uZWxs=2006-12-03%2022%3A36%3A44&ODJ9dvCE=&O89Dcjdg=29232%2F708&static=yes&width=1024&height=740&sok=JURER%20%20%28nvepensg_trarevp%20YVXR%20%27Obrvat%20767%25%27%29%20%20BEQRE%20OL%20cubgb_vq%20QRFP&photo_nr=2&prev_id=1148497&next_id=1148449&size=L

The exhaust is almost never placed directly under the wing to prevent it from lifting the wing up during reverse thrust (a problem with early 'short pipe' 737s).

Answer 8

no. the engines are mounted to exhaust either above or below the plane of the wing. FOD from the engine could not hit the wing but could cause cattastrophic dis-assembly of the engine which could tear the wing off of the airplane and send it plummeting to the ground in a mass of burning .............well. you get the picture.

Answer 9

It is in front of the wing so the engine gets "free air" or undisturbed air entering the engine.

Answer 10

kinda unlikly other then on the ground