Posts: 146
Joined: Tue Dec 28, 1999 3:59 am

Weight Of Engines?

Sun Feb 27, 2000 10:25 pm

Can anyone tell me about the weight of engines? I was just looking at a picture of a Trident, and it struck me that those engines must be very heavy. Same with DC10, Tristar,727 etc. Now,it seems that all lof the weight is at the rear end of the airplanes and it seems to me that there is no weight at the front to counterbalance the weight of the engines.So how does the airplane stay level without tipping backwards? Also, to show my ignorance in such matters, I see these truck size engines hanging under the wings of airplanes and (now I am ducking!) I have to wonder why the wings don't snap off from the weight. Can anyone tell me how much tonnage say, a 747 has got hanging under the wings? Guys, make allowances for this old sea dog's ignorance. I know ships but not airplanes. Thanks. Peter.
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: Weight Of Engines?

Sun Feb 27, 2000 10:58 pm

In round figures:-

1. a JT9D on 747 weighs 10,000 Lbs

2. an RB211-524 weighs 14,000 Lbs installed (this includes the thrust rev).

3. a CF6-80 weighs 12,000 Lbs

This weight will be counter balanced by the fuselage in front of the wings. You will note on the examples you gave the wings are towards the rear of the a/c so the greater "overhang" ahead of them.
Purdue Arrow
Posts: 947
Joined: Tue May 25, 1999 1:49 pm

RE: Weight Of Engines?

Sun Feb 27, 2000 10:59 pm

The CF6-50 engine, used on DC-10s, has a weight of 8225 pounds each. The planes are kept balanced by moving the wing farther back than it would be if there were no tail engine. This moves the center of lift rearward and keeps the plane in balance. While the DC-10 wing is set a little farther back than it would be, this is most evident on planes like the 727 and the MD-80, on which all of the engines are tail mounted. On these aircraft, the wings are set back quite noticably.
Posts: 1665
Joined: Mon Dec 20, 1999 3:16 am

RE: Weight Of Engines?

Mon Feb 28, 2000 12:58 am

"Small Block" JT8's weigh about 3800 lbs "naked" (w/o T/R or inlet cowl) IIRC. CFM56-2 or 3 about 4700 lbs.
Posts: 256
Joined: Sat Jan 29, 2000 7:58 am

RE: Weight Of Engines?

Mon Feb 28, 2000 1:26 am

What is neat about wing engines is they actually help keep the wing on the airplane. The lift comes from the wings and they always want to bend up. With the weight of the engines and fuel holding them down, you don't need as much structure to keep them sticking out where they are supposed to be.

And thank you for your question -- I hadn't actually stopped to wonder how much the engines weigh. Say, does anyone know the weight of those new 90,000 lb thrust type engines they use on the 777?
Posts: 130
Joined: Tue Nov 23, 1999 1:35 am

RE: Weight Of Engines?

Mon Feb 28, 2000 11:12 pm

On a rear mounted jet, wings are moved back. If it is extended, the plugs are usually installed in front of the wing to counterbalance the weight of the engines. The engines actually help the wing balance while in flight because engine and fuel counteract lift that is generated and the wing wanting to move up.
Posts: 146
Joined: Tue Dec 28, 1999 3:59 am

RE: Weight Of Engines?

Tue Feb 29, 2000 6:46 am

Those numbers are astonishing to me. One engine alone weighing 10,000lbs. Thats 5 TONS!!!! Times 4. That means a 747 has got 20 TONS hanging under the wings. Wonders never cease. Many thanks guys, very informative. Peter.
Posts: 1008
Joined: Fri Nov 05, 1999 11:28 am

RE: Weight Of Engines?

Tue Feb 29, 2000 11:14 am

Hi Guys,

The CRJ-200 (twin rear-mounted engines) is actually nose heavy, and requires about 200 kg's (440 pounds) of additional weight behind the wings to keep the aircraft in trim.This causes problem for Load Control when passengers request to sit at the front of the aircraft (which they often do when they notice they are empty).


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