vikinga346
Posts: 314
Joined: Wed Oct 04, 2006 9:45 pm

772LR Climb Performance On One Engine

Sat Mar 01, 2008 5:47 am

Taking the EK 772LR as an example, if that plane was at MTOW and it lost an engine on rotation, how many feet per minute would the heavy jet be able to climb on one engine?

Props to anyone who can give me an accurate number.
...you will walk the earth with your eyes turned skyward, for there you have been and there you shall return
 
wilco737
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RE: 772LR Climb Performance On One Engine

Sat Mar 01, 2008 9:02 am



Quoting VikingA346 (Thread starter):

Lets say it that way: you need enough remaining thrust on that engine to clear all obstacles! (makes sense eh?)
You have a required climb gradients for the take off which is sparated in 4 segments. Usually the 2nd segment is the most restrictive segment. On the MD11 you need 2.7% climb gradient. The actual climb rate in feet/ min varies with the speed. The standard ILS glideslope is 5.2% descent angle. So your climb out will be a lot shallower than your descent on the ILS. I would say its roughly 300 to 400 ft/ min.... The actual could be pretty close to that if you are 2nd segment climb limited!

WILCO737 (MD11F)
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FredT
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RE: 772LR Climb Performance On One Engine

Sat Mar 01, 2008 9:36 am

FAR 25.121


(b) Takeoff; landing gear retracted. In the takeoff configuration existing at the point of the flight path at which the landing gear is fully retracted, and in the configuration used in §25.111 but without ground effect:

(1) The steady gradient of climb may not be less than 2.4 percent for two-engine airplanes, 2.7 percent for three-engine airplanes, and 3.0 percent for four-engine airplanes, at V2with:

(i) The critical engine inoperative, the remaining engines at the takeoff power or thrust available at the time the landing gear is fully retracted, determined under §25.111, unless there is a more critical power operating condition existing later along the flight path but before the point where the airplane reaches a height of 400 feet above the takeoff surface; and

(ii) The weight equal to the weight existing when the airplane's landing gear is fully retracted, determined under §25.111.
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flyf15
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RE: 772LR Climb Performance On One Engine

Sun Mar 02, 2008 2:24 am



Quoting FredT (Reply 2):

(1) The steady gradient of climb may not be less than 2.4 percent for two-engine airplanes

A 2.4 percent gradient at 150kts (just a random guess for a V2 speed, I'm not really sure what the 777's V2s typically are) is 364fpm. So, thats all thats required. Of course, its going to be able to do more than this... depending on weight, elevation, temperature, etc, but is not required to (unless the specific departure requires a higher than standard climb gradient).

Airliners can climb on one engine, but not very quickly. I actually do not mind loosing an engine during training in the simulator. The plane climbs so slowly that things don't happen very quickly. Its not really all that stressful.
 
EA772LR
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RE: 772LR Climb Performance On One Engine

Mon Mar 03, 2008 7:11 pm



Quoting Flyf15 (Reply 3):
Airliners can climb on one engine, but not very quickly. I actually do not mind loosing an engine during training in the simulator. The plane climbs so slowly that things don't happen very quickly. Its not really all that stressful.

Try saying that with 300 people on board at 760k lbs TOW, at 40 deg C (104F), in the middle of July out of DXB, on one engine... wink  I know what you're saying. Twins are allowed to fly because they're designed to be able to fly on one in all situations, except initial takeoff down the runway.
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vikinga346
Posts: 314
Joined: Wed Oct 04, 2006 9:45 pm

RE: 772LR Climb Performance On One Engine

Mon Mar 03, 2008 10:02 pm



Quoting EA772LR (Reply 4):
Try saying that with 300 people on board at 760k lbs TOW, at 40 deg C (104F), in the middle of July out of DXB, on one engine... I know what you're saying. Twins are allowed to fly because they're designed to be able to fly on one in all situations, except initial takeoff down the runway.

That's what I'd like to know! Taking heat into account - taking off from DXB MTOW in 40deg C heat - can the 77L still climb assuming single engine failure on rotation? I'd assume yes, but the heat makes it much harder so it must be real tough.
...you will walk the earth with your eyes turned skyward, for there you have been and there you shall return
 
OldAeroGuy
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RE: 772LR Climb Performance On One Engine

Mon Mar 03, 2008 10:29 pm



Quoting VikingA346 (Reply 5):
Taking heat into account - taking off from DXB MTOW in 40deg C heat - can the 77L still climb assuming single engine failure on rotation? I'd assume yes, but the heat makes it much harder so it must be real tough.

If the 772LR couldn't meet the required minimum 2.4% climb gradient under these conditions, then the takeoff would not be legal. TOW would be a fall out of the field length/climb gradient requirements.

Let's assume climb gradient is limiting rather than field length. If field length were limiting, climb gradient would greater than 2.4%.

Lift off would probably be close to the 235 mph tire speed limit, so climb rate would be:

ROC = (235*5280/60)*.024 = 496 ft/min

Note that the tire speed limit is a true airspeed in this case with an assumption of zero wind.
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vikinga346
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Joined: Wed Oct 04, 2006 9:45 pm

RE: 772LR Climb Performance On One Engine

Fri Mar 07, 2008 10:45 pm

Interesting - thanks much for that.

Even though its capable of doing it - I bet there would be a lot of soiled seats if the 77L lost an engine on rotation in DXB in 40degree C heat...
...you will walk the earth with your eyes turned skyward, for there you have been and there you shall return
 
rendezvous
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RE: 772LR Climb Performance On One Engine

Sat Mar 08, 2008 12:28 am

Just to note, the plane has to be able to continue from V1 with an engine out - this it not the same as the rotation speed, it could be quite a few knows slower in some cases. If an engine is lost on the initial cimb out or during rotation, I'm not sure that the passengers would be entirely aware of it, unless it was a catastrophic failure of some kind.

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