Thrust / ETOPS

[fray bentos pielot]

1 - The GE90-115B recently set a new world record for thrust totalling 127,900 pounds of thrust. What does “pounds of thrust” actually mean? How is it quantified?

2 - Can a Boeing 777-300 rotate and climb away at its max take off weight (297,560kg) on one engine? What sort of rate of climb could be expected? Would it struggle to meet minimum height restrictions on a SID or go around procedure?

3 - During an approximately 13 hour Seattle to Taipei test flight, a 777-300ER crew shut off one of the two General Electric GE90-115B engines and flew the plane for 330 minutes on the other engine. Does 330 minute ETOPS exist yet?

[Jetstream Rider]

1. Its the force generated by the engine, measured in pounds of force, rather than pounds of weight. It is the amount it would push on a test rig, measured in pounds. You could also measure it in Newtons or other force measurements.

2. a )Yes it could. It has to to be certified. Don't forget that the aircraft is held up by its wings, not directly by the engines, so the amount of thrust generated need not equal or exceed the weight (force due to gravity) of the aircraft.

b) Don't know for sure and it would depend on the temperature and a few other things. It would definitely climb though.

c) Unlikely but it depends where you are. In most cases the SID could be followed, but in areas of high ground there are often "emergency turn procedures" which you would follow in the case of an engine failure. These ensure a greater terrain clearance, even though the SID might still be safe - the emergency turn would be safer.

3. 330 mins ETOPS does not yet exist as far as I know, but you can get up to some pretty wacky stuff on a test flight. After all, you need to test some thing you would never do on line operations.

Hope that helps.

[PIGDOG]

127,900 lb of thrust is equal to the force that 127,900 lb of mass would produce while being accelerated by gravity.

A boulder weighing 10,000 lbs is being constantly acted on by gravity. It has a downward force at all times. If the equivelent force were produced by an engine, the engine would be reated as producing 10,000 lb of thrust.

Hope this helps

[Old Smokey]

A B777-300 at 299.7 Tonnes has a V2 (Flaps 5°) of 192 Knots. Under the most limiting conditions it must achieve a climb gradient (Gross) of 2.4%, and 2.4% of 192 Knots in the Standard Atmosphere is a Rate of Climb of 467 Feet per Minute.

That's the minimum performance.

Regards,

Old Smokey