Piaforme From Denmark, joined Sep 2001, 164 posts, RR: 1 Reply 3, posted (10 years 2 months 2 weeks 1 day 4 hours ago) and read 3698 times:
I remember that approx. a year ago there was a thread comprehensively addressing the issues of 4 engine ACs flying on 4-3-2 and one engine and the implications on cruise altitude, sinkrate and climb/descent rate etc etc etc.
411A From United States of America, joined Nov 2001, 1826 posts, RR: 9 Reply 4, posted (10 years 2 months 2 weeks 14 hours ago) and read 3555 times:
Personally have completed (in the aircraft, not the simulator) a three engine inop (idle thrust) ADF circling approach, descending all the time.
Level flight was not possible, even at lighter training weights.
Speed required with flaps 25 (circling maneuvering flap setting) was 190 knots, rudder boost ON...rudder boost OFF, not possible.
These maneuvers are certainly NOT done any longer in the actual aircraft...with very good reason.
It ain't easy.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 7, posted (10 years 2 months 2 weeks 12 hours ago) and read 3524 times:
Can the 747 and 340 maintain level flight on one outboard engine only?
Jhooper has no idea what he is talking about...particularly if he doesn't specify a weight, and absolutely b/c he doesn't have a performance manual for the 747-xxx/a340-xxx in front of him. A med/heavy 747/A340 would have severe difficulties on 2 engines maintaining 10k msl; anyone that flies either of those a/c can verify but I doubt performance charts are even printed for single engine. A single engine 727 is in a descent, period, and that's a better thrust to weight ratio than a 747/A340 on one.
A bit of advice-Jhooper- a guess may cost you a job, when they come back, b/c it sounds like a guess; which it is...
Positive rate From Australia, joined Sep 2001, 2143 posts, RR: 1 Reply 9, posted (10 years 2 months 2 weeks 9 hours ago) and read 3479 times:
In a 4 engined jet like the 747 or the A340 it cannot maintain height on one engine alone because don't forget one engine= only 1/4 of the toal power supply. But how about a tri-jet say an L1011 or a DC-10? Would one of these be able to manintain level flight on say the centre engine alone??? On a tri-jet one engine= 1/3 of the total power therefore wouldn't it be easier than a 4 engined jet???
411A From United States of America, joined Nov 2001, 1826 posts, RR: 9 Reply 10, posted (10 years 2 months 2 weeks 1 hour ago) and read 3433 times:
Lockheed L1011 (524B powered),
Level flight is possible, at weights below approximately 275,000 pounds with MCT set on the (one) operating engine, provided flaps/slats are retracted, speed is maintained above 210-220 knots, at altitudes no higher (depending on temperature) than 8,000 feet.
Doug_or From United States of America, joined Mar 2000, 3158 posts, RR: 4 Reply 11, posted (10 years 2 months 2 weeks 1 hour ago) and read 3410 times:
A single engine 727 is in a descent, period, and that's a better thrust to weight ratio than a 747/A340 on one.
not necesarily. At least in the -100 (even with weak 'ole -7 engines) if you can dump down to a normal post cruise landing weight 110-120ish, and you are smooth on the controls and maintain about 200-210 knots single engined level flight is possible. Though obviously not at cruise altitude.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 13, posted (10 years 2 months 1 week 6 days 12 hours ago) and read 3322 times:
From my perf manual for the for -7, -15 and -17 powered 727s...Assume a linear relationship b/t the following points, gross weight(x coord) vs density altitude (y coord), 1 pack, anti ice off, clean a/c, max cont epr:
-7: (110000 lbs, 12000 ft) and (152000 lbs, 0 ft)
-15: (110000 lbs, 16000 ft) and (170000 lbs, 0 ft)
-17: (110000 lbs, 17000 ft) and (177500 lbs, 0 ft)
With MGTOWs rangine approx from 176500 lbs - 220000 lbs, and MLW of around 155000 lbs, a 110000 lb 727 is so very light that its probably the empty a/c plus a few thousand pounds of fuel - not a very likely scenario. A crew couldn't dump/burn fuel fast enough at typical takeoff weights; the a/c is coming down, as I said.
If an -15 powered a/c left DEN (or anywhere) weighing 175000lbs, it's max altitude at 7000 ft is 143000 lbs...A -7 powered a/c would have to weigh 127000 or less to maintain 7000 ft. Even at max dump rates, the point is that the single engine operating envelope is extremely small to the point of being unrealistic for any revenue operation.
Jhooper-this was advice, and it came off harsh...sorry.
I'm trying to encourage you to expand your knowledge base, so you are ready when the returns. There will always be more people willing to fly a/c for a living, part. 121, than there are seats available. Many CFIs are given those exact types of questions at interviews, and blow it. Knowledge is cheap; particularly when compared to experience.
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 16, posted (10 years 2 months 1 week 5 days 22 hours ago) and read 3261 times:
Yes, it's possible, but as I said - for all practical reasons impossible if the a/c is loaded for any kind of revenue flight. Obviously you haven't understood what I've written about how very light a single engine 727 has to be in order to have enough performance to make a VFR circuit. 114500 is almost the BOW for most 727-200advs. And most fleets don't have the -17s at any rate...I think all of UAls were -15 powered, as were most of NWAs...I think AAL's were -9s.
There are also a critical issues with which engines are lost in terms of hydraulic configuration, icing conditions, etc. which further decrease the odds...but you know all of those, right?