Juventus From United States of America, joined Dec 2004, 2835 posts, RR: 2 Posted (10 years 7 months 3 weeks 5 days ago) and read 3674 times:
My friend is a CO mechanic, based in IAH. I asked about the 757-winglet project that CO has undertaken. He said they are having problems, ``the winglets and autoland are not getting alone``. Is this true? Is it a speed, or a flare problem? anybody...
Sinlock From United States of America, joined Dec 2000, 1689 posts, RR: 2
Reply 6, posted (10 years 7 months 3 weeks 4 days 22 hours ago) and read 3329 times:
I recall reading that in the early in the 737 (BBJ) winglet program that the center of lift on the wing moved forward a small %. Now that caused the Trim characteristics to change, in this case it made the 737 tend to over trim.
If an aircrafts center of lift moved aft then it would tend to under trim.
The 737s was having this issue at cruise and the autopilot was updated with a the changes.
A 757 in a landing configuration is very different from a 737 in cruise, but the principal of center of lift would basically be the same. A trim issue would certainly show up with the autopilot in an autoland mode, as most of the flight down the glideslope is done with trim, with the flare being done with elevator input.
Calpilot From United States of America, joined Oct 1999, 1001 posts, RR: 13
Reply 9, posted (10 years 7 months 3 weeks 3 days 16 hours ago) and read 2984 times:
Well From what I heard from a IOE Captain this is not nonsence Aero.
After the engineering came out, they discovered that the airplane would lose Cat3 because the Auto flight system softwear, did not recognize the changes during the "flare mode". They relized that the increased lift during ground effect, was going to produce a unacceptable over shoot in the touchdown zone.
I suspect the computer experts will solve this soon...?
Max Q From United States of America, joined May 2001, 5684 posts, RR: 19
Reply 13, posted (10 years 7 months 2 weeks 6 days 11 hours ago) and read 2559 times:
Even if this was true, it's a non event, the NG 737's had the same problem, it will just require some refining and software changes, that's what a flight test program is for.
The bs that float's around airlines is endless but baffling in it's number of believers, before our 764's were delivered such priceless one's as 'there's no tail clearance so you'll have to rotate at 200kts' or 'with the new windows and the weight saved in the structure it bend's too much and will have to be redesigned' or 'it's so underpowered it will barely make NY-LA'
I wouldn't put much stock in ANYONES opinion until the flight test program is complete, as noone would know until then.
The best contribution to safety is a competent Pilot.