ZBBYLW From Canada, joined Nov 2006, 2019 posts, RR: 4 Posted (8 years 6 months 1 week 5 days 21 hours ago) and read 14575 times:
I was having a quick chat with a buddy and talking about different approach speeds with various a/c and the 747 came up with a touch down in and around 150ish. Anyhow we do know that because of the sweep back and higher speed design in this wing, they need lots of flaps. If you loose your flaps in a 747 whats the stall speed/approach speed you would use (rough speeds I dont care about a 5 not difference due to extra weight, just a typical landing weight).
AirportSeven From United States of America, joined Feb 2007, 327 posts, RR: 0
Reply 2, posted (8 years 6 months 1 week 5 days 21 hours ago) and read 14567 times:
I'll have to do some digging to come up with a source, but I remember reading that there is no published no flaps landing speed for the 747 because the flaps are gravity driven for the first notch or so, and that the touchdown speeds with no flaps would blow out all the tires on the main landing gear.
"Few airlines offer their pilots procedures for flaps-up landings in a 747, according to one pilot. Their manuals, however, provide data allowing crews to determine how much runway will be needed. They know what to expect: The aircraft will approach as slowly as possible, but will still be faster than the design limit for the tires. Most of the tires will fail during the touchdown. One airline has pilots practice making no-flaps approaches, but the training is never carried through to touchdown.
Given the available backup systems on board, it is unlikely a 747's flaps would ever fail to come down. For example, there are ways to substitute the use of electric motors for lost hydraulic power. In addition, when alternate flap-control measures are used, all leading edge flaps extend simultaneously as soon as the flap handle is moved from its Up detent. That lowers stall speeds by 20 knots and approach speeds, while still faster than normal, are then within tire limits."
PhilSquares From , joined Dec 1969, posts, RR:
Reply 5, posted (8 years 6 months 1 week 5 days 12 hours ago) and read 14436 times:
Taken from the 744 FCTM (Flight Crew Training Manual)
All Flaps Up Landing
The probability of both leading and trailing edge devices failing to extend is
extremely remote. System reliability and design have reduced the need
for some traditional non-normal landing procedures. As a result, an all
flaps up landing NNC was not required for airplane certification and does
not appear in the Airplane Flight Manual or in the QRH.