saafnav From South Africa, joined Mar 2010, 236 posts, RR: 0 Posted (5 months 3 weeks 4 days 14 hours ago) and read 2610 times:
I'm currently in a debate at work. The popular opinion is that the heavy birds like B747, A380 etc has the ability for the landing gear bogeys to turn sideways in preparation for a crosswind landing.
From what I know, the only aircraft that can do it is the B-52 with the x4 Main wheel bogeys, and the B747's wing main gear bogeys can turn while taxiing above a certain speed by arming them. Also, the B777's rear axle can steer as well, but that wouldn't help with crosswind landings.
Lieut's opinions don't count, so I'd appreciate an 'official' answer
vikkyvik From United States of America, joined Jul 2003, 9010 posts, RR: 28 Reply 2, posted (5 months 3 weeks 4 days 13 hours ago) and read 2565 times:
Quoting saafnav (Thread starter): From what I know, the only aircraft that can do it is the B-52 with the x4 Main wheel bogeys, and the B747's wing main gear bogeys can turn while taxiing above a certain speed by arming them. Also, the B777's rear axle can steer as well, but that wouldn't help with crosswind landings.
B-52 gear can indeed be turned for crosswind takeoffs, and I assume landings, though I don't know.
B747 body gear can turn during taxi for improved turning radius and reduced tire scrubbing. The wing gear stays fixed. I believe A380 body gear can also turn, or maybe it's just the rear axle. B777 rear axle can also turn. C-5 aft main gear bogeys can turn as well, I think. AN-225 (and maybe -124?) has turning bogeys toward the rear of the main gear as well.
In general, with the exception of the B-52, these all only occur during taxi; far as I know, they're generally locked out during takeoff and landing.
Pihero From France, joined Jan 2005, 3813 posts, RR: 73 Reply 7, posted (5 months 3 weeks 4 days 8 hours ago) and read 2324 times:
Quoting saafnav (Thread starter): From what I know, the only aircraft that can do it is the B-52 with the x4 Main wheel bogeys,
That's correct, although it was tried on the B-47 first.
An interesting piece of aviation history is that this feature was otiginally on the C-5 prototypes and on the C-5A.
It disappeared on the C-5B and was subsequently removed from all C-5As.
Reasons were maintenace issues, complexity and improved landing techniques.
That swivelling capability was 20° and the system used inertial reference to orient the wheels in the direction of the aircraft heading.
KPWMSpotter From United States of America, joined Dec 2006, 384 posts, RR: 2 Reply 9, posted (5 months 3 weeks 3 days 18 hours ago) and read 2113 times:
There were a number of light tail-wheel aircraft in the late '40s and early '50s which featured "crosswind gear". Most of these arrangements were after-market modifications to the main landing gear, allowing the axles to pivot freely 10 to 15 degrees. The most popular crosswind gear was on the Cessna 190/195, but I've seen similar arrangements installed on Cubs, Luscombes, and similar.
I have a book which shows some of the rather elaborate contraptions installed on Piper Cubs, I'll try to scan in some photos this evening.
As for heavy transport aircraft, the B747, A380, etc, cannot adjust their gear to compensate for crosswind landings. The 747 center bogies and the trailing axle of the 777 are steerable (I do not believe any of the main gear on the A380 are steerable), but only on the ground. The B-52, though, is rigged to land in a crab; the low wing tips of the aircraft prevent transitioning to a wing-low approach in a crosswind so the gear are adjustable to compensate.