Tuesday, November 10, 2020

Slip slidin' away - aviation edition


The Aviationist brings us this video of B-52 Stratofortress bombers surging down the runway at a 20 degree angle prior to takeoff.  It's weird to watch, but there's a good reason for it.  The article explains:

The video in this post was taken ... in April last year, at RAF Fairford, UK. It shows one of the 6 B-52H Stratofortress bombers, belonging to the 2nd Bomb Wing, from Barksdale Air Force Base, Louisiana, deployed to the UK as part of a Bomber Task Force rotation in Europe, the largest Stratofortress deployment since Iraqi Freedom in 2003, taking off as “PROSE” flight.

What makes the footage particularly interesting is that the take off occurred in crosswind conditions and the clip clearly shows the B-52’s peculiar steerable dual-bicycle landing gear which allows the crew to “crab” the airframe by 20 degrees, i.e. to keep the gear along the runway while the fuselage is pointing up to 20 degrees off the runway centerline.

In fact, the U.S. Air Force iconic B-52 bomber was designed in such a way the landing gear can be set up to 20 degrees left to right of centerline for both takeoff and landing.

As explained by NASA (that has been a BUFF operator) on its website, “the landing gear of the B-52 is of the same bicycle arrangement as employed on the B-47 but has four two-wheel bogies instead of the two bogies used on the earlier aircraft. As compared with their location on the B-47, the outrigger wheels are positioned much nearer the wingtip on the B-52. An interesting feature of the B-52 landing gear greatly eases the problems posed by crosswind landings. Both the front and rear bogies can be set at angles of as much as 20° to either side of the straight-ahead position. In a crosswind landing, consequently, the aircraft can be headed directly into the wind while rolling down a runway not aligned with the wind.”

There's more at the link.

If the embedded video below doesn't play, you'll find it here.

It must be a weird sensation for the pilots, drifting down the runway at so great an angle to the center line.  I guess they have to undergo some pretty extensive training to get used to it, before they're allowed to do it for real.



Beans said...

Even weirder is the C-5 has somewhat the same type of undercarriage because it basically, sideways, is a flying barn. Huge sideways surfaces to catch cross winds.

BUFFS... Seems like they'll fly forever or such. Can't wait to see what they do with the potential re-engine later this year or next year, assuming we have a Defense Department...

kamas716 said...

I'm sure the pilots get plenty of practice up here in ND. It's always windy, and never seems to be from quite the same direction as the day before.

Sam L. said...

When I was in the missile biz,I got a chopper ride out to one of launch control sites, and the pilot said he was being reassigned to B-52s, "and there's just no comparison".
I said, "Not so! You both take off nose-down."

scamorama said...

Saw a B-52 land with the gear sideways once.

When it was down, the plane straightened out as it rolled down the runway -- one of the weirdest things I've ever seen.

Sherm said...

My FIL is 97, a retired aerospace engineer who once worked on the B-52. His son, my BIL, 39 years his junior, was working on a B-52 project a few years ago and found himself using working papers prepared by his father years before. Sadly, none of his children have chosen to carry on the engineering legacy so there won't be three generations working on the same aircraft.

I lived near a SAC base once upon ago. Watching one take off, even in normal winds, is memorable.

Will said...

Hmm, doesn't appear that the wing gear rotates to match the main gear angle.

A dim memory is that the wingtip gear was borrowed from a current fighter plane when designed. F-86?

Ross said...

My father was a BUFF pilot, Viet Nam and Cold War era. As I have aged I have learned to ask questions as his memory fades.

As I recall, that 20 degree truck angle translates into a 40 knot crosswind. If I am wrong I will happily be corrected by those with more knowledge than I. Another interesting tidbit I learned form a customer that flew later is the wing tip gear is about chest height when the aircraft is light and becomes air born around 40 knots heavy.

I still can picture sitting in the left hand seat as a 10 year old.

Oh, and here is a cross wind landing: https://www.youtube.com/watch?v=TCUHQ_-l6Qg


Ritchie said...

Also because of the gear design, the plane is not really able to pitch up on takeoff. It has to levitate.

Craig Mark said...

My brother flew BUFFs in the late 80s and here is what he had to say.

"The wingtip gear would caster on their own. Only the main gear was set by the pilots with a cam in the console between the pilot and copilot seats just aft of the throttles.

After landing, there was a button you pushed that re-centered the main gear. During pre-takeoff taxi, one of the checklist items was to check the gear crab and re-center operations.

In the before takeoff and before landing checklists, there was chart with the crab settings that corresponded to crosswinds. And of course with crab set in, you had to visualize where the center of the cantered fuselage needed to be over the centerline of the runway.

I remember landing from the copilot’s seat with a 20 deg crab to the right looking down the runway out the pilot’s window. That’s one weird sensation!"

matism said...

Even more interesting about the BUFF is flying low level routes and watching the wingtips flap up and down a total of 40 feet!!!