A few days ago I put up a video of a Boeing 737 being pushed around by the wind at an icy Siberian airfield. In a comment to that post, Chuck Pergiel linked to this video of Russian Ilyushin Il-76 transports on an ice runway in the Antarctic. The slipping and sliding starts at about the 5-minute mark. (Apologies to Paul Simon for the title of the post!)
It’s impressive to see a couple of hundred tons of fully-loaded aircraft sliding around like that! It must have been an ‘interesting’ assignment for the flight crews involved. I noted with interest that during one landing, initially all four engines were put into reverse thrust; but within a few seconds, the inside engines’ thrust reversers were shut off, and only the outer engines’ reversers used to slow the aircraft. I wonder if that produced less sliding?
Peter
More than one of those landings showed that 4 to 2 reverse thrust switch.
Perhaps it changes the surface conditions of the ice under the gear.
It may create visual problems for the pilot, by stirring up snow/ice particles close to the body.
I don't see a cleared area for the aircraft to turn around. I wonder if they are letting it slide/rotate around to keep it on the runway, which is swept or plowed, apparently. That hill they are trying to stop on makes it more interesting for the pilot. I wonder why they didn't extend the landing strip further the other direction, to allow the aircraft to stop prior to going into that valley?
The outboards give the pilot more/faster lateral control… 🙂 And they should have grooved the ice! WHen they do that, it's just like landing on a regular runway!
Those things have come into the Long Beach airport many times, bringing either a satellite from Europe, or the Block-DM Upper Stage for the Zenit 3-SL rockets I used to help loft for Sea Launch.
Pretty neat airplane…..
Perhaps the reason for shutting down the reverse thrust on the inboard engines is to prevent FODing the engines. The airflow at lower speeds could carry debris flung up by the wheels into the inlet. Cessna Citation thrust reversers will blow air forward under the wing at low speeds (below 40kts IIRC) to be sucked into the fan along with anything on the taxiway. Don't ask how I know this.
Al_in_Ottawa
Just a guess- the moment arm of the outboard engines is much greater than the inboard engines. Thus the outboard engines will contribute more yaw force in relationship to acceleration or deceleration.