Thursday, November 22, 2007

Thanksgiving Day Geometry

5 Comments:

Blogger Duck said...

That's a DC-10, right?

November 23, 2007 7:19 AM  
Blogger Hey Skipper said...

I see Blogger bit-bucketed my first reply.

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Close. It is an MD-11, which is structurally very similar to a DC-10, but is about 20' longer, has elaborate winglets, a glass cockpit, and scads more power than almost anything not prefixed with an 'F'.

How much power? On one recent flight that was only an hour long, hence not a lot of fuel on board, we went from 0 - 150 mph less than 2000 feet.

November 24, 2007 8:58 PM  
Blogger joe shropshire said...

How about the safety issues: the cargo door, cable-actuated flaps, hydraulic routing, etc. Any of those addressed in the MD-11?

Also, if Skipper's back there, who's flying the danged thing?

November 24, 2007 9:32 PM  
Blogger Duck said...

What do you mean by a glass cockpit? Are you talking about the windscreens, the instrumentation panels, or what?

November 25, 2007 6:42 AM  
Blogger Hey Skipper said...

Joe:

How about the safety issues: the cargo door, cable-actuated flaps, hydraulic routing, etc. Any of those addressed in the MD-11?

The cargo doors were fixed on the DC-10.

I don't know what they did with the slats (leading edge flaps), but slat asymmetries, which are not uncommon on the -10s, are nearly unheard of on the -11. The asymmetry results in a no-slat / flaps 22 degrees landing, which causes touchdown speeds around 220 mph, vice around 160 mph.

There is no fixing hydraulic routing with a tail mounted engine. Following the Sioux City accident, a valve was added to the number three hydraulic system that shuts off all flow behind the wing should quantity fall below 4.7 gallons.

Should an uncontained engine failure shred all three hydraulic systems, the crew would still be left with roll control, which the Sioux City crew did not have (they had to use differential power to create yaw, which couples into roll on a swept wing aircraft), plus electric pitch trim.

This change takes the Sioux City scenario, which we practice in the simulator, from the realm of the heroic into the difficult, but doable.

November 27, 2007 2:05 PM  

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