Tuesday, December 10, 2013

Long Beach Region Code Four

     I don't usually publish about my Latino heritage or livelihood, with the exception of ranting about the maldito Tri. But the former company McDonnell Douglas really had its heart set out with its clients in Mexico. In fact, two airliners had variants designed specifically for their use in Mexico City. Now, it isn't because the city has some exclusivity from other cosmopolitan global cities (although being the one of the largest in area and population doesn't hurt a bit). The reason Mexico City (or DF in Spanish for Distrito Federal or Federal District, kind of like how people call the US capital D.C. from District of Columbia) got special treatment from this Long Beach, CA manufacturer was because it is a city that is hot, humid, and high. While this sounds like a splendid way to spend an intimate night with a few people, they are three ingredients that combine to give a groin-kick to an aircraft's engines.
Tom Hanks starring as nature and college kid as the jet engine
     For starters, have you ever exercised during the year? If you have, did you notice that you are out of air quicker in the summer than in the fall, or winter? Hot air is less dense than cold air. That means the molecules are further apart and you need to gasp more air to get the same amount of air molecules than in cooler weather. Same thing happens for a jet engine. These machines needs to swallow more air to produce the same thrust as in a cooler day. So an aircraft takes longer to get more thrust and might use more runway as a result. 

      So we move on to humid air. For those who lived somewhere that becomes swampy in the summer, you also notice that you are short of breath when it gets really humid. Even as a couch potato, you might try to desperately find a nice place with air conditioning. At least I do, but I live in the desert and those humid places are mythical lands that I sometimes visit when I get the courage to travel to those spots on my map that say "here be dragons."

     The aircraft engines are like a jogger in a humid area in the summer. The jogger usually is short of breath and has to gasp more frequently if they are accustomed to nicer weather. The same thing happens to the jet engine. The machine is pushing to get that thrust with the same air and needs more time to get the aircraft to a proper speed to take off. This means it needs a longer runway.
And we get to higher altitudes. As you go higher air becomes less dense...and you get the idea; the jogger is being revived by a passing police officer, couch potato is inside ordering a number 6 at an air conditioned Wendy's, and I'm breathing through my shirt in a vain hope that it will improve my breathing.  So you are now saying, Hot, humid, high = longer runways, case solved, right? Not in the case of Mexico City.

     The Benito Juarez International Airport is like many urban airports where it was built in the outskirt of a city in an era long ago but is now deep within the metropolitan complex due to population growth. Local politics have prevented moving it elsewhere and extending the runways means fighting with nearby neighborhoods to demolish them to extend the asphalt. The runways were originally built for the original Jet Era of the 1960s where jetliners were single aisled and the size of a Southwest (or Easyjet, Air India Express, GOL Airways, etc. depending where you are from) aircraft. They were not built for the A380s, 777, 747, and other massive jumbo jets going in and out of this airport today. So when jumbo jets first came to the scene in the 1970s, there was a problem. The airliners needed more runway than what was available in Mexico City but also needed to keep its cargo and seats to profit from these flights. The problem was so serious that Boeing Aircraft Company considered installing Rocket Assisted TakeOff (RATO) devices onto Mexicana 727s. These are essentially rockets slapped onto an airliner to get it to takeoff. Military aircraft normally use RATOs to get to the air (like the Blue Angels C-130 transport).
I swear I'm not making this up!
They even filmed a test flight with these rockets:
     So when McDonnell Douglas designed its three engined big fella, the DC-10, they had in mind many versions. The DC-10-10 would not have the middle center landing gear and less powerful engine but would serve domestic flights in the United States of America. The DC-10-30 and DC-10-40 would have more powerful engines, larger fuel tanks, and a central main landing gear to carry more and travel intercontinental. But in the middle was the DC-10-15.

      This aircraft was specifically designed for two airlines, Aeroméxico, and Mexicana.  This aircraft had the same powerful General Electric CF6-50C2F (just say the "CF6 family of engines" and you get a gold star sticker amongst pilots if you aren't the aviation nerd type) engines of the DC-10-30 but had the body and fuel tanks of a DC-10-10. This meant that it was a lighter aircraft with more powerful engines. And following Jeremy Clarkson's concept of POWEEERRRR over everything (or greater thrust vs. weight ratio) you have an aircraft capable of getting to the air with the available asphalt at Benito Juarez. 

     And there was also a similar story with McDonnell Douglas' smaller airliner, the DC-9. Although not specifically designed for Mexico City, there was a DC-9-20 that had the powerful engines of the DC-9-30 but was the smaller size of a DC-9-10. But the Mexican airliners had no problem using the normal variants in Mexico City.

As a result, the DC-9-15 and DC-9-30 variants will haunt my memories as some of the scariest rides with the fondly cheap but hilariously bad maintained Aero California fleet.

Image sources:
Daily Mail
wikimedia commons

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