Guppy Maximus

Guppy Maximus

Guppy Maximus


The Boeing 737 MAX: Guppy or Sardine?

Almost two years, several flight physicals and a few check rides ago, I reluctantly transitioned from the left seat of the Mad Dog to the left seat of the Guppy (see “Guppy School,”  T &T Jan., 2017 and “In the Groove,” T & T Jun., 2017). The latest iteration of the long-lived line of the B-737 Guppy is called the MAX and you’ll likely not hear it called the “Guppy” anymore. The original 737-100’s signature, short and plump “guppy” namesake no longer describes its profile. 

The length is now proportional to the girth as the MAX is the longest bodied variant of the venerable airliner to date. It can be recognized by downward projecting winglets called scimitars (sim-it-tars; for better aerodynamic efficiency), the not-as-flat on the bottom, large diameter Leap 1B engine inlets (for 15% better fuel efficiency), the scalloped trailing edges of the engine cowls (for noise reduction), a longer tail cone as well as the longer fuselage. While these are all great improvements for pilots and profitability, some contend that it’s not so nice for passenger comfort – more on this in a bit. 

The Airframe

According to Boeing, the new 737 MAX scimitar winglets are the most efficient ever designed for a production airplane. The combination of advanced design and manufacturing techniques allow for natural laminar flow and delivers the greatest contribution to improved fuel efficiency of any winglet. The fly-by-wire spoilers incorporate automated maneuver load alleviation for certain flight conditions, emergency descent speed brake assist logic that allows extension beyond the normal in-flight range and an automated landing attitude modifier program for flight deck perceptions similar to previous 737’s; including tail strike prevention during takeoff and landing. There are also new struts and nacelles for the heavier engines, a beefier main landing gear and supporting structure and thicker fuselage skins; all resulting in a 6,500-pound increase in the MAX 8’s EOW (empty operating weight). 

Any handling differences due to engine thrust line and airframe changes are tuned out by the flight control system in order to maintain the same type certificate. There were no major modifications for the 737 MAX flight deck as Boeing wanted to maintain commonality with the 737 NG family. The main avionics change is the addition of four 15.1-inch landscape liquid crystal displays supplied by Rockwell Collins, as used on the 787 Dreamliner and the HUD uses a new software version which is also being retrofitted on earlier versions of the NG. Sticker price: $110 million.

Motoring by the Numbers

CFM International, Leap 1B, Twin Spool, 68″ diameter intake, high bypass turbofans producing 27,900 lbs. thrust each. Compressor: 1 fan, 3-stage low pressure and 10-stage high pressure compressor, 22:1 ratio. Combustor: second generation, twin-annular, pre-mixing, swirler combustor. Turbine: 2-stage high pressure, 7-stage low pressure. Overall pressure ratio: 50:1. The fan has flexible blades manufactured using a resin transfer molding process, which untwist as the fan’s speed increases. The motor also incorporates BRM (Bowed Rotor Motoring). When an engine cools, air rising to the top causes uneven cooling of the core shaft and the shaft will bow. After the engine start switch is moved to GND, the EEC (Electronic Engine Control) performs Bowed Rotor Motoring. BRM will be active from 6 to 90 seconds and MOTORING will be displayed on the N2 gauge between 18-24 percent. The only inconvenience this presents, other than a lengthy start cycle, is getting “Sister Christian (Motoring – what’s your price for flight?) by Night Ranger stuck in your head as you stare at the motoring icon. Compared to the NG’s CFM56 engines, these features result in 15 percent less thrust specific fuel consumption, 20 percent lower carbon emissions and 50 percent lower nitrogen-oxide emissions. Price tag per engine: about $14.5 million.

Do These Engines Make My Fuselage Look Fat?

It’s not uncommon for airplanes to be quite functional while having very little ramp appeal. The Shorts 360, Piper Apache and 737-100 Guppy come to mind. I’m slightly biased since I own and operate the sexiest airplane ever built by human hands (except for perhaps the P-51D Mustang, F4U Corsair and T-38 Talon). So for those who have owned, loved or flown any of the previously listed, “un-handsomely-fine” aircraft, I mean no disrespect. Not only was the original 737 fuselage disproportionately short, plump and un-handsome, but the small diameter engines on the original -100 model accentuated the impression of excessive fuselage girth. With a five-foot longer, slender looking body and larger jugs hanging from the wings, the proportions of the MAX are more, well – shapely. While aesthetically pleasing, the fuselage stretch did not come without compromise. Its design necessitated some Disney-like Imagineering including moving the engines higher and forward, auto-assisted control of pitch during lift off and in the landing flare to prevent tail strikes, a re-lofted and re-contoured tail cone and a taller nose gear assembly for engine cowl clearance. All this to make a shapelier airplane you ask? We can dream, but no. Next to the dollar-sign shaped sugar plums dancing in their heads, the marketing folks dreamed of more fuel-efficient engines propelling a long fuselage full of lots and lots of paying passengers, to places far, far away. I don’t fault them because that’s their job and it’s the paying passengers that make the mortgage payment on a great looking Duke. Unfortunately, for the profitability thing to work, marketing needs us to carry lots and lots of people all on the same airplane – this means adding more seats. 

Size Matters

Responding to the profitability conundrum and competition from the Airbus A321neo in September 2014, Boeing launched a high-density version of the 737 MAX: the MAX 200. Named for seating up to 200 passengers in a single-class high-density configuration with “slimline” seats. Variants of the MAX have passenger seating numbers similar to airline ticket prices in that it’s difficult to know which number is the real number due to configuration variables and marketing spin. But published numbers say the MAX-7 version to the MAX-10 version have a seating capacity ranging from 138 to 230 passengers with a maximum takeoff weight ranging from 177,000 pounds to 194,700 pounds. In order to squeeze in that much payload, some Jenny Craig life-changes occurred to our plump little Guppy. In the T & T story about my transition to the Guppy, I said of the 737NG (Next Generation): “…not that it matters to the ladies, but there is little room to stand straight-up, guy fashion, in the forward lav – the one us folks at the pointy-end use.” Unfortunately, the lavatories in the MAX are even smaller than the NG. So small that you must decide before entry if you will go in facing frontwards or backwards. For us guys, doesn’t that kind of telegraph which “business” we are about to undertake? Also, since there is zero maneuvering room once inside the lav, for those that elect to go in backwards, pulling down one’s britches before entering and after exiting seems socially questionable if not liberating. We have actually had passengers that required assistance in extrication once they had shoehorned themselves into the loo and onto the throne, pants down being another conversation.

Does This Seat Make My Butt Look Big…ger?

There is also a well-publicized uproar over less seat pitch, seat width and tighter spacing between rows of seats. Some creative “geometry-engineering” with the tail cone, seat spacing and fewer galleys created the additional space for more of those seats of which the marketing folks dreamed. The less-publicized result born of the sardine-liner arrangement is a policy that if you can’t put down the armrests on both sides of your seat due to your Guppy-like-girth, then you have to pay for the additional adjacent seat(s) in order for them to remain unoccupied. For skinny folks that have endured “encroachment” from adjacent Guppy-like passengers, this seems a fair, welcome and most excellent strategy. But we have yet to determine if the PC police and public opinion will abide by such a transparent bias against those of us whose center sections are more aggressively influenced by gravity, particularly when in a seated position. 

Fly Like You Stole It

How does it fly? I can’t tell you because I haven’t flown one yet. But I have flown the B-727, DC-10, MD-80 and a couple older flavors of the Guppy. I expect the MAX flies like a typical airliner: a huge, heavy, smooth but sluggish GA airplane that most pilots, mechanics, fuelers and baggage handlers could fly – with or without permission. The consensus among those waiting for a crack at the jet is one of anxiousness. We all hope to fly with a pilot that has flown the airplane already rather than someone that has not. Fortunately, everyone I’ve talked with that has flown the MAX say that it’s the same as the NG with the only noticeable difference being BRM and learning the new location of old switches. It looks quite shapely and I’m excited to get my hands on one. And since I don’t have the $110 million, I’ll be sure to get company and ATC permission before I take it around the patch.

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