The Navy ordered the first of 14 C-40As, in 1997 to replace the C-9b in the logistics role.
The C-40 is based the 737 NG, for ‘Next Generation’, which constitutes the family (737-600/700/800/900). The four B models were ordered by the USAF in 2000, dubbed the ‘office in the sky’ for senior military and government travelers, the B has a broadband communication suite. The C model lacks the comms, but has the ability to reconfigure seating to handle from 43 to 111 passengers, 6 were built. AEgis model is representative of a B or C model, since they look pretty much alike.
The first 737 NG with ‘blended winglets’ flew in September 2000. Winglets were built into the following C-40 production, and retrofitted to those already in service. Wait…, what? Blended Winglet?
My first car was a hand-me-down from my Dad, a 1963 Mercury Comet with 170 cid inline six engine, and ‘3 on the tree,’ manual transmission. I still remember the shift pattern in my sleep. I even got where I could shift and steer with the same hand, a bit of a trick. Wish I still had that car. I do still have the Mercury head fuel cap!
It looked just like this one, even was this color, turquoise…. It had fins…. Yea, I’m that old….
By 63, fins on cars were on the way out. It was an automotive phenom for about 10 years, 55-65. During that period, the head designers at GM, Chrysler, and Ford were in a style arms race, they tried each year to outdo each other.
The 59 Cadillac is thought by many to have been penultimate apogee for automotive fin-aticism..
10 years after my Comet was made, the USA was sucking the dry siphon of major a fuel crisis. NASA started looking for a way to make aircraft more efficient by reducing aerodynamic drag. From the website:
“Following the Arab oil embargo of 1973, American aviation faced nearly industry-crushing increases in the cost of fuel. In an attempt to make flight operations more efficient, NASA formed the Aircraft Energy Efficiency (ACEE) program. One aspect of that program, called Energy Efficient Transport, was handled at Langley Research Center (LaRC). There, a talented engineer named Richard T. Whitcomb elaborated on a concept introduced in the late 1800s by British aerodynamicist Frederick W. Lancaster: wing endplates.
The idea of adding vertical plates at the end of an aircraft’s wings to increase efficiency had been explored before. But Whitcomb believed that plates alone would not sufficiently reduce drag or enhance fuel performance. Instead, he designed what he called “winglets”: vertical wing extensions engineered with as much care and precision as an aircraft’s wing. His design inspiration came, in part, from studying the ways in which birds in flight curled their wingtip feathers upward when seeking greater lift. The resulting winglets featured an airfoil shape similar to that of an aircraft wing, but in miniature”.
Notice it says Whitcomb’s inspiration came ‘in part’ from birds wingtips. The other part? Well obviously, it was Finspiration!
I think we have all seen those little vertical surfaces on the wingtips of airliners when we are boarding for a flight in recent years, and those of us with a curious bent have probably wondered as to their purpose.
Aerodynamicists have determined that the rotational ‘vortices’ that trail off the end of a wing moving through the air constitute a pretty significant amount of drag. Drag is an aero term for a force that holds that airplane back.
But these wake vortices, (you can even see them on a warm rainy day at the airport if you watch the other planes landing and taking off) are a form of induced drag due to the way the air flows over the wing.
Winglets can reduce the effect of this drag force by as much as 4%. Now 4% may not seem like much, but over the last 15 years or so, since winglets have become a common feature, the aviation industry typically uses over ten thousand MILLION gallons of jet fuel a year!
So if we do a little math, 15 years of flying uses 150,000 million gallons, times .04, for 4%, why that’s 6,000,000,000 gallons saved. That’s 6 billion gallons saved, and maybe even adds a little retro style to your airplane.
Now get this, winglets are not even the most efficient wingtip add-on that has been developed by aerodynamicists.
The ‘raked wingtip span extension’ can produce as much as 6% drag reduction. The C-40s cousin, the P-8 Poseidon (we have a model of this one too) uses the raked wingtip. Trouble is, the extra wingspan is trouble for airport terminals designed around a given wingspan, so winglets, since they don’t add any additional span, make more sense for aircraft using commercial airports. But that’s not a problem for a purely military version of 737 like the P-8.
When aero structural optimization is performed, a winglet configuration is found to be optimal when the overall span is constrained, and a wing with a raked wingtip is optimal when there is no such constraint
A configuration control board composed of Boeing personnel and representatives from the Naval Air Systems Command PMA-290 procurement team approved the change after determining the new design provides the same efficiencies as the blended winglet, but increases overall performance for maritime patrol missions, it said.
“It’s indicative of the teamwork developed between the Navy and our industry team that we were able to identify a way to enhance the 737’s performance in the maritime patrol environment,” said Jack Zerr, vice president of the MMA program for Boeing.
It is also believed that the raked winglet will be de-iced all the way to the tip unlike the present NG’s in which the outboard slat has no de-icing.
When I flew for Delta, we were told the raked wingtips on the 767-400 provided a 6.0% drag decrease as opposed to the 767-300 wing. This compares with Blended winglets of about 4.45% on 737NG’s at cruise and somewhere around 3% overall. The Navy 737 with raked wingtips burn 2.5% less fuel than they would with blended winglets, I’m told by someone who has flown 737’s with both types. It seems the raked wingtip is far superior, but they add a significant amount of span.
Scott Booth Bio: Often found mucking about with 3D content development for visual simulations, or occasionally small UAS simulation. Usually found in the company of: salty NCOs, (yeah, you Tony), pilots- all types, gun nuts, manned space flight advocates, old car/truck/jeep fans, Sci-Fi readers, military historians, genius software programmers who like corny jokes, rocket scientists, dark beer drinkers, type-A sales guys, and other related near-do-wells.
Experience – 30 years visual simulation content development, company co-owner-founder – CG2 1995-2004, Small UAS simulation, AEgis-Vampire, Raven operator license, class 11-008, 2011.
Visual recognition expert, aircraft, armor, ships, subs, small arms, amateur military historian and shade tree auto mechanic.