A Barrel of Oil Does Not Go As Far As It Used To In The Air It Goes Much Further The Untold Green Revolution in Aviation Essay by Esteban Erik Stipnieks

A revolution unrecognized?  There has been a revolution a Green Revolution occurring over head and since 1975 the revolution has occurred with hardly a notice.  If its got wings and it was built after 1975 the State of Art has hardly stood still where big business was involved the heaviest on the demand side the change has been the most dramatic war mongers and the pursuit of profit is powerful technological combination where the market has been the smallest naturally change has been the least.  I will take you from the pukity puck private airplane to the  Change to blend digital and physical.  From Cessna to 777! 

The Mooney 201 which debuted in 1977 was the first hint of what was possible.  It was a Carter era airplane take a standard Mooney airframe and have a genius jack up the speed without adding 1 horse power.  Flying Magazine did a profile on the airplane Lo Presti focused on cleaning up the airplane aerodynamically speaking to get speed out of the horsepower of the engine....it hinted at what was to come as GA at that level remained beneath surface as homebuilders and enthusiasts stepped up laying the grounds for what would flourish after product liability lawsuits were curtailed.  What happened next was an industry waking up after slumber.  Mooney did not go the composite route but showed what refinement of existing technology can do.  The Mooney Ovation offered an induction system that Flying Magazine noted that had a full equal distant journey of the fuel air mixture to all six cylinders what happened?  20 mpg at 200 miles an hour of airspeed.  So two people in a car going sixty miles per hour to a business meeting are only saving at best a couple gallons not burned going less then 1/3 the speed.  Keep in mind though any traffic along the way will alter it and a VFR flight generally operates in a straight line shaving distance.  You had the ability to lean the fuel air mixture with a greater precision you also had continuation of an older theme that Lo Presti had established.  The composite revolution that the kit and homebuilders had been working on became manifest with the debut of Cirrus SR-22 and their fleet the themes of great ability to lean the engine a cleaner airframe remained.  The net effect was greater fuel efficiency.  What had been mocked as spam in can had faced its own quiet changes.  When Cessna resumed production of the Cessna 172 it was a different bird.  It was slightly more fuel efficient.  The Composite influence has increased the speed of trainers and touring airplanes in use today Diamond Aircraft has shown this in their line.  Piper's line has likewise been cleaned up offering more speed for the drop and horsepower of fuel.  Older Models from Piper have continued to been refined for less drag and more speed then what had gone before.  General Aviation gets more for the gallon of 100LL from Skyhawk to Mooney just well the progress is at best somewhat impressive.  Liability lawyers did much to hinder and only now are starting to see the composite effect stay tuned weights will lighten and speeds will heighten and fuel efficiency will grow.   

Now Business jets on the ramp all look about the same today as they did when Carter was in the oval office.  The Pilot operating handbooks and cockpits say otherwise.  What looks the same is really a bird of a much more fuel efficient feather.  The GII to the data of the Gulfstream 550 from a range of under translantic without stops to an airplane that the same flight would be considered barely a leg stretch.  How fuel efficiency has increased?  You have greater energy extracted from molecules of get fuel through the jet engines.  The Rolls Royce Speys mounted in a GII were great noise makers they did not however extract energy nearly as efficiently as even the Allisons on a Citation X which is the fastest set of Wings right now!  The higher bypass ratios of commercial engines have been adapted to smaller jets.  The digital revolution has been felt in the design and in the control of these airplanes that you can either call engines of commerce or signs of gluttony.  The aerodynamic refinements have been subtle have had had an effect on parasitic drag making the modern biz jet cleaner aerodynamically coupled with engines that have been forced to be quieter while extracting more thrust from a hydrocarbon based fuel.  Put the same load of Fuel in a G-550 that would take you 2,000 miles in a GII bottom line you are going further, faster and in greater comfort.  

The airplanes that move you out of your hometown airport look surprisingly similar to the ones that moved the skies under Carter....they ain't the same.  Those things on the tips of the wings and fatter engines well they may only have a minor change in looks of a given airplane but the accountant knows otherwise.  The Southwest airline flight from SAT to DAL assuming it is in a 737-700 will consume easily 30% less fuel then the same flight made in 1975 in a 737-200 the wing on the engines on the -700 are 30% more fuel efficient the new wing on the airplane adds to the fuel efficiency. The 737-200 was hardly the main line airplane for Continental, Delta, American, in the early 1980s.  That brings us to the 727 which was in the early 80s the predominant airliner that burned 26 gallons of jet fuel per minute at cruise.  In short the flight in practically standard equipment today v standard equipment of the 1980s is at least 1/3 and with honest accounting more then that in short medium range routes of America. 

  A retired airline pilot recalled the fuel flow on the first generation of jet airliner being 4,000lbs per hour per engine (These were considered obsolete by the mid 1970s) we are talking 16,000lbs of fuel per hour four an airplane seating.  The airplane had 4 of those bad boys hanging off its wings generating more noise then a Grateful dead concert.  In McGraw Hills book Profit Strategy for Air Transportation cites that the conversion of the CFM-56 turbo fans from the JT-3D turbo fans would yield 17%  gain in thrust per pound of fuel consumed.  The DC-8-70  was the end of the first generation of jet transport with engines from the 2nd generation of jet transport.  The shift in engines meant a gain of 17% fuel efficency.  Now a twin engine 767-300 flying the same route carrying double the load will burn 10,000lbs of fuel per hour carry 25-50% more people!  Each of the engines on a 767-300 burn 5,000lbs per hour.   The glam routes of the Pacific and North Alantic needed bigger aircraft to deal with the demand.  Engines have evolved.  One captain of them said that on a first generation 747 they expect to burn 28,000lbs the first hour of cruise.  The seating capacity of the DC-8 mentioned was roughly 120 people in what was then a 2 class cabin.  The 747 of the early 1980s had a three class cabin that could easily seat over 300 comfortably! The 747s of the early 1980s are old passe technology the 777-200 has similar seating capacity and has replaced DC-10s,L1011s it just burns less fuel per seat.  The 777-300 is considered to be 30% more fuel efficient then quote 747 classics.    Those classics were right around 20% more fuel efficient then the first generation jet airliners they replaced by the early 1980s. 

I have shown you the numbers now lets look at what caused the technologies and how the market has driven them.  In the piston engine airplane world particularly single engine airplane world drag is a vice but not a big one without spoilers general aviation airplanes from cruise to landing is an awkward thing the cleaner an airframe the longer the let downs.  Mooney 201s and all Mooneys were later equipped with speed brakes.  Lo Presti's impect from Mooney to Piper is now secure he increased the need for spoilers and speed breaks to slow down general aviation airplanes.  The end result is through innovation higher cruise speed on the same horsepower.  The winglet and other far more subtle refinements have been made from long haul airliner to business jet further reducing wind resistance as a computers and new generations of engines power the change.   

The high bypass ratio Turbo fan was born in 3 locations. It was first concieved as a weapon for war to drive the C-5 galaxy.   The first generation JT-9D along with the RB-211 and the first CF6 were the engines that powered the very first wave of this revolution.  They have been refined.  The technology has found its way down to smaller airplanes including regional jets.  The leap in fuel efficency closely mirrors this design.  The bottom line is far energy is extracted from hydrocarbons then the first and second generation of jet engines.

Finally we get to computers.  The PC that I am writing this essay on could have handled the moon landing in sleep mode and had caverns of computing capability left over!  The computer has rendered the wind tunnel a more effective tool and has found its way onto the cockpit.  I remember reading Flying talking about how on a Lufthansa flight in the new Airbus A340 climbed.  It pumped fuel to a rear fuel tank so that the whole tail plane could return to neutral reducing drag an therefore fuel consumption.  The 777 is fly by wire computers dictate how its going to climb and which control surface will be used to obey the  command given by the pilot.  Auto throttles computerized where introduced in the first generation of the 747 and have been refined.  They are now common equipment in the latest generation business jets.  An Airbus A380  and an MD-80 will have computers controlling the engines.  Computers have had their role in driving thrust for the buck up and in the process of keeping Green in airplane owner pocketbooks have made aviation more green. 

It has been said that money talks.  The revolution of fuel efficiency has been driven by the bottom line.  The story of the radical greening of commercial aviation has been the story of money driving innovation after innovation.  That trip over the North Atlantic and particularly across the Pacific since stops have dissapeared may require half the fuel to get you there then it did in 1975!  No fleet efficiency standards.....no forced mandates to get technology on the line from on high just profit motive in its raw form.  The net effect is that barrel of oil does not go as far in the air as it used it goes 1/3 to nearly twice as far!   

Back the Backroads Buzzard's Cafe