For a quicker reference to definitions of each metric go here
Interpretting the Analytic numbers:
Analytics- . . . Fuel Efficiency(nmpg): 29.6 . . . . . Time Efficiency(nmph): 65 . . . . . (1000 lbs) per Gallon: 29.9 . . . . . F-T: 19.3 . . . . . F-T-Payload: 19.5 . . . . . HP Efficiency: 5.2
The first two are fairly intuitive. Fuel Efficiency is the NMPG “miles per gallon” that aircraft gets. If you wanted to compare the aircraft to your car, just remember these numbers are in nautical miles, so you’ll need to convert them to statue miles or Kilometers. Just multiply the Nautical miles by 1.15 and you will have statute miles. The second is how far the aircraft will take you in one hour, hence NMPH (Nautical Miles per Hour).
The next metrics are little less intuitive but are very useful. Carry Efficiency or (1000 lbs) per Gallon is how efficiently will it carry payload. The higher the number the better. The number reflects how far the aircraft will carry 1000 pounds of useful load on a gallon of fuel. It basically is the useful load of the aircraft divided by 1000 pounds multiplied by the amount of miles the aircraft travels on one gallon in cruise. However! you may ask what if the aircraft can’t carry 1000 lbs of payload, what if it would take a fleet of two Cessna 140’s to carry that? No problem, this is the distance your “fleet” or single airplane should carry a 1000 lbs of useful load on a gallon of fuel.
F-T metric is a combination of how well does the aircraft turn fuel into time and distance efficiently. It is an abstract number helpful in determining how efficiently the aircraft will get you from point B with respect to time. For example if an aircraft gets great fuel efficiency but travels very slow in the process, and another gets the same efficiency but does it quicker, the second aircraft gets a higher score. This metric is very useful for someone who wants to use the aircraft to get somewhere and not take all day to do it.
F-T payload metric is the same as the F-T metric but it takes into consideration the airplanes ability to carry something in the process. The higher the number the better. So you might have two airplanes who get the same F-T metric but they both carry a different amount of payload, the aircraft that carries more useful load has the higher F-T payload number.
The Last Metric (HP) is more for Fun. It asks the question how well does the airplane convert Horsepower into Speed. Its a reflection of the aerodynamics of the airplane. Its also is good evidence to support the reality of parasite drag, the faster you go the harder it is to overcome it.
Comparing Aircraft Performance to Automotive Efficiency
– Alot of us like to compare the General Aviation aircraft to the gold standard of American travel; the Car. So for comparison sake, and for a good benchmark to compare the aircraft numbers to lets look at a 2003 Nissan Sentra’s numbers.
Well assume the payload of the Nissan is about four 200 pound adults, plus 120 pounds of bags and a fuel tank of fuel. Comes out to be about 1010 pounds. Highway speed is about 75 mph which converts to 65 “nautical” mph. Fuel burn at this speed is about 35 mpg or about 2.2 gallons per hour. Range of this bad boy is 352 nautical miles with a 30 minute fuel reserve (How many of us really drive the car all the way to empty- ok maybe a few, for those add another 32 miles to the range)
Nissan Sentra Analytics– . . . Fuel Efficiency(nmpg): 29.6 . . . . . Time Efficiency(nmph): 65 . . . . . Carry Efficiency (1000 lbs MPG): 29.9 . . . . . F-T: 19.3 . . . . . F-T-Payload: 19.5 . . . . . HP Efficiency: 5.2
The first two numbers are pretty self explanatory, its Nautical Miles per Gallon and Speed are straight forward. As can be seen the Nissan Sentra will carry 1000 pounds about 29.9 miles on a gallon. Interestingly its F-T and F-T Payload numbers are as good as some of the airplanes just because it takes so long to get somewhere, but it has very competative efficiency compared to many aircraft so the F-T metric helps take both into consideration and awards a value. It’s also evident in the HP Efficiency metric that many of the airplanes are more aerodynamic even at higher speeds, which is rather interesting. Take these numbers or other numbers for different vehicles and input them into the cost calculator on a particular aircraft page. By comparing them with some of your favorite airplanes, you might find some interesting things.
We must not that this is assuming pure highway driving, and a route that must be just about as direct as the bird flys.
