Jet Aircraft Comparison?

Question

Hi, I preparing a spreadsheet for comparing different types of corporate jets, and I'm trying to find the most fuel-economic jet available in the market, I came up with the following formulas which I think are helpful, let me start with the following examples:

Aircraft #1: The Cessna Citation-X:

Max. Range: 5,686 Km

Max. Fuel Capacity (with full load): 5,304 Kg

Aircraft #2: Bombardier Learjet 40XR:

Max. Range: 3,378 Km

Max. Fuel Capacity (with full load): 2,268 Kg

the formula I came up with is as follows:

Range/Max. Fuel Capacity (with full load)

when applied to the figures above for both aircrafts, we get the following results:

Citation-X: 1,071 km/kg

Learjet 40XR: 1,489

Does this mean that the Learjet is more fuel-efficient than the Citation?

I know this does not mean that the the Citation-X will fly 1,071 KMs per on kilograme of fuel, there are other factors that can affect a jet's fuel consumption, but I think that it works for the sake of comparison.

Answer 1

a couple issue to consider:

Max Range may not be with full load (which one has to define).  I would suspect that the "full loadout" for the Lear is much less than that for the Citation-X.  Which may mean that the Lear is maybe carrying 4xpassengers, plus luggage and fuel for 3378Km, while the Citation-X carries say 8xpassengers, luggage and fuel 5686kM.  If this is true, then the Citation is actually the more efficient jet-need fewer sorties to move the same amount of cargo; AND over a longer distance.

To get a statistically rigorous answer, one has to normalize both "Max. Range" (which can mean either with a standard reserve OR flying until dry), and as I mentioned "full load".

Answer 2

You may want to throw in passenger miles per gallon if each aircraft has different seating capacity.

Since they have different ranges it might also help to compare apples to apples (both planes flying a fixed distance with similar payload).

Total range is misleading because:

1. More fuel=more weight=smaller payload.

2. It implies you will run the plane till it drops from the sky.  Comparing fixed distances may be more useful.

Remember, the longer the flight, the more efficient the plane becomes.