Daily Archives: March 22, 2010

In a previous post we introduced some comparisons of aircraft by its price per kilogram. There, we could see a trend in bigger aircraft being cheaper in this per kg basis. This raises the question: do bigger aircraft require less weight per seat? Are they lighter in a kg per seat basis?      

This is what intuition seems to tell us; after all, once you have put in place the engines, wing, tail… what can be the difference between a larger or smaller fuselage…     

Let’s use the same sources we used in the previous post and take the typical seat configuration that the OEMs (Original Equipment Manufacturer) indicate for each aircraft model. We get the following table:     

 

Our intuition wasn’t very successful again. In the upper part of the table we find the A320 family and 737s aircraft (those used by e.g. Easyjet and Ryanair in short-haul routes). In the bottom of the list we find the A380, A340, A330, 787, 777…, the biggest aircraft.     

We see that the average is about 400 kg per seat. Let’s compare this figure again with cars, with the same cars as we did in the previous post. We now get following table:     

 

It turns out that cars also need around 300-500 kg of structure per seat (an average for these ones of 360 kg). Since most cars carry 5 passengers, here it’s easy to see the trend: bigger cars employ more kilograms per seat.     

Let’s go for a closer comparison:     

• Small for small: take the A321 with 253 kg/seat, it is quite similar to the Renault Megane with 230 kg/seat.
• Large for large: take the A380 with 527 kg/seat, it is almost identical to the Audi Q7 with 527 kg/seat.

One step further: The A380 used so far is the 3-class configuration with 525 passengers, but wasn’t there a high density configuration with 853 passengers in a single class? (This matches well with the jargon: cattle-class…). This configuration gives us 325 kg/seat… this is again almost identical to the 329 kg/seat given for the Audi Q7 in “high density” configuration, obtained with the optional 3rd row of seats, which only adds 35 kg to the weight of the car. Aren’t these remarkable coincidences? Is it a constant of the universe? 🙂     

Let’s compare these results with buses, city buses and minibuses:     

 

When we compare the figures of touring and city buses in an all-seated configuration we get again similar figures than planes and cars (~290 kg/seat ~ A320 family). If we take a fully loaded city bus we descend to the crude reality of mass transportation and complete lack of comfort (100 kg/seat; that is cattle-class…). We may notice as well that a minibus weighs less than a Q7 and carries twice or three times as many people.     

Let’s now see the train and subway. For this purpose, we’ll check the coaches R-142A and B of the subway of New York which are built by Kawasaki Heavy Industries (which a supplier for the Boeing787 as well). The train we’ll use is the AVE Series 100 of RENFE, built by Alstom, which was the first high-speed train ever used in Spain in 1992. See them in the following table:       

 

The subway is below the levels of aircraft, but not that low as city buses. As far as the train is concerned: that’s another story, a luxurious experience (achieved with ~1,200 kg/seat) that can only be improved by Singapore Airlines Suites.     

Below we can see again a graphic with all modes of transportation compared, there we may spot some trends.     

 

We could say that comfort starts above 300 kg/seat… How heavy is your car?