Here’s why the 747 is a popular cargo aircraft:
- High-lift wings
- High MTOW
- Weight reduction and optional further weight reduction on freighter models or the -100/-200 due to a lack of an extended hump
- Large door. Very important.
So why are these things important?
Well let’s start with the first two. Lots of lift and the ability to carry a lot of weight mean that freight companies can load it with stacks of cargo and it can still fly safely.
The third point mentions weight reduction. What I mean is that unlike the A380, the 747 only has a partial upper deck. Obviously, half a deck weighs less than a whole deck. The 747’s upper deck has been extending since the 1980s/1990s, so Boeing introduced their newest freighters with a short upper deck.
These are actually the same plane, but one has a shorter upper deck because a lounge/extra 100 seats isn’t needed to carry cargo.
But the fourth point is the most important. It’s the reason the 747 exists, and the reason they’re still able to build 747s 50 years later whereas the future of the A380 is looking bleak after just 10 years. And unfortunately kids, we’re going to have to use maths.
The only way to fit two objects of a similar length inside one another is to insert it through an opening that extends from one side of the larger object to another. That’s why cereal boxes, glue sticks, pencil cases, glasses boxes, Kit Kats, guitar cases, and pretty much every non cubical or spherical shape we see around us is designed that way.
I did a quick diagram to show you what I mean. Let’s say the big cylinder is our plane, and the smaller cylinder is our freight. In order to fit this particular piece of cargo inside the plane, we’d need to have a reasonable sized hole where either of the red lines are. The blue line is as wide as front red line, but because it’s on the wrong axis, we can’t fit our cargo in through the blue door. That means that only the red lines can be used for this job.
So obviously, we can’t cut a huge gaping hole across our plane, so we have to use the red line at the front, right? Hmm… I wonder if anyone’s thought of that…
So let’s explain what we can actually see here.
Obviously, when you order your X-Box or your pot plant online, they don’t have to use that massive nose door. So for smaller cargo, this plane actually uses that smaller door you can see under the “Boeing” logo to the left of the nose door. That’s actually the “cargo hold” and it’s on pretty much every plane – even passenger ones.
In fact, opening that big nose door takes quite a lot of time:
If you’re anything like me, you probably skipped most of that video out of boredom.
So usually they actually use another door, located where that blue line from my diagram is.
This allows for quicker (and often easier) loading of cargo, especially small cargo like containers.
So that brings the question: why have the big door in the first place?
Well we get 747–8Fs in outback Australia. I’m not sure about you, but I can’t see a great deal of demand for packages into outback Australia. So what do they carry?
Drills for mining operations, of which Australia has quite a few.
This is one of the smaller drills, but notice how it’s long and thin? That’s perfect for fitting inside a plane.
The only problem is, some other large cargo freighter like a 777F or an MD-11F can’t fit that inside it because they only have the side cargo door, whereas the 747 can fit the whole drill inside in one piece.
Now here’s a curveball for you: we know why it does have the front door, but do you know why it can? Think about it.
The answer is the position of the cockpit. The 747 was originally designed to compete with the Lockheed C-5 Galaxy, and when the United States Air Force chose the Galaxy instead, Boeing turned the 747 into a passenger freighter. Let’s have a look at the C-5:
You can see a similar technique used for front loading – in addition most other military cargo planes also have a back loading door for the same reason.
So when the 747 was rejected by the USAF, Boeing simply took the cargo bay, added windows and seats, and sold it as a passenger airliner.
Years later when people were interested in flying cargo with 747s, Boeing was like, “yeah um I think the 747 could possibly carry cargo…” 🙂
So once again they removed the seats, blocked/removed the windows, and sold it as a cargo aircraft.
Now here’s the catch:
When Boeing introduced the 747–300, it came with an extended hump for more seating in the upper deck. This hump was not needed for cargo, but nobody really liked the -300 anyway so the few 747–300Fs are converted freighters and have a full upper deck.
Then, Boeing made the 747–400. This featured the same upper deck but was a much better aircraft in general. It was very popular and a lot of people bought them. When people asked to turn this 747 into a freighter, Boeing did. And they really did.
Notice the shortened hump? That’s because obviously there’s no need for passengers/additional cargo, so they use the shorter hump for a crew rest area.
Now when Boeing made the 747–8, it had an even longer upper deck.
This was one of the few 747s that was actually really popular with cargo airlines, but not so much with passenger airlines. Here you can see the difference in the upper deck length.
So let’s get back to the A380.
The A380 was not designed as a cargo aircraft. It was designed as a passenger aircraft. It has a cockpit on the bottom to allow for a better field of vision for pilots, which means that cargo cannot be safely stored there.
The wings have a bit of lift but it has a longer runway length than the 747 and doesn’t have as much stopping power as a 747.
I mean, it technically has a higher MTOW? But most of that is just because of the higher empty weight, so this doesn’t help at all.
The A380 has a lot more weight per fuselage than the 747. Its hump extends all the way to the back, almost doubling as much weight as a 747F. It also doesn’t have any way to reduce this weight unlike the 747.
But the main thing is that there’s nowhere to put a really big cargo door. Let’s have a look at the other very large cargo aircraft out there:
All of these aircraft have a nose door, because the only way that they can have a “leg-up” over the other, more economic cargo aircraft is to carry stuff that those planes physically cannot, such as drill bits.
The A380 has no way of having this door, so it wouldn’t have any advantage over any other large cargo aircraft like a DC-10F or a 777F.
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