Freighters with front-opening cargo doors after the 747?
With the delivery of the last 747-8F freighter later this year, the aviation world potentially loses a trick it’s had up its sleeve for decades. The ability to carry oversized loads often depends on the presence of a door that allows loading lengthwise in the cab. And that means having a front or rear cargo door. Or in some cases, both.
The reason the 747 has a front-opening cargo door is because its designers intended it to be a freighter from its inception. We thought back to the days of Boeing in the 1960s and the fact that its management believed the future of long-haul passenger transportation was…supersonic. Of course, this was not Boeing’s idea; pretty much everyone in the industry thought the same.
Front-opening loading door: protection against obsolescence
And so, with US government funding at hand, Boeing got to work designing its 2707 SST (SuperSonic Transport). But there was a problem. Boeing knew the 2707 would be slow to come to market. Additionally, he had already worked on the design that would become the 747, so the company gave him a very tall cockpit, to make room for a front-opening cargo door.
And so, the 747’s two-deck layout was born. This was a truly new feature, for a pressurized commercial aircraft design. Military aircraft, as well as some small-scale conversion efforts we’ve seen, had attempted the same idea. But the design of this front-opening cargo door gave the 747 another string to its bow. It wasn’t just the largest commercial freighter. It was also great for all sorts of oversized…anything.
This niche for oversized freight allowed the 747 to outlive its former replacement: the Airbus A380. Early in the design of the A380, other ideas for its cockpit placement came and went. There are concept images there, showing it with the same elevated cockpit position as the 747. But ultimately, Airbus didn’t pursue the forward-opening cargo door idea too seriously. Orders for a planned A380F freighter have come – and gone.
Some very special freighters
Today, there are a few other alternatives, for loads that won’t fit through the side cargo door of a 777F, or a future A350F. One of the first, almost at the same time as the 747 design, was the “Super Guppy”, as we have seen. But it was an aircraft with a highly specialized role. He could carry very bulky things… but not necessarily very heavy, for their size.
It will be the same later for the Airbus Beluga and Beluga XL. These designs feature a front opening door that opens upwards, again for specific needs, [relatively] light loads. Airbus learned a lesson from using the Super Guppy and wanted the cockpit out of the way. The design of the Guppy meant that all connections between the cockpit and the flight controls had to be disconnected and reconnected, every time the door opened!
The problem with the Airbus Belugas, as with the Guppy and the Boeing Dreamlifter, is that their cargo space is not pressurized. This isn’t an issue for some loads, but it certainly can be for others. It is therefore unlikely that these front-opening cargo door designs can truly replace the 747. In addition, 747 freighters can carry more weight.
Restoration for a niche
One design that can get the job done is the Antonov An-124 – and if another flies again, the An-225. Boeing actually relied on the An-124s to transport the 777X’s monstrous GE9X test engines. But as impressive as their cargo loads may be, these planes aren’t as efficient as the 747-8F. If desired, their front-opening cargo doors (and rear ones – they have both!) make for an even smaller niche design.
AAnd it’s the niche nature of oversized load transport that presents us with obstacles as we look to the future. Could there be a new freighter design, which allows oversized cargo to be loaded through a front-opening door? Or a rear? Consideration has been given to making civilian versions of military freighters – most recently the Embraer C-390.
But the cabin of this aircraft has a section similar to that of a C-130. It could become a good all-terrain freighter for remote areas, but its rear door will not allow it to replace large carriers. Developing an all-new cargo plane with a front-opening door would be prohibitively expensive. So are there any other options out there?
Cargo Conversion With a front opening door?
Well, there could be. Let’s go back to this idea of Super Guppy. Again, it worked fine, but disconnecting and reconnecting flight controls, hydraulics, and other systems between flights was a handling nightmare. However, should this also be the case today? We now have planes like the 787, for example. It is a fly-by-wire jet, which uses minimal hydraulic systems.
Here is a hypothesis. Suppose Boeing (or someone else?) has converted a 787 with a front-opening (hinged?) section, including the cockpit, allowing cargo loading. What sort of mechanical connections would that actually involve? And would the 787’s composite fuselage, built from sections of cannon, make such a task easier? And the Airbus A350?
This author’s background is in economics, not engineering – so until more qualified people get involved, we won’t know the answers. But again: designing an all-new, custom widebody cargo plane with a front-opening door would be financially prohibitive. Aircraft manufacturers must now sell several hundred aircraft to make their initial investment profitable. Boeing sold a lot of 747 freighters, but the program wouldn’t have survived on those alone.
The loss of a cargo plane with a front-opening door is not necessarily an urgent problem. The 747-8Fs (and those Antonovs) will continue to fly around the globe for a few more decades, at least. But when a successor comes, it will most likely be a conversion of some kind. Unless other technologies allow manufacturers to produce new aircraft at a lower cost, making them profitable with only a few dozen aircraft sold.