Freighters are some of the most impressive airplanes flying today. But as always, the most striking ones never left the drawing board. Let’s look at several unrealized transport aircraft projects that, had the situation been just a bit more beneficial, could have been hauling cargo in the skies today.
The criteria is simple: the bigger the payload capacity, the higher slot on the list. Just like with our 10 largest passenger airplanes, an aircraft must have been in a design phase in order to avoid fictional ones.
Also, a question of “what constitutes an aircraft” becomes rather relevant in some of these, as many heaviest freighters were designed to use wing-in-ground (WIG) effect: an air cushion which forms below the wing as an aircraft flies near the ground, increasing lift.
Such machines – also called ground-effect vehicles, wingships or ekranoplans – often can be considered as a cross between a ship and an airplane. Nevertheless, all of them can fly, some – even land on runways. Also, most of the ones contained within this list were designed to be able to fly at higher altitudes, albeit with smaller payloads. Thus, from here downwards, all WIG vehicles are considered aircraft.
All the payload weights below are in metric tons.
Honorable mention. Airbus A380F: 150 t.
Before we lose a touch with reality, let’s briefly discuss the project which came closest to be realized. When Airbus designed their A380 (the largest passenger airplane to ever fly), they intended it to have a freighter version, capable of carrying 150 tonnes (330,000 lb) of cargo. Despite some initial interest from FedEx and UPS, it never attracted actual orders – mostly due to complicated double-decker design, high price, and a combination of other factors.
In mid-2020, it was reported that Lufthansa Technik intended to start converting passenger A380s into freighters. That may eventually happen, but since Airbus announced stopping their A380 production, it is quite certain that true A380F is destined to never be built.
By the way, the aforementioned payload capacity of 150 tonnes was intended for regular, non-enlarged aircraft. Had it been successful, Airbus would have pursued the development of further modifications with bigger fuselage and upgraded engines, something like A380-900F or A380-1000F, with even bigger capacities.
Semi-honorable mentions. Tupolev Tu-404 and Lockheed Martin VLST: 126 and 185 t.
Both of these were passenger aircraft projects intended to rival the Airbus A380 in the early 90s, yet were never realized. They had their freighter variants planned too.
Tupolev Tu-404, the largest passenger aircraft project ever, had two versions – a stranger one, called by the designers the ‘flying wing’, and the conventional one, a four-engine doubledecker. The first one, although its development reached a rather late stage, never had a freighter variant. The second one had though, with a planned payload capacity of 126 tonnes. Sadly, its blueprints or concept drawings are nowhere to be found.
Lockheed-Martin VLST had passenger, freighter and combi versions present in an initial pitch at the company, latter ones optimized to carry regular shipping containers. Despite smaller size and passenger capacity than the Tu-404, it would have been able to lift more cargo. Interestingly, this stupendously large aircraft was rather tame in comparison with all the super-heavy freighter projects developed by Lockheed-Martin at the time. Spoiler alert: the company is going to have a rather heavy presence on this list.