That’s because it’s real. What you’re looking at is the General Electric Propulsion Test Platform, a specially modified Boeing 747-400 used to try out new jet engines. In this case, it’s testing out the huge new GE9X meant to power the next generation of Boeing 777.
While both the Boeing 747 and Boeing 777 are very large planes, when it comes to engines they go for different philosophies. When the 747 was first designed in the 1960s, the most important thing was redundancy. Regulations stipulated that if an airliner was to fly far from land, it needed more than two engines in case one broke down in the middle of a flight. If one engine went down it was alright, since there were three more to back it up. Since fuel was cheap and plane tickets were expensive, the fuel efficiency of four relatively small engines all running together wasn’t as big a priority.
But then in the 1980s, with a recognition that jet engines were becoming more reliable, a new set of regulations known as Extended Operations, or ETOPS, was introduced. That enabled big jets to use two big engines, instead of four small engines for long flights, and since two big jet engines are more fuel efficient than four smaller engines, airplane designers went with that. And (I acknowledge I’m generalizing quite a bit here) since a bigger fan diameter tends to result in a more fuel efficient engine, the engines themselves got much larger in dimensions.
Which is how you got planes like the 777, which isn’t that much smaller than a 747, but which has two engines that over 10.5 feet tall, as opposed to the engines on the original Boeing 747-100, with four engines each just over 7.5 feet tall.
Back to the plane you see above, however. The Boeing 777 has now been in service for over 20 years, and engine technology has advanced enough where planes still in production could use a new, more efficient set of jets to get through the air. While Boeing is designing the upgraded plane, known as the Boeing 777-8 or 777-9 depending on length and range, GE is working on those new engines, known as the GE9X.
To test out the new engine it helps to put it on an already-existing aircraft. In this case, it means GE’s Propulsion Test Platform, which makes for strange looking videos like this:
The GE9X is over 11 feet wide, and looks absurd on a plane with three much smaller units.
Anything for a few extra MPGs, I suppose.