Why do commercial jet aircraft have two or more engines? Why don’t airlines operate single-engined aircraft for short-haul routes or areas that have low demand? Let’s explore the paradox of single jet engine commercial aircraft.
Does a single jet engine commercial aircraft exist?
You only need to look to the military to see what is possible with a single jet engine aircraft. Air forces around the world have multiple fighter jet designs that can fly as fast as a Concorde with a single jet-engine and are far simpler to repair and engineer.
However, when you look at commercial passenger aircraft (such as from Boeing and Airbus), no single-jet engined plane exists. Well, almost none.
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The Cirrus Vision SF50, which hit the market back in 2016, was the world’s first civilian single-jet aircraft. It can carry seven passengers up to a range of 600 nautical miles (690 mi, 1,100 km). It doesn’t go very fast, only 300 knots (350 mph, 560 km/h) maximum cruise, which is around half the speed of a typical commercial aircraft.
So while we certainly have the knowhow to build a single-engine aircraft, and engines powerful enough to enable a plane as big as the Boeing 737 to fly, why don’t they exist?
It turns out there are some problems with the single-engine concept.
The problems with a single-engine
There are few problems with the single-engine jet concept beyond light aircraft:
- A single-engine would need to be placed at the rear of the plane (not on the wings) and would take up valuable cabin space. Airlines are already struggling to fit in enough passengers, and putting in non-revenue earning machinery in their place would be a backward step
- A large engine needs clearance between the fuselage and the engine itself; otherwise, there would be more drag. The higher the engine is mounted, the more engineering and maintenance problems (like the third engine on the trijet)
- Passengers in the rear of the plane would be right under the engine and would find it very loud and uncomfortable
- The aircraft would be rear heavy, making tail strikes a greater risk
And we haven’t even mentioned the safety problems.
Surprisingly, despite all of the above reasons not to build a single-engine aircraft, you can’t deny that the costs to develop and operate such an aircraft would be cheaper.
However, there are some safety factors to consider, especially for a plane carrying 100-200 passengers.
According to the FAA, there cannot be any single point of failure when it comes to aircraft. Each aircraft needs at least two of everything, from wheels to pilots to engines, to ensure if there is any loss, the plane can keep flying.
For each powerplant and auxiliary power unit installation, it must be established that no single failure or malfunction or probable combination of failures will jeopardize the safe operation of the airplane except that the failure of structural elements need not be considered if the probability of such failure is extremely remote. – FAA regulation
These regulations are in place because some of the very first commercial aircraft (Like the Junkers F-13 and Fokker FII) had a single-engine and had a much higher chance of accidents.
Lastly, we need to consider ETOPS ratings. If an aircraft has a single-engine, it is unlikely that the FAA (or any aviation authority) would allow it even close to a bathtub, let alone to fly over an ocean. A plane needs two engines to ensure it can make it to the next runway if one failed.
As for the personal Cirrus Vision SF50 featured at the start of this article, they actually have a parachute included in the fuselage that allows the aircraft to safely float down in case of an engine failure.
What do you think? Would you fly on a single-engine commercial aircraft? Let us know in the comments.