As technology progresses, you might notice that things are getting smaller. Your iPhone is thinner, your flat screen television is narrower, and you can fit a digital camera in your palm. That’s because technology tends to get smaller when it becomes more efficient.
So, why are jet engines getting bigger? Jet engines are getting bigger since the larger they are, the more fuel-efficient and powerful they become. With a larger size, the bypass ratio increases, meaning that more air can go through the engine and help propel the aircraft.
It’s easy to just take our word for it when we say that jet engines are getting bigger. So, we’re going to go over a brief history of the first jet engine and how its size, power, and efficiency compares to the jet engines of today.
Table of Contents
Looking Back at the History of the Jet Engine
The first official jet engine was developed in 1936 by a German physicist by the name of Hans von Ohain. He sought to develop a more fuel-efficient and powerful airplane engine that used a turbine instead of a propeller.
By 1939, von Ohain’s engine was used for the first time in the Heinkel He 178. This marked the first time a turbojet engine was successful in flight. This would set the stage for the advancement of jet engines to what they are today.
The Heinkel HeS 3
The Heinkel HeS 3, von Ohain’s first jet engine, weighed a startling 790 pounds, which was pretty large considering the size of the average airplane in the 1930s and 1940s. For comparison, the Heinkel He 178 used with this engine was only 24.5-feet long.
Despite its immense weight, the first jet engine was only 58 inches long and 37 inches in diameter. It was also incredibly weak compared to today’s jet engines, at a mere 1,100 pounds-force of thrust.
Typical Sizes Today
While we can’t determine a definitive size of today’s jet engines, we can provide some estimates based on some of the more popular jet engine models. For example, the widely-used General Electric GE90, which is used on Boeing 777s, is over 17,000 pounds.
It’s also nearly 24-feet long and has an average diameter of nearly 13 feet. The modern-day jet engine is clearly more powerful, at over 80,000 pounds-force of thrust on takeoff.
What It Means
The physical size isn’t as important as the thrust-to-weight ratio. The higher a thrust-to-weight ratio, the more efficient an engine typically is. Basically, a heavier engine should be more powerful and vice versa.
Well, the thrust-to-weight ratio of the first jet engine was somewhere around 1.3. Today’s jet engines are usually 5.5 and above.
So, even though today’s jet engines are much larger, they’re also much more efficient than they once were.
Maybe Bigger Really is Better
There’s no doubt about it: Jet engines are getting bigger every decade. What’s really interesting is that planes aren’t getting any bigger at the same time. That’s because a lighter plane is much better at gliding through the air while a larger engine is more powerful.
When you combine a lighter plane and a more powerful engine, you’re ultimately getting greater engine efficiency. But, to fully understand how bigger is better in this circumstance, you’ll have to learn about how a jet engine really works.
How Size Impacts Efficiency
Think about a 50-pound child trying to push a heavy 130-pound box across the carpet. The child might be able to make it budge a little bit, but it won’t go all that far, and the child will likely be exhausted and weak after only a few seconds.
Now, picture a 150-pound adult attempting the same task. Though it’s still difficult and requires a good deal of effort, they’re able to complete the task much quicker and without becoming so tired at the end.
This is efficiency.
It’s very similar to how jet engines work as well. The larger the jet engine, the less it has to work to propel the plane through the sky. That also means less energy loss along the way.
The Role of Bypass Ratio: Why Bigger Jet Engines Are Better!
One of the major reasons for this greater efficiency is a higher bypass ratio of the turbofan engine. This ratio basically compares the amount of air that goes through the turbofan versus the amount of air that goes through the center of the engine.
The bypass ratio is often directly linked to the size of the fan. The higher the bypass ratio, the more air is coming into the engine and being used efficiently.
So, a larger engine with a larger fan will have a greater bypass ratio. Thus, the larger engine should have greater fuel efficiency in the long run.
The Limitations in Size
Though bigger is definitely better when it comes to power and efficiency, there’s definitely a limit. Remember that an engine must not only propel the weight of the plane through the sky but also its own weight.
Right now, a 17,400-pound engine is great at maneuvering a hefty Boeing 777 with ease. Yet, if this engine were to suddenly weigh 25,000 or even 50,000 pounds, that adds to the overall mass of the plane and requires greater effort to keep it airborne.
Otherwise, it can cause drag. This can keep the plane from reaching an optimal speed or from accelerating as quickly as it can with a smaller engine.
Why Fuel Efficiency Matters
So, now we know that bigger engines are better in terms of fuel-efficiency. Even if you don’t drive a fuel-efficient vehicle, most cars are capable of getting between 20 to 40 miles per gallon, right?
Well, even though jet engines are extremely fuel-efficient, they’re nothing like small vehicles (i.e., Your car or SUV). They actually burn a ton of fuel every trip, and aircraft manufacturers are looking for new ways to go green and save the environment.
Just how much fuel does a plane use?
Think about this. The average car can hold about 12 gallons of gasoline in its fuel tank. Some large airplanes (like Boeings) are capable of holding more than 200,000 gallons of fuel in a single tank.
Jet engines are much more fuel-efficient than they’ve ever been, but they do burn through a lot of fuel on every trip. Large commercial planes can burn one gallon of fuel for every second spent in flight.
That means airlines are spending a ton of money every single day to keep their flights in the air. So, while boosting the fuel-efficiency of their jet engines, they’re also able to save themselves a little bit of money at the same time.
And also, there’s the obvious benefit of producing less toxic pollution as a result of more fuel burned. That’s a clear benefit for the entire world.
Conclusion
It seems like every year, jet engines are getting bigger and bigger. That’s true to some extent, but it’s for a good reason. It’s mostly because larger jet engines mean greater power and great fuel-efficiency. Here are some reasons that jet engines are getting bigger.
- The larger a jet engine, the more efficient the propulsion and power
- Less fuel used means more money saved by the airlines
- Many airlines and major corporations are taking initiatives to reduce environmental pollution, like gasoline burned in flight
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