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Engines are designed to power the propulsion systems of an aircraft. As such, most engines on a plane are fitted based on the airline’s needs.
However, unlike in the past, there are many different types of aircraft engines today based on a few factors such as thrust and total capacity. The first operational internal combustion engine ever used in an aircraft was made during World War One.
Though an experimental aircraft, the X-57 Maxwell by NASA has the most engines ever. Powered by 14 electric motors, the aircraft is modified using electric propulsion systems from the twin-engine Italian-made Tecnam P2006.
So much so that I decided to conduct some research to learn more about these fantastic powerhouses. For the past century, airplanes have transformed travel and given millions of people a way to live life to the fullest.
However, there’s a lot more to most engines on a plane than first appears. Few people know that all airplanes are fitted with engines, which come in various sizes, forms, and capacities.
Which Aircraft Has The Most Engines In The World?
Next, let's explore the most engines on a plane and the different airplanes they power.
NASA X-57 Maxwell
NASA has for decades been experimenting on the environmentally friendly aircraft the X-57 Maxwell. This makes it the earliest version of all-electric aircraft developed at Nasa’s aeronautics laboratory in California.
The 14 electric motor X-57 aircraft uses an electric propulsion system and is a modification of the Italian-made twin-engine Tecnam P2006T piston aircraft. NASA started the development process of an aircraft with zero-carbon emissions in 2015.
The Maxwell X-57 aims to provide possible design and technological standards alongside standards for safety, airworthiness, energy efficiency, and noise reduction. The P2006T 100hp Rotax 912S engines were replaced with 12 small motors plus two larger cruise motors mounted on the wingtips.
The driving force behind the design for the Maxwell X-57 is to achieve zero carbon emissions in the aviation industry. What's more, the Nasa X-57 can run using renewable-based electricity, thus delivering economic and environmental advantages.
When the German aircraft manufacturer Dornier produced the Do-X flying boat in 1929, it was the biggest, most powerful, and heaviest flying boat ever built. To answer the need for a patrol seaplane that could land and refuel at sea, the Swiss division of Dornier began designing and developing the "Do-X" flying boat in 1927.
And what came out of it was an aircraft powered by an impressive 12 Siemens Jupiter engines. The engines were arranged in six tractor-pusher-style nacelles found on struts above the wing. The three Do-Xs were used to test various engines. And were later re-engineered with 12 Curtis V-1570 610 hp engines.
To get around the Treaty of Versailles, which prohibited any aircraft exceeding predetermined speed and range limits from being built in Germany after World War I, the Do-X was funded by the German Transport Ministry.
It was then assembled in a specially built plant at Altenrhein, along the Swiss portion of Lake Constance. Although the design was well-liked by the general public, only three copies were produced due to a lack of business interest and a series of small mishaps.
After more than 240,000 labor hours, construction on the Do-X began on December 19, 1927, and was finished in June 1929.
The Do-X was launched on July 12 1929 and started taxiing tests right away. These quickly led to 122 flights being completed over the next six months, during which the aircraft was briefly grounded to enable the installation of new Curtiss Conqueror engines in place of the earlier Bristol Jupiter ones.
The Dornier Do-X was a pioneer in showcasing the possibility of a commercial passenger air service. This was the biggest heavier-than-air plane of its day.
Convair B-36 Peacemaker
The B-36 Peacemaker is the biggest combat aircraft ever constructed to be powered by a piston engine. It established a link between WWII pistons and Cold War jets, equipped with six radial and 4 jet engines.
Early stages of producing the B-36D, Convair introduced a set of General Electric J47-19 engines mounted at the end of each wing; they were also adapted to all existing B-36Bs.
As a result, the B-36 was designed with 10 engines, that is six radial propeller engines plus four jet engines, giving rise to the B-36 motto "six turnin' and four burnin' ". More engines were installed in the B-36 than any mass-produced aircraft. The takeoff and dash speeds over the target were considerably enhanced by the jet pods.
The engines were normally only used during takeoff and were never needed for extra speed above a bombing target. Despite being created during World War II, as the only prototype, the XB-36 made its first flight in August 1946.
The engines were turned off during a typical cruising flight to save fuel. To cut drag and guard against sand and dirt ingestion, louvers on the front of the pods closed off when the engines were turned off.
Whether flying or on the ground, the B-36's cockpit crew was responsible for opening or closing the engine louvers. The B-36's total power for a brief period was 40,000 horsepower (30,000 kW) from its two pods of four turbojet engines and six-piston engines.
Boeing B-52 Stratofortress
The B-52 has eight Pratt & Whitney J57 turbojet engines, has an unrefueled 8,800 miles range, and can carry a payload of 70,000 pounds. It's the only aircraft with the most engines on a plane in active military service and it’s fitted with eight engines.
The B-52 is the aircraft that the Air Force finds it most difficult to let go of. The B-52's operating capabilities have evolved over time to meet the growing national security demands. It was first built as a high-altitude, intercontinental nuclear bomber.
The B-52's gunner was originally located in the aircraft's tail. In later designs, the gunner advanced alongside the crew.
The gunner location and defensive machine guns were phased out after the end of the Gulf War. Today, the B-52 is still in service and it has received major upgrades to help extend its life beyond 2040.
On June 29, 1955, at the California Castle Air Force Base, the B-52s were given to the 93rd Bombardment Wing, and the first Boeing B-52s went into service. They were long-range, subsonic, jet-powered strategic bombers with a 185-foot wingspan.
Serving in nearly all conflicts from the onset of the Cold War to the present day, the B-52 has played an important role in America’s airborne defenses.
Soon after World War II, Northrop created the Northrop YB-49, a large bomber prototype powered by jets. The prototype’s first flight was on October 21, 1947. The YB-49 was a flying wing aircraft made with the U.S. Air Force in mind.
Eight J35-A-15 engines, created by General Electric and produced by Allison Engine Company, were used to power the YB-49. The J35 was an axial-flow, single-spool turbojet engine with a single-stage turbine and an 11-stage compressor section.
The engine weighed 2,400 pounds (1,089 kilograms) and measured 3 feet, 4.0 in (1.016 meters) in diameter by 14 feet (4.267 m) in length.
The YB-49's cruising speed was 429 miles an hour (690 km/hr.). Mach number prevented it from traveling faster than 499 mph (802 kph) at 18,000 feet (5,486 meters).
There were just two Northrop YB-49s made. They underwent nearly two years of testing by both the Air Force and Northrop. Although nine more YB-35s were set to be modified, the B-49 was never put into production.
Hughes H-4 Hercules
The Hughes H-4 Hercules (often referred to pejoratively as the Spruce Goose or occasionally by its registration “NX37602”) was a Hughes Aircraft Company prototype strategically developed for airlift flying boats. It was never finished in time to be deployed during World War II as a transatlantic flying carrier.
Although it was among the largest airplanes ever made, the H-4 Hercules was just a prototype. This was equipped with eight 28-cylinder air-cooled P&W R-4360 Wasp Major radial piston engines, each of which produced 3,000 horsepower (2,200 kW).
Intended for transport use during the Second World War, this flying boat can transport 750 soldiers or two M4 tanks weighing 30 tons. Unfortunately, it didn't start flying until 1947, which was long after the war was over, meaning it was never put into mass production.
With the second largest wingspan ever (the first being the Stratolaunch, which we’ll look at shortly), at 97.8 meters, and runs on eight Pratt & Whitney R-4360 engines. During the war period, it had a wooden fuselage to save metals, earning it the nickname "Spruce Goose."
As the only prototype, this aircraft undertook test flights but never entered service. Today, it remains well-maintained and is shown at the Evergreen Aviation and Space Museum in Oregon, US.
Hercules is the largest Flying Boat ever built with the largest wingspan of any airplane in history. It survives in good condition at the Evergreen Aviation Museum in McMinnville, Oregon, USA.
Antonov An-225 Mriya
The An-225 was based on Antonov's older An-124 and its fuselage barrel extensions were extended fore and aft the wings. Additionally, root extensions were added to the wings to improve span.
The revised wing roots now housed six Ivchenko D-18T Progress Lotarev, three-shaft turbofan engines, and used anhedral wings.
With a maximum of 710 tons of takeoff weight, the An-225 Mriya is the heaviest plane ever built. It has the highest payload airlifted totaling 559,580 pounds and 418,830-pounds single-item payload records. Its 290-foot wingspan is the longest of any aircraft in use today.
The aircraft can turn within a runway that is 60 meters wide (200 feet) thanks to a 32-wheel system with improved capacity, of which some are steerable. The An-225, like its predecessor, had a nose gear that could "kneel" to make loading and unloading cargo easier.
To reduce weight, the An-225 design did not include a rear cargo door or ramp, unlike the An-124, and it replaced the single vertical stabilizer on the empennage with two twin tails and an enormous, swept-back horizontal stabilizer.
Scaled Composites Stratolaunch
The Stratolaunch Scaled Composites Model 351 developed the Stratolaunch or Roc aircraft for Stratolaunch Systems to transport air-launched rockets.
This machine came equipped with six Pratt & Whitney PW4056 engines, each producing 56,750 lbf (252.4 kN) of thrust and mounted on pylons outside of each fuselage, to power the Stratolaunch vehicle.
The maximum takeoff weight for the Stratolaunch is 1,300,000 pounds (590 t), with a payload capacity of 550,000 pounds (250 t). At 35,000 feet, the rocket should be let go (11,000 m).
The engines, flight deck, landing gear, and other systems of the aircraft have all been adapted from the B747-400, which has reduced development costs.
The flight controls feature split rudders, horizontal stabilizers mounted twin tail units, and twelve hydraulically operated cable-driven ailerons. The wing includes 14 trailing-edge split flaps that are hydraulically activated, electrically indicated, and also serve as speed brakes.
This enormous double-fuselage airplane boasts the astounding 117-meter-longest wingspan of any aircraft ever built (the closest behind the Roc was the An-225 Mriya at 88.4 meters).
How Many Engines Does An Aircraft Need?
Jet engines propel the plane forward with immense thrust, allowing it to fly at high speeds. Remember that most engines on a plane will vary based on different elements. Even then, some aircraft have just one engine while other planes have two or more engines.
With that in mind, a four-engine arrangement is rather common. Each wing of an airplane normally houses two engines. It increases thrust, enhances safety, and allows for a greater passenger capacity; it was previously necessary for transatlantic flights.
Engines are essential for propelling aircraft and power planes by producing propulsion, while wings and other flight controls are in charge of producing lift. For example, the air is drawn into jet engines from the front such that fuel is burned in it.
The leftover gasses are then expelled from the back of the aircraft, which gives it forward thrust. However, most commercial aircraft are equipped with four engines rather than just one.