Modern aircraft undergo rigorous tests before being deemed safe for operation. Almost all the aircraft's parts, from the wings to its fuselage and engines have to be tested before commerical/private operations. Newer aircraft are focused on designing engines that can run on Sustainable Fuels, but certifying the Sustainable Aviation Fuel (SAF)-operable engines as safer for operations is a time consuming process.

✕ Remove Ads Related What Are Aircraft Engine Testbed Facilities & Why Are They Important?

Testbeds are essential to the success of jet engine programs.

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This is because aircraft engine testing involves a lot of procedures. Let's take a look at five things you might not know about aircraft engine testing.

1 Going through a hot and cold campaign From blazing high temperatures to icy cold conditions

According to Brian Roggow, the associate dean for the College of Aviation at Embry‑Riddle Aeronautical University's Prescott Campus, extreme heat that aircraft encounter is a challenge that needs to be addressed well:

"Pilots include weather considerations -- such as temperature, pressure, precipitation, wind velocity and more -- into every flight....As we reach extremes in any one of these categories, operations may either be delayed or canceled. In the case of extreme heat, aircraft performance data may be unavailable if the manufacturer was not able to test or publish values."

Photo: Skybrary.aero ✕ Remove Ads

As a result, aircraft need to undergo testing at either extremely high or low temperature. One of the tests that aircraft need to undergo is a hot section inspection (HSI). This involves an examination of the following engine parts:

Combustion chamber Compressor turbine disk Turbine blades Stators Vane rings

Undergoing an HSI helps identify minor cracks in non-rotating parts and check whether some parts need replacement, reported pratt and whitney. Aircraft can also be taken to freezing temperatures to check whether they would be able to withstand extreme conditions, reported BBC:

"...to examine the latest Airbus A350 XWB's ability to withstand freezing temperatures, the plane manufacturer's engineers took it to Iqaluit, the capital of Canada's Arctic territory of Nunavut. It stayed there for a week, and the tests included operating the plane on the ground and in the air in temperatures as low as -28C (-18F) and performing thrust-reversed tests with snow - basically, the effects of sudden braking that you might find on an aborted take-off."

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At Boeing's Research Aerodynamics Icing Tunnel (Brait), engines can be subjected to temperatures of -40C (-40F) to simulate conditions of rain, ice and cloud that engines might encounter.

2 Noise of aircraft engines is measured with precision of a fraction of a decibel NASA's Glenn Research Center leads US's efforts to reduce aircaft engine noise

The noise produced by aircraft engines is one of the problems that needs to be reduced if the aviation community is to achieve its sustainability goals. Engine manufacturers such as Rolls-Royce use highly sensitive microphones to detect engine noise that is as small as a fraction of a second.

The microphones that are placed around the engine test beds monitor noise levels when the engines are operated at low or maximum power. To ensure that ground air turbulence doesn't interfere with the nose of the engine, "the engine intake is fitted with what looks like a giant golf ball".

Photo: Rolls-Royce ✕ Remove Ads

According to Rolls-Royce, the engine manufacturer is looking for unprecedented results in the reduction of engine noise:

"Aircraft today are perceptibly quieter than 20 years ago, and alongside the wider aviation industry we're working towards environmental goals that will see us reduce noise by 65% by 2050 relative to 20 years ago. New and improved technology means that engines such as the Trent 1000 and Trent XWB are quieter than ever before."

Some of the methods used to reduce engine noise include the following:

Integrating new technology that reduces fuel consumption Using wind-tunnel simulations 3 NASA's engine testing facilities built in 1950's exist even to this day Large steel castings are used for the two altitude test chambers

After the end of World War II, stronger, more powerful aircraft were on the horizon. As a result, testing of the highly powerful engines necessitated state-of-the-art testing facilities. So, the National Advisory Committee for Aeronautics (NACA) constructed the following facilities:

✕ Remove Ads Propulsion System Laboratory (PSL) No.1 Propulsion System Laboratory (PSL) No.2 Photo: NASA

According to NASA, the space race also changed the nature of the way testing was carried out in PSL No. 1 and 2:

" Lewis researchers initially used the facility to test the new jet engines of the early 1950s and the ramjet engines that powered the Navaho and Bomarc missiles. With the arrival of the space program, they transitioned to chemical rocket engines, including Pratt & Whitney's renowned RL-10, which propelled the Centaur rocket . In the late 1960s, the focus returned to aero propulsion, as engineers used PSL to study complex problems such as flutter, inlet distortion and fly-by-wire control systems."

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In the 1970s, NASA created two larger chambers, PSL Nos. 3 and 4, which form part of the space administration's solitary test facilities. These facilities help develop and research aircraft engines and propulsion systems.

4 A chicken gun fires dead birds into the engine Used to meausre how resistant engines are to bird strikes

Every year, hundreds of aircraft worldwide report incidents of bird strikes. Sometimes, bird strikes tend to cause both engines of the aircraft to fail, as was the case in the Miracle on the Hudson. Therefore, (aircraft) engines need to undergo rigorous testing to check how forceful an impact with a bird they can withstand.

Photo: Flying Magazine | Wikimedia Commons

Talking to CNN, senior research officer at the National Research Council of Canada (NRC), Azzedine Dadouche, explained how the engine is calibrated to determine if it can withstand the bird strike:

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"To do the calibration test, we can use gelatin-based birds, or we can use chickens that we buy at the grocery store. Once we are in the range, we use real birds to finalize the calibration, and of course we use real birds to do the certification test. The birds - always dead ones only - go into the cannon with the feathers, the head, legs, everything. We get those birds from specialized companies that use birds of prey to scare away birds from the airport area. Sometimes the small birds get killed."

Here are some other interesting facts about the chicken gun:

They are able to fire a two-pound gelatin-based projectile at a speed of 1,000 mph (Mach 1.36). Super Cannon, the biggest operating gun in the world, has a diameter of 17.25 inches. 5 The world's largest on-ground engine testbed is in Derby, UK The internal area is greater than a football pitch

Located in Derby, UK, Rolls-Royce's Testbed 80 is the world's largest on-ground engine testbed. Here are a few interesting facts about Rolce-Royce Testbed 80:

✕ Remove Ads It allows "data collection of more than 10,000 different parameters at a rate of up to 200,000 samples per second". It is equipped with a fuel tank that has a capacity to fill up an average car 3000 times. The X-ray machine in the testbed can capture 30 images per second. Photo: Rolls-Royce

The platform can also run engines on sustainable aviation fuel (SAF) and, according to Rolls-Royce, it is the most complex testbed it has built:

"The completion of the project is a major milestone after almost three years of construction and a £90m investment. With an internal area of 7,500m2, making it larger than a Premiership football pitch, Testbed 80 was designed with distinctive technologies and systems which are more capable and complex than any of our other testbeds."

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