The Avro RJ100, also known as the BAe-146, is an interesting and unique aircraft. With its four engines, high wing, T-tail design, and broad body, it stands out among other planes. In the Philippines, airlines like Asian Spirit, Sky Jet, and Royal Air have utilized this aircraft. Interestingly, what sets the Avro RJ100 or BAe-146 apart is the absence of reverse thrust. Indeed, this jet does not have reverse thrust! But, what’s the reason behind this unique feature?
Reduced Effectiveness of Thrust Reversers
The absence of thrust reversers on the Avro RJ and BAe-146 is primarily due to their “perceived reduced effectiveness in anticipated conditions.” This reduced effectiveness is attributed to the aircraft’s low landing speed and the close proximity of the engines to one another on each side. When reverse thrust is employed at low speeds, it can lead to the risk of Foreign Object Debris (FOD) ingestion and the potential stalling of the nearby engine.
Furthermore, the BAe-146’s touchdown speed is only around 90 knots, and since thrust reversers are not typically used below 60 knots, their effectiveness would be limited in such circumstances. Incorporating reverse thrust would also subject each engine to an additional cycle per flight, increasing wear and tear on the engines.
The Benefits of Air Brakes
The Avro RJ100 and BAe-146 feature air brakes, which offer several advantages. For one, they enable these aircraft to fly steep approaches into airports like the old Caticlan Airport, gateway to the world-famous Boracay Island. In fact, for several years, the BAe-146 was the only conventional jet aircraft capable of operating from Caticlan before the runway was extended to accommodate Airbus jets.
These aircraft also have a high thrust-to-weight ratio, which allows them to climb more steeply, reducing noise impact and enabling high payload. This high ratio also makes operating from short runways and runways within cities possible. For example, the thrust-to-weight ratio for the RJ100 is 0.28:1, compared to 0.16:1 for the comparable Boeing 717. The ratio is even higher for smaller RJ variants.
The maximum descent rate achievable with air brakes is 7,000 feet per minute, and at speeds of less than 250 knots and below 10,000 feet, there is still 4,000 feet per minute available. By comparison, a typical airliner descent rate on approach is around 2,000 feet per minute. BAe-146 operators can also use air brakes during the landing roll.
Spoilers vs. Air Brakes
It’s essential to differentiate between air brakes and spoilers. Air brakes are designed to increase drag while making minimal changes to lift. In contrast, spoilers reduce the lift-to-drag ratio and require a higher angle of attack to maintain lift, resulting in a higher stall speed.
The Avro RJ100 and BAe-146 are equipped with wing spoilers, which aid in braking as they transfer more weight to the wheels and help reduce the likelihood of a bounced landing.
The decision not to include reverse thrust on the Avro RJ100 and BAe-146 was based on their limited effectiveness in specific conditions and the benefits of alternative design choices, such as air brakes. These aircraft have proven their efficiency and reliability in various situations, thanks in part to their unique design features.
First love never dies. I fell in love with airplanes and aviation when I was a kid. My dream was to become a pilot, but destiny led me to another path: to be an aviation digital media content creator and a small business owner. My passion for aviation inspires me to bring you quality content through my website and social accounts. Aviation is indeed in my blood and blog!
