Of Course It's Loud - It's a JET!

Our next vintage airliner ad featuring the Douglas DC-8 brings us to the business end of the airliner’s classic Pratt & Whitney JT3C-6 turbojet engine. Although it is highly doubtful that a First Officer ever escorted two passengers out on the ramp while performing his preflight, this co-pilot is proudly showing-off the “daisy petal” noise suppressor fitted to the exhaust of his DC-8’s left outboard engine.

A civilian version of the military J57, this third-generation turbine powerplant produced 11,700 pounds of dry thrust (13,500 with the injection of distilled water for thrust augmentation on takeoff), and all with a screaming turbine whine from the air intake and roaring exhaust noise at the aft end. Multiply this by four engines, and you have the first causal factor for awareness of aviation’s environmental impact.

But despite this fact, something else was happening at the dawn of the Jet Age - something fascinating and almost inexplicable. It was the mass public’s utter fascination with the jet airliner, a new, exciting, and “future-ramic” means of transportation that cut travel times in half between any two places on Earth. Growing up in the late 1950s, it was not uncommon to see someone gazing upward at a swept-wing shape in the sky, exclaiming, “Look, it’s a JET!”

It was also not uncommon to see graphic comparisons made in advertising copy, stating that each generation of powerplant superseded the previous generation by leaps and bounds. For instance, one engine on a Douglas DC-3 produced more power than all three engines on a Ford Tri-Motor combined. One engine on a Lockheed Constellation produced more power than both engines on a DC-3, and so on. (And yes, one JT3 on a DC-8 produced more power than all four engines on those first Connies.)

To put this in perspective, that theory still holds true, for one GE90 engine on a Boeing 777 produces more power than all four of the DC-8’s noisy, smoky, and by today’s standards, somewhat anemic Pratt & Whitneys.

Granted, I’m omitting a crucial milestone in the evolution of the jet engine – the turbofan. By placing a larger disc of fan blades at the front (or rear) of the turbojet, the core exhaust emanating from the engine’s “hot section” was now surrounded by a shroud of cooler air that both increased thrust and reduced noise. Jumbo jets of the 1970s featured “high-bypass ratio” turbofans that upped the amount of fan air significantly, elevating turbine engines to the 50,000-lb.-thrust category.

Today, the GE90 on a 777-300ER produces 115,000 pounds of thrust without breaking a sweat, and here’s where we’ve come full circle. A DC-8 carried 125 passengers, weighed 250,000 pounds at takeoff, and created an ear-splitting roar whereas the 660,000-pound 400-passenger 777-300 today produces barely a whisper. While the airplane in this ad may have been “the world’s most advanced jetliner” in 1959, technical innovation was measured quite differently back then. When it comes to jet noise today, less is more.