8/20/1986: First Test-Flight of a Propfan Engine

DALLAS — The prototype GE36 engine embarked on its first flight test today in 1986, installed on a Boeing 727 aircraft.

The GE36 propfan engine, a groundbreaking advancement in aviation technology, underwent rigorous testing before taking to the skies. Initially, the engine was subjected to 2,500 hours of model-scale testing.

Following this extensive evaluation, a prototype was developed and ground-tested for an additional 162 hours.

Over the course of the testing period, which lasted until mid-February 1987, the engine was tested in 25 flights, accumulating over 41 hours of flight time out of a planned 75 hours. During these flights, the GE36 reached impressive performance milestones, including a flight speed of Mach 0.84 and an altitude of 39,000 feet (12,000 meters).

In April 1987, Boeing officially selected the GE36 as the powerplant for its future Boeing 7J7 aircraft. The decision was made after determining that the GE36 offered better fuel efficiency compared to the IAE SuperFan ultra-high bypass (UHB) geared turbofan and greater power output than the Pratt & Whitney/Allison 578-DX geared propfan.

At the Paris Air Show in June 1987, General Electric (GE) and Snecma announced that they were in the process of building components for a fully designed production engine, with plans to begin testing on a Boeing 727 in 1989.

However, by August 1987, Boeing decided to postpone the service entry date for the 7J7 from 1992 to 1993, and by December of that year, the project was delayed indefinitely.

Engine makers are a prime target for reducing aviation's impact on the planet. As well as reducing emissions from their power plants, they must also strive to reduce fuel burn, thus reducing costs for their airline customers.

Over the years, there have been various innovative designs, one of which was the 'Prop-fan/Unducted fan,' also known as an 'Open Rotor Engine'. you can read more on our deep dive into the history of the unducted fan engine.

The featured image shows the GE36 UDF demonstrator installed on the Boeing 727 testbed in 1986.