When it comes to designing a fighter aircraft, speed and stealth may have been in demand up until a few decades ago, but versatility and multi-capability have instead taken the front row today. A new generation modern fighter, large or small, has to be designed as a well-balanced aircraft, capable of fulfilling a wide range of missions. For Gripen, this was one of the key aspects kept in mind during the design period, even while choosing the engine for it. In the last of a four-part series that talks about the design of Gripen, Millennium 7 * HistoryTech draws attention to the Gripen engine and the role it plays in making Gripen the fighter it is today.
While transitioning from Viggen to Gripen, Saab had to make sure the engine in question does not cause a pressure surge at large angle of attacks. "A military engine must be 100 percent reliable, particularly in the hands of a hard-fisted combat pilot fully occupied with these tasks," says the YouTuber. "For Saab, the 100 percent military General Electric F404 engine represented a natural answer for a lightweight fighter propulsion unit," he adds.
The F404, which was small in size and had a thrust to weight ratio of 7:8, was already flying in the early F-18 fighters at the time. And since Gripen was not designed to have a twin configuration like on the F-18, some more thrust was required. The version that Volvo derived from the F404-400 for Gripen, which was the designated RM12, had its maximum thrust increased upto 80 kN from the 71 kN version in the US Navy.
"Other than having a good thrust-to-weight ratio and an acceptable specific fuel consumption, it proved itself to be remarkably insensitive (resistant) to the angle of attack or sideslip," he says.
The Gripen E-series features a new and more powerful engine, F414-GE-39E turbofan, also developed by General Electric. The engine offers 25 percent more thrust (up to 98 kN, or 22,000 pounds with powered afterburner) resulting in an improved air-to-surface capability and enhanced electric airborne attack.
As compared to its predecessor F404, F414 also promises significant improvements in aircraft performance, survivability and payload. It also features 3d aerodynamics, an improved high pressure turbine, and an advanced cooling system (16 percent more airflow than the F404 fan).