To keep the Saab 37 Viggen’s landing distance short, Saab developed a thrust reverser integrated with the rear fuselage, still the only one of its kind on single-engine aircraft.
The Saab 37 Viggen incorporated a highly advanced aerodynamic design for its era, featuring a primary delta wing alongside delta-shaped canard foreplanes. As described by Jan Jørgensen, Anders Nylén, and Peter Liander in their book Saab 37 Viggen—The Ultimate Portfolio, this unique design allowed the Viggen to fulfill the Swedish Air Force’s requirement of exceeding Mach 2 at high altitudes while being capable of operating from runways as short as 500 meters.
The Volvo Flygmotor RM8A/B afterburning turbofan powered the Viggen. To minimize landing distance, Saab created a thrust reverser that is incorporated into the rear fuselage, which remains the only one of its type on single-engine planes.
‘Many jets have thrust reversers that turn part of the air stream from the engines forward to create a braking effect after touchdown,’ explains pilot Thomas Kolb on Quora.
‘The Saab 37 Viggen fighter, however, had a thrust reverser that could actually be used to taxi backward just like a car. Other aircraft had similar constructions, but not as intricate.’
‘With the Viggen, three triangular metal “petals” in the engine exhaust could be folded down by the pilot pulling out a T-shaped lever on the left side of the dashboard in the cockpit. This would then direct the entire air stream from the engine forward through slits around the back of the fuselage. If the reversor was activated in flight, the system would become armed so that the reversor plates would automatically close as soon as the main and the nose undercarriages became compressed when touching the ground. By pushing the throttle forward and adding power, the pilot could then get the aircraft to a surprisingly short stop. This was necessary because the Viggen was designed to operate from short, makeshift runways, such as car roads.
‘While backing up, the pilot, however, needed to be very careful not to use the wheel brake toe pedals, as the aircraft could easily tip over backward for a tail strike.’
‘It was a popular maneuver with the Viggen during air shows to land in front of the audience, come to a full stop, perform a Y-turn on the runway, and take off in the opposite direction.’
Kolb concludes,
‘In the picture below [taken by Milan Korbar and featured on PlanePictures.Net], the topmost of the three “petals” is folded down (it actually always dropped down by itself as the hydraulic pressure was released when parking).’
Photo from YouTube video screenshot and Milan Korbar / Source: PlanePictures.Net
