Competitive Dominance
The JS-1 Revelation established itself as the premier competition sailplane of the 2010s through unprecedented competitive success. At the 2015 UK Nationals, seven JS-1s competed and finished in the top seven positions, demonstrating the design's overwhelming superiority. The aircraft's dominance extended internationally, with JS-1C variants achieving 2nd and 3rd place finishes plus three additional top-ten positions at the 2014 World Gliding Championships Open Class. Designer Attie Jonker personally validated the aircraft's capabilities by winning the 18-meter class South African National Championship in 2008.
Revolutionary Jet-Sustainer Technology
The JS-1TJ variant introduced sophisticated jet-sustainer technology that distinguished it from traditional self-launching gliders. The retractable MD-TJ42 turbojet engine, manufactured by M&D Flugzeugbau, deploys through an innovative three-door system comprising two main doors and one "finger door." This configuration produces less drag when deployed than an extended landing gear, maintaining the aircraft's exceptional aerodynamic efficiency.
The engine installation features a monocoque carbon-fiber sustainer box bolted to the fuselage, with deployment controlled by an electro-mechanical linear actuator via tubular pylon structure. The engine angles slightly in the deployed position to direct hot exhaust away from the fuselage and vertical stabilizer. A sliding throttle with detents for deployment and retraction, managed by an Engine Control Unit, provides precise power management. Unlike self-launching motorgliders, the sustainer lacks sufficient thrust for independent takeoff but enables sustained flight without altitude loss.
South African Innovation
Jonker Sailplanes, founded in 2004 by brothers Attie and Uys Jonker in Potchefstroom, South Africa, created the first and only completely indigenous South African aircraft certified by the country's Civil Aviation Authority. The company invested heavily in advanced manufacturing capabilities, including a multi-million Rand CNC milling machine, enabling in-house production of approximately 90 percent of components.
By the 100th aircraft's completion, more than 90 percent of production was exported, generating over R40 million in foreign currency for South Africa. The company achieved certification from South Africa's CAA, with European certification handled by M&D Flugzeugbau under the designation JS-MD Single. This certification allows unrestricted operation in any ICAO-signatory country.
Advanced Aerodynamic Design
Attie Jonker led structural design while Johan Bosman developed airfoil and aerodynamic features in cooperation with Delft University of Technology. The design incorporated breakthrough technologies including a double-hole blowing/suction system in the wings to minimize drag by preventing turbulent flow at specific locations for different flap settings. Full-span flaperons with elliptical planform and winglets provided exceptional control authority across the flight envelope.
The custom JS-02-127 T12 airfoil system features six variations along the wing span, optimizing lift distribution. Modular construction allows 18-meter JS-1B aircraft to accept optional 21-meter wing extensions, creating the JS-1C Open Class variant with increased water ballast capacity and 17-liter wingtip tanks.
Performance Specifications
The JS-1B 18-meter variant achieves a maximum lift-to-drag ratio of 53:1 with minimum sink rate of 0.50 meters per second. Empty weight of 280 kilograms allows maximum gross weight of 600 kilograms including 200 kilograms of water ballast. Maximum speed reaches 290 kilometers per hour with stall speed of 75 kilometers per hour. The 21-meter JS-1C variant increases maximum takeoff weight to 720 kilograms and claims best glide ratio approaching 60:1.
Wing loading ranges from 31.2 to 53.6 kilograms per square meter depending on ballast configuration. The 7.17-meter fuselage accommodates a single pilot in a reclined position optimized for long-duration competition flights. Aspect ratio of 28.8 maximizes efficiency while maintaining structural integrity under high G-loads.
Production Legacy
Between 2006 and 2018, Jonker Sailplanes produced 128 total JS-1 Revelations comprising 5 JS-1A prototypes, 43 JS-1B 18-meter aircraft, and 80 JS-1C 21-meter Open Class variants. The first flight occurred on December 12, 2006, with series production beginning shortly thereafter. By July 2012, approximately 34 aircraft had been completed, with the jet-sustainer variant first flying on September 7, 2011.
This production total established the JS-1 as one of the most successful modern competition sailplanes, representing South Africa's emergence as a significant player in advanced composite aircraft manufacturing. The aircraft continues competing at the highest levels of international gliding competition, with examples operating worldwide in both 18-meter and Open Class categories.