MAY 2021 VOLUME 14 - No 8 GLIDINGlNTERNATIONAL May 2021ANOTHER JONKER TRIUMPH 1 May 2021 VOLUME 14 - No 8 Editor: John H. Roake Manager: Janice Armstrong Correspondents: lNTERNATIONAL Aldo Cernezzi GLIDING Robert (Bob) Downe Joseph King Myles Hynde Arthur Liddington Gliding International published by: Gliding International Ltd From Offices At: 79 Fifth Ave, Tauranga, New Zealand Phone +64-7-571-4161 Office email: [email protected] Editor’s email: [email protected] The magazine’s web pages can be viewed INDEX at www.glidinginternational.com Introducing the GFW – 4 4 You can subscribe through our web page Squawk 1202 – Compulsory ? 8 Gliding International is published Viewing Thermals Now Possible 9 monthly with the exception of December German Aerospace Centre Update – Hydrogen Power 10 and January Ten issues per annum. 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Club Week-end Accommodation 33 Jonker JS2 Test Report 34 New subscriptions can be originated through the magazine’s secure web site New Moin Camera (for Glider Pilots) 36 by using a Visa or MasterCard credit Battery Research from Sweden 37 card at: www.glidinginternational.com Gliding And Cannabis Study 38 Advertising: International News for Glider Pilots 39 Contact the magazine’s advertising Things With Wings 46 department by email at: [email protected] Cover: Spectacular Finish from the pilot of the Jonker JS2 Test Flight (See page 34) 2 Gliding International May 2021 3 Introducing the GFW - 4 The idea for this concept first surfaced in 1961 ARTHUR LIDDINGTON ou can be excused for believing that the first power construction (TH Dresden - Technical High School Dresden) Ysource for a glider was the petrol engine mounted on involving the efficiency of motor glider propulsion. a pylon and which rested inside the fuselage when not required. But you are wrong! By my calculation, one of the As a student, he was involved in the construction of the first motor gliders of our generation was the forerunner of Miniature glider, the Weber-Wagner WW-1, that has a the GFW-4, an ultra-light motor glider in the 120 kilogram laminar profile as well a continuously adjustable flap. He class. also worked in the AKUS plastic glider working group a TH Dresden in 1969. This was followed by a doctorate in There were two not dissimilar designs prior to GFW-4 reinforced fibreglass plastics that led to working on the but those predecessors captured little imagination. The DOWA 81 (1979 to 1981) the one-way escape aircraft. The unusual propeller arrangement was not new although now company went into receivership and the DOWA 81 is now described as being extremely rare. Those two precursors in the German Museum Flugwerft at OberschleiBheim. were the C 10 of the aeronautical working group Chemnitz and the WK-1 by Werner Kuttner. While studying, a lecturer showed the student Wagner a picture of the C 10 from Chemnitz. That was the first The GFW first saw the light of day in 1961, but that design acquaintance with the extraordinary configuration of the has seen numerous updated changes, i.e. when Gerhard circulating mounted propeller ring unit. Gerhard asked through a steel pipe to the tail support. It worked! The In 1983, during the presentation of the WK-1 at the F. Wagner from Kaiserslautern, Germany flew into town Wagner to join him in a study/thesis evaluation of all two propeller blades, and the centrifugal force generated Paris Aerosalon, Kuttner, an experienced metal aircraft to show off his version - an ultra-light motor glider in the currently flying motor glider configurations involved provided speeds higher than ever anticipated. With this construction manufacturer was looking for a possible 120 kg class with a three-blade folding propeller built into aerodynamics, beauty as well as weight and statistics. success, Hans Wunscher achieved one interesting solution partner company for a series production run. The creation the fuselage - mid-way between the cockpit and the tail. The research clearly came out in favour of the fuselage to the motor glider problem, the one that interferes with of a driving forward unit, the heart of the WK-1, wanted the The uneducated describe it as a “propeller ring on the tail mounted ring propellor. So at this stage, the propeller ring gliding. How to avoid air resistance generated by the designer position reserved for Wagner who would make boom”. had proved itself to be the best solution at that time. stationary propeller. The Second World War allowed for the maiden flight of the WK-1 in Paderborn-Lippstadt on little or no sport gliding of any consequence in Germany. July 13, 1984. As confidence grew, Gerhard Wagner became the first to Quick to take advantage of the work to date, Hans There were still two C 10’s, in Chemnitz built and used have an electric motor as his power source, replacing his Wunscher and Karl Fritsch from the aeronautical working by several pilots. The core of their two-seater, the WK- In 2017 Werner Kuttner worked on one Airplane family earlier internal combustion engine. group at Chemnitz joined up with Weber and Wagner. The 1, the prototype, was the drive unit with its two-cylinder with different structures. Different one and two seaters peculiarity of the single-seater and the Umlauf Propeller motorcycle engine (BMW R 90 / S) with cooling air on the Wasserkuppe. GFW-4 by Gerhard F. Wagner. Before Dr.-lng. Gerhard Wagner is by profession a structural tail unit, was completely new to those joining the group. blower in the gear box, in a reduction gear and the power Gerhard Wagner started building the GFW-4, he created engineer, but aircraft construction is his prime (devoted) The two-bladed propeller had eight fan belts and was transmission from motor to propeller ring via the toothed with the GFW-3. GFK-CFK construction is an ultra-light sideline. As early as 1961, the then student Gerhard powered by a two-cylinder two-stroke Kroeber M4 boxer belt. one. In 2011 this glider won the Oskar Ursinus Prize of F. Wagner was working at the lnstitute for Aircraft engine. The propeller hub of the folding propeller led 4 Gliding International May 2021 5 Cockpit Fuel Tank Motor Belt Drive Flight testing of the GFW-4 started Propellor on April 23, 2019 and the glider self launched to 400 metres. By June 16 of that year regular self launches were reaching 700 metres and only using half Not New! of the total power available. The cooling of the electric motor with • Assembly Axle & Belt Drive the current pulse circulation turned out Separation Point Cooling Air to be adequate. The temperature of the Flow converter is also not critical. Concept Wheel Cooling Air Hood First After accumulating six hours of testing, the designer and builder decided it was Considered the OUV. That little one-seater later served as the basis time for me to fly “his baby.” for the GFW-4, whose construction began in 2013. Both In planes originated in a rather tightly dimensioned domestic It was quite exciting for me. I strapped myself in and 1961 basement. mentally prepared for this exciting addition to my gliding experience. His goal before starting work on the GFW-4 was a self- launching sailing Werner Kuffner’s WK-1 with an extended l quickly rose to 300 metres, and entered my first thermal. • rear edge rotary brake flap and a three-bladed folding I circled at 60 kilometres per hour at an incline of 30 to 40 propeller with which he could both develop his ideas in degrees. I increased verage speed kph. At a slower climb, design and method of construction. the GFW-4 was pleasantly thermally sensitive. L/D 34 suited me fine! The testing of the all new electric power source and its performance for a self launch to 600 metres was an Flight behaviour is stable. After a two hour flight, I am exhilarating reward for their persistent research. The 600 ready to make my first GFW-4 landing but conscience of metre goal was high enough for the developers. the fact that the deep position of the tail wheel needed Above: The Werner Kuffner’s WK-1 is regarded considerable respect. No problems! My approach stabilised as the first “ring propeller” experiment followed by GFW-3 and the GFW-4 The GFW-4 has a two-part negative hull made of plywood, at a comfortable 65 kph, the air brakes adequate and foam, GRP and CFRP. The structure came into being below effective, and my beautiful flight came to an end. their total maximum design weight. Air brake construction for weight reasons was a CFRP feature. Predominantly In 2019 the OUV honoured Gerhard Wagners Services for carbon fibre in lieu of glassfibre provided a weight the self creation/construction of an aircraft just like his saving of over 20 kilograms, weight sorely needed for the award for his GFW-3.