Reinhold PLATZ

...It is likely that it was on one of his sailing trips in the waters around Veere that Platz got the idea of converting sailboat aerodynamics into sailplane ones. He knew that the course of a sloop-rigged sailing boat can, within certain limits, be controlled by hauling in or paying out the jib sail. He simply transposed the sail-plan of a sloop into the horizontal plane, doubled up to form a symmetrical shape and hypothesized that, like in his sloop, the angle of the two jib sails (the canard, we might say) would control the angle of attack of the main sails.

To try this out, he cut out the planform of his invention from paper, and weighed the nose with a paperclip. It turned out to fly beautifully, and very stable too; and not only could the angle of attack be controlled by varying the jibs, but they also could be set to turn, when one was tilted upward more than the other. In fact, while a normal rudder would function only with sufficient horizontal speed, the "jib rudder" works even if the model is released without any forward speed at all.

As the paper model had shown his theory worked, Platz built a model of his envisioned glider, with a wing span of 1,30 m. and 40 cm² surface. This model was tested from the dunes between Vlissingen and Koudekerke, to find the right settings for the jibs, and to adjust the centre of gravity.

In November 1922 the model soared for some time along an 8 m. high stretch of dune. Before building the final thing, still a lager model was built to make sure of some details. This model had 2,50 m. wingspan and 1,30 m² surface. While the smaller model still had rigid wing surfaces, this time the sails had been made from cloth, and it had to be checked whether they would billow into the desired airfoil shape...

Though unbattoned, the larger model flew well; like the small one, it could soar the dune lift band and stay at altitude for some time. So finally, back at the Fokker factory the definitive glider was made. It measured 6,60 m. span, 16 m² surface, and tethered loading with a 100 kg man had proven the structure generated sufficient lift.

A close look at the photographs reveals that, between the tethered tests and the free flights, somehow a correction had been made to the jib assembly. Not only has the upturned front part of the keel been cut down some, but the jib sail seems to hinge on a point behind the leading edge. Of course, originally the pilot had been supporting a certain percentage of the lift with his hands; by moving the hinge point back, the force needed to hold the control surfaces in position could be largely diminished. Finally, the glider was considered safe enough for free flight. On a day in February 1923, on the Dutch coast near Vlissingen, the glider soared for some time along the dunes.

The glider weighed 40 kg; quite heavy for nowadays standards, but then, the materials were canvas sails, wooden booms and some iron hardware. Even though, it may well have been one of the lightest gliders for years; and surely it was the very first with a cantilever wing!

To ensure directional stability and to do away with a tailfin, which due to the absence of adverse yaw did not require a rudder anyway, Platz had chosen to give the structure quite a lot of dihedral. On the model gliders this had proven to work well.

The keel construction (no hang glider keel ever deserved that name more than this one!) was a bent iron tube at front, with a wooden boom stuck into it for the aft end; at the junction, two butts of tube were welded on at right angles, to stick the wooden wing booms into.

The only moving part of the glider was the connection of the jib sails. They had a pivoting anchor point at the front end of the keel, and the aft ends were hand held by way of controls. Surely, compared to early Rogallo hang gliders which measured up to 20 m², the wing surface of 16 m² was quite small; especially considering the tips were very pointed, like on the first Rogallos, and thus must have been quite ineffective.

However, with his canard wing, there was no need for Rogallo wing billow, rather, as in the sailing boats that inspired the concept, he had every reason to make the sail as tight as possible, as the pictures show. This, of course, is an advantage over early Rogallo type wings.

The Platz glider of 1923 in the photo was the subject of some great scheming, planning, and dreams of mine about a year or two ago. I was just absolutely certain that I wanted to build one, and hordes of great thoughts came rolling along... carbon fiber tubes making the whole thing weigh 70 pounds... powered paraglider backpack engine on the pilot... being able to market the world's simplest rigid ultralight.

With my first 16 inch span free flight stick and tissue model I found out the same thing that Reinhold Platz found out in 1923, it doesn't fly well at all. I rigged up a trim system in which you could position the canards (jibs in sailboat speak) in any position to trim the thing for level flight. That barely worked, but was manageable.

When I tried to use the differential position of the canard/jibs to make it turn, the little glider would have no part of it! Even a 20-25 degree differential angle on the canards made almost NO difference, and it droned along in a straight line into the nearest wall. This insurmountable problem occurred with and without the micro electric motor and propeller.

All I can suspect is that the mild turning force of the canards (when positioned at a differential angle) was completely offset by either adverse yaw, or the drag of closing off one aerodynamic "slot" between the canard and main wing. It was the equivalent of a car going in a straight line with the driver madly turning the wheel one way and another, with the front wheels turning one way and another, and making no difference to the trajectory at all.

The problem is fix-able, if anyone out there wants to build a Platz Glider, but it will not be an accurate replica. You need a movable vertical rudder, that is attached to the control system. You'll need to rig it up with a stick that moves the rudder left and right, and then moves the canards up and down equally like an airplane's elevator. I strongly suspect that this would make it flyable and controllable, however it will not be a three axis control.

It does not matter what that book's caption, or anyone else's hopes and dreams claimed the Platz Glider configuration is not controllable with the minimalist canard grips alone, as cool as that might have been.

Platz' more successful designs all had rudders, and were noted for their excellent maneuverability and controllability. His Fokker D-VII was the only aircraft so feared and respected by the enemy (Allies) that they were specifically ordered to be turned over at the end of WW1 as part of the armistice.

Platz Glider
Designer :  Reinhold Platz

The Platz glider was a very simple, though unusual, collapsible canard glider designed and tested in Germany in the early 1920s. The Platz glider predated the well known Rogallo designs by over two decades. But in the same decade of the 1920s was a device that had also a high second deck: the Argabrite man-carrying device that featured a triangle undercarriage with wheels on the basebar.[1][2]

The Platz glider was intended to provide a cheap, easily transported, and simple to fly introduction to the increasingly popular sport.

Platz recalled sailing a sloop rigged boat, which had been very stable upwind and capable of maintaining its course without rudder input. He reasoned that the same stability he saw in that boat might be achieved by a similarly rigged glider with a small forewing and a larger rear plane. Just as the sloop could be controlled by adjusting its jib, the glider could be controlled by foreplane trimming. After some preliminary experiments with simple paper models, Platz designed the one-man canard glider which was then named after him.[5]

The Platz glider was built around a central, two part boom. A curved, circular cross-section steel tube reached from the nose at least as far aft as the welded sockets which received the ends of the main wing spars. A solid, circular section wood beam was inserted into this steel tube, extending it rearwards.[5] The wing spars were also circular, solid and wooden, set with strong dihedral which took their tips to the height of the extreme nose so that the foreplanes, elevators or jibs could be attached between these three points. Their inner trailing edges were directly controlled by the pilot, who sat over the central beam-wing spar joint. They were initially hinged together at their leading edges, but later the hinge point was moved rearwards towards the aerodynamic centre to reduce pilot load and separated only behind the hinge. Since there were no ribs, the airfoil was determined by the airflow and the pilot, as for the sloop's jib. The main wing, a single surface stretched between the spars and the extreme tail, also had its camber determined by the airflow, like the mainsail of the sloop.[5][6] Both wing sheets were produced by sewing together narrow strips of material; the longitudinal joints between them are prominent in some back lit, better quality images.[5][7]

The Platz could be disassembled into a 3,300 mm (130 in) × 350 mm (14 in) × 250 mm (10 in) pack, weighing 40 kg (88 lb) in fifteen minutes and reassembled in ten.[5] Transport by bicycle, with care, was possible.[6]

First flight     February 1923. Free flight trials began without pilots and with increasing loads (up to 75 kg (165 lb)) into strengthening wind and eventually over sandhills as high as 25 m (82 ft). With a pilot in place, the glider was then flown tethered like a kite. Several people, with weights up to 100 kg (220 lb) flew it this way, all reporting that forewing control loads were low. In February 1923 it was free flown in a moderate wind over 10 m (33 ft) dunes. Platz decided that the dunes did not provide usable soaring, their next goal, after which the experiments would end. He noted that, whilst his design could not compete with the best conventional gliders, it had met the initial targets outlined above and thought it or something similar would be of great value, seemingly content to leave others to judge his design.
Sailplane & Glider Vol 21 #4
G1 Reinhold Platz Glider Kite 2012 ( By Team Impian )
Reinhold Platz

A person, close connected to the pre 1930 era of the Fokker company was Reinhold Platz. He was born january 16th, 1886 at Cottbus in the province of Brandenburg. Being a welder of profession, he went to Fokker at Johannisthal in 1912, and built the first welded steel tube ‘Spin’ fuselage. After the death of Martin Kreutzer in 1916, Fokker’s designer of the D.I to D.V, he became the chief designer at the Fokker Works at Schwerin. Platz was not an educated designer, like for instance Dr. Hugo Junkers, but neither was Fokker himself. They both were man from the practice, and together they made a strong team. Fokker, who had the ideas, and Platz, who made them work. This was during World War I, a time when things happened fast in aviation. Creating a new design was not always done on paper, at the Fokker Works, and drawings were not always available. For instance, when Albatros had to build D.VII’s under license, they received a D.VII as example, and no drawings. After the war, Platz worked for Fokker, first at Schwerin, and later at Amsterdam. He stayed there until 1931. There has been much said about Fokker and Platz. The name of Platz appears only once in Fokker’s autobiography /‘The Flying Dutchman’,/ and then only as /‘the manager who has been working with me for 15 years’/ (translated from the Dutch version). In /‘Fokker, the creative years’/, by A.R. Weyl, it is stated that Fokker on purpose held Platz in the background, that Fokker himself had nothing to do with the designs made, like the Dr.I and D.VII. These statements can not be true. As stated above, Fokker and Platz were a team. But, Fokker was the one in charge. When Platz left Fokker in 1931, he /‘had no reason either professionally nor financially to be discontented’/, as said by Fokker’s Dutch Manager B. Stephan, and can be read in /‘Fokker, the man and the aircraft’/ by H. Hegener. Reinhold Platz died in Ahrensburg on September 15, 1966.

Related :
Plutz and Zero-G

The Plutz, designed by Chee Wan Leong is a kite that I started seeing just in the last year, and has now been adapted to the new Prism Zero-G under license. This type of kite has a very unique kind of structure that gives it an interesting feel compared to other gliders. Having flown a Plutz on a rod, I noticed that the kite has a fantastic glide, and it will turn very easily. The way this kite flies, can be very nice and smooth, but it also has a unique characteristic where it almost flies in straight lines, while making sharp corners, sort of like flying a box with a sport kite. This is something I had never seen in a glider before...

Zero-G, per the Prism website:
Conceived in collaboration with celebrated Malaysian designer Ceewan, the Zero G concept was inspired by Reinhold Platz, chief designer for the Fokker Aircraft Company after WW1. Decades before the modern hang glider, he built and flew a full-scale canard-winged craft that folded up to carry on a bicycle. With small wings in front, the canard configuration allows a virtually stall-proof glider that will float eerily in a level attitude even when it’s barely flying forward. A clever dynamic bridle adjusts the angle of the forward wings in flight according to the tension on the line, allowing the kite to behave as a kite under tension and a glider whenever the line is released.

Chee Wan Leong Patents :
Kite -- CN103623591A
The invention discloses a kite comprising a boosting fan, a circuit and an energy storage battery. The boosting fan is located at the upper end portion of the kite. The energy storage battery is located in the middle of the kite. The boosting fan and the energy storage battery are connected through the circuit.

Kite suspension platform -- CN106886223
The invention provides a kite suspension platform, and the platform comprises a ground system and a suspension system communicating with.... The suspension system comprises a flight control device, an electronic speed regulator, a motor, and a kite posture adjustment device... tail wing. Because a kite and an unmanned plane are combined at the same time, the formed kite suspension platform ...

An improved framework for a kite is disclosed comprising a plurality of spars including a leading spreader spar...
Prism Zero-G -- Howie Bashant -- Wash Park Rec Center -- May 7, 2012
Kite-Lab Zero-wind kites by Thomas Horvath
Borelli Glider Kite
Build a low wind/no wind kite... Find the plans here, in Spanish:
Or as a PDF, also in Spanish:
( 728 kB ) [ PDF ]