http://forums.sailinganarchy.com/index.php?/topic/163686-zero-wind-glider-kite/
...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.
http://cdn1.bigcommerce.com/server2500/lu4j0e/product_images/uploaded_images/platz-origional-1.jpg
.
https://en.wikipedia.org/wiki/Platz_glider
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.
http://www.lakesgc.co.uk/mainwebpages/Sailplane%20&%20Glider%201930%20-%201955/Volume%2021%20No.%204%20Apr%201953.pdf
Sailplane & Glider Vol 21 #4
https://www.youtube.com/watch?v=YlGrDwjjm7o
G1 Reinhold Platz Glider Kite
2012 ( By Team Impian )
http://www.aerofile.info/wordpress/?page_id=81
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 :
https://kitelife.com/2012/02/15/the-glider-craze/
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 ...
A FRAMEWORK FOR A KITE AND AIRBORNE
MACHINES -- WO2009134207
An improved framework for a kite is disclosed comprising a
plurality of spars including a leading spreader spar...
https://www.youtube.com/watch?v=zd9lArWlPkk&app=desktop
Prism Zero-G -- Howie Bashant
-- Wash Park Rec Center -- May 7, 2012
https://www.horvath.ch/en/setup-and-flight-without-wind/
Kite-Lab Zero-wind
kites by Thomas Horvath
http://northernelectric.ca/kites/borelli/borelli.htm
Borelli Glider Kite
Build a low wind/no wind kite... Find the plans here, in Spanish:
http://www.batoco.org/planos/2008/04/planobarriletegliderborreli.html
Or as a PDF, also in Spanish:
http://www.batoco.org/planos/files/BorelliGlider.pdf
( 728 kB ) [ PDF
]
