Flapping flight
by Erich von Holst and Karl Herzog
Prof. Dr. Erich von Holst (1908-1962)
the great ornithopter-experimenter with one of his models.
His approach to flapping flight, combining theory and practice,
give direction to the development of the
EV-ornithopters very strong.
(To the video of his flapping wing models:
please take a look at external link 1)
Here some of his papers to the theme Flapping Wing Flight.
Tierflug und Modellflug
Luftfahrt und Schule, 6. Jahrgang, Dez. 1940, Heft 3, Seite 24-26
Berlin-Charlottenburg 2
pdf
(in German)
1.6 MB
Animated pictures of a slow motion film from
this article.
One can see the rise off ground of a rubber-powered ornithopter and particularly
the changing of the angle of incidence at the wing root recommended by Erich
von Holst.
0.9 MB
Biologische und aerodynamische Probleme des Tierflugs.
Die Naturwissenschaften, 29. Jahrgang 1941, Seite 348-362
Springer-Verlag, Berlin
pdf
(in German)
2.2 MB
Gesammelte Abhandlungen
look at
literature
Also a great admirer of E. v. Holst has been my pen friend Karl Herzog.
In the year 1963/64 the modelling magazine Mechanikus
published a series of articles of the academic painter and artist
Karl Herzog,
titled
Der Schwingenflug in der Natur und in der Technik
(English:
Flapping wing flight in nature and science
)
Among other things he described there how rubber powered ornithopter models are constructed. Below, the sequences are available in pdf-format (all in German). Regrettably, my Mechanikus originals are very yellowed. Therefore a heigh resolution was necessary to make it passably readable.
Of these series there is also an old abbreviated
English version
(PDF 2.4 MB) with partly different pictures.
It was rediscovered by
Graham Stabler
and also translated in the Netherlands
(PDF 1.2 MB).
or
Swan in large size (300 KB)
April
1963
Flapping wing models
by E. v. Holst *)
(PDF 0.8 MB)
There is also a video of this
Swan
in flight.
(please take a look at
external link 1)
-
- Erich von Holst
with his modelSwan
Karl Herzog
with one of his model wings.
Buzzard
with an electric drive
and with a crank drive mechanism according to E. v. Holst
and the relevant plans by Karl Herzog respectively,
by Horst Händler (1988).
*) Today,
the Aue-Verlag, Möckmühl, Germany, owns the copyright
of these series. Text and drawings may not be published elsewhere.
Later Karl Herzog has written
the book
Anatomie und Flugbiologie der Vögel
,
published 1968. At the pages 136 to 168 it contains
the chapter Demonstration of the animal flight on
the basis of bird models and flapping flight gadgets
.
Regrettably the book is not available today.
or
large size (364 KB)
Furthermore, Karl Herzog has drawn and build other bird models according to the models by E. v. Holst.
He has written a discowce about the Stammesgeschichtliche
Entwicklung des Flugvermögens der Vögel
, a chronological listing
of the developments of flying models and much more.
Here a picture of a test flight of his buzzard
Herzog has also played an important part in the
design of the permanent exhibition Flight in nature
in the Deutsches Museum in Munich.
run (1.4 MB)
Show-case in the Deutsches Museum
Demonstration model with an active arm wing twisting by a pitching
motion of the spare, built 1985 by suggestion
and plans of Karl Herzog.
or
large size (300 KB)
Plan of the functional model
to show the stroke- and twisting motions of the wings during
the flapping flight of birds.
Drawing of a model
for demonstrating the folding of the bird's wing.
Bird's wing in cross-section,
please take a look at
external link 2
Crank
drive for generating
the stroke and twisting movement
of a flapping wing
The rubber powered crank drive developed by Prof. E. v. Holst generates the stroke and the twisting movement of the wing at the same time. Thereto, the linkage coming from the crank pin is pivot-mounted only in stroke direction at the spar of the flapping wing. But in rotating direction it is not pivotable.
Thereby, the up and down movement of the crank pin is used to drive the stroke movement of the spar. At the same time the back and forward movement of the crank pin is used for rotating the spar. Furthermore, the spar is inflexible connected with only one of the outer ribs (Ri). Thus, the crank mechanism actively effects the twisting of the flapping wing. Stroke and rotating movement of the wing spars are phase-delayed by 90 degrees.
External link
- Video of the flapping wing models by Erich von Holst:
http://www.ornithopter.org/video.shtml - Cross-section through the middle part of a bird's wing (without contour feathers):
http://www.flightglobal.com/pdfarchive/view/1913/1913%20-%201092.html