KRONFELD ON GLIDING AND SOARING.pdf - Lakes Gliding Club

278 KRONFELD ON GLIDING & SOARING
some successful flights in the " Rhongeist," a sailplane of
this type, in 1928 and so brought it into notice.
The sailplane which has hitherto proved most successful
is the " Wien," with which three world's records for
distance flights and two for height were achieved in 1929.
It was designed for me by Alexander Lippisch and Emil
Pohorille. In this sailplane certain constructive ideas
emanating from the " Professor " type are cleverly developed.
The aspect ratio is i to 20. The wing area is the
same as that of the " Professor/' but the span is sixty-three
feet. To reduce weight, the wing is built in two parts
instead of the usual three. It is rectangular in the middle
and tapers sharply towards the tips. The ailerons are
unusually large. Each plane has one main spar, with an
additional light auxiliary rear spar, and is braced by Vee
struts. The fuselage has an oval cross-section. As in the
" Professor," the elevators are carried upon a revolving steel
tube spar, which projects from each side of the fuselage.
The special care bestowed upon the construction of this
machine has made it practically the best and most reliable
that has yet been built. In spite of its span and light weight
it has repeatedly withstood exceptionally heavy stresses,
many of which were far greater than those attained in normal
soaring flight. Its flying qualities are equally good in stormy
weather or in the lightest breeze in which it has been found
possible to fly.
The " Fafnir " is worthy of special notice on account of
the successful flights and records which Groenhoff made on
it during 1930 and 1931. This design of Lippisch's was
built especially strong and is therefore heavier than other
high-performance sailplanes. The wing is cantilever. The
wing section, Gottingen 652, becomes symmetrical towards
the tip, the angle of incidence diminishing noticeably. The
ailerons are very large. The small middle section of the
wing is directly attached to the fuselage. Each plane has a
marked dihedral angle near the centre section, while the
outer portions are set at zero dihedral, although on the
ground the planes appear to droop giving the machine the
appearance of possessing a negative dihedral angle. The
pilot's cockpit is completely enclosed, leaving only side