Spinproof sailplanes

Why a flying wing ?

How can one come to understand the Fauvel flying wing formula as
opposed to a more classic formula? The complete answer to this
question requires delving deep into the inner workings of these
machines. Summarized here are some ideas that explain the advantages
of this formula.

The stability of the "tailless flying machine" is often put into
doubt. That is the way it is with many people, pilot or not, held back
psychologically by the idea that an airplane cannot safely and with a
sufficient margin of stability operate with no tail. Yet, the various
flying wing machines created by Fauvel and other designers leave no
doubt that such devices are no less stable than those of a more
classic design. And that the added "tailless" advantages are not to be
disregarded...

When you think of a classic airplane, endowed with a stabilizer at the
rear, you must know that:

- the machine can stall,
- an accidental spin can be triggered while turning within a narrow
circle at minimum speed,
- vertical acceleration loads can become critical at high speed in
turbulence, and are amplified if the wing loading is low,
- the biggest part of the fuselage exists for nothing more than a link
to the tail of the aircraft, and adds nothing but weight for no other
apparent contribution.

In a Fauvel flying wing, these constraints do not exist. Jim Marske, a
creative designer of this form of sailplane, expresses his thoughts
thus :
"When you see a flying wing take off for a flight, do you think, what
a brave man to fly such a dangerous machine. Believe me, that is what
I think when I see a tailed sailplane go off on tow."

Of all the fatal accidents involving general aviation at least half
happen too frequently due to stalls and spins at low altitudes. In the
domain of motorless flight, a sailplane that is more stall resistant
is a considerable asset for the pilot who wishes to exploit weak
thermal conditions close to the ground. The Fauvel flying wing has the
ability to fly at low speeds with confidence because unexpected "stall
breaks" translate into simple up and down motion often referred to as
"porpoising". The tailless airplane is also endowed with good
penetration of rough air at high speeds thanks to the reduced drag of
the fuselage and the absence of interactions with a stabilizer. The
compactness of the formula permits one to achieve much lighter
structures, simpler mechanical interfaces and are cheaper to build.
Thus, rather than to strengthen the structure of the device by the use
of expensive material or by lowering the margins of safety, one
decreases the parts count of the aircraft. In spite of popular
thought, it is necessary to accept the fact that the flying wing will
be the strongest structural design for a given weight. The AV-36, for
example, was calculated to have the coefficient of 12 (number of G's
before structural failure) with a mass weight of only 225 kg!

Present techniques of computer analysis permits one to have no fear of
the aerodynamic phenomena that governs the domain of flight of these
tailless machines. Of course, it is not all about a magic formula, and
it doesn't provide the answer for all kinds of applications. Like all
aeronautical concepts, it is a compromise between different
parameters. As it happens, the Fauvel flying wing presents a
remarkable compromise between security, cost, performance and
complication, well adapted to the present needs of general aviation
and the sportsman. Think of all these advantages the next time you
board an airplane or a conventional sailplane, or if you think about
designing your own flying machine !

--- Translated into English by Noble Faubion )
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