A2A Simulations BONANZA ACCU-SIM V35B, Manual

Page: 55 / 112

www.a2asimulations.com ACCU-SIM V35B BONANZA ::: A2A SIMULATIONS
55
FOR SIMULATION USE ONLY
B
efore you learn about how different
propellers work, first you must under-
stand the basics of the common airfoil,
which is the reason why a wing creates
lift, and in this case, why a propeller
creates thrust.
It is interesting to note when dis-
cussing Bernoulli and Newton and how they relate to lift,
that both theories on how lift is created were presented
by each man not knowing their theory would eventually
become an explanation for how lift is created. They both
were dealing with other issues of their day.
THE BERNOULLI THEORY
This has been the traditional theory of why an airfoil cre-
ates lift. Look at the image below which shows you how the
shape of an airfoil splits the oncoming air. The air above is
forced to travel further than the air at the bottom, essen-
tially stretching the air and creating a lower pressure, or
vacuum. The wing is basically sucked up, into this lower
pressure. The faster the speed, the greater the lift.
THE NEWTON THEORY
As the air travels across the airfoil’s upper and lower sur-
faces, lift is created by BENDING the air down with great
force at its trailing edge, and thus, the Newtonian force of
opposite and equal reaction apply.
WHAT WE DO KNOW (AND WHAT
THE PILOT NEEDS TO KNOW)
The airfoil is essentially an air diverter and the lift is the
reaction to the diverted air. An airfoil’s lift is dependent
upon its shape, the speed at which it is traveling through
the air, and its angle to the oncoming air (angle of
attack).”
It is important that you note that we have deliberately
not entered into the details and complete aerodynamics
involved with either of the above explanations for lift as
they go beyond the scope of this manual.
Unfortunately over time, the Bernoulli theory specifi-
cally has been misrepresented in many textbooks causing
some confusion in the pilot and flight training community.
Misrepresentations of Bernoulli such as the “equal tran-
sit theory” and other incorrect variations on Bernoulli have
caused this confusion. Rather than get into a highly tech-
nical review of all this we at A2A simply advise those inter-
ested in the correct explanation of Bernoulli to research
that area with competent authority.
The main thing we want to impress upon you here is
that when considering lift and dealing with Bernoulli and
Newton, it is important and indeed critical to understand
that BOTH explanations are COMPLETE EXPLANATIONS for
how lift is created. Bernoulli and Newton do NOT add to
form a total lift force. EACH theory is simply a different way
of COMPLETELY explaining the same thing.
BOTH Bernoulli and Newton are in fact in play and acting
simultaneously on an airfoil each responsible completely
and independently for the lift being created on that airfoil.
Hopefully we have sparked your interest in the direction
of proper research.
WHAT IS A STALL?
In order for a wing to produce efficient lift, the air must flow
completely around the leading (front) edge of the wing, fol-
lowing the contours of the wing. At too
large an angle of attack, the air cannot
contour the wing. When this happens,
the wing is in a “stall.”
Typically, stalls in aircraft occur
when an airplane loses too much air-
speed to create a sufficient amount
of lift. A typical stall exercise would
be to put your aircraft into a climb,
cut the throttle, and try and main-
tain the climb as long as possible.
You will have to gradually pull back
harder on the stick to maintain your
climb pitch and as speed decreases,
the angle of attack increases. At some
point, the angle of attack will become
so great, that the wing will stall (the
nose will drop).