SEPTEMBER 2019 FLYINGMAG.COM | 73ISTOCK/BENJAMINSCHAEFERlift at half that angle, a quarter at a
quarter and so on. The characteristic
speeds of the airplane, because they
correspond to certain angles of attack,
also correspond to certain fractions of
the maximum available lift.
Suppose that instead of an airspeed
indicator, we have an instrument that
displays percent of available wing lift
on a scale of zero to 100, with 100 rep-
resenting the maximum lift available,
just before the stall. This lift gauge
would be similar to an angle of attack
indicator, but it would cover a wider
range of angles of attack than usual.
Angle of attack indicators tend to focus
on the low-speed range; at high speeds,
changes in angle of attack are small,
hard to measure and of little practical
importance. But I think angle of attack
information would be useful at least as
far as the maneuvering speed.
Although I and my fellow aviation
writers have been singing the praises
of angle of attack indicators for ages—I
have been f lying with, and relying on,
a Safe Flight SC-150 for 40 years—it
was not until recently that a number
of them appeared on the market. But
they are still small, auxiliary-looking
instruments, advertised as providing
pilots with an extra margin of safety.
That is putting the cart before the
horse. A direct indication of the
fraction of available lift being used
ought to be primary for operations
at airspeeds at or below the best
rate-of-climb speed.
Unfortunately, pilots are indoc-
trinated from the very start of their
training with a religious regard for
the airspeed indicator. We become
conditioned—perhaps brainwashed
would be a more appropriate word—
to think of our f light state in terms of
speed, not angle of attack or its equiv-
alent, lift fraction. The presentation
of angle of attack in an ancillary role
merely reinforces that tendency.
The lift gauge, as I envision it,
would be central and conspicuous.
It would have markings at 50 (best
rate of climb) and 60 (approach
speed 1.3 V) and an ominous-looking,
orange-grading-to-red band between
75 and 100. Because Gweight is pro-
portional to angle of attack, what
we now call “maneuvering speed”
would become, for a normal-category
airplane, a mark at 26 ( because the
limit load factor, 3.8, times 26 equals
100). Whenever the moving index
was between that mark and 100, you
would have the protection provided
by maneuvering speed on the
airspeed indicator. Below 26 would
be the yellow arc.
Each type of airplane has its own
characteristic speeds and its own setof airspeed-indicator markings. The
lift gauge, however, would conceal
those differences. It would be exactly
the same in all airplanes, regard-
less of speed range or wing loading,
and would be used in the same way. It
would automatically account for vary-
ing weights, G loadings and flap config-
urations. Unlike an airspeed indicator,
it would be responsive to gusts: A pos-
itive gust would make the index jump
upward, and if you saw the index
repeatedly getting close to 100, you
would know to lower the nose. This
would represent an improvement over
the current “10 knots for grandma”
system for approaches in turbulence.
Airspeed indicators cannot be ban-
ished altogether. Let commerce f lour-
ish. The airspeed indicator supplies
the dynamic-pressure-related speeds,
provides a backup in case of failure
of the lift indicator, enables pilots tocomply with ATC speed instructions
and in some cases, is an aid to boasting.
I leave the physical implementation
of this device to someone more inge-
nious than I. It is unlikely that lift
fraction could be sensed directly,
with conveniently linear variation,
by measuring either pressures or
f low directions; that difficulty has
always been an obstacle to simple,
cheap AOA instrumentation. Instead,
some AOA-related variation in someparameter or other would be detected,
and a microprocessor would be
trained to translate it, for each air-
plane type, into fractions of available
lift. This would then be conspicu-
ously displayed—either on a gauge or
as a portion of an electronic display—
in such a way that it overshadows the
airspeed indicator. In this case, size
really does matter. A little brute force
will be required to wean pilots from
their airspeed indicators and train
them to rely on a lift gauge instead.
The sainted author of the
foundational how-to-f ly book Stick
and Rudder, Wolfgang Langewiesche,
always insisted that when we fly, we
are f lying a wing. Wings don’t think
about speed, they think about lift, and
we ought to start doing the same.Near a stall, the airspeed indicator is a
mediocre substitute for angle of attack.