Aerobatics Made Easy
By John Glezellis Illustration by FX Models
Fly the 3D Humpty
with a Half-Roll
While the maneuver of the month is a humpty bump at heart, it contains a combination of three different 3D maneuvers to result in an exciting and aggressive
figure that both pilots and spectators will enjoy.
For those unfamiliar with the term “3D,” it is
traditionally defined as a type of flight where
the aircraft is past the point of stall and the
thrust produced by the motor keeps the model
flying at specific attitudes.
In this month’s column, we will begin our
exploration of the 3D humpty with a half-roll
by examining certain programming and setup
fundamentals. We will then provide a general
overview of the maneuver and will break down
the stunt into four fundamental steps, which
review the necessary control inputs required.
Without hesitation, let’s get started!
Before We Begin
With many modern-day aerobatic airplanes
that have large control surfaces and high
power-to-weight ratios, it is important to use
dual or triple rates and exponential settings to
achieve consistent control.
I prefer using a three-position flight mode,
where rates for all control surfaces are found
on a single switch. Always use a switch that is
easily accessible and does not require you to
glance at the transmitter to find it. Use your rate
for precise control with little control-surface
deflection before the maneuver begins. You’ll
need a 3D rate for the actual stunt, in which
about 45 degrees of control-surface deflection
is required on all surfaces. While some aircraft
can perform 3D figures with 35 degrees of
travel on most surfaces, many require
45 degrees of travel for the elevator with
65% exponential across the board. And since
large deflection amounts are used, exponential
use is mandatory as it will soften how the
airplane responds to certain control inputs
around neutral control inputs.
An overvie W of the 3D humpty
With A hAlf-roll
A traditional humpty bump is performed when a
pilot pulls to establish a vertical upline, executes
a half-roll, performs a half inside loop over the
top, flies a downline segment that is equal to
the earlier one, and pulls a gentle quarter loop
to an upright level exit. The subject of this
month is similar in form but also includes three
3D maneuvers: the wall, the parachute, and an
As a recap, the wall is a sudden pull to vertical
where all forward movement comes to a halt
and, ultimately, little to no vertical movement
is performed. The parachute is similar to the
wall but done while the aircraft is traveling on a
vertical downline and an aggressive pull is done
to transition the airplane to upright level flight
and to stop downward travel. Last, the waterfall
is typically done when the model rotates in pitch
and makes little to no forward movement while
on a vertical line; it is almost stationary in forward
travel but tumbles end-over-end in pitch.
The 3D humpty starts with a violent
maneuver to stop all forward movement and
establish a vertical upline, which is the wall.
A half-roll is done on the upline and an inside
variant of the waterfall, where the airplane will
pivot 180 degrees in pitch while the pilot pulls
full up-elevator to stop upward movement and
transition to a vertical downline. As the aircraft
travels downward, another aggressive pull will
stop all downward movement. Additionally,
from start to finish, this figure will take roughly
10 seconds to execute from start to finish.
Simply said, a lot will happen in a relatively short
period of time!
It is important to perform the maneuver at a
slight distance away so that you can view the
entire move and see exactly how the aircraft
responds to certain pitch commands. Some
models might “snap” out of certain portions of
the maneuver when you input a lot of elevator
deflection. If you’re far enough away, you’ll be
able to see the plane and apply any required
corrective control inputs to ensure proper
alignment during the fall.
Let’s simplify matters and divide this exciting
figure into four separate steps.
Step 1. For the first attempt, begin by orienting
the model so that it is upright, parallel to the
runway, and traveling into the wind. Next,
ensure that the low-rate setting is activated.
Keep throttle at the cruise setting. Increase
throttle rapidly and return it to 75%, activate
the 3D rate, and aggressively pull maximum
elevator and release elevator input as soon
as the aircraft is completely vertical. Increase
throttle as needed so that the model climbs
vertically. Remember, throttle percentages
Step 2. While climbing on the upline, apply full
throttle and prepare to execute a half-roll. The
half-roll must be centered, but it can be flown in
whatever direction you prefer. In this example,
we’ll fly a right half-roll. Apply any corrective
inputs, which will typically be rudder to correct
for the natural yawing tendency of the airplane
as it is traveling upward.
Step 3. Apply full up-elevator while simultaneously decreasing throttle. If done correctly,
the model will quickly change in orientation and
will face the ground when the pivot is complete.
The plane will rotate 180 degrees and then you
will allow it to establish a downline.
Step 4. As the aircraft approaches the altitude
in which the maneuver began, apply full
up-elevator and appropriate throttle amounts
to stop the descent, transition the airplane to
a nose-high attitude, and ensure that altitude
is maintained. When looking to exit the harrier
variation, apply additional throttle, slowly
It Is Important to
perform the maneuver
at a slIght dIstance
away so that you can
vIew the entIre move
and see exactly how
the aIrcraft responds
to certaIn pItch