E-flite Ascent EP Park Glider ARF - Manual (Page 20)

21
• Pitch Attitude
• Minimum Sink Speed
• Maximum Lift/Drag (L/D) Speed
• Best Penetration Speed
Once the fundamentals of launch, trim, and control of the
Ascent
™ are learned, it's time to consider getting the most out of
the it's ability to perform. To do that, one must learn how to trim
your Ascent for maximum performance, whatever the current
conditions are at the time. The key to trimming for maximum
performance is to become knowledgeable of three key speeds:
minimum sink, maximum lift/drag (L/D), and best penetration.
These three speeds are what we call airspeeds, not ground
speeds (the aircraft's speed across the ground). Thus the
airspeed of the plane is relative to the air mass surrounding it.
Pitch Attitude
To determine the Ascent’s airspeed, you will have to watch care-
fully for its pitch attitude. Pitch attitude can best be described as
the amount (degree) the nose of the aircraft is above or below a
line relative to the horizon. The angle of attack term is used to
describe the angle between the chord (width) of the wing and the
direction the wing moves through the air.
Minimum Sink Speed
In our discussion of thermals, we know sink is the cooler air
moving downward to replace the warm air that is rising.
Minimum sink speed is the speed at which a park glider loses
altitude most slowly. As the term then implies, minimum sink
speed gives the glider the maximum amount of time aloft from a
given altitude. This is the speed to fly at when you are circling in
thermals, or whenever you need the maximum lift the glider can
produce. The pitch attitude will appear to be more nose-up.
To determine what this speed is for your Ascent, fly it at a slow
speed, slowing down until it just stalls, then, trim it to fly
at a speed just above where it begins to stall. Observe the pitch
attitude at this speed. You will need to practice flying at this
speed without stalling so you can come back to it whenever
you want to when you are in a thermal or trying to maintain
maximum lift.
Maximum Lift/Drag (L/D) Speed
This is the speed at which you can fly the maximum distance for
a given altitude. It's used when you move from one thermal to
another, or when you need to cover the maximum distance over
ground. This will be a moderately faster airspeed than the mini-
mum sink speed. You will have to experiment by starting from
the minimum sink speed and add small amounts of down trim to
increase speed slightly. This is the speed the Ascent performs
the best for duration, and the speed at which you will do most of
your flying. It will take practice until you are familiar with the
Ascent's attitude at this speed. Remember you will be flying
slightly faster, at a lower pitch attitude as compared to minimum
sink speed.
Best Penetration Speed
This is the speed at which the Ascent EP will travel forward
against the wind or a thermal, as far and as quickly as possible.
This speed will vary with the conditions, such as windy situations
or very strong thermals. You will want to use this speed to
escape from very strong lift (or sink). This speed has a more
pronounced nose down appearance, which will vary with the
conditions encountered. It will also not be a consistent attitude,
but vary with the strength and direction of the lift/sink or wind.
Once you have learned to launch and control your Ascent in a
consistent manner, you will want to then proceed with practicing
these three speeds. Remember these are trim speeds, so you will
be using your trim lever to obtain them. For maximum perform-
ance, remember to use trim sparingly, don't depend on the stick,
as you will only impart small movements that result in drag and
battery drain.
Practice smooth control inputs and use the trim lever.
(Remember you trimmed the Ascent in the first flights, and then
set the mechanical linkages to reflect the trim imparted.
You then set your trim levers back to neutral. Now you know
why we performed that procedure, to allow you to use the trim
lever for in-flight trim to better control flight performance.)
There are other things that can be done to bring the performance
level of your Ascent to its absolute best. However, they should
not be attempted until you have become proficient in the launch,
control, and trim of your model.
The more you learn how to trim your Ascent for optimum
performance, the more fun you can have chasing thermals!
Section 10: In-Flight Adjustments for
Performance and Conditions
Pitch
Attitude
Longitudinal
Axis
Nose
Center of
Gravity
Horizon
Line Relative to Horizon