E-flite Odyssey EP Electric Glider - Manual (Page 20)

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Once the fundamentals of launch, trim, and control of the
Odyssey EP 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 the Odyssey for maximum performance, whatever the
current conditions are at the time.
The key to trimming the Odyssey EP 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 air-
craft's speed across the ground). Thus the airspeed of the
Odyssey EP is relative to the air mass surrounding it.
To determine the Odyssey's airspeed, you will have to watch
carefully for its pitch atttitude. 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.
Pitch Attitude
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 sailplane 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 Odyssey EP, you will
need to fly 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 Odyssey 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
Odyssey'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 Odyssey 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 situa-
tions 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 Odyssey EP
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
performance, 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 Odyssey EP in the first flights, then
set the mechanical linkages to reflect the trim imparted. You then
set your trim levers back to neutral. Now you know why we per-
formed 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 Odyssey EP 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 Odyssey EP for optimum
performance, the more fun you can have chasing thermals!
Section 12: In-Flight Adjustments for
Performance and Conditions
Horizon
Line Relative toHorizon
Pitch
Attitude
Longitudinal
Axis
Center of
Gravity
Nose