Other Items Required - Top Flite Douglas DC-3 User Manual

TWIN ENGINE AERODYNAMICS
A twin engine model flies no differently than a single
engine model - as long as both engines are properly
tuned and as long as both engines stay running! But -
sooner or later, you will lose an engine. I ask you, how
often do you lose an engine on your single engine
models? You'll lose one twice that often on a twin!
If you lose an engine on a twin, there will be a directional
control problem! If the right engine fails, the left engine will
pull the nose of the aircraft to the right. On a full size aircraft
you use rudder to control the yaw and carefully control the
airspeed with the remaining engine. Do not use the rudder
on this DC-3 if an engine quits. Flying at too slow an
airspeed with one engine at full power could exceed the
ability of the control surfaces to control the yaw.
But with a model, you are standing on the ground and
can't really tell which engine quit. About the only thing
you will notice from the ground when an engine fails is
that the wing will drop slightly on that side and the nose
will yaw a bit, much like hitting a bit of turbulence. You
simply don't have enough visual clues to know which
control inputs will help and which will hurt.
Fortunately, the Top Flite DC-3 flies so well with an engine
out that you do not need to make any immediate control
inputs to control the model. As long as you maintain
adequate flying speed you will hardly notice that an engine
failed. This is where your engine selection will have an
influence. If you have installed .40 size 2-stroke engines,
or .30 Wankels, the model has more than adequate power
to continue flying on one engine. It will slow somewhat,
but it will fly very nicely. You will have plenty of time to
enter the pattern and land. If you have installed .25 size 2-
stroke engines the model will slow quickly and you will
need to make an immediate landing. Just don't allow the
model to get slow as there won't be enough power to
accelerate without descending.
HOW TO HANDLE AN ENGINE FAILURE
If you have installed .25 size engines the model will slow
rapidly when an engine fails. The DC-3 is after all a high
drag aircraft. In this case you should reduce power on the
remaining engine and then glide back for a landing, just as
you would with a single engine model. DO NOT ATTEMPT
TO STRETCH YOUR GLIDE BACK TO THE RUNWAY
WITH HIGH POWER ON THE REMAINING ENGINE.
If you have installed larger engines you should have
adequate power to continue flying almost normally. I say
"almost" as there is a very important thing to consider; If
you allow the model to get too slow, you will lose control
when the yaw from the remaining engine overpowers the
effectiveness of the rudder. On twin engine aircraft the
fin/rudder will stall long before the wing does - full size or
model. The key is don't get slow if the remaining engine
is at a high power setting. If you do, the model will do a
most beautiful snap roll. Recovery is easy - pull the good
engine to idle, lower the nose and glide in for a landing.
For additional information on how to handle your DC-3
in an engine out situation, refer to the "Engine Out"
section on page 65.
FLIGHT CHARACTERISTICS
Other than engine-out flying characteristics, there are a
few other flight qualities you should be aware of. The
engines are placed quite low in relation to the center of
the aircraft. This causes a pitch change when power is
changed. This is most noticeable when you go from idle
power to full power at a low airspeed - such as during a
go-around. Be prepared for this, adding a little down
elevator until the speed increases. Larger engines make
this characteristic more pronounced.
The placement of the fuel tanks in this model is difficult.
Although the best location for the tanks is in the nacelles,
if you are installing retracts the only available place is in
the wing center section. Modern engines have good fuel
draw so this should not create a problem, but older tired
engines may have difficulties. We did not experience any
problems with the many types of engines we tested on
our prototypes, but we did note one unusual thing: In a
turn the engines will have a slight RPM change. The low
engine will decrease RPM by a couple hundred and the
high engine will gain a couple of hundred. While slight,
this is enough for the aircraft to yaw slightly. It appears
that the aircraft is skidding in the turn, and it is! (A skid is
where the nose turns into the turn).
- 5 -
TWIN ENGINE TRAINING
Your Top Flite DC-3 represents a substantial investment
in time and money. For that reason, I suggest that you
start your multi-engine training with a model that you
won't be so emotionally involved with. Get a Hobbico
TwinStar ™ for your training. It's an ARF and will go
together in a couple of weekends. It is an excellent twin
engine trainer. It will save some serious knee knocking
time verses risking your Top Flite DC-3 and, it's
inexpensive. Use the same engines on it that you will
use on your DC-3 so that you may thoroughly break
them in.

OTHER ITEMS REQUIRED

These are additional items you will need to complete
your DC-3 that are not included with your kit. Order
numbers are in parentheses (GPMQ4130). Our
exclusive brand is listed where possible: TOP is the Top
Flite brand, GPM is the Great Planes brand, and HCA is
the Hobbico brand.
4 to 8 Channel radio with 6 to 9 servos (2 micro
servos required for throttle)
Y-connector for aileron servos
(2) 12" Servo extensions for aileron servos
Y-connector or (2) 12" extensions for throttle servos
(see page 46 for more info on throttle hookup)
(2) 3-1/4" Main Wheels (GPMQ4226)
(4) 3/16" Wheel Collars (only required if installing
fixed landing gear) (GPMQ4309)
1-1/2" Tail wheel (GPMQ4283)
(2) 3/32" Wheel Collars for tail wheel (GPMQ4302)
(2) 8 oz. (GPMQ4103) (for smaller engines) or 10 oz.
Fuel Tanks (GPMQ4104)
Approximately 80" medium silicone fuel tubing
(3) 36" pkgs. (GPMQ4131)
(2) Fuel filler valves (GPMQ4160)
(2) Propeller hubs (GPMQ4630)
1/2" (HCAQ1050) or 1/4" (HCAQ1000) R/C Foam
rubber padding
3 rolls of Top Flite Super MonoKote covering, see
Finishing on page 58
Paint, see Finishing on page 58
Propellers