78 MODEL AVIATION
BY STEVE KALUF
Swash Plate: Align T-Rex 450SE (CDE)
Type: Mini-class helicopter
Length: 630mm
Height: 230mm
Main rotor: 680/700mm
Tail rotor: 150mm
Motor gear: 15 teeth/13 teeth/11 teeth
Main gear: 150 teeth
Tail-drive gear: 22 teeth
Weight (without power system):
365 grams
Weight (including power system):
690 grams
Power: 11.1 volts (1300 mAh or more)
Radio system required: Six-channel
helicopter transmitter, six-channel
microreceiver, gyro, three miniservos,
one tail-rotor drive servo
Price: $542.99
Specifications
• 32 precision bearings
• Autorotation system
• Rear tail servo mount
• Collective pitch system
• Tail-rotor drive-belt system
• Main drive gear with cooling fan
• Professional servo control lever design
• Carbon-fiber frames available in black or
silver
• Anodized aluminum mechanics
Features
• Align 430L 3550-kilovolt motor
• Align RCE-BL35G ESC
• Futaba R319DPS synthesized receiver
• JR DS281 digital servo (CCPM)
• Futaba GY401 gyroscope
• Futaba S9650 digital servo for tail rotor
• Futaba 9C transmitter
• Li-Poly batteries tested: Thunder Power
Pro Lite 11.1-volt /2100 mAh, Align 11.1-
volt/1900 mAh, E-flite 11.1-volt/2100 mAh
Equipment Used
ALIGN IS A large Taiwanese corporation
that manufactures vacuums, power feeds, and
several other household appliances, as well as
OEM (original equipment manufacturer)
products. The company burst onto the radiocontrol
market approximately three years ago
with a miniature electric-powered helicopter
that took the world by storm: the T-Rex 450.
The 450 is a fairly low-cost machine;
however, it is also a great model that is
extremely well thought out and flies great. It
is also supported by low-cost parts, which is
one of the keys to any helicopter’s success.
As good as the original T-Rex was, that
did not stop the aftermarket producers from
coming up with a ton of add-ons and hop-up
parts. Not to be outdone, Align started
producing upgraded helicopters.
It added metal parts, a longer tailboom, and
constantly improved an already great machine.
This made the model even more popular
because the Align parts for the improved
version were mostly bolt-ons to even the most
basic T-Rex.
It did not take long for Align to introduce a
Collective Cyclic Pitch Mixing, or CCPM (the
company calls it CDE), version and more
metal parts. Align also sells a nice variety of
motors and ESCs, chargers, batteries, and rotor
blades. That means it can combine
components that work extremely well together.
It has been amazing to see how many
helicopter pilots have T-Rexs. It seems to
be one of those “must-have” items. It is,
without a doubt, at the top of the mini
helicopter food chain.
The current highest-end T-Rex—the
450SE (Superior Edition)—is the subject of
this review, and it is considered the T-Rex
with the ultimate in “bling.” This model
features (silver or black) carbon frames,
anodized metal parts, carbon rotor blades, a
metal head, a metal tail-rotor assembly, and
much more. It’s also the priciest of all the TRexs,
retailing at more than $500.
However, as this review will prove, the
450SE is not all show. It is almost as solid
and capable as you can make a mini
helicopter. The bling makes this aircraft look
great, but it is also functional.
The SE kit comes packaged in a slick
aluminum box, which does a super job of
assuring that all components get to you in
prefect condition. The box is not large enough
to carry the assembled T-Rex; however,
Align offers a nice carrying case with enough
space for the T-Rex and your transmitter,
charger, and battery packs. The box
containing the kit makes a great tote for tools,
blades, and things of that nature after you
have finished construction.
As you can see from the photographs, the
kit is neatly packaged. As has become the de
facto standard for helicopter kits, the T-Rex’s
parts are carefully packaged in numbered
plastic bags that correspond to steps in the
instruction manual.
The 450SE has a high degree of
prefabrication, so many bags contain finished
06sig3.QXD 4/23/07 11:09 AM Page 78
June 2007 79
Photos by the author
This model is loaded with nice finishing
details such as anodized-to-match washers
and finely machined aluminum parts.
The T-Rex 450SE is neatly packaged in a nice aluminum case
that can be used to store maintenance and flight accessories.
Parts bags containing the main mechanics, such as the rest of the
assemblies, are labeled and referenced in the instruction manual.
The included brushless motor has an
internal fan for sufficient cooling. The 13-
tooth pinion seems to be most popular.
The carbon fiber used in manufacturing is coated with aluminum dust to create a
flashy appearance.
Once the linkage rods are assembled,
stick them to masking tape with partidentification
letters written on it.
Remember: the links go on only one way.
+•
Highest standards in machining and
parts quality.
• Kit includes motor and speed control.
• Plastic canopy with optional smoked
windshield.
• Strong and lightweight, with broad use
of carbon fiber and aircraft-grade
aluminum.
• Widely available and inexpensive
replacement parts support. -•
One-way bearing may slip if
overlubricated.
• Ball links tighten in temperatures
below 40°.
Pluses and Minuses
06sig3.QXD 4/23/07 12:00 PM Page 79
80 MODEL AVIATION
The head is installed in the frames along
with the main gear assembly. The gear
lash should be set at this time.
The main rotor assembly is completed with the linkage rods
attached before it is mounted to the main frame.
The three JR DS281 digital servos have been installed and wiring
has been routed. The CCPM mixing is a solid setup.
Be sure to assemble the model using thread-locking compound. The T-Rex 450SE flies
like it is on rails and looks super in the air.
subassemblies. A plastic box holds the motor,
ESC, and motor/ESC connectors. Two sets of
main rotor blades (325mm wood and 315mm
carbon) are included.
Align includes tools and thread locker in
all its kits. The box contains a screwdriver
and hex wrenches, as well as red and blue
thread locker.
The provided motor is Align’s 430L
outrunner. It does not appear to be an
outrunner at first because the outermost can
does not rotate. However, if you disassembled
the motor you would find that it is indeed an
outrunner. The 430L is rated at 3550 kilovolts
(kV).
The Align RCE-BL35G programmable
ESC is stock in the kit, and it is a nice match
for the 430L motor. I’ll have more about both
items later in the review. I also acquired an
Align 1900 mAh 3S Li-Poly battery pack for
the T-Rex and an Align balance charger.
The T-Rex’s assembly is fairly
straightforward, especially if you have built
any other helicopters. The manual is well
illustrated, and each section has a parts listing
at the top of the page that includes item
numbers.
However, the manual is lacking in words
to adequately describe several assembly
sequences. This is not a huge problem, but it
could cause some difficulties for you—
especially if this is one of your first helicopter
models.
In addition, the manual does not take into
account the preassembled components. It
shows how to construct each set of parts,
regardless of whether they are preassembled
or not.
I normally like this, but I prefer the main
part of the manual to show only the necessary
assembly sequences and a second part of the
manual to show the more detailed assemblies
in case you need to take something apart that
was originally preassembled. This should not
be considered a fault of the manual, but rather
my personal preference.
Although Align is thoughtful to include a
screwdriver and hex wrenches, I do not
recommend using the latter. In fact, I do not
recommend using any hex wrenches except
the type used by and sold by RC car and
some helicopter suppliers. They normally
have large anodized handles and hardened
straight hex shafts.
You’ll need a 1.5mm and a 2.5mm
wrench. Anything else is too soft or too
inaccurate of a fit for the button-head hex
bolts used for most of the 450SE’s assembly.
I even tried a high-quality set of “L”
wrenches I had, and they did not work well
either. The car/helicopter-specific type work
perfectly.
Also be extremely careful not to
overtighten the bolts and screws. If you are
not used to the size of micro/mini helicopter
parts, you could easily overtighten and strip
the supplied hardware. The supplied
screwdriver is adequate.
Please take the time to check each
preassembled component to make sure the
fasteners are tight and have thread lock
06sig3.QXD 4/23/07 11:12 AM Page 80
applied where appropriate. I did not find a
single loose fastener, but this is a good habit
to get into when dealing with an RTF, an
ARF, or any machine with some degree of
preassembly.
The manual begins with diagrams of the
various bolts and screws used to put the
model together. Those drawings are useful in
identifying the parts.
Then there is a description and diagram of
the linkages you’ll have to assemble. Those
visuals are not to scale, which I find to be a
problem. However, they do have the correct
measurements for the linkage-rod length,
which is one of the most crucial stages of
assembling any helicopter.
The linkage rods must be assembled to the
correct length. If they are, you will typically
be rewarded with a nice, level swashplate
right off the bat and a correct servo arm/rod
geometry. I use a metric steel rule and a
metric digital caliper to ensure that the linkage
rods are the correct length.
A trick I use to keep the linkage rods
straight is to place them, after I’ve assembled
them, on a piece of masking tape I’ve marked
with the part number or letter and the number
of rods of that size. This way they don’t get
lost and I can easily identify each rod during
construction.
I like to assemble all the rods before I do
anything else. This is also a good time to size
each ball link end.
Many people like to simply put the link on
the ball and squeeze it with a pair of needlenose
pliers. Without a doubt this technique
works, but it is kind of a ham-handed method
of doing it and too much pressure can lead to
a broken link or deformed ball.
I prefer to use a simple ball-link sizing
tool, which is available from several suppliers.
To use it you snap the link onto the sizing
tool. It contains a small blade that cleans up
and properly sizes the link. Most devices have
a small amount of adjustment that allows you
to set the sizing tool to the dimension that
works best for the links you are using.
As are those on JR helicopters, the Align
links are full turn only. Each link has an “A”
on it; that side that must face away from the
ball. The link will not fit on the ball with the
“A” toward it.
Once the links are completed, you can
move on to the final assembly of the head.
There is not much to do here since it is almost
fully put together. You have ball ends to place
on the mixing levers (be sure to use thread
lock), and the feathering shaft, bearings, Oring
dampeners and spacers, blade grips, and
flybar are basically the only parts you have to
put on the head.
As with any helicopter you must be sure
everything works smoothly, with no binding.
Take the time at this stage to thoroughly
check out the head and make sure it is right.
You will be rewarded in the end.
You do have a decision to make as you
assemble the head. Two sizes of spacers are
provided that will stiffen or soften the head
dampening. Use the smaller 1.5mm spacer if
you like a softer head (for hovering and
beginners).
If you’ll be doing aerobatic flight at all,
you’ll want the larger spacer to stiffen the
head. Many pilots feel that the head is still too
soft for 3-D flight with the larger spacer, and
they install additional spacers to stiffen it even
further. You have to decide what works best
for you.
Next in assembly is constructing the main
frames, which have an upper and lower
assembly. The separate upper and lower
frames are preassembled, with the exception
of putting the two together into a single unit
and adding a few standoffs, canopy mounts,
and the antirotation bracket.
Once the frames are assembled, it’s time
to mount the motor. Solder the supplied
connectors onto the motor leads before you
mount the motor in the frames. Installing the
pinion gear at this time is easier than after
mounting.
You have three pinions to choose from
(11-, 13-, and 15-tooth), so look at Align’s
recommendations and pick the pinion that will
give you the head speed you want for the type
of flying you do. The 11-tooth version is fine
for hovering and flying around. You will want
to use the 13- or 15-tooth pinion for aerobatics
or any 3-D flying. Align’s latest
recommendation is that the 15-tooth pinion be
used only on motors rated above 3550 kV.
Mounting the motor is simple using only
two bolts. There are two different-size bolt
holes on the top of the motor. Determine
82 MODEL AVIATION
06sig3.QXD 4/23/07 11:25 AM Page 82
which two holes are the proper size for the
motor-mount bolts, and orient the motor
properly as you insert it into the frames.
It’s a good idea to leave the motor a bit
loose at this stage. You still need to insert
the main gear and set the gear lash between
the motor pinion and the main gear.
When this was written Align had
84 MODEL AVIATION
recently come out with a new gear for the
tail rotor; it is the gear that directly turns
the tail rotor via the belt drive. The new
version is blue and reduces the tail-rotor
rpm from what the original white gear
provided.
If your new 450SE kit did not include
this blue gear, I strongly recommend that
you obtain one and install it at this stage of
assembly. The original tail-rotor rpm made
available by the white gear is simply too
high.
Before each flying session I recommend
that you check the tail-rotor blade grip
bolts and the bolts that actually hold the
grips to the spindle. These items are subject
to high stress, and checking them should be
part of your regular preflight inspection.
The main gear/autorotation tail-drive
gear assembly goes in next, which means
you’ll also be installing the head assembly
at this time. This is an easy step since the
bearing blocks are preinstalled in the
frames. Everything lined up perfectly in my
kit.
Be sure to lubricate the one-way
bearing before sliding the main shaft
through it. If the main gear seems to
separate from the autorotation/tail-drive
gear, you have the pinion gear set too high
on the motor shaft. Loosen it and lower it a
bit. Just be sure the entire main gear is in
contact with the pinion.
Now you can set the gear lash between
the pinion and the main gear. Do not set
this up too tight; that will cause premature
wear and rob you of power/run time.
I like to feed a piece of copy paper that
is roughly 3/16 inch wide and 4 or 5 inches
long between the gears as I rotate them. It
should feed smoothly between the gears
and come up the other side with an
accordion-looking fold to it.
If the paper feeds hard and comes out
sharply creased, you probably have the
gear lash set too tight. If the gear lash is too
loose, it will feed too easily and the paper
will come out with rounded-looking
creases. Once you have the gear lash set,
tighten the motor-mounting bolts.
Your servos can go in next. I chose JR
DS281 digitals for the head. They are fairly
fast and have excellent resolution and a
robust gear train. The diagrams in the
assembly manual are good, but pay
attention to the direction the servos should
be oriented.
The rearmost servo (elevator, if you
will) must have its output shaft oriented
toward the front of the machine to obtain a
90° angle between the servo arm and
linkage rod. Although the manual does not
indicate the proper length the servo arms
should be, this is critical to a CCPM setup.
I used the longest arm supplied with the
DS281 servos; it seems perfect. The
measurement from the center of the arm to
the hole I used is 12.4mm. The servos
mount with self-tapping screws that go into
little plastic nuts.
The nuts are somewhat hard to hold in
place while getting the screws started. I
ended up using a pair of forceps to hold them.
Most servos will be a perfect fit in the
slots supplied in the frames. The frames are
drilled for one mounting screw on each end
of the servo, so if your servos have four
mounting screw locations you’ll need to drill
the appropriate mounting holes in the frames.
I strongly recommend obtaining servos that
fit the frames properly; most submicros do.
The last things to do are install the
landing skids, do the final assembly of the
tail-rotor system, put the fins on the
tailboom, and install the tailboom. This is
simple; however, I do recommend that you
spend extra time with the tail-rotor assembly.
Take the blade grips off and make sure
the bolts that hold the grips to the spindle are
black hex-head bolts. Apply fresh thread
lock and reinstall.
When you adjust the tail-rotor drive-belt
tension, set it a bit looser than the manual
shows. I set mine so that the two sides of the
belt just touch when you press on one side
with your fingertip.
Some also suggest spraying the belt with
WD-40 or something similar to extend its
life. You can shoot the WD-40 onto the belt
at the tail-rotor box; just spin the head and
shoot enough to cover the whole belt. Do this
every flying session.
Accurate and careful setup is vital to the
T-Rex’s flying well. This is a highperformance
machine, and on top of that it is
small. That seems to make proper setup even
more important than with larger, lowerperformance
machines. Pay close attention to
pushrod lengths, look for interaction in the
CCPM head, and program it out if there is
any at all.
The geometry of your model’s rods/arms,
etc. is important, but especially so in this
aircraft. Take your time to get it all right; you
will be rewarded with a super helicopter.
It is vital that the pushrod for the tailrotor
pitch has a straight run from the servo
to the control arm. This takes some
experimentation to achieve.
You will need to rotate the servo mount
on the boom while sighting down the
tailboom to get the alignment as accurate as
possible. Servo-wheel size and hole location
are also important to achieve this alignment.
Remember to clip the pushrod into the
support hook on the stabilizer’s mount. This
keeps the pushrod from flexing under high
loads.
Once you think you have it right, pull the
servo wheel off. While holding the wheel
above the output shaft of the servo, move the
pushrod to see if it travels freely and
smoothly. If it does not, keep working until
it’s perfect. Also make sure the control arm
for the tail rotor is parallel to the tailboom.
I recommend that you invest
(approximately $14) in a pitch gauge for
mini helicopters. Align makes a nice one; it
helps a bunch with setup because normalsize
gauges won’t work for this-size
machine. Be sure to pitch both blades when
you do.
Tracking comes out right on or extremely
close with good blades. I set the T-Rex for
06sig3.QXD 4/23/07 12:14 PM Page 84
+9/-9°; hover happens at approximately 6°
for my model.
The T-Rex 450SE comes with two sets of
main blades: 315mm carbon and 325mm
wood. I’ve done most of my flying with the
315s only because I get longer run times and I
don’t need a ton of power.
Many hard-core 3-D fliers like the 325
woodies. They are nice blades, are accurately
manufactured, and are stiff enough for hard
flying. I can switch between the 315s and 325s
on my T-Rex without having to retrack the
blades.
The ESC provided with the 450SE is nice.
It features soft start, battery protection, motor
timing, governor mode, and brake (not for use
with a helicopter). Programming is easy using
your transmitter’s throttle stick. As do most
ESCs, the BL35G beeps out the programming
at start-up.
I chose the Align 11.1-volt, 1900 Li-Poly
and the Thunder Power Pro Lite 2100 batteries
for the T-Rex. Both perform great. The
Thunder Power 2100 mAh pack’s extra
capacity gives me roughly three more minutes
of run time in a hovering or gentle flight. It
provides a bit less with a more aggressive
flight.
Be prepared the first time you spool up this
machine; the head speed is high! Depending on
the pinion gear you select and the throttle curve
you use, you might see as high as 3,000 rpm!
This thing sounds like a turbine as it comes up
to speed.
I used the 11-tooth pinion for my initial test
flights. My tachometer does not go high
enough to check the head speed, but according
to the charts provided with the machine’s
instruction manual I should be turning 2,320-
2,800 rpm, depending on the flight mode
selected. The 2,800 rpm seems extraordinarily
high, but the model performs great at that head
speed.
Most pilots who fly 3-D are selecting the
15-tooth pinion and regularly turn more than
3,000 rpm in idle-up/stunt modes. If you crank
your 450SE’s head speed this high, it is
imperative that you obtain and install the newer
tail-drive gears/pulleys to reduce the tail-rotor
rpm. There are known cases of tail blades
leaving helicopters when this was not done.
Many sport-type pilots prefer the 13-tooth
pinion. It seems to give a nice balance of
performance and economy. I now use the 13-
86 MODEL AVIATION
tooth pinion, and it gives the best overall
performance for my style of flying. When I
land the T-Rex the batteries, ESC, and motor
are still cool.
Flying: “Wow” is an accurate description of
how this little helicopter flies. I made all my
initial flights inside in a fairly confined space
since it was winter in Indiana when I did this
review.
The first time I listened to this model spool
up in a confined space, it was slightly
intimidating. If you take your time with setup,
the intimidation factor will go down at roughly
the point you lift the T-Rex into its first hover.
This is a stable aircraft, especially for its
size. But make no mistake—it is responsive—
so use caution as you stir the sticks the first
time.
After the first flight I dialed in exponential
(expo) to soften things around center. This
kept me from overcontrolling. I started with
approximately 30% and soon reduced that to
20%, and now it’s only roughly 8% (for
indoor flying). Outside I run full throw with
no expo.
The tail rotor has a huge amount of
authority. You’ll want a good gyro and tailrotor
pitch control servo to handle the tail.
I chose the Futaba GY401 gyro and Futaba
S9650 digital servo. This is a great
combination that locks the tail up no matter
how hard you push the T-Rex. The GY401 is
perhaps the most popular heading-hold gyro,
and its price and size are perfect for the T-Rex.
Do be sure, as I mentioned previously, to
obtain and install the blue tail gear and pulley
set to reduce the tail-rotor rpm.
When pushed into forward flight the T-Rex
picks up speed immediately. It can really blast
away if you desire! This is a small machine, so
it can get far away quickly. Forward flight is
smooth and predictable.
The T-Rex tracks like it is on rails. The
amount of power the 430L motor delivers is
incredible. You have to really be pushing it to
bog the motor down at all.
The CCPM set up with the JR DS281
servos seems to be the hot ticket for this
machine. Control of the head is nearly perfect
with this setup.
JR now has a DS285 servo, which boasts a
higher speed (.18) than the DS281 (.23). I
believe the DS281 has been replaced by the
DS285. Either servo is an excellent choice.
The 450SE’s turns are smooth and
predictable. Stall turns are precise, with the
turn stopping as soon as you neutralize the
tail-rotor stick, as are pirouettes. Loops and
rolls are almost beginner easy.
I’m far from being a 3-D pilot, as I’ve
mentioned before, but I have seen some of the
top pilots in the country put the T-Rex through
an incredible amount of hard 3-D flying. As
far as I can tell, there is not much (if anything)
this machine cannot do.
The small 450SE does not have as much
stored energy in the blades as larger machines
during an autorotation. However, it manages
to do them well.
There is an altitude that may be no-man’s
land (too high for the already stored energy to
save you and too low to spool the rotor back
up), but that area is small. The nice thing
about an electric-powered helicopter is that
you don’t have too many unintentional
autorotations to worry about.
This is an incredible helicopter. Almost the
only negative I can think of (outside of a few
minor hits in the manual) is that belt life is
questionable at times.
Lubricate the belt with WD-40, silicone, or
something similar. Watch the tension and
inspect it after every flight. If you see any
obvious wear or yellow threads are showing,
don’t fly! Replace the belt!
I’m hopeful that Align will come up with a
new belt that will last a bit longer. In these
days of belts lasting for almost the life of the
machine, a helicopter of this quality should
have a high-quality belt. But don’t let that
minor issue get in the way of your building a
T-Rex 450SE.
This is one of those models that almost
everyone who flies helicopters just has to
have! It has the looks, the inexpensive parts,
the availability, the overall price, and the
performance (oh man, does it have the
performance) that make it a must-have! MA
Steve Kaluf
[email protected]
Distributor:
Align RC/Assurance RC
14565 Suite #H Valley View Ave.
Santa Fe Springs CA 90670
(562) 926-5357
www.align.com.tw/html/en/c_rindexe.htm
Other Published Resources:
RCUniverse
www.rcuniverse.com/magazine/article_displa
y.cfm?article_id=572
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06sig3.QXD 4/23/07 12:15 PM Page 86