THIS IS USUALLY the time of year when
we sit indoors, watch the snow fall, and
yearn for the warmer weather. Not
anymore! With the advancement of Li-Poly
batteries, brushless motors, and mini/micro
helicopters, indoor flying has never been
this much fun! Gymnasiums, field houses,
and armories are great places to hold indoor
fun-fly events.
The Align T-Rex distributed by Empire
Hobby (www.empirerc.com) has been my
helicopter of choice for this type of activity.
I started playing with this model a few years
ago when it was first introduced.
The original T-Rex looked much like a
miniature Thunder Tiger Raptor. Align
continued to respond to customer feedback
and made many changes and improvements,
to eventually come out with the Align TOptimizing
the Empire Hobby-distributed Align electric-powered T-Rex
[[email protected]]
Radio Control Helicopters Ray Stacy
All versions of the T-Rex come well packed
in a cool metal case that can later be used
to hold batteries, spare parts, etc.
Align sells a nice carrying case that will hold the T-Rex,
transmitter, and other essentials. It’s a nice addition.
The XL does a nice job of using push/linkages on the servo setup.
This helps keep control-system play to a minimum.
The T-Rex SE is the Cadillac of the line and comes fully upgraded
and tricked out with all of Align’s options.
Performance Hobbies owner Tom McCoy checks out Ray’s SE.
Ray sees this expression a lot when he brings out this model.
Rex 450 XL HDE, T-Rex 450 XL CDE,
and T-Rex 450 CDE SE.
The T-Rex 450 CDE SE is in a league of
its own. It is a fully upgraded version that
includes every metal improvement available
from Align and carbon-fiber-type side
frames. The new 430L motor and Align
speed controller are included. I like the
servo layout on the SE because the servos
connect directly to the swashplate.
The T-Rex 450 XL HDE utilizes Raptorlike
mechanical mixing for the swashplate
movement and is a good choice if you don’t
have a helicopter transmitter that is capable
of doing Collective Cyclic Pitch Mixing
(CCPM). The 450 XL CDE is identical to
the HDE for the most part; the difference is
that the XL CDE comes with the CCPM
retrofitting components.
I prefer the XL CDE or the CDE SE
because I like the simplicity and ease of
setup of a CCPM system. I also like the idea
of spreading the swashplate load across
three servos.
The T-Rex 450 CDE SE is the only
version that comes with the subassemblies
completed. If you go with the SE, please
check all the screws for proper tightness.
Make sure thread locker has been applied to
the appropriate places.
All this was done correctly on my model,
but it is still worth your time to check. This
is especially true for the preassembled rotor
head. All other versions of the T-Rex are in
kit form.
All the T-Rex helicopters come in neat
metal cases that you can use for transporting
parts and tools to the field. Align even
supplies a set of screwdrivers, Allen
wrenches, and some spare hardware.
This is a small helicopter with small
screws. It is easy to strip a screw head or the
hole into which it is going. Gorilla strength
will not work well when assembling the
helicopter. I use the Ofna hex wrenches
without the handle and jeweler’s
screwdrivers to limit the amount of torque
applied to the screws.
I have tried several popular microservos
and keep coming back to the JR DS281
submicro digital servo. The DS281 remains
tight flight after flight and maintains the
accuracy required for small helicopters.
Other servos I have tried became sloppy and
would not center properly after a few
flights. Some just weren’t up for the task
and stripped in flight!
The DS281 has a gear set that will not
strip out in flight. I have had a few crashes
on my T-Rex and haven’t stripped a servo
yet. I did manage to break a case when I
nailed a concrete floor, but the servo still
worked!
My favorite feature of the DS281 is that
it uses a real JR servo arm and not some thin
piece of plastic. There is no need to beef up
or extend the arm.
The only drawback to this servo could be
the transit speed of .23 second, which is
slow by today’s standards. This has not been
a problem in any of the 3-D flying I have
done, but I am sure someone would notice
the difference in speed compared to the
Hitec HS-56, which has a transit time of .10
second.
I am currently testing a 6-volt BEC on
my night-flying setup to see if makes a
XL and SE tail assemblies. Both work well, but the SE delivers
smoother and crisper control with its upgraded pitch control.
Custom-painted T-Rex canopies from Dave Yost Designs. Check
out his work at www.dydhelmets.com/rchelipaint.asp.
difference. The servos are noticeably
faster, and so far they do not seem to have
a problem with the 6 volts.
For tail rotor control I like the Futaba
9650 servo or the Airtronics 94761. Either
one supplies the speed, accuracy, and
reliability I need at the tail. The 9650 might
seem a bit large back there on the boom at
first, but it mounts fine using one screw on
each side. Use the smallest servo wheel
you have and mount the ball as close to
center as possible.
I don’t bother with the tail-rotor
pushrod guide on the bottom of the
horizontal fin clamp. Most of the time the
guide doesn’t line up with the pushrod and
only causes drag on it. I simply cut the
guide off.
My preferred gyro is the Futaba 401. Its
size and performance make it a perfect fit
for the T-Rex. Don’t be surprised when
you have to turn your gain down to
approximately 40%; this is normal.
I have tried the new CSM 720 gyro, but
it has an annoying drift I can’t seem to
resolve. The same drift has appeared on
two other gyros. I am working with CSM
to fix this, but so far I have had little
success. I will keep trying and report to
you on my findings.
Before I go into motors, I want to point out
that I am mostly naive about their size
numbers. It isn’t like our nitro
counterparts, where bigger is usually
better. I don’t understand the KV rating
system, and in the end I can only tell you
how well the motor performed by the “seat
of my pants” flying. When evaluating a
motor I check for flight time, performance,
and motor temperature at the end of a
flight.
While attending the iHobby Expo in
Los Angeles, California, I was given the
opportunity to try the new Align 430L
motor with 13-tooth pinion. Wow! The
head speed jumped to 3,000 rpm, which
takes a bit of getting used to, but theApril 2006 131
increased response is worth it.
My flight time may have dropped from
13 minutes to eight to 10 minutes, but it
was well worth the tradeoff. I have since
installed the 430L in all my T-Rex
helicopters. The motor continues to run
well for me.
I recently had the chance to try the
450TH motor from JustGoFly.com. The
450TH is lighter and smaller than the 430L,
but it performs just as well.
Using a 13-tooth pinion the head speed
dropped to roughly 2,600 rpm, but the
helicopter’s performance did not suffer in
any way I could notice. In fact, it is
difficult to bog this motor down. I was
amazed by how cool the motor was after a
flight. I hope to try a 15-tooth pinion and
make it work a little harder.
There are a number of motor controllers
available for your use. I have tried Align,
Castle Creations, Hyperion, and Quark
types, all of which have worked very well.
I have always picked a 30-amp or larger
controller.
The Quark controller from Sky &
Technology (www.sky-technology.net) has
a smooth transition and appears to provide
extra power and run time, which I found to
be interesting. This is from actual flying
experience—not detailed bench testing.
I have read on online forums that some
people spend time trying to use the speed
controller’s governor mode. Some have had
success and some have not. I have never
taken the time to do this.
I run the controller in a normal mode
with soft start enabled and the brake
disabled. This configuration and a simple
throttle curve has worked exceptionally
well. My stunt throttle curve consists of
three points: 100%, 80%, and 100%. It
can’t get much simpler than that.
For power I use the Thunder Power
(www.thunderpower-batteries.com)
ProLite 2100 mAh 3S pack or the Hyperion
(www.empirerc.com) Velocity Lite 2100
mAh pack. The Thunder Power pack has a
rating of 15C and the Hyperion pack has a
rating of 18C. The C rating refers to the
discharge capacity of your battery. To
calculate the actual discharge rate, multiply
the C rating by the capacity of the battery.
The following are examples.
• 2100 mAh battery, 10C = 2,100 x 10 =
21,000 milliamps, or 21.0 amps
• 2100 mAh battery, 18C = 2,100 x 18 =
37,800 milliamps, or 38.8 amps
In testing I found that the Thunder
Power and Hyperion packs perform
identically.
At the time of this writing I received a
Cellpro Slimline 2100 mAh 3S pack from
Greg Covey at FMA Direct (www.fma
direct.com). The pack doesn’t have a C
rating on it and I couldn’t find this exact
pack on the FMA Direct Web site, but I
would guess that it is comparable to the
Hyperion and Thunder Power packs I am
running.
I decided to take a break from writing this
column to go out and do a quick comparison
of the three battery packs. I found that each
pack will give me a solid 10 minutes of good
3-D performance before the head speed starts
to drop. During this quick test I had my first
swashplate failure, which I will go into later.
I use two chargers to keep my battery
packs ready at all times, the first of which is
the ElectriFly Triton from Great Planes. This
universal charger does a nice job of letting
me know exactly how much of a charge I
used during a flight.
After the 10-minute flight with the
Cellpro Slimline, I recharged the pack on my
Triton and found that it took a charge of 1810
milliamps. This tells me I depleted most of
the usable electricity on the 2100 mAh pack
and it was time to land.
If I am uninterested in evaluating a battery
pack and simply want to bring everything
back to full charge, I use the ElectriFly
PolyCharge4 from Great Planes. It has four
independent outputs capable of charging oneto
four-cell Li-Poly batteries. This is a nice
charger to have at fun-fly events when you
tend to go through batteries quicker than you
can recharge them.
The T-Rex comes with a set of wood blades
and a set of carbon-fiber blades. Both do well
for most of the flying, but for serious, hardbanging
3-D I prefer a stiffer carbon-fiber
blade. It provides the crisp response required
for that type of flight.
I have tested two brands of blades: the
SABs and the Hyperions. Both deliver
superior quality and performance while
reducing drag, therefore placing less load on
the drive train and motor. The result is a
smoother-running helicopter and longer run
times.
I have a couple of tips for you for when
you build your T-Rex. Use a ball-link
reamer on all of the links. A small amount
of drag will quickly destroy your helicopter’s
performance.
I recently test-flew a friend’s new TRex.
He had not used a ball-link reamer
during assembly, and even though the links
felt good I was always chasing the machine
for control. Loosen the links and you will
be fine.
Don’t run the tail-rotor belt too tight. I
didn’t know this at first and could never
understand why I was tearing up belts and
pulleys every six or seven flights. Either the
belt would shred or it would get jammed in
the tail rotor housing and melt a pulley.
While attending the World Heli Micro
Cup in Los Angeles (www.rcuniverse.com/
magazine/) I mentioned this to Jason
Krause. His first comment was that the belt
was too tight. I looked at Jason’s T-Rex,
and there was no twang tension on the belt.
Since loosening the belts I have not
destroyed one belt or pulley. If you were to
look at my model’s belt you might think it
was so loose that it would slip, but it never
has.
Check your swashplate! It can separate
and most certainly will cause a crash. Either
the metal or plastic swashplate can separate.
I had read about this happening but never
experienced it firsthand until today.
While doing some extreme 3-D flying
for the battery testing, the helicopter started
to flutter and would not respond to
directional control. Postcrash investigation
showed that the swashplate had come apart.
I understand that Align is looking into a
new swashplate design that should be
available by the time you read this. Online
helicopter dealer Modefo’s Helis (www.
modefosheli.com/) has this tip on his Web
site for checking the existing swashplate.
Following are my tips and how I will repair
mine.
1) Don’t take a chance with any Align
swashplate. When you remove it from the
package, do some work on it.
2) Sometimes heat and pressure is not
even necessary to “pop” these swashplates
apart. If it is, I used a soldering iron—the
same one I use to solder Deans plugs and
wires—and heated the inside of the
swashplate from underneath.
Then I placed my swashplate on top of a
7/16 socket (it fits the underside perfectly). I
pushed down a few times on the outer
swashplate balls, and “pop”! It came right
off. I tried using my thumb underneath, and
it didn’t get the job done. The secret was the
7/16 socket.
3) Scrape away the old glue; it might be
tough to see because it’s pretty much clear,
but it’s there. I used a small flathead
screwdriver to get the job done.
4) Get some decent Loctite; opinions
vary about what to use, but I employ the
same stuff Hacker technicians told me to use
on my metal-to-metal Hacker motor: green
Loctite. I use Permatex brand.
Place one drop on a scrap piece of
plastic. Using a toothpick (I used my
smallest flathead micro screwdriver) spread
the adhesive on the inner swashplate surface
and spread it out so it’s the thinnest layer.
You will be able to discard most of the
drop of Loctite that is left. I mention this
because if you use too much you take the
chance of gumming up the bearing.
5) Let the Loctite dry overnight, and then
do a quick thumb test again. Don’t use a
socket this time because you don’t want to
get it back off—just test it.
Neither Loctite nor its competitors is
recommended for the swashplates that are
all plastic or the plastic/metal combo; it can
make the plastic brittle. In that case I would
think cyanoacrylate would be the best
choice, although I have heard of people
using JB Weld.
Go easy on the screws! I know I
mentioned this earlier, but I am repeating it.
They will strip without warning.
I found a cool cheat sheet for making the TRex
links on www.rcgroups.com. Craig
Harvey of Canada found that the T-Rex
manual could be confusing when assembling
the many required links. He created a PDF
file that lays out the exact lengths for all the
links, and it is extremely helpful during the
assembly.
According to Craig it is important to print
the page using “None” for the Page Scaling
option, and you’ll be able to quickly and
easily adjust any XL linkage to the correct
(as shown in the manual) length. You can
download the PDF at www.rcgroups.com/
forums/showthread.php?t=440578.
When attaching the ball links to the
tail-rotor pitch plate, make sure not to
overtighten the screws that secure the links.
If a little play is unavailable in this area,
there will be some binding on the slider as
it passes over the midpoint. This can cause
a tail wag that will cause you to spend
time looking at the gyro and tail-rotor
servo. Ask me how I know.
For those who love to buy “bling,” Align,
and many aftermarket companies, sell
numerous upgrades for the T-Rex. I was
amazed by how affordable the upgrades
are. You could go crazy buying blue metal
parts for your model, and eventually you
would end up with the T-Rex 450 CDE
SE. I hold back on installing upgrades
unless they offer something in enhanced
performance.
The only upgrades I feel are necessary
for the T-Rex XL are the metal head block
with mixer base and the metal swashplate.
Once you start looping and rolling, the
plastic head block will quickly loosen on
the main shaft and the plastic mixer base
gets sloppy on the guide pins. Align’s new
tail-rotor pitch plate (part HS1138T) is a
nice addition; it removes any binding in
the tail-rotor control system.
If you do get the new pitch-plate
assembly, also get the upgraded tail-rotor
hub (part HS1103). Make sure this tailrotor
hub assembly has hardened 2mm
Allen-head screws to attach the blade
grips. The original soft screws may break
and throw a tail-rotor blade. If you already
have this assembly and did not receive the
new screws, E-mail Align or your
distributor and it will get you the screws.
Most of the other upgrades are more
nice to have than required. I tend to stay
away from the metal blade grips. I like the
blade breaking off in a crash and taking its
energy with it.
Remember that crash I mentioned
earlier? One of the blade grips broke, but
the Hyperion carbon-fiber blades did not.
For when your helicopter is complete,
Align has a nice carrying case that will
hold the T-Rex. There is room in the case
for your transmitter, batteries, and
assorted tools. This is a great accessory if
you plan on traveling with your model.
The cool thing about any T-Rex
configuration is that with the right setup
and attention to maintenance it is capable
of many hours of serious 3-D-type
performance. I have found that it does
well indoors and outdoors. I have flown
mine in a light breeze with no problem.
Drop the head speed, and you have a
nice helicopter that can be used to learn
to fly.
Crashing a T-Rex won’t break your
bank account. Align has made sure all
spare parts are reasonably priced.
If you have been looking to get into
electric-powered helicopters but were
concerned about performance or fragility,
check out the T-Rex. At less than $200 for
the kit, the T-Rex XL will give you real
helicopter performance at a price that
Edition: Model Aviation - 2006/04
Page Numbers: 129,130,131,132
Edition: Model Aviation - 2006/04
Page Numbers: 129,130,131,132
THIS IS USUALLY the time of year when
we sit indoors, watch the snow fall, and
yearn for the warmer weather. Not
anymore! With the advancement of Li-Poly
batteries, brushless motors, and mini/micro
helicopters, indoor flying has never been
this much fun! Gymnasiums, field houses,
and armories are great places to hold indoor
fun-fly events.
The Align T-Rex distributed by Empire
Hobby (www.empirerc.com) has been my
helicopter of choice for this type of activity.
I started playing with this model a few years
ago when it was first introduced.
The original T-Rex looked much like a
miniature Thunder Tiger Raptor. Align
continued to respond to customer feedback
and made many changes and improvements,
to eventually come out with the Align TOptimizing
the Empire Hobby-distributed Align electric-powered T-Rex
[[email protected]]
Radio Control Helicopters Ray Stacy
All versions of the T-Rex come well packed
in a cool metal case that can later be used
to hold batteries, spare parts, etc.
Align sells a nice carrying case that will hold the T-Rex,
transmitter, and other essentials. It’s a nice addition.
The XL does a nice job of using push/linkages on the servo setup.
This helps keep control-system play to a minimum.
The T-Rex SE is the Cadillac of the line and comes fully upgraded
and tricked out with all of Align’s options.
Performance Hobbies owner Tom McCoy checks out Ray’s SE.
Ray sees this expression a lot when he brings out this model.
Rex 450 XL HDE, T-Rex 450 XL CDE,
and T-Rex 450 CDE SE.
The T-Rex 450 CDE SE is in a league of
its own. It is a fully upgraded version that
includes every metal improvement available
from Align and carbon-fiber-type side
frames. The new 430L motor and Align
speed controller are included. I like the
servo layout on the SE because the servos
connect directly to the swashplate.
The T-Rex 450 XL HDE utilizes Raptorlike
mechanical mixing for the swashplate
movement and is a good choice if you don’t
have a helicopter transmitter that is capable
of doing Collective Cyclic Pitch Mixing
(CCPM). The 450 XL CDE is identical to
the HDE for the most part; the difference is
that the XL CDE comes with the CCPM
retrofitting components.
I prefer the XL CDE or the CDE SE
because I like the simplicity and ease of
setup of a CCPM system. I also like the idea
of spreading the swashplate load across
three servos.
The T-Rex 450 CDE SE is the only
version that comes with the subassemblies
completed. If you go with the SE, please
check all the screws for proper tightness.
Make sure thread locker has been applied to
the appropriate places.
All this was done correctly on my model,
but it is still worth your time to check. This
is especially true for the preassembled rotor
head. All other versions of the T-Rex are in
kit form.
All the T-Rex helicopters come in neat
metal cases that you can use for transporting
parts and tools to the field. Align even
supplies a set of screwdrivers, Allen
wrenches, and some spare hardware.
This is a small helicopter with small
screws. It is easy to strip a screw head or the
hole into which it is going. Gorilla strength
will not work well when assembling the
helicopter. I use the Ofna hex wrenches
without the handle and jeweler’s
screwdrivers to limit the amount of torque
applied to the screws.
I have tried several popular microservos
and keep coming back to the JR DS281
submicro digital servo. The DS281 remains
tight flight after flight and maintains the
accuracy required for small helicopters.
Other servos I have tried became sloppy and
would not center properly after a few
flights. Some just weren’t up for the task
and stripped in flight!
The DS281 has a gear set that will not
strip out in flight. I have had a few crashes
on my T-Rex and haven’t stripped a servo
yet. I did manage to break a case when I
nailed a concrete floor, but the servo still
worked!
My favorite feature of the DS281 is that
it uses a real JR servo arm and not some thin
piece of plastic. There is no need to beef up
or extend the arm.
The only drawback to this servo could be
the transit speed of .23 second, which is
slow by today’s standards. This has not been
a problem in any of the 3-D flying I have
done, but I am sure someone would notice
the difference in speed compared to the
Hitec HS-56, which has a transit time of .10
second.
I am currently testing a 6-volt BEC on
my night-flying setup to see if makes a
XL and SE tail assemblies. Both work well, but the SE delivers
smoother and crisper control with its upgraded pitch control.
Custom-painted T-Rex canopies from Dave Yost Designs. Check
out his work at www.dydhelmets.com/rchelipaint.asp.
difference. The servos are noticeably
faster, and so far they do not seem to have
a problem with the 6 volts.
For tail rotor control I like the Futaba
9650 servo or the Airtronics 94761. Either
one supplies the speed, accuracy, and
reliability I need at the tail. The 9650 might
seem a bit large back there on the boom at
first, but it mounts fine using one screw on
each side. Use the smallest servo wheel
you have and mount the ball as close to
center as possible.
I don’t bother with the tail-rotor
pushrod guide on the bottom of the
horizontal fin clamp. Most of the time the
guide doesn’t line up with the pushrod and
only causes drag on it. I simply cut the
guide off.
My preferred gyro is the Futaba 401. Its
size and performance make it a perfect fit
for the T-Rex. Don’t be surprised when
you have to turn your gain down to
approximately 40%; this is normal.
I have tried the new CSM 720 gyro, but
it has an annoying drift I can’t seem to
resolve. The same drift has appeared on
two other gyros. I am working with CSM
to fix this, but so far I have had little
success. I will keep trying and report to
you on my findings.
Before I go into motors, I want to point out
that I am mostly naive about their size
numbers. It isn’t like our nitro
counterparts, where bigger is usually
better. I don’t understand the KV rating
system, and in the end I can only tell you
how well the motor performed by the “seat
of my pants” flying. When evaluating a
motor I check for flight time, performance,
and motor temperature at the end of a
flight.
While attending the iHobby Expo in
Los Angeles, California, I was given the
opportunity to try the new Align 430L
motor with 13-tooth pinion. Wow! The
head speed jumped to 3,000 rpm, which
takes a bit of getting used to, but theApril 2006 131
increased response is worth it.
My flight time may have dropped from
13 minutes to eight to 10 minutes, but it
was well worth the tradeoff. I have since
installed the 430L in all my T-Rex
helicopters. The motor continues to run
well for me.
I recently had the chance to try the
450TH motor from JustGoFly.com. The
450TH is lighter and smaller than the 430L,
but it performs just as well.
Using a 13-tooth pinion the head speed
dropped to roughly 2,600 rpm, but the
helicopter’s performance did not suffer in
any way I could notice. In fact, it is
difficult to bog this motor down. I was
amazed by how cool the motor was after a
flight. I hope to try a 15-tooth pinion and
make it work a little harder.
There are a number of motor controllers
available for your use. I have tried Align,
Castle Creations, Hyperion, and Quark
types, all of which have worked very well.
I have always picked a 30-amp or larger
controller.
The Quark controller from Sky &
Technology (www.sky-technology.net) has
a smooth transition and appears to provide
extra power and run time, which I found to
be interesting. This is from actual flying
experience—not detailed bench testing.
I have read on online forums that some
people spend time trying to use the speed
controller’s governor mode. Some have had
success and some have not. I have never
taken the time to do this.
I run the controller in a normal mode
with soft start enabled and the brake
disabled. This configuration and a simple
throttle curve has worked exceptionally
well. My stunt throttle curve consists of
three points: 100%, 80%, and 100%. It
can’t get much simpler than that.
For power I use the Thunder Power
(www.thunderpower-batteries.com)
ProLite 2100 mAh 3S pack or the Hyperion
(www.empirerc.com) Velocity Lite 2100
mAh pack. The Thunder Power pack has a
rating of 15C and the Hyperion pack has a
rating of 18C. The C rating refers to the
discharge capacity of your battery. To
calculate the actual discharge rate, multiply
the C rating by the capacity of the battery.
The following are examples.
• 2100 mAh battery, 10C = 2,100 x 10 =
21,000 milliamps, or 21.0 amps
• 2100 mAh battery, 18C = 2,100 x 18 =
37,800 milliamps, or 38.8 amps
In testing I found that the Thunder
Power and Hyperion packs perform
identically.
At the time of this writing I received a
Cellpro Slimline 2100 mAh 3S pack from
Greg Covey at FMA Direct (www.fma
direct.com). The pack doesn’t have a C
rating on it and I couldn’t find this exact
pack on the FMA Direct Web site, but I
would guess that it is comparable to the
Hyperion and Thunder Power packs I am
running.
I decided to take a break from writing this
column to go out and do a quick comparison
of the three battery packs. I found that each
pack will give me a solid 10 minutes of good
3-D performance before the head speed starts
to drop. During this quick test I had my first
swashplate failure, which I will go into later.
I use two chargers to keep my battery
packs ready at all times, the first of which is
the ElectriFly Triton from Great Planes. This
universal charger does a nice job of letting
me know exactly how much of a charge I
used during a flight.
After the 10-minute flight with the
Cellpro Slimline, I recharged the pack on my
Triton and found that it took a charge of 1810
milliamps. This tells me I depleted most of
the usable electricity on the 2100 mAh pack
and it was time to land.
If I am uninterested in evaluating a battery
pack and simply want to bring everything
back to full charge, I use the ElectriFly
PolyCharge4 from Great Planes. It has four
independent outputs capable of charging oneto
four-cell Li-Poly batteries. This is a nice
charger to have at fun-fly events when you
tend to go through batteries quicker than you
can recharge them.
The T-Rex comes with a set of wood blades
and a set of carbon-fiber blades. Both do well
for most of the flying, but for serious, hardbanging
3-D I prefer a stiffer carbon-fiber
blade. It provides the crisp response required
for that type of flight.
I have tested two brands of blades: the
SABs and the Hyperions. Both deliver
superior quality and performance while
reducing drag, therefore placing less load on
the drive train and motor. The result is a
smoother-running helicopter and longer run
times.
I have a couple of tips for you for when
you build your T-Rex. Use a ball-link
reamer on all of the links. A small amount
of drag will quickly destroy your helicopter’s
performance.
I recently test-flew a friend’s new TRex.
He had not used a ball-link reamer
during assembly, and even though the links
felt good I was always chasing the machine
for control. Loosen the links and you will
be fine.
Don’t run the tail-rotor belt too tight. I
didn’t know this at first and could never
understand why I was tearing up belts and
pulleys every six or seven flights. Either the
belt would shred or it would get jammed in
the tail rotor housing and melt a pulley.
While attending the World Heli Micro
Cup in Los Angeles (www.rcuniverse.com/
magazine/) I mentioned this to Jason
Krause. His first comment was that the belt
was too tight. I looked at Jason’s T-Rex,
and there was no twang tension on the belt.
Since loosening the belts I have not
destroyed one belt or pulley. If you were to
look at my model’s belt you might think it
was so loose that it would slip, but it never
has.
Check your swashplate! It can separate
and most certainly will cause a crash. Either
the metal or plastic swashplate can separate.
I had read about this happening but never
experienced it firsthand until today.
While doing some extreme 3-D flying
for the battery testing, the helicopter started
to flutter and would not respond to
directional control. Postcrash investigation
showed that the swashplate had come apart.
I understand that Align is looking into a
new swashplate design that should be
available by the time you read this. Online
helicopter dealer Modefo’s Helis (www.
modefosheli.com/) has this tip on his Web
site for checking the existing swashplate.
Following are my tips and how I will repair
mine.
1) Don’t take a chance with any Align
swashplate. When you remove it from the
package, do some work on it.
2) Sometimes heat and pressure is not
even necessary to “pop” these swashplates
apart. If it is, I used a soldering iron—the
same one I use to solder Deans plugs and
wires—and heated the inside of the
swashplate from underneath.
Then I placed my swashplate on top of a
7/16 socket (it fits the underside perfectly). I
pushed down a few times on the outer
swashplate balls, and “pop”! It came right
off. I tried using my thumb underneath, and
it didn’t get the job done. The secret was the
7/16 socket.
3) Scrape away the old glue; it might be
tough to see because it’s pretty much clear,
but it’s there. I used a small flathead
screwdriver to get the job done.
4) Get some decent Loctite; opinions
vary about what to use, but I employ the
same stuff Hacker technicians told me to use
on my metal-to-metal Hacker motor: green
Loctite. I use Permatex brand.
Place one drop on a scrap piece of
plastic. Using a toothpick (I used my
smallest flathead micro screwdriver) spread
the adhesive on the inner swashplate surface
and spread it out so it’s the thinnest layer.
You will be able to discard most of the
drop of Loctite that is left. I mention this
because if you use too much you take the
chance of gumming up the bearing.
5) Let the Loctite dry overnight, and then
do a quick thumb test again. Don’t use a
socket this time because you don’t want to
get it back off—just test it.
Neither Loctite nor its competitors is
recommended for the swashplates that are
all plastic or the plastic/metal combo; it can
make the plastic brittle. In that case I would
think cyanoacrylate would be the best
choice, although I have heard of people
using JB Weld.
Go easy on the screws! I know I
mentioned this earlier, but I am repeating it.
They will strip without warning.
I found a cool cheat sheet for making the TRex
links on www.rcgroups.com. Craig
Harvey of Canada found that the T-Rex
manual could be confusing when assembling
the many required links. He created a PDF
file that lays out the exact lengths for all the
links, and it is extremely helpful during the
assembly.
According to Craig it is important to print
the page using “None” for the Page Scaling
option, and you’ll be able to quickly and
easily adjust any XL linkage to the correct
(as shown in the manual) length. You can
download the PDF at www.rcgroups.com/
forums/showthread.php?t=440578.
When attaching the ball links to the
tail-rotor pitch plate, make sure not to
overtighten the screws that secure the links.
If a little play is unavailable in this area,
there will be some binding on the slider as
it passes over the midpoint. This can cause
a tail wag that will cause you to spend
time looking at the gyro and tail-rotor
servo. Ask me how I know.
For those who love to buy “bling,” Align,
and many aftermarket companies, sell
numerous upgrades for the T-Rex. I was
amazed by how affordable the upgrades
are. You could go crazy buying blue metal
parts for your model, and eventually you
would end up with the T-Rex 450 CDE
SE. I hold back on installing upgrades
unless they offer something in enhanced
performance.
The only upgrades I feel are necessary
for the T-Rex XL are the metal head block
with mixer base and the metal swashplate.
Once you start looping and rolling, the
plastic head block will quickly loosen on
the main shaft and the plastic mixer base
gets sloppy on the guide pins. Align’s new
tail-rotor pitch plate (part HS1138T) is a
nice addition; it removes any binding in
the tail-rotor control system.
If you do get the new pitch-plate
assembly, also get the upgraded tail-rotor
hub (part HS1103). Make sure this tailrotor
hub assembly has hardened 2mm
Allen-head screws to attach the blade
grips. The original soft screws may break
and throw a tail-rotor blade. If you already
have this assembly and did not receive the
new screws, E-mail Align or your
distributor and it will get you the screws.
Most of the other upgrades are more
nice to have than required. I tend to stay
away from the metal blade grips. I like the
blade breaking off in a crash and taking its
energy with it.
Remember that crash I mentioned
earlier? One of the blade grips broke, but
the Hyperion carbon-fiber blades did not.
For when your helicopter is complete,
Align has a nice carrying case that will
hold the T-Rex. There is room in the case
for your transmitter, batteries, and
assorted tools. This is a great accessory if
you plan on traveling with your model.
The cool thing about any T-Rex
configuration is that with the right setup
and attention to maintenance it is capable
of many hours of serious 3-D-type
performance. I have found that it does
well indoors and outdoors. I have flown
mine in a light breeze with no problem.
Drop the head speed, and you have a
nice helicopter that can be used to learn
to fly.
Crashing a T-Rex won’t break your
bank account. Align has made sure all
spare parts are reasonably priced.
If you have been looking to get into
electric-powered helicopters but were
concerned about performance or fragility,
check out the T-Rex. At less than $200 for
the kit, the T-Rex XL will give you real
helicopter performance at a price that
Edition: Model Aviation - 2006/04
Page Numbers: 129,130,131,132
THIS IS USUALLY the time of year when
we sit indoors, watch the snow fall, and
yearn for the warmer weather. Not
anymore! With the advancement of Li-Poly
batteries, brushless motors, and mini/micro
helicopters, indoor flying has never been
this much fun! Gymnasiums, field houses,
and armories are great places to hold indoor
fun-fly events.
The Align T-Rex distributed by Empire
Hobby (www.empirerc.com) has been my
helicopter of choice for this type of activity.
I started playing with this model a few years
ago when it was first introduced.
The original T-Rex looked much like a
miniature Thunder Tiger Raptor. Align
continued to respond to customer feedback
and made many changes and improvements,
to eventually come out with the Align TOptimizing
the Empire Hobby-distributed Align electric-powered T-Rex
[[email protected]]
Radio Control Helicopters Ray Stacy
All versions of the T-Rex come well packed
in a cool metal case that can later be used
to hold batteries, spare parts, etc.
Align sells a nice carrying case that will hold the T-Rex,
transmitter, and other essentials. It’s a nice addition.
The XL does a nice job of using push/linkages on the servo setup.
This helps keep control-system play to a minimum.
The T-Rex SE is the Cadillac of the line and comes fully upgraded
and tricked out with all of Align’s options.
Performance Hobbies owner Tom McCoy checks out Ray’s SE.
Ray sees this expression a lot when he brings out this model.
Rex 450 XL HDE, T-Rex 450 XL CDE,
and T-Rex 450 CDE SE.
The T-Rex 450 CDE SE is in a league of
its own. It is a fully upgraded version that
includes every metal improvement available
from Align and carbon-fiber-type side
frames. The new 430L motor and Align
speed controller are included. I like the
servo layout on the SE because the servos
connect directly to the swashplate.
The T-Rex 450 XL HDE utilizes Raptorlike
mechanical mixing for the swashplate
movement and is a good choice if you don’t
have a helicopter transmitter that is capable
of doing Collective Cyclic Pitch Mixing
(CCPM). The 450 XL CDE is identical to
the HDE for the most part; the difference is
that the XL CDE comes with the CCPM
retrofitting components.
I prefer the XL CDE or the CDE SE
because I like the simplicity and ease of
setup of a CCPM system. I also like the idea
of spreading the swashplate load across
three servos.
The T-Rex 450 CDE SE is the only
version that comes with the subassemblies
completed. If you go with the SE, please
check all the screws for proper tightness.
Make sure thread locker has been applied to
the appropriate places.
All this was done correctly on my model,
but it is still worth your time to check. This
is especially true for the preassembled rotor
head. All other versions of the T-Rex are in
kit form.
All the T-Rex helicopters come in neat
metal cases that you can use for transporting
parts and tools to the field. Align even
supplies a set of screwdrivers, Allen
wrenches, and some spare hardware.
This is a small helicopter with small
screws. It is easy to strip a screw head or the
hole into which it is going. Gorilla strength
will not work well when assembling the
helicopter. I use the Ofna hex wrenches
without the handle and jeweler’s
screwdrivers to limit the amount of torque
applied to the screws.
I have tried several popular microservos
and keep coming back to the JR DS281
submicro digital servo. The DS281 remains
tight flight after flight and maintains the
accuracy required for small helicopters.
Other servos I have tried became sloppy and
would not center properly after a few
flights. Some just weren’t up for the task
and stripped in flight!
The DS281 has a gear set that will not
strip out in flight. I have had a few crashes
on my T-Rex and haven’t stripped a servo
yet. I did manage to break a case when I
nailed a concrete floor, but the servo still
worked!
My favorite feature of the DS281 is that
it uses a real JR servo arm and not some thin
piece of plastic. There is no need to beef up
or extend the arm.
The only drawback to this servo could be
the transit speed of .23 second, which is
slow by today’s standards. This has not been
a problem in any of the 3-D flying I have
done, but I am sure someone would notice
the difference in speed compared to the
Hitec HS-56, which has a transit time of .10
second.
I am currently testing a 6-volt BEC on
my night-flying setup to see if makes a
XL and SE tail assemblies. Both work well, but the SE delivers
smoother and crisper control with its upgraded pitch control.
Custom-painted T-Rex canopies from Dave Yost Designs. Check
out his work at www.dydhelmets.com/rchelipaint.asp.
difference. The servos are noticeably
faster, and so far they do not seem to have
a problem with the 6 volts.
For tail rotor control I like the Futaba
9650 servo or the Airtronics 94761. Either
one supplies the speed, accuracy, and
reliability I need at the tail. The 9650 might
seem a bit large back there on the boom at
first, but it mounts fine using one screw on
each side. Use the smallest servo wheel
you have and mount the ball as close to
center as possible.
I don’t bother with the tail-rotor
pushrod guide on the bottom of the
horizontal fin clamp. Most of the time the
guide doesn’t line up with the pushrod and
only causes drag on it. I simply cut the
guide off.
My preferred gyro is the Futaba 401. Its
size and performance make it a perfect fit
for the T-Rex. Don’t be surprised when
you have to turn your gain down to
approximately 40%; this is normal.
I have tried the new CSM 720 gyro, but
it has an annoying drift I can’t seem to
resolve. The same drift has appeared on
two other gyros. I am working with CSM
to fix this, but so far I have had little
success. I will keep trying and report to
you on my findings.
Before I go into motors, I want to point out
that I am mostly naive about their size
numbers. It isn’t like our nitro
counterparts, where bigger is usually
better. I don’t understand the KV rating
system, and in the end I can only tell you
how well the motor performed by the “seat
of my pants” flying. When evaluating a
motor I check for flight time, performance,
and motor temperature at the end of a
flight.
While attending the iHobby Expo in
Los Angeles, California, I was given the
opportunity to try the new Align 430L
motor with 13-tooth pinion. Wow! The
head speed jumped to 3,000 rpm, which
takes a bit of getting used to, but theApril 2006 131
increased response is worth it.
My flight time may have dropped from
13 minutes to eight to 10 minutes, but it
was well worth the tradeoff. I have since
installed the 430L in all my T-Rex
helicopters. The motor continues to run
well for me.
I recently had the chance to try the
450TH motor from JustGoFly.com. The
450TH is lighter and smaller than the 430L,
but it performs just as well.
Using a 13-tooth pinion the head speed
dropped to roughly 2,600 rpm, but the
helicopter’s performance did not suffer in
any way I could notice. In fact, it is
difficult to bog this motor down. I was
amazed by how cool the motor was after a
flight. I hope to try a 15-tooth pinion and
make it work a little harder.
There are a number of motor controllers
available for your use. I have tried Align,
Castle Creations, Hyperion, and Quark
types, all of which have worked very well.
I have always picked a 30-amp or larger
controller.
The Quark controller from Sky &
Technology (www.sky-technology.net) has
a smooth transition and appears to provide
extra power and run time, which I found to
be interesting. This is from actual flying
experience—not detailed bench testing.
I have read on online forums that some
people spend time trying to use the speed
controller’s governor mode. Some have had
success and some have not. I have never
taken the time to do this.
I run the controller in a normal mode
with soft start enabled and the brake
disabled. This configuration and a simple
throttle curve has worked exceptionally
well. My stunt throttle curve consists of
three points: 100%, 80%, and 100%. It
can’t get much simpler than that.
For power I use the Thunder Power
(www.thunderpower-batteries.com)
ProLite 2100 mAh 3S pack or the Hyperion
(www.empirerc.com) Velocity Lite 2100
mAh pack. The Thunder Power pack has a
rating of 15C and the Hyperion pack has a
rating of 18C. The C rating refers to the
discharge capacity of your battery. To
calculate the actual discharge rate, multiply
the C rating by the capacity of the battery.
The following are examples.
• 2100 mAh battery, 10C = 2,100 x 10 =
21,000 milliamps, or 21.0 amps
• 2100 mAh battery, 18C = 2,100 x 18 =
37,800 milliamps, or 38.8 amps
In testing I found that the Thunder
Power and Hyperion packs perform
identically.
At the time of this writing I received a
Cellpro Slimline 2100 mAh 3S pack from
Greg Covey at FMA Direct (www.fma
direct.com). The pack doesn’t have a C
rating on it and I couldn’t find this exact
pack on the FMA Direct Web site, but I
would guess that it is comparable to the
Hyperion and Thunder Power packs I am
running.
I decided to take a break from writing this
column to go out and do a quick comparison
of the three battery packs. I found that each
pack will give me a solid 10 minutes of good
3-D performance before the head speed starts
to drop. During this quick test I had my first
swashplate failure, which I will go into later.
I use two chargers to keep my battery
packs ready at all times, the first of which is
the ElectriFly Triton from Great Planes. This
universal charger does a nice job of letting
me know exactly how much of a charge I
used during a flight.
After the 10-minute flight with the
Cellpro Slimline, I recharged the pack on my
Triton and found that it took a charge of 1810
milliamps. This tells me I depleted most of
the usable electricity on the 2100 mAh pack
and it was time to land.
If I am uninterested in evaluating a battery
pack and simply want to bring everything
back to full charge, I use the ElectriFly
PolyCharge4 from Great Planes. It has four
independent outputs capable of charging oneto
four-cell Li-Poly batteries. This is a nice
charger to have at fun-fly events when you
tend to go through batteries quicker than you
can recharge them.
The T-Rex comes with a set of wood blades
and a set of carbon-fiber blades. Both do well
for most of the flying, but for serious, hardbanging
3-D I prefer a stiffer carbon-fiber
blade. It provides the crisp response required
for that type of flight.
I have tested two brands of blades: the
SABs and the Hyperions. Both deliver
superior quality and performance while
reducing drag, therefore placing less load on
the drive train and motor. The result is a
smoother-running helicopter and longer run
times.
I have a couple of tips for you for when
you build your T-Rex. Use a ball-link
reamer on all of the links. A small amount
of drag will quickly destroy your helicopter’s
performance.
I recently test-flew a friend’s new TRex.
He had not used a ball-link reamer
during assembly, and even though the links
felt good I was always chasing the machine
for control. Loosen the links and you will
be fine.
Don’t run the tail-rotor belt too tight. I
didn’t know this at first and could never
understand why I was tearing up belts and
pulleys every six or seven flights. Either the
belt would shred or it would get jammed in
the tail rotor housing and melt a pulley.
While attending the World Heli Micro
Cup in Los Angeles (www.rcuniverse.com/
magazine/) I mentioned this to Jason
Krause. His first comment was that the belt
was too tight. I looked at Jason’s T-Rex,
and there was no twang tension on the belt.
Since loosening the belts I have not
destroyed one belt or pulley. If you were to
look at my model’s belt you might think it
was so loose that it would slip, but it never
has.
Check your swashplate! It can separate
and most certainly will cause a crash. Either
the metal or plastic swashplate can separate.
I had read about this happening but never
experienced it firsthand until today.
While doing some extreme 3-D flying
for the battery testing, the helicopter started
to flutter and would not respond to
directional control. Postcrash investigation
showed that the swashplate had come apart.
I understand that Align is looking into a
new swashplate design that should be
available by the time you read this. Online
helicopter dealer Modefo’s Helis (www.
modefosheli.com/) has this tip on his Web
site for checking the existing swashplate.
Following are my tips and how I will repair
mine.
1) Don’t take a chance with any Align
swashplate. When you remove it from the
package, do some work on it.
2) Sometimes heat and pressure is not
even necessary to “pop” these swashplates
apart. If it is, I used a soldering iron—the
same one I use to solder Deans plugs and
wires—and heated the inside of the
swashplate from underneath.
Then I placed my swashplate on top of a
7/16 socket (it fits the underside perfectly). I
pushed down a few times on the outer
swashplate balls, and “pop”! It came right
off. I tried using my thumb underneath, and
it didn’t get the job done. The secret was the
7/16 socket.
3) Scrape away the old glue; it might be
tough to see because it’s pretty much clear,
but it’s there. I used a small flathead
screwdriver to get the job done.
4) Get some decent Loctite; opinions
vary about what to use, but I employ the
same stuff Hacker technicians told me to use
on my metal-to-metal Hacker motor: green
Loctite. I use Permatex brand.
Place one drop on a scrap piece of
plastic. Using a toothpick (I used my
smallest flathead micro screwdriver) spread
the adhesive on the inner swashplate surface
and spread it out so it’s the thinnest layer.
You will be able to discard most of the
drop of Loctite that is left. I mention this
because if you use too much you take the
chance of gumming up the bearing.
5) Let the Loctite dry overnight, and then
do a quick thumb test again. Don’t use a
socket this time because you don’t want to
get it back off—just test it.
Neither Loctite nor its competitors is
recommended for the swashplates that are
all plastic or the plastic/metal combo; it can
make the plastic brittle. In that case I would
think cyanoacrylate would be the best
choice, although I have heard of people
using JB Weld.
Go easy on the screws! I know I
mentioned this earlier, but I am repeating it.
They will strip without warning.
I found a cool cheat sheet for making the TRex
links on www.rcgroups.com. Craig
Harvey of Canada found that the T-Rex
manual could be confusing when assembling
the many required links. He created a PDF
file that lays out the exact lengths for all the
links, and it is extremely helpful during the
assembly.
According to Craig it is important to print
the page using “None” for the Page Scaling
option, and you’ll be able to quickly and
easily adjust any XL linkage to the correct
(as shown in the manual) length. You can
download the PDF at www.rcgroups.com/
forums/showthread.php?t=440578.
When attaching the ball links to the
tail-rotor pitch plate, make sure not to
overtighten the screws that secure the links.
If a little play is unavailable in this area,
there will be some binding on the slider as
it passes over the midpoint. This can cause
a tail wag that will cause you to spend
time looking at the gyro and tail-rotor
servo. Ask me how I know.
For those who love to buy “bling,” Align,
and many aftermarket companies, sell
numerous upgrades for the T-Rex. I was
amazed by how affordable the upgrades
are. You could go crazy buying blue metal
parts for your model, and eventually you
would end up with the T-Rex 450 CDE
SE. I hold back on installing upgrades
unless they offer something in enhanced
performance.
The only upgrades I feel are necessary
for the T-Rex XL are the metal head block
with mixer base and the metal swashplate.
Once you start looping and rolling, the
plastic head block will quickly loosen on
the main shaft and the plastic mixer base
gets sloppy on the guide pins. Align’s new
tail-rotor pitch plate (part HS1138T) is a
nice addition; it removes any binding in
the tail-rotor control system.
If you do get the new pitch-plate
assembly, also get the upgraded tail-rotor
hub (part HS1103). Make sure this tailrotor
hub assembly has hardened 2mm
Allen-head screws to attach the blade
grips. The original soft screws may break
and throw a tail-rotor blade. If you already
have this assembly and did not receive the
new screws, E-mail Align or your
distributor and it will get you the screws.
Most of the other upgrades are more
nice to have than required. I tend to stay
away from the metal blade grips. I like the
blade breaking off in a crash and taking its
energy with it.
Remember that crash I mentioned
earlier? One of the blade grips broke, but
the Hyperion carbon-fiber blades did not.
For when your helicopter is complete,
Align has a nice carrying case that will
hold the T-Rex. There is room in the case
for your transmitter, batteries, and
assorted tools. This is a great accessory if
you plan on traveling with your model.
The cool thing about any T-Rex
configuration is that with the right setup
and attention to maintenance it is capable
of many hours of serious 3-D-type
performance. I have found that it does
well indoors and outdoors. I have flown
mine in a light breeze with no problem.
Drop the head speed, and you have a
nice helicopter that can be used to learn
to fly.
Crashing a T-Rex won’t break your
bank account. Align has made sure all
spare parts are reasonably priced.
If you have been looking to get into
electric-powered helicopters but were
concerned about performance or fragility,
check out the T-Rex. At less than $200 for
the kit, the T-Rex XL will give you real
helicopter performance at a price that
Edition: Model Aviation - 2006/04
Page Numbers: 129,130,131,132
THIS IS USUALLY the time of year when
we sit indoors, watch the snow fall, and
yearn for the warmer weather. Not
anymore! With the advancement of Li-Poly
batteries, brushless motors, and mini/micro
helicopters, indoor flying has never been
this much fun! Gymnasiums, field houses,
and armories are great places to hold indoor
fun-fly events.
The Align T-Rex distributed by Empire
Hobby (www.empirerc.com) has been my
helicopter of choice for this type of activity.
I started playing with this model a few years
ago when it was first introduced.
The original T-Rex looked much like a
miniature Thunder Tiger Raptor. Align
continued to respond to customer feedback
and made many changes and improvements,
to eventually come out with the Align TOptimizing
the Empire Hobby-distributed Align electric-powered T-Rex
[[email protected]]
Radio Control Helicopters Ray Stacy
All versions of the T-Rex come well packed
in a cool metal case that can later be used
to hold batteries, spare parts, etc.
Align sells a nice carrying case that will hold the T-Rex,
transmitter, and other essentials. It’s a nice addition.
The XL does a nice job of using push/linkages on the servo setup.
This helps keep control-system play to a minimum.
The T-Rex SE is the Cadillac of the line and comes fully upgraded
and tricked out with all of Align’s options.
Performance Hobbies owner Tom McCoy checks out Ray’s SE.
Ray sees this expression a lot when he brings out this model.
Rex 450 XL HDE, T-Rex 450 XL CDE,
and T-Rex 450 CDE SE.
The T-Rex 450 CDE SE is in a league of
its own. It is a fully upgraded version that
includes every metal improvement available
from Align and carbon-fiber-type side
frames. The new 430L motor and Align
speed controller are included. I like the
servo layout on the SE because the servos
connect directly to the swashplate.
The T-Rex 450 XL HDE utilizes Raptorlike
mechanical mixing for the swashplate
movement and is a good choice if you don’t
have a helicopter transmitter that is capable
of doing Collective Cyclic Pitch Mixing
(CCPM). The 450 XL CDE is identical to
the HDE for the most part; the difference is
that the XL CDE comes with the CCPM
retrofitting components.
I prefer the XL CDE or the CDE SE
because I like the simplicity and ease of
setup of a CCPM system. I also like the idea
of spreading the swashplate load across
three servos.
The T-Rex 450 CDE SE is the only
version that comes with the subassemblies
completed. If you go with the SE, please
check all the screws for proper tightness.
Make sure thread locker has been applied to
the appropriate places.
All this was done correctly on my model,
but it is still worth your time to check. This
is especially true for the preassembled rotor
head. All other versions of the T-Rex are in
kit form.
All the T-Rex helicopters come in neat
metal cases that you can use for transporting
parts and tools to the field. Align even
supplies a set of screwdrivers, Allen
wrenches, and some spare hardware.
This is a small helicopter with small
screws. It is easy to strip a screw head or the
hole into which it is going. Gorilla strength
will not work well when assembling the
helicopter. I use the Ofna hex wrenches
without the handle and jeweler’s
screwdrivers to limit the amount of torque
applied to the screws.
I have tried several popular microservos
and keep coming back to the JR DS281
submicro digital servo. The DS281 remains
tight flight after flight and maintains the
accuracy required for small helicopters.
Other servos I have tried became sloppy and
would not center properly after a few
flights. Some just weren’t up for the task
and stripped in flight!
The DS281 has a gear set that will not
strip out in flight. I have had a few crashes
on my T-Rex and haven’t stripped a servo
yet. I did manage to break a case when I
nailed a concrete floor, but the servo still
worked!
My favorite feature of the DS281 is that
it uses a real JR servo arm and not some thin
piece of plastic. There is no need to beef up
or extend the arm.
The only drawback to this servo could be
the transit speed of .23 second, which is
slow by today’s standards. This has not been
a problem in any of the 3-D flying I have
done, but I am sure someone would notice
the difference in speed compared to the
Hitec HS-56, which has a transit time of .10
second.
I am currently testing a 6-volt BEC on
my night-flying setup to see if makes a
XL and SE tail assemblies. Both work well, but the SE delivers
smoother and crisper control with its upgraded pitch control.
Custom-painted T-Rex canopies from Dave Yost Designs. Check
out his work at www.dydhelmets.com/rchelipaint.asp.
difference. The servos are noticeably
faster, and so far they do not seem to have
a problem with the 6 volts.
For tail rotor control I like the Futaba
9650 servo or the Airtronics 94761. Either
one supplies the speed, accuracy, and
reliability I need at the tail. The 9650 might
seem a bit large back there on the boom at
first, but it mounts fine using one screw on
each side. Use the smallest servo wheel
you have and mount the ball as close to
center as possible.
I don’t bother with the tail-rotor
pushrod guide on the bottom of the
horizontal fin clamp. Most of the time the
guide doesn’t line up with the pushrod and
only causes drag on it. I simply cut the
guide off.
My preferred gyro is the Futaba 401. Its
size and performance make it a perfect fit
for the T-Rex. Don’t be surprised when
you have to turn your gain down to
approximately 40%; this is normal.
I have tried the new CSM 720 gyro, but
it has an annoying drift I can’t seem to
resolve. The same drift has appeared on
two other gyros. I am working with CSM
to fix this, but so far I have had little
success. I will keep trying and report to
you on my findings.
Before I go into motors, I want to point out
that I am mostly naive about their size
numbers. It isn’t like our nitro
counterparts, where bigger is usually
better. I don’t understand the KV rating
system, and in the end I can only tell you
how well the motor performed by the “seat
of my pants” flying. When evaluating a
motor I check for flight time, performance,
and motor temperature at the end of a
flight.
While attending the iHobby Expo in
Los Angeles, California, I was given the
opportunity to try the new Align 430L
motor with 13-tooth pinion. Wow! The
head speed jumped to 3,000 rpm, which
takes a bit of getting used to, but theApril 2006 131
increased response is worth it.
My flight time may have dropped from
13 minutes to eight to 10 minutes, but it
was well worth the tradeoff. I have since
installed the 430L in all my T-Rex
helicopters. The motor continues to run
well for me.
I recently had the chance to try the
450TH motor from JustGoFly.com. The
450TH is lighter and smaller than the 430L,
but it performs just as well.
Using a 13-tooth pinion the head speed
dropped to roughly 2,600 rpm, but the
helicopter’s performance did not suffer in
any way I could notice. In fact, it is
difficult to bog this motor down. I was
amazed by how cool the motor was after a
flight. I hope to try a 15-tooth pinion and
make it work a little harder.
There are a number of motor controllers
available for your use. I have tried Align,
Castle Creations, Hyperion, and Quark
types, all of which have worked very well.
I have always picked a 30-amp or larger
controller.
The Quark controller from Sky &
Technology (www.sky-technology.net) has
a smooth transition and appears to provide
extra power and run time, which I found to
be interesting. This is from actual flying
experience—not detailed bench testing.
I have read on online forums that some
people spend time trying to use the speed
controller’s governor mode. Some have had
success and some have not. I have never
taken the time to do this.
I run the controller in a normal mode
with soft start enabled and the brake
disabled. This configuration and a simple
throttle curve has worked exceptionally
well. My stunt throttle curve consists of
three points: 100%, 80%, and 100%. It
can’t get much simpler than that.
For power I use the Thunder Power
(www.thunderpower-batteries.com)
ProLite 2100 mAh 3S pack or the Hyperion
(www.empirerc.com) Velocity Lite 2100
mAh pack. The Thunder Power pack has a
rating of 15C and the Hyperion pack has a
rating of 18C. The C rating refers to the
discharge capacity of your battery. To
calculate the actual discharge rate, multiply
the C rating by the capacity of the battery.
The following are examples.
• 2100 mAh battery, 10C = 2,100 x 10 =
21,000 milliamps, or 21.0 amps
• 2100 mAh battery, 18C = 2,100 x 18 =
37,800 milliamps, or 38.8 amps
In testing I found that the Thunder
Power and Hyperion packs perform
identically.
At the time of this writing I received a
Cellpro Slimline 2100 mAh 3S pack from
Greg Covey at FMA Direct (www.fma
direct.com). The pack doesn’t have a C
rating on it and I couldn’t find this exact
pack on the FMA Direct Web site, but I
would guess that it is comparable to the
Hyperion and Thunder Power packs I am
running.
I decided to take a break from writing this
column to go out and do a quick comparison
of the three battery packs. I found that each
pack will give me a solid 10 minutes of good
3-D performance before the head speed starts
to drop. During this quick test I had my first
swashplate failure, which I will go into later.
I use two chargers to keep my battery
packs ready at all times, the first of which is
the ElectriFly Triton from Great Planes. This
universal charger does a nice job of letting
me know exactly how much of a charge I
used during a flight.
After the 10-minute flight with the
Cellpro Slimline, I recharged the pack on my
Triton and found that it took a charge of 1810
milliamps. This tells me I depleted most of
the usable electricity on the 2100 mAh pack
and it was time to land.
If I am uninterested in evaluating a battery
pack and simply want to bring everything
back to full charge, I use the ElectriFly
PolyCharge4 from Great Planes. It has four
independent outputs capable of charging oneto
four-cell Li-Poly batteries. This is a nice
charger to have at fun-fly events when you
tend to go through batteries quicker than you
can recharge them.
The T-Rex comes with a set of wood blades
and a set of carbon-fiber blades. Both do well
for most of the flying, but for serious, hardbanging
3-D I prefer a stiffer carbon-fiber
blade. It provides the crisp response required
for that type of flight.
I have tested two brands of blades: the
SABs and the Hyperions. Both deliver
superior quality and performance while
reducing drag, therefore placing less load on
the drive train and motor. The result is a
smoother-running helicopter and longer run
times.
I have a couple of tips for you for when
you build your T-Rex. Use a ball-link
reamer on all of the links. A small amount
of drag will quickly destroy your helicopter’s
performance.
I recently test-flew a friend’s new TRex.
He had not used a ball-link reamer
during assembly, and even though the links
felt good I was always chasing the machine
for control. Loosen the links and you will
be fine.
Don’t run the tail-rotor belt too tight. I
didn’t know this at first and could never
understand why I was tearing up belts and
pulleys every six or seven flights. Either the
belt would shred or it would get jammed in
the tail rotor housing and melt a pulley.
While attending the World Heli Micro
Cup in Los Angeles (www.rcuniverse.com/
magazine/) I mentioned this to Jason
Krause. His first comment was that the belt
was too tight. I looked at Jason’s T-Rex,
and there was no twang tension on the belt.
Since loosening the belts I have not
destroyed one belt or pulley. If you were to
look at my model’s belt you might think it
was so loose that it would slip, but it never
has.
Check your swashplate! It can separate
and most certainly will cause a crash. Either
the metal or plastic swashplate can separate.
I had read about this happening but never
experienced it firsthand until today.
While doing some extreme 3-D flying
for the battery testing, the helicopter started
to flutter and would not respond to
directional control. Postcrash investigation
showed that the swashplate had come apart.
I understand that Align is looking into a
new swashplate design that should be
available by the time you read this. Online
helicopter dealer Modefo’s Helis (www.
modefosheli.com/) has this tip on his Web
site for checking the existing swashplate.
Following are my tips and how I will repair
mine.
1) Don’t take a chance with any Align
swashplate. When you remove it from the
package, do some work on it.
2) Sometimes heat and pressure is not
even necessary to “pop” these swashplates
apart. If it is, I used a soldering iron—the
same one I use to solder Deans plugs and
wires—and heated the inside of the
swashplate from underneath.
Then I placed my swashplate on top of a
7/16 socket (it fits the underside perfectly). I
pushed down a few times on the outer
swashplate balls, and “pop”! It came right
off. I tried using my thumb underneath, and
it didn’t get the job done. The secret was the
7/16 socket.
3) Scrape away the old glue; it might be
tough to see because it’s pretty much clear,
but it’s there. I used a small flathead
screwdriver to get the job done.
4) Get some decent Loctite; opinions
vary about what to use, but I employ the
same stuff Hacker technicians told me to use
on my metal-to-metal Hacker motor: green
Loctite. I use Permatex brand.
Place one drop on a scrap piece of
plastic. Using a toothpick (I used my
smallest flathead micro screwdriver) spread
the adhesive on the inner swashplate surface
and spread it out so it’s the thinnest layer.
You will be able to discard most of the
drop of Loctite that is left. I mention this
because if you use too much you take the
chance of gumming up the bearing.
5) Let the Loctite dry overnight, and then
do a quick thumb test again. Don’t use a
socket this time because you don’t want to
get it back off—just test it.
Neither Loctite nor its competitors is
recommended for the swashplates that are
all plastic or the plastic/metal combo; it can
make the plastic brittle. In that case I would
think cyanoacrylate would be the best
choice, although I have heard of people
using JB Weld.
Go easy on the screws! I know I
mentioned this earlier, but I am repeating it.
They will strip without warning.
I found a cool cheat sheet for making the TRex
links on www.rcgroups.com. Craig
Harvey of Canada found that the T-Rex
manual could be confusing when assembling
the many required links. He created a PDF
file that lays out the exact lengths for all the
links, and it is extremely helpful during the
assembly.
According to Craig it is important to print
the page using “None” for the Page Scaling
option, and you’ll be able to quickly and
easily adjust any XL linkage to the correct
(as shown in the manual) length. You can
download the PDF at www.rcgroups.com/
forums/showthread.php?t=440578.
When attaching the ball links to the
tail-rotor pitch plate, make sure not to
overtighten the screws that secure the links.
If a little play is unavailable in this area,
there will be some binding on the slider as
it passes over the midpoint. This can cause
a tail wag that will cause you to spend
time looking at the gyro and tail-rotor
servo. Ask me how I know.
For those who love to buy “bling,” Align,
and many aftermarket companies, sell
numerous upgrades for the T-Rex. I was
amazed by how affordable the upgrades
are. You could go crazy buying blue metal
parts for your model, and eventually you
would end up with the T-Rex 450 CDE
SE. I hold back on installing upgrades
unless they offer something in enhanced
performance.
The only upgrades I feel are necessary
for the T-Rex XL are the metal head block
with mixer base and the metal swashplate.
Once you start looping and rolling, the
plastic head block will quickly loosen on
the main shaft and the plastic mixer base
gets sloppy on the guide pins. Align’s new
tail-rotor pitch plate (part HS1138T) is a
nice addition; it removes any binding in
the tail-rotor control system.
If you do get the new pitch-plate
assembly, also get the upgraded tail-rotor
hub (part HS1103). Make sure this tailrotor
hub assembly has hardened 2mm
Allen-head screws to attach the blade
grips. The original soft screws may break
and throw a tail-rotor blade. If you already
have this assembly and did not receive the
new screws, E-mail Align or your
distributor and it will get you the screws.
Most of the other upgrades are more
nice to have than required. I tend to stay
away from the metal blade grips. I like the
blade breaking off in a crash and taking its
energy with it.
Remember that crash I mentioned
earlier? One of the blade grips broke, but
the Hyperion carbon-fiber blades did not.
For when your helicopter is complete,
Align has a nice carrying case that will
hold the T-Rex. There is room in the case
for your transmitter, batteries, and
assorted tools. This is a great accessory if
you plan on traveling with your model.
The cool thing about any T-Rex
configuration is that with the right setup
and attention to maintenance it is capable
of many hours of serious 3-D-type
performance. I have found that it does
well indoors and outdoors. I have flown
mine in a light breeze with no problem.
Drop the head speed, and you have a
nice helicopter that can be used to learn
to fly.
Crashing a T-Rex won’t break your
bank account. Align has made sure all
spare parts are reasonably priced.
If you have been looking to get into
electric-powered helicopters but were
concerned about performance or fragility,
check out the T-Rex. At less than $200 for
the kit, the T-Rex XL will give you real
helicopter performance at a price that