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Introduction and Hints on the Raptor Helicopter
Part 1
Written and copyright by James Wang
The idea of this writing was developed out of a conversation
with Eric Hawkinson, President of HeliProz Inc. Eric asked if
I could share some of my thought each month with fellow modelers,
and he would place it on his web for the modelers. People who
have read my magazine article in the past decade know I really
enjoy building and flying models. I have been flying RC helicopters
for about 25 years. Any spare time I have I always to put in
some flights. I enjoy 3-D flying because there are always so
much more I can learn. I enjoy going to fun flies and meet other
pilots and watch top pilots perform. I also love to examine all
helicopters that have been on the market in the last three decades.
I usually keep every helicopter I have build so I can study and
compare them later on. Through this porthole, I will share some
of my thought with on RC helicopters in general. It will be an
informal environment for us to enjoy this wonderful hobby together.
I will try to generate some diverse and interesting topic each
time.
We will start the first of our story series by looking at
the new 30-size model that has become very popular in one year.
Eric says this is one of his best sellers so he would like me
to tell people more about its design background and provide some
hints on setting it up. In the future we will look at the Ergo,
Vigor and the Xcell.
The Raptor was designed by the world famous model helicopter
engineer, Mr. Shigetada Taya. Ten years ago, Mr. Taya's Concept
30 design almost revolutionized the pint-size helicopter market.
The Concept 30 allowed many people to try RC helicopter at a
reasonable cost. The Concept 30 encouraged many intermediate
level pilots to learn 3-D aerobatics without breaking their bank.
Well, Taya san has done it again. The Raptor represents a culmination
of a decade of design experience from Mr. Taya. The Raptor possesses
features that beginners and advanced 3-D pilots have requested
for in a high performance, but affordable, model helicopter.
The glass-filled nylon parts are precisely molded. The metal
parts are true. The model is maintenance-free and a delight to
fly.
How did the Raptor achieve its wonderful handling qualities?
Mr. Taya himself is a talented and accomplished RC helicopter
pilot. Mr Taya was the World Champion of the first ever F3C RC
Helicopter World Championship; which was held in London, Ontario,
Canada in May, 1985. Taya san personally tests all his own helicopter
design. He owns the Taya Engineering firm in Japan. Taya specializes
in industrial mechanical and electronic design. Taya also designed
the new high bandwidth TG-8000 piezoelectric gyro that we are
using in our Raptor. The TG-8000 is a competition quality gyro,
but marketed at an affordable price so even the beginners can
buy it as a first gyro.
In 1998, Mr. Taya teamed up with Thunder Tiger in Taiwan to
design and manufacture the Raptor. Thunder Tiger has been in
the model engine business for 30 years. In recent years, Thunder
Tiger has become one of the biggest RC product manufacturers
in the world. Thunder Tiger has offices and distributors on six
continents. The company has 500 employees in Taiwan and has received
the world recognized ISO-9001 quality manufacturing certificate.
The ex-chief engine designer from O.S. Engines is now working
for Thunder Tiger. Their product line includes over 55 different
model engines, RC airplane kits, gliders, cars, boats, radio
equipment, and accessories such as starters, ni-starters, wheels,
tanks, pushrods, etc.
When Taya and Thunder Tiger decided to launch their new helicopter
line, they decided "quality" and "performance"
are number one. People who have started flying RC helicopters
fifteen years ago all reverend Mr. Taya as an icon and they know
Taya does the best engineering in our field. Taya san does not
cut corners. He won the F3C Helicopter World Champion through
talent and hard work. Thunder Tiger has spent nearly one million
dollar in developing the high quality molds and toolings for
manufacturing the Raptor 30. Thunder Tiger and Mr. Taya want
to make sure the Raptor is the best 30-size helicopter in production.
Through modern manufacturing process the kit prices are inexpensive.
In the US, the Raptor is distributed by Ace Hobbies. Ace is
offering the Raptor in four versions: (1) an almost ready to
fly, ARF, version with 49 ball bearings and including a Thunder
Tiger 36H ABC engine and a muffler (2) an ARF version with 29
ball bearings and including a TT 36H engine and muffler, (3)
a kit version with 29 ball bearings and a TT 36H engine and muffler,
and (4) a kit version with 29 ball bearings and no engine. The
very affordable price alone makes the Raptor very attractive.
In the 49-bearing Raptor, every moving bellcrank or mixing
arm is supported by ball bearings. The ARF model comes 90%
built; even all the pushrods are made with the ball links attached
close to the proper length. All you have to do is install the
servos. For beginners who does not need the +12 to -10 degrees
collective travel, the travel range can be reduced using the
ATV in the transmitter. It took me 5 hours flat from opening
the box to hovering it switchless inverted. After I flew it then
I spent another hour adding the decals. The easiest way to cut
the decals is to use a sharp X-Acto knife. After applying the
decals, we smeared some Zap-A-Dap-A-Goo on the sharp corners
to prevent peeling. The Raptor control system is fairly slop-free.
I did not even need to build the model, and it costs less than
$400, including the engine and muffler.
With other ARF models, one still has to install the rotor
hub or assemble the landing gear. The Raptor has the main rotor
head and landing gear on the helicopter already. You simply plug
in the tail boom. Make sure the tail rotor belt is turned 90
degrees in the correct direction so the tail rotor blades swings
upward into the main rotor blades. Just look at the instruction
manual. I removed the engine mounting bolts to check whether
the factory has used Locktite or not. Yep, Locktite was used
on all engine mounting bolts. The workmanship was good enough.
But please check every engine bolt on the engine, occasionally
some of the bolts are not very tight when they come from the
factory. Also check the nut that holds the carburetor. Also check
to make sure the tail rotor belt is turning in the correct direction
on the ARF model.
The 29 ball bearings Raptor kit is a bargain at less than
$250. If you choose to build the kit version, you will notice
every part fits perfectly on the Raptor. The Raptor uses a hardened
and hollowed 10 mm main rotor. Most 30-size models, with the
exception of the Ergo 30 and Xcell 30, have a wimmpy 8 mm main
shaft. If you own one of those cheap 30-size helicopters, then
you know how easily those 8 mm main shafts bend when the blades
barely touch the ground.
The main rotor blades come prefinished with the lead weight
epoxied in and then shrink covered with transparent socks to
show the beautiful wood grains. The main rotor blade bolts are
4 mm instead of 3 mm. The main rotor head is a floating axle
design with each blade grip supported by two radial bearings
and a thrust bearing. The 5 mm main rotor spindle is supported
at the center by an aluminum yoke with a hole. This elegant idea
takes the helicopter weight off the two O-rings. It is a simple
and very effective design; we like it. Collective pitch change
on the Raptor is by rocking the roll servo platform up and down.
This arrangement is similar to the Bergen Intrepid. The system
works extremely well. The weight of the roll servo is used as
a counter balance to help raise the swashplate, consequently
only a small servo force is required control the collective.
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The white landing gear struts are fairly thick so they can
take some abuse. For beginers, it is best to order a set of training
gear from the hobby shop. The training gear is usually made of
wood dowels and Whiffle balls, and it will help prevent the model
from turning over. The molded one-piece polypropylene canopy
is nearly indestructable. The Raptor is designed to last and
take abuse. I have flown my Raptor for hundreds of flights, and
the only thing I have done is wipe off the exhaust oil after
each flight.
The engine is started by using a 6 mm hex extension that must
be supplied by the modeler. The kit includes a steel hex socket
on the engine clutch shaft. The clutch shaft sits in an one-way
Torrington bearing, thus, after the engine starts, the 6 mm hex
extension will not jump out. This is excellent. JR Ergo uses
similar design. Many other helicopters using the hex start system
do not have this safety one-way bearing, and the hex extension
can hurl out after the engine is started.
The only part on the Raptor that I have found some freeplay
is between the top and bottom plates on the plastic swashplate.
The play comes from the bearing. Any 10 mm i.d. metal swashplate
from any 60-size helicopter can be used on the Raptor. But, I
have flown the Raptor for many flights with the stock swashplate,
and the freeplay is not noticeable in flight, so we never changed
it. With other cheap 30-size models, the plastic swashplate usually
has a lot of slop and progressively become unacceptable after
100 flights. Now there is an optional metal swashplate for the
more demanding pilots. (HeliProz Note - most 60 swashplates
are way too thick for the Raptor, limiting control travel severely.
Since the Ace all-metal swash
is very competitively priced you should only consider that one
- part #PV0092 - as an upgrade).
How does it fly? The Raptor flies even better than the
hot Concept 30 SRX. I like the Raptor because its handling
are "predictable" and, hence install confidence in
the pilot. My friend in Maryland describes the Raptor main rotor
somehow gives an automatic exponential feel. The Raptor is very
stable. The Raptor weighs 6 and 1/4 pounds. The Raptor does not
pitch up in fast forward flight. With no modifications at all,
the Raptor gives +10 to -10 degrees of collective travel and
enough cyclic to give a fast roll rate and fast tumble rate.
The Hiller control paddles give a good balance between "controllability"
and "stability." The kit does not include flybar weights,
and they are not needed, even for beginners. Another innovative
feature is a pitch scale is molded onto the left side of the
sideframe. As shown in the manual, there are three scales: the
smaller range scale is for beginners (it gives +12 to 0 degree
of collective travel), the middle scale is for intermediates
(it gives +12 to -4 degrees of collective travel), and the large
scale is for FAI and 3-D (it gives +12 to -8 degrees of travel).
I set mine to give -10 instead of -8 so it will climb inverted
like a rocket, too. However, for beginner, I recommend purchasing
a pitch gauge instead of trusting the build-in gauge.
Here are a few building tips that we like to offer. In general,
when installing a machined screw into a plastic piece, there
is always a chance of over-torquing and stripping the plastic.
The screws also tend to loosen from the plastic piece after a
while. The trick is to add a tiny drop of CA glue on the tip
of the machine screw right before screwing in the screw. Never
overtighten the screw because plastic can strip easily. That's
why we add a drop of CA glue to prevent the screw from loosening.
This building tip is applicable to any model helicopter. Please
check the two screws at the pivoting point of the Raptor collective
pitch control arm. The collective pitch control arm is the up-and-down
rocking tray with the roll servo on it. Once you have added a
drop of CA glue on these screws, then they should stay in forever.
The other place to add a drop of CA glue is on the outside tip
of the brass sleeve for the tail rotor pitch control slider.
Add a tiny drop of CA glue, then screw on the plastic tail rotor
pitch control plate.
The ARF kit comes with a thin paper gasket in between the
engine exhaust flange and the muffler. This gasket needs to be
replaced periodically. Instead of using the gasket, we use high
temperature silicone in between the engine exhaust and the muffler
to give a leak-proof seal.
I use Powermaster 15% or 30% nitro fuel with synthetic low
viscosity oil, and OS #8 or Enya #3 glow plug with the TT 36
H ABC engine. Even thought the Thunder Tiger instruction manual
says the TT 36H develops 1 hp, and the O.S. ad says the O.S.
32 SX-H develops 1.2 hp. I have ran both engines in the Raptor
and the TT 36H ABC engine has as much power, or slightly more
power than the OS 32 SX.
Richen the low end idle mixture screw will keep the engine
hover in a nice milky rich condition, but that causes the idle
to run very rich and floods the engine and cause the engine to
quit when throttling up from idle. Then you have to pinch the
line before revving up to takeoff. It is the same routine that
we have always been doing on OS 61 SFN with the 6B carb.
TT 36 likes to have the idle mixture screw slightly on the
lean side. This gives a very reliable idle, fast transition to
hover, and still provides a smooth hover. For a new TT 36 engine,
try half to one turn open on the low end mixture screw and 2-1/2
turn open on the main needle. The idle screw should be checked
only when the throttle barrel is in the closed position. Otherwise
the barrel can move the mixture needle in and out. James has
provided a new low speed needle design to TT. It helps get rid
of the rich spot at the 1/3 throttle position. All TT 36 engines
manufactured after September 1999 has this new needle. Earlier
owners in the United States only can obtain the new low speed
needle for free by sending a self-addressed-and-self-stamped
envelope to "Free TT36H Low Speed Mixture Screw Request,
Ace Hobby Distributor, 116W 19th Street, MO 64037. To remove
the old low speed mixture screw, you need to unscrew it completely,
then remove the main needle and use a sewing needle to push the
mixture screw out. The new mixture screw has a slightly different
tip shape, but it will be nearly impossible to distinguish the
fine differences by looking. The latest news is that TT factory
has a new prototype needle that is even better, but it is not
available yet. Rumor is they are also working on a new ABC piston
material that will make the engine power transition smoother
and also produce even more power.
The trick with the TT 36 H is to lean the idle screw in until
the engine gives a reliable idle and transition into hover without
hesitation. Then, you will find the hover rpm will be high because
the engine will be on the lean side. Then back out about 1/8
turn to get a nice balance of good smoke in hover and reliable.
It takes two to three gallons to fully breaking in the TT 36
H. Once it is broken in the idle becomes very reliable and the
transition and hover all become very smooth. It almost becomes
a different engine.
The TT 36 H has the same crankshaft thread size, and mounting
and exhaust hole dimensions as the OS 32SX and Webra 35. Therefore,
all three engines will fit in the Raptor without modification.
There is no need to use a washer underneath cooling fan. The
cooling fan is threaded onto the engine shaft. Do not attempt
to pull or press it out. With either the OS 32SX or the TT 36
H, the engine will run rich when the tank is full and leaner
when the tank is near empty. This is also true on the Ergo 60
and other helis. It is normal. The change is equivalent to about
two clicks on the main needle. A feeder tank solves the problem.
I do not run a header tank because the stock tank gives about
12 minutes of 3-D flying and 15 minutes of hover. Slide a quarter
inch long piece of tubing over the main needle also helps the
engine run much more consistent.
The engine heat sink on the Raptor is exposed like on the
Ergo and Shuttle. I experimented and glued an extension inside
the cooling shroud so the air will flow closer to the fins. But
there is no noticeable improvement in engine performance. The
TT36H comes with a head shim in the box. A shim is usually needed
nitromethane to reduce compression to prevent pre-ignition when
using fuel with greater than 15%. I ran the TT36H with and without
the shim using Powermaster 30% fuel and discover no significant
change in hover smoothness. So we don't bother installing the
shim anymore.
To Raptor Review
Part 2
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