RADIO CONTROL HELICOPTERS - 2003/01

116 M ODEL AVIATION
iT’s AnoTher greAT month to be
enjoying the sport of Radio Control
helicopters! And for us Northerners it’s a
good month to be savoring every possible
opportunity to fly in good weather because
soon we’ll be flying over snow again.
First thing this month is a shortened version
of an important notice to pilots using the JR
8411/8411SA servos.
“ … Although there are thousands of 8411
servos being used successfully without
incident, we have learned through extensive
testing and research on this issue that our
DS8411 and DS8411SA servos are prone to
experiencing a higher than average failure rate
when in a Helicopter application.
“Our findings have shown that these
failures are primarily attributed to an increase
in the availability and use of .80-.90 size heli
engines and the extreme 3D maneuvers
becoming more prevalent in today’s typical
Heli environment. These recent changes have
in turn added new loads to the model and
control system, and most importantly, the
servos. This increase in load has been
determined as the primary cause of the
increase in 8411 servo failures.
“JR has determined that a new Heli
specific servo is needed, with a motor that is
specifically designed to handle the strains of
this environment. This new servo, the
DS8311, will have the following performance
specifications:
“Torque: 125 oz
“Speed: .18 sec/60 degrees
“Gears: All Nylon
“Part Number: JRPS8311
“MAP Price: $99.99
“Open Stock Availability: November
2002
“JR now recommends that the current
DS8411 and DS8411SA servo be used only
for Airplane applications.
“For our Heli customers that are currently
using the DS8411 or DS8411SA servos in
their models, JR and Horizon will be offering
a free servo update. The Horizon Service
Center will convert existing DS8411 and
DS8411SA servos for our Heli customers to
the new DS8311 specifications by performing
a motor and servo label change to your
existing equipment.
“JR and Horizon strongly suggest that all
helicopter pilots using DS8411 and
DS8411SA servos take advantage of this free
update offer by contacting the Horizon
Service Center at (877) 504-0233.”
I commend Horizon Hobby for taking this
Eric Hawkinson, 319 Yellowstone Ave., Billings MT 59101; E-mail: [email protected]
RADIO CONTROL HELICOPTERS
This is the pump installation on Eric’s Vigor. It is usually easiest to use a header tank
(such as DBC shown) so you don’t have to install third fuel line on main tank.
Billings, Montana, pilot Mark Curtiss loves his smooth, quiet Kyosho Caliber 30. He
went to a local vinyl sign shop to get a trim scheme more to his liking.
118 M ODEL AVIATION
Both of our shop helicopters running the .91
have been converted to the Perry P30 pump
setup, and on Kurt Kreiger’s the pump
solved a “shake” problem that had been
pestering him since he installed the engine.
My Vigor didn’t have any shaking problems
with the O.S. .91 (nor did two other local
pilots’), but the engine “seems” slightly
smoother after installing the pump.
This is not a power enhancement. If your
.91 is running smooth and happy, you
probably shouldn’t spend the time or money
to install the pump. If, on the other hand,
you have a shake that is not related to a bad
part or improper gearing (the .91 likes 8.1 to
8.4 just fine), this will likely solve your
problem.
The most secure way to mount the pump
itself is to scuff the plastic clamp and clean
the pump with alcohol. Position it as
desired, mix a few drops of J.B. Weld and
spot it on the pump, clamp it in place, and
let it dry.
Remove the backplate, and carefully drill
the center-section and tap it with a 6-32 tap
for the pressure tap. Do not do this while the
backplate is on the engine! After drilling,
make sure you remove all metal filings from
the backplate. Use J.B. Weld to secure the
pressure tap. If you drill the hole in the
center of the backplate, the tap will not stick
through the backplate. It must not protrude
inside, or it will interfere with the crank
and/or rod. Use the stiff, red tubing that
comes with the P30 pump between the
pressure tap on the backplate and the
pressure inlet on the back end of the P30
pump.
See the accompanying photograph to
make sense of these installation instructions.
The top (pink) line is the pressure line from
the muffler to the tank vent, like always. Of
course, with a header tank it is attached to
the clunk line of the main tank.
The bottom fuel line goes from the clunk
line outlet of the tank through the “T”d
fueling filter, then into the P30 pump inlet.
Notice that the bottom of the pump has
arrows that mark the travel direction of the
fuel. Another chunk of line goes from the
outlet of the pump through another T-Fitting
and on to the carburetor. The third line from
the T-Fitting goes back to the fuel tank to
return any excess fuel into the tank via that
third inlet. This line has a check valve in it
which is oriented so that the fuel can go
from the “T” to the tank and not the other
way.
We have been doing as Curtis
Youngblood suggests: removing the internal
spring on the pump (under the hex-head
grub screw with which you adjust pressure)
and stretching it to roughly twice its original
length then reinstalling it.
It appears—based on the fact that the
installation really does improve the
smoothness—that the .91 may have a slight
leaning tendency in the mid range or maybe
just marginal fuel draw in the upper ranges.
until next time, fly safely and happy
rotoring. MA
step; it will cost the company a lot of money
to convert all the existing helicopter servos at
no charge.
i have had a chance to spend some time with
a new (for me) helicopter and engine, and I
have been having a blast. I got one of the first
O.S. .70 SZ-H helicopter engines and needed
something to put it in, so I bought a Raptor
60 Almost Ready to Fly (ARF) and a
Mavrikk muffler, and a day later I had what
turned out to be an enjoyable, low-cost 3-D
monster.
The Raptor 60 is not new, but I hadn’t
flown one except to hover around with coworker
Joel Atkins’ a few times. I was
expecting a moderately agile helicopter, but it
turns out I was expecting too little. With
stock gear ratio in the Raptor, after two tanks
the O.S. .70 SZ-H was tuned to a smooth,
slightly rich setting and the stock Raptor 60
paddles were removed to make room for a set
of V-Paddles. By the third tank I had a new
3-D machine with an engine that is easily the
best on the market in the 60-80 range.
I had to richen the idle slightly from the
standard setting to get a good, smooth
transition. The carburetor is new, looking like
the three-needle carburetor on the .61 WC
but working out to be a much more friendly
unit.
There is no doubt that the .70 SZ is a
much more powerful engine than the O.S. .61
SX-H WC, and it’s a peer to the YS 80
(without the need for the gear change the YS
needs). The .70 is also extremely consistent,
unlike the WC.
The street price is approximately $40
more than the WC—closer to the O.S. .91—
but you can use any modern, well-designed
60 muffler, so that may make the .70 much
less expensive if you already have the
muffler. I flew mine with the Mavrikk 60
muffler and an expensive Hatori O.S. .91
muffler, and there was no change in power.
The O.S. .70 is an extremely good engine.
The Raptor 60 is almost stock. I did use
the metal swash upgrade and the metal
bearing blocks along with a DBC boom
mount for the tail servo, and I immediately
discarded the stock paddles as mentioned
earlier. The only nicer-flying big helicopter I
have ever flown is my O.S. .91-powered
Vigor CS, which is not in the same price
range. With the O.S. .70 the Raptor can fly
huge loops, tight multiple flips, and climb
with the best of them.
So far the only thing I haven’t been
completely happy with is the dampening
system on the main rotor head. As did Joel’s,
the stock setup had more head bob than a
prize fighter. Changing paddles (to almost
any other paddle besides the stock ones)
solves most of this, but a bit of oscillating
after quick maneuvering persists as soon as I
get a gallon or so on the rubber dampeners.
Joel had just changed his Raptor’s head
block to use the Revolution O-ring dampener
set designed for the Vigor/Ergo; it’s an easy
upgrade that requires only a bit of shimming
to adapt to the Raptor head. It seemed to
work pretty well. I used the past tense
because we didn’t get to see how well it held
up to a case or two of use; Joel was finally
able to completely stop the head bob by way
of a generous application of dirt. (He got
disoriented while working on an inverted
hover and pushed full up-collective. Oops!)
I’ll be converting my Raptor to the O-ring
dampeners, and I’ll let you know how it
holds up.
some people have experienced problems
getting the O.S. .91 SX-H to run smoothly.
I’m not sure why some do and some don’t,
but there is a fix if you are having problems.