Control Line Combat - 2009/05

126 MODEL AVIATION
Fuel-shutoff ideas from around the world
[[email protected]]
Control Line Combat Rich Lopez
Also included in this column:
• 2008 MACA Top 10 pilots
• Cyclon Fortune F2D engine
The H&R bellcrank shutoffs are designed for external controls.
It’s easy to see how the fuel line is pinched.
The swing-arm-type shutoffs were originally designed for AMA
Fast Combat. Correct spring tension is the trick.
Spring-type shutoffs, mounted and working. One is in the start position and the other
is in the shutoff position.
I HAVE BEEN writing about the newfor-
2009 FAI F2D fuel-shutoff rule in all
of my columns this year. As I suspected,
the new requirement has unleashed an
abundance of ideas from all parts of the
world.
Henning Forbech in Denmark
continues to add information to his Web
site and has included something called
the “Fact Finding Mission.” It has a
bunch of data on line tension. I have not
studied it in detail as I write this column.
Rafael Unruh of Germany has posted
some information about his design.
Henning has also done some incredible
work, posting his 3-D interactive drawing
of the design. The Italians also have ideas
worth looking at. Make it a point to visit
Henning’s Web site to see all of these
ideas.
• Swing arm: Some of the shutoff ideas
came from the AMA .36-powered Fast
Combat event. They have already proven
to be effective and have found a new
application in the F2D event.
Chuck Rudner designed the swingarm
device many years ago and has
decided to continue developing the idea
through refinements. Chuck was
responsible for getting the Russians
(Alexsandr Gievsky) to produce
sufficient quantities to meet the demand
of the Fast Combat market some 15 years
ago.
• Electronic devices: Probably the most
exciting ideas are those that involve an
electronic transmitter built into a control
handle and receiver in the model.
The basic idea is that a button on the
handle would activate current flow from
the transmitter to the model; as long as
there is current, the fuel valve will remain
open. Each transmitter will have an
identification number for each pilot so
that there will be no unexpected
shutdowns should the lines touch or
become tangled.
Alex Prokofiev has some postings that
you can view to fully understand the
concept.
• Sliding bellcrank: Jeff Rein and Bill
05sig4.QXD 3/24/09 12:32 PM Page 126
Huber have been manufacturing the H&R
bellcrank shutoffs for many years and
have proven that this system works
effectively time after time.
These bellcranks were developed for
external-control-type models in which the
control lines attach directly to the
bellcrank. These bellcrank shutoffs have
been in use for sometime. Bobby and
Andy Mears had a similar type of
bellcrank shutoff that utilized an O-ring as
the tension creator.
• Coiled expansion spring: Pete Athans is
“thrifty” by nature and is always looking
for the best deal in town; he can get you
something at a discount, cheaper, or for
free. Pete developed the idea of attaching
a spring to the engine mounts that
connected to the leadouts via a line.
A piece of fuel line passes through one
of the coils in the spring when it is
stretched open by the tension on the lines.
When there is no tension, the spring
pinches the line closed.
I purchased a variety of springs at the
local Ace Hardware store for either $1.29
or $1.39 each. These can be cut in half to
yield two shutoffs. The line can be 20- to
25-pound-test monofilament fishing line.
A spool of this stuff at Big 5 Sporting
Goods costs roughly $1.99.
It takes a bit of experimentation to get
to the correct length of line for the right
amount of tension. I tried two of these for
the first time, and both worked well.
Pete had the original idea, but Don
Jensen adapted it to store-bought Eastern
European models. Don also figured out an
arming/starting device that consisted of a
piece of wire embedded in the top inboard
spar at approximately a 45° angle to the
inboard. He simply used his wire cutters to
snip off the extra length of unneeded wire.
I prefer to use a straight pin with a ball
head, such as the ones you get when you
buy a new dress shirt. A mini wood screw
would probably also work.
I’ll try to explain how this works. The
full-length spring has a loop at each end.
When you cut it in half, you will need to
bend one or two of the coiled loops so you
have a perpendicular loop at each end. Tie
the fishing line to one loop, and the other
loop will be attached to the engine
mounts.
You will need to connect the two
leadouts via a piece of 4- to 5-inch fishing
line. I use an antique Perfect-brand 1/2A
line connector that attaches to this leadout
line. The other end attaches to the spring.
The line connector needs to be able to
slide on the line between the two leadouts,
so that your control will not be affected as
the stabilator is given up or down control.
The loop of the spring is pulled over the
arming/starting pin and held in place by
the 45° angle.
It is important that the spring stretches
just enough to permit fuel flow when it is
hooked onto the arming/starting pin. The
spring loop will pop out of the arming/
starting pin when there is full tension on
the lines.
On one of my early attempts, the loop
did not want to pop out. Slightly bending
the loop angle cured the problem, so that it
popped out effortlessly.
The whole setup weighs close to 4
grams and costs roughly $1.50. The
downside is that there is a “heavier” feel
on the lines during landing and you have to
be really careful.
2008 MACA Top 10: The Miniature
Aircraft Combat Association (MACA)
began keeping track of contest results in
1974. At that time, the only results that
were counted were those for AMA Fast
Combat and Western Associated Modelers
(WAM) BC Combat.
The WAM BC class used similar
equipment to that in AMA Fast Combat,
but with different rules. FAI, 1/2A, Slow,
and Speed Limit were not included at that
time.
The first MACA number-one pilot was
Richard Stubblefield in 1974. He can still
boast a Top 10 rating 34 years later. He
also won the AMA National
Championships that year in Lake Charles,
Louisiana.
The current tabulations include all of
the aforementioned events.
Congratulations to: Roy Glenn, first; Neil
Simpson, second; Jeff Vader, third; Phil
Cartier, fourth; Brian Stas, fifth; Louis
Lopez, sixth; Richard Stubblefield,
seventh; Brad LaPointe, eighth; Dan
Reedy, ninth; Mark Rudner, 10th; Mike
Willcox, 11th; Glenn Simpson, 12th; Greg
Hill, 13th; Paul Kubek, 14th; Ken Burdick,
15th; George Cleveland, 16th; Alex
Prokofiev, 17th; Allen Deveuve, 18th; Chris
Lopez, 19th; and Dave Fischer, 20th.
Cyclon Fortune F2D: My testing of this
engine has continued but has not yielded
the results I was seeking. The pistoncylinder
fit comes a bit too snug, creating
too much effort during starting.
I have lapped one engine twice, so now
it starts relatively easily. I have been able
to get speed only into 19 seconds per eight
laps. The Fortune runs steadily and pulls
strongly. It needed its head clearance set at
.0165 during break-in and is now running
at .015.
When I removed another .0015 gasket,
it started blowing glow plugs. I will keep
you posted. MA
Sources:
Henning Forbech
www.f2d.dk/
Alex Prokofiev electronic shutoff:
www.e-shutoff.com
H&R bellcrank shutoffs:
www.clcombat.info/huber.html
MACA
www.maca.hobby-site.com:3535
Cyclon (Russia)
+7 383 279 37 71
+7 383 217 32 78
+7 913 910 65 41
www.rusengines.ru/?lang=en