According to this
1960 Air Trails magazine "Starting Control Line Combat" article, the
first appeared in the AMA (Academy of Model Aeronautics) rulebook in 1950. Hard
to believe that was 72 years ago as of this writing. It's equally hard to believe
it was only 8 years before I was born - ugh. Control line combat remains a
very popular sport today, and is one of the relatively few aspects of the hobby
which has not changed considerably. Engines have gotten more powerful and reliable,
and building materials have improved, but the basic outline of the airframe is about
the same. The story reports on combat rounds having up to five planes flying at
once, duking it out for air superiority. Too bad there's not a video of it with
all the flyers trying desperately to not become entangled in each other's lines
or even keeping out of each other's way. There must have been a lot of smashed balsa
after that event. Anyway, this article provides a lot of detail concerning all aspects
of model construction, engine and fuel tank setup, and flying. Interesting fact:
In the early days of control line combat, prolonged inverted flight was permitted,
which meant closing speeds of a couple hundred miles per hour - what a mess that
must have made during a head-on collision!
Use hardwood for engine mounts, maple or birch is better than pine or bass. Mount
engine angled outward a few degrees to aid flying trim. Use fuel tank size adequate
for five-minute flight. Mount tank firmly to prevent· foaming and erratic engine
Use maximum size engine allowable. Best props for .35 engines: 10D-6P, 9D-8P,
9D-7P, experiment to find best for your engine and ship. Balance new propellers.
Whole control system must be rugged. Put bellcrank pivot on engine bearer. Pushrod
wire 3/32" dia. wire instead of 1/16" dia.
Change needle valve and body to left side.
Elevator horn 1/32" thick steel preferred. Make strong eye ends in leadout wires.
Here are methods for "serving" wire ends. Flexible cable can be twisted over
itself then served with fine soft wire. Double' wrap method very strong. Heat from
soldering weakens wire.
Combat model is expendable. Use simplest, lightest structure for quick building
and high performance. Align structure carefully. Apply minimum finish, five coats
of dope over heavy tissue is adequate.
Put lead ballast in outward wingtip to counterbalance leadouts and flying wires.
Use good knot to tie streamer to model. Losing a streamer can lose the contest
for you. Learn to tie the bowline.
Install ample hinge area. Fabric "Z" hinges are simple, strong and flexible.
Opinions may differ as to exactly when control line combat flying started its
climb to popularity, but the event wasn't in the AMA rule book before 1950. With
the upsurge of interest in yo-yo flying during the post World War II years it was
inevitable that sooner or later several flyers would get into the same circle and
chase each other.
As early as the 1947 Nats in Wichita, Kansas, a group of flyers put five ships
in the air at once just for fun. What a show! Flyers were tripping over each others
feet, models tangled wires and the rat fight ended in one grand mess.
Control-line's godfather, Jim Walker, flew three ships at once early in the game.
In the 1948 Nats, young Dave Slagle flew two stunt ships at once. With streamers
on both ships he succeeded in engaging himself in combat! Whew! Soon other modelers
picked up the idea and before long combat flying and streamer cutting became a popular
exhibition event. Then it was strictly for fun and a great crowd pleaser.
In the East, credit must be given to Sterling's combat team that toured contests
flying the YAK-9 and P-51 kit ships. And so the trend was started, such events as
Team Racing (and later Rat Racing) showed that the fun factor went up considerably
when there was more than one flyer in the center of the circle.
The present AMA rules for combat are the outgrowth of several years of acute
growing pains. The event's popularity has made some rules necessary that do not
please all flyers. This is inevitable of course, but earlier, when prolonged inverted
flying at 3-inch altitude was permitted, combat was mad, mad, mad, and model mortality
Space does not permit a rundown of the complete AMA combat rules here, but the
important points relating to design and flying are: Maximum engine displacement
permitted is ,36 cu. in. Flying lines must be 60 ft. from center of model to center
of handle. Pull test is 20 times model weight. Each flyer permitted only two models
and two official flights (attempts and unofficials detailed in AMA regulations).
No flying inverted or less than 8 ft. altitude for more than one lap. Center circle
is 10 ft. diameter. Streamers are 8 ft. long with 4 ft. string leader. Flight time
is 5 minutes, scoring of "cuts" and "kills" must be done in shortest possible time.
Points are deducted from score for time elapsing after starting. Two-minute starting
time allowed, both ships must fly one level lap before starting combat. Unsportsmanlike
or discourteous flying, deliberately causing crash or collision is cause for disqualification.
First and foremost the combat plane must be a full stunt ship, capable of good
speed and high maneuverability, indeed most combat jobs are good stunt trainers.
Attack and evasion tactics require quick response yet stable characteristics so
that the flyer can watch his opponent's ship and still fly his own without having
to pay much attention to it.
The combat ship therefore must be a light weight for speed and stunting. So far
a big ship has been better than a small one. The largest engine permitted should
be used, you want all the power you can get. Remember that the combat model is highly
expendable, so although it must be rugged enough for high speed and air loads it
should have a minimum of materials; construction should be simple and require a
minimum of work and building time. Don't bother with a twenty-coat hand-rubbed finish.
Enough dope to keep the oil out is all that is necessary. Fancy stripes and gaudy
decals make a colorful model, but are wasted on a combat ship. Build 'em "quick
and dirty" ... let's qualify that to not too dirty.
Anything less than a hot running engine is a real drag when the fight is on.
Your engine should start easily and run like the well-known watch. Fuel tank and
lines must be clean, tank should be at least 2 1/2 to 3 oz. capacity for 5-minute
flight depending upon engine. Any good stunt tank will do the job. Veco (Froom)
tanks are popular. Tank center should be level with needle valve and firmly mounted
to prevent foaming and poor fuel flow. Some engines tend to run rich in air even
when leaned-out on the ground. Pressurization can help this problem. Cap vents with
length of fuel line beveled at 45° with bevel facing forward. Experiment with
different propellers to get best running and top speed. For .35 engines, 10"D-6"P,
9"D-8"P and 9"-7"P are preferred.
Simple beam mounts for the engine are best, these should be hardwood. Pine and
bass crush easily at mount bolts because of vibration. Use birch or maple if possible.
The engine beam mounts should extend well back into the structure for maximum strength
needed to tie wing and fuselage together. The control system should be rugged. If
possible, the bellcrank should be mounted on an engine bearer, not on a flimsy bit
of plywood stuck on balsa fuselage side or wing rib. The engine bearers and bell-crank
mount should form the strongest part of the model since combat ships are subjected
to a pull test of 20 times the model's weight. Plenty of combat flyers are eliminated
by the pull test during processing-before they even get to start an engine. The
strength of bellcrank mount should extend throughout the control system. Use a 3/32"
dia. wire push rod where you would ordinarily use 1/16" dia. wire. The elevator
horn should be at least 1/32" thick aluminum, brass or steel, the latter being
preferred be cause it stands up better under engine vibration. Make good strong
wraps and eye ends on lead-out wires from bell-crank. If you like to use regular
flying wires and simple handle, there are ready-to-use lines available made by Pylon.
If you use a U-Reely control handle be sure the reel lock works properly.
Like any other high performance model, the combat ship should be built with as
accurate alignment as possible. This applies particularly to wing structures, since
warped surfaces. cause erratic flying. A warp that causes the model to bank into
the circle is particularly troublesome and can cause loss of control during tight
maneuvers. Proper balance is also very important for a good flying combat ship.
Center of gravity should fall between 20% and 25% of wing chord. Models with regular
tail surfaces can balance at 25% but flying wings should balance at 20%. Of course
the bellcrank pivot and leadouts should be located behind C.G. position. Rearward
C.G. position will cause model to turn into circle, while forward C.G. will make
model too stable and make maneuvering sluggish.
Since combat flying is conducted in all kinds of windy weather, a few degrees
outward offset of the engine thrust line will help keep the model out on the end
of the lines where it belongs. Engine thrust offset is more effective than rudder
offset so the rudder can be mounted straight ahead, its main function anyway is
to provide a place to attach streamer. Add a bit of weight to outside wingtip to
help compensate for leadout and flying line weight. Don't use spinners on a combat
model, they add unnecessary weight, some cause vibration and a prop change is time
consuming when a spinner must be fitted during a re-start. Even though they may
have a very short life, balance propellers carefully. As manufactured, props sometimes
need careful trimming or sanding to balance exactly because of varying wood density
or uneven varnishing.
Although the green beginner has on occasion jumped into combat competition and
wiped out the old hands, this is not often the case. Flying a hot combat ship in
the same circle with others takes a little getting used to for most yo-yo-fliers,
so a little ground school should precede soloing in competition. Practice the stunt
pattern to gain confidence and get to know your model thoroughly first. Fly in windy
weather to learn how your model behaves under extreme conditions. Then try flying
with your friends two at a time and later with three in same circle. Practice chasing
tails (without streamers); don't try for kills or near misses at first. Get used
to the footwork needed to pass each other and following each other around in the
air. As your proficiency gains put streamers on your ships and have at it. If you
are a club flyer, all the better. You can practice with fellow members.
When flying in competition you and your helper should be a real team. He should
have your engine starting down pat, so that he can re-start for you without your
having to leave the center of the circle. Hand launching is best way to get a combat
ship into the air, since wheels are seldom used. A light ship with big engine will
practically fly off your hand without much of a push. Have your helper familiar
with launching your ship VTO or HTO. Do not hold full up during launch or you are
liable to lose a helper. A hot ship will turn in its own length at low speed and
whango, right back at your helper's back. When landing, try to put your ship down
close to your helper so he won't have to chase around the circle.
Stick with a proven ship design, build duplicates of the same model so that a
new design won't come as a complete surprise to you in competition. Some flyers
like conventional types while others like the flying wings; fly which ever you like
best after trying out different designs. If you are flying two different ships be
sure flying lines and leadouts add up to 60 ft. on both. There are numerous good
combat model kits available such as T-square, Bandit, 1/2 Fast III, Omega and Quicker.
Posted September 24, 2022