84 MODEL AVIATION
IF IT FLIES, I’m interested in it! It’s really that simple, and there
is usually something in almost every corner of the aeromodeling
universe that grabs my attention. Since I was a youngster I have
been active in all disciplines—FF, CL, and RC—even if I wasn’t
an expert at a lot of it!
Even so, through the years I have learned a bunch about how to
make a model airplane fly. But most important I’ve learned that
for every specialty in model airplanedom there has to be
somebody out there who knows more about it than I do.
I’ve made it a point to get to know as many of those people as I
can, and if there is a way I can add value to the whole deal, it is by
putting all these different bits of aero-savvy together so some
useful cross-pollination might take place. I’m going to give you
some examples of that, and I promise to take the scenic route
while telling the story! This is, after all, my excuse to introduce
myself.
Maybe it’s corny, but I don’t ever remember not being fascinated
by things that fly. Fortunately my family lived near enough to the
traffic pattern of Teterboro Airport in New Jersey that I was
spared the harmful effects of sensory deprivation as a small child.
Ever since I started to learn to fly RC at roughly 7 years old,
my biggest focus has been RC Aerobatics, or Pattern. I had the
best teachers around—my dad Jim and his buddy Herb—but my
addiction to Aerobatics happened because I was also exposed to a
small group of excellent fliers at the home club.
These “model-airplane uncles” flew in the Pattern event, and I
always knew that was what I wanted to do. After all, the models
looked cool, were fast, and at least back then they screamed like
banshees. Ah! The sound of high performance.
While I was busy soaking up whatever I could learn from that
group, I was also involved in CL Aerobatics, or Stunt. I flew it
poorly as a kid, but my building, trimming, and flying skills
improved as I gathered friends who flew “real” Stunt.
Sometimes—actually almost all the time—simple exposure to
“what it’s supposed to look like” is the critical missing element in
learning to do something better. This isn’t true just in
aeromodeling.
One of those Stunt-flying friends I had gathered was Bob Hunt,
who was fresh from his win at the Stunt World Championships in
1978. We swapped ideas and tall stories about how to build better
airplanes while collaborating at a combined RC and CL air show.
Approximately five years later that led to my becoming a writer
for Bob, who was the editor at Flying
Models magazine.
I dabbled in FF throughout it all,
learning to trim a decent Hand Launch
Glider (HLG) and running my young legs
off hoisting Towline Gliders, losing more
than a few 1/2As in the process.
I have a silly story to tell you. I
A new contributor introduces himself and sets the tone for the column
If It Flies... Dean Pappas | [email protected]
Also included in this column:
• How to trim those toystore
ARFs
Dean’s still-flyable Pulsar was built from a Cass Engineering kit in 1974. He witnessed
the birth of IMAC and Turnaround Pattern while flying it competitively as a teen. It is
now legal for some “Classic” events.
The Straycat catapult-launch Glider. These trim out like
traditional HLGs but without the big throwing arm. Kruse photo.
When Dean bought the Hasbro Air Surfer for his son, its trim
problems were so severe that only traditional OHLG technology
could save it! Larry Kruse photo.
08sig3.QXD 6/22/07 10:42 AM Page 84
old CBGB night club. I drove into the city
one Saturday night for a show and parked
the beater I drove as a student on the street.
When I returned, a window was
smashed and the tape deck had been ripped
out of the car. I was perplexed about why
some idiot would smash the window to get
into an unlocked car, but mostly I was
furious that the thief took the time to smash
the Outdoor HLG that was sitting on the
parcel shelf below the rear window. Why?
That glider was really good!
It takes time to dial in a good OHLG,
and sometimes if the wood you use ain’t
just right it never measures up. It has
something to do with the structure’s subtle
flexing under the stress of the high-speed
launch. One of these months I will have to
get a couple experts who know about
discus launching (DL) to tell us all about
the special structural and trimming
techniques DL requires.
DL is one of those interesting crosspollination
deals I referred to. Almost
everything in aeromodeling was invented
by the FFers or based on something they
have used for years. Early RC was little
more than FF where the airplane’s trim was
occasionally messed up via radio!
Then along comes DL. Like a salmon
swimming back to its spawning stream, the
technique was invented in the RC world,
where the radio was a vital part of getting a
successful transition from the spinning
launch to a stable glide.
It took almost a decade for the
technique to swim back upstream to the
headwaters. Just recently the OHLG event
at the Nats was won using the DL. I’ll bet
specialized trimming techniques were used,
and I have not learned about it yet. We will
learn about it together. I’ll look for an
expert in the field right away.
I didn’t fly much in college, mostly
limiting myself to teaching at the home
club and grubbing flights on my buddy’s
Pattern equipment. The Hackensack Valley
Flyers still fly on the edge of that same
swamp, with the Manhattan skyline as a
distant backdrop. We watched as the World
Trade Center towers were built and
measured the progress by how many flying
sessions it took.
I think I flew in one contest while in
engineering school. Model-flying professor
Norm Cassella lent me a well-trimmed
Pulsar for a week, and I took a trophy away
from my only class “D” contest.
Years later that contest CD’s grandson
would take a page from Dylan and turn the
Aerobatics competition world upside down
by going to electric power! It’s serendipity.
As a young adult I pursued my
competitive career in Pattern with a singlemindedness
I was only able to muster while
still single, but the urge to dabble in other
areas was strong. In 1985 the importership
of YS engines changed hands, and my
competitive engine program was suddenly
deprived of spare parts. (This is certainly
no longer an issue for YS; first Futaba and
then Performance Specialties have done an
admirable job!)
A new development program was
needed, and a reliable source of engines
and spare parts was one of the criteria. Lots
of quiet horsepower was the other.
The noise-limit rules in the event had
ratcheted down another notch. My partner
in crime was Rich Tower, a sometimes
drag racer, sometimes CL Stunt flier, and
always an excellent motor head. We built a
piped 60-size engine using an OPS aero
engine crankcase, marine rear-intake front
and back, special low-rpm cylinder liner,
and retrofitted O.S. carburetor.
It ran great—sort of. The engine was
powerful, reliable, and ran happily at less
than 10,000 rpm, but in order to fly at the
desired 90 mph or so I needed a 10- or 11-
inch-pitch propeller. The best I had for that
first day of in-air testing was a laminated
wood 12 x 8.
Every time I ran the throttle up to full in
level flight, the airplane would speed up
some and then the engine would go flat
(actually a little rich). When I dove the
model to gather speed for a maneuver, the
engine sounded like a potato had been
stuck into the exhaust. No matter what I
tried the airplane would go no faster than
maybe 75 mph.
I started goofing off, flying consecutive
loops without backing off from wide-open
throttle. The engine behaved like an
airspeed regulator; it cleaned up and
jumped onto the pipe, getting a boost on
the way up one side of the loop, and the
potato brake kept things nice and slow on
the way down.
Rich and I chuckled and made some sort
of joke about how it was a shame we
hadn’t flown much CL Stunt together
recently. You see, we had stumbled onto
the now-accepted “tuned-pipe Stunt” setup.
This discovery sat unused for a year or
so, until the Stunt team came back from the
1986 World Championships in Hungary
with a mandate to make their airplanes
quieter. Refining the system took much of
our effort for the next two years, and it is
probably the aeromodeling project of
which I am proudest.
The tuned-pipe setup was eventually
used to win several World Championships,
and all because we applied a technique that
was learned “over here” to another kind of
flying “over there.”
To tie up the history, tuned-pipe use
actually started in CL Speed with the
stunning performance of Bill Wisniewski’s
ground-breaking Pink Lady and the
excellent tell-all article in the March 1967
Model Airplane News magazine. (Bill
passed away approximately three weeks
before I wrote this.)
As used by the CL Speed crew back
then, tuned pipes were finicky, unreliable,
and unpredictable. They got much better at
it, with time, and the rest of the
aeromodeling world watched and learned.
Today we know how to use tuned pipes to
reliably make horsepower and quiet. That’s
good for all of us.
This column, at best, is the place where
your questions meet the best information I
can pull together from the many corners of
model aviation. To that end,
Not only is it possible to buy a “proper”
model airplane that is either almost ready
to fly (ARF) or ready to fly (RTF and Plug-
N-Play) in RC, CL, and FF, but it is
possible to find flyable airplanes in the
retail toy stores. The potential for growth is
both staggering and oddly limited.
Staggering? I’ll bet they sell many
hundreds of those RTFs in the toy stores in
every county in the land. Imagine the
difference if just 100 of those people join
the local club’s request for a permanent
flying site in the county park.
Limited? Yes, but in a way that is
completely within our power to change as
model-aviation enthusiasts. What if
someone buys one of those toy-store RTFs
and encounters nothing but frustration?
To begin with, he or she is likely to
abandon in disgust the attempt to learn to
fly. When such a person hears about that
same petition to the county for a
permanent flying site, is he or she likely to
help? Is he or she likely to disregard the
whole deal as being less worthy of a piece
of the county park than another soccer
pitch? Of course it is worth our while to
help these people.
Many of the toy-market RTFs have the
potential to fly well if they are properly
adjusted or trimmed. Unavoidable
production variations and airframe warping
caused by transportation and storage in
tractor-trailers left in the August noonday
sun in Albuquerque mean that many new
fliers are introduced to model aviation with
an airplane that would fly if only a
knowledgeable person made the proper,
minor adjustment to it.
The other night at a club meeting we
were treated to a presentation by one of the
“retiree squad” who had been flying the
daylights out of a $79 RTF trainer. He had
a shopping list of small modifications he
had made to this trainer.
Although roughly half of them were
gilding the lily, a few of the changes really
made a difference in the model’s
controllability. I remember his describing
how the ruddervators would flap while in a
dive and lead to a partial loss of control.
(Yes, it had a V-tail.) All it needed was a
better choice of rubber band!
Getting to my point, the necessary
adjustment techniques for these airplanes
are much the same as those the majority of
RC fliers used in the late 1950s and early
1960s. That was back when Class 1 or
rudder-only control was the affordable and
most commonly used RC system. That is,
they are much like the setup techniques for
gas-powered FFers. The setup techniques
for this kind of airplane are all but a lost art
at the RC field.
Remember when I claimed that FFers
invented everything in aeromodeling? This
is useful cross-pollination.
Let’s get a little bit technical. In this
column you’ll find a picture of a Hasbro
Power Air Surfer. This was purchased
during the closeout sale at the local Zany
Brainy toy store. My son, Zack, flew it
dozens of times before the electronics gave
up the ghost.
Directional control was accomplished
by running the twin electric motors
differentially, and the power was either all
on or all off. It flew quite well after I
stabbed a half dozen four-penny nails into
its foam nose to adjust the balance point or
CG, but before that it flew unpredictably
and occasionally speared itself into the
ground after a prolonged 45° dive.
The tiniest disturbance, such as a gust
of wind or messed-up turn, would send it
into the death dive. As the airplane dove
and accelerated, there was not even a hint
of a pullout. Man, did it bounce high after
impact!
I had seen this before. It’s what happens
after a less than perfect launch, especially
when an OHLG is trimmed a bit too close
to its max performance.
The Air Surfer was tail-heavy, but only
marginally so. The trim tabs on the flying
wings needed to be bent upward to add
aerodynamic nose-up trim. This caused the
airplane to pull out of the dive as it
accelerated because the trim tabs became
more effective with higher airspeeds.
To counteract the upward-bent trim tabs
at the airspeed of normal level flight, slight
nose weight was needed. That’s where the
nails came in handy. It’s not terribly
intuitive, is it? The diving problem was
fixed by adding nose weight!
The test-and-tweak sequence is as
follows. Test-glide the model from
shoulder height into tall grass (or thick
weeds!), taking care to launch it level in
pitch and roll. It may take a few tries to get
the speed right, but eventually you will
find a launch speed that puts the airplane
into its natural glide angle.
If it climbs and then dives suddenly,
slow the launch. If the glide steepens
continually from the moment the model
leaves your hand, add more speed to the
launch.
Now that you have found that glide
speed, does it seem too fast and steep? Is it
too slow and mushy, like a falling leaf
rather than an airplane? If the glide is fast
and steep, add some up-trim tab. If it
mushes, add some nose weight!
Adjusting this way guarantees that the
model will either be properly balanced or
nose-heavy. Nose-heavy is the safe
direction in which to err. The important
thing is that a minor adjustment goes a
very long way. Make small adjustments or
add a bit of weight and try the test glides
again. Before long you will dial in a
decent glide.
It’s time to make a powered flight. If
the model climbs too steeply under power,
reduce the up in the trim tab a tiny bit and
maybe remove a little nose weight to
restore a nice glide.
Try the powered climb again. If it is not
steep enough, add some up-trim tab and
only add nose weight if the glide gets
mushy. If the airplane flies well but starts a
stall/dive/swoop cycle when disturbed by a
wind gust or a badly done turn, you need a
bit of nose weight.
This has been the Reader’s Digest
version of how to pitch-trim an RTF that
does not have a separate pitch or elevator
control. You can find a more complete
version intended for full-function RC
airplanes in the “Trimming From the
Ground Up” article in the July 2006 MA.
Maybe someday we will revisit the subject,
but for now I will await your questions and
suggestions.
Remember, if it flies we’ll discuss it here.
See you at the field. MA