Control Line Aerobatics-2011/11

“Builder of the Model” rule vs. composite construction
[[email protected]]
Control Line Aerobatics Bob Hunt
Also included in this column:
• 3M #77 alternative
I REALLY didn’t have much in mind to
write about this month, so I decided to “blue
sky” a bit about things that have been on my
mind concerning modern CL Stunt model
construction, how it is affected by the
current event rules, and how it will be
affected in the future by potential rules that
many have proposed recently.
The entire CL community is a traditional
group and not one normally prone to make
sweeping changes or adopt new
technologies rapidly. There are exceptions
to this, but by and large they are slow to
adopt change.
Many in this community are ready at a
moment’s notice to defend their events from
any modifications that might alter longstanding
rules and/or concepts. This is not
necessarily a bad thing; however, changes
should not be made just for the sake of
doing something different. Sometimes
change is good, and sometimes it is
unavoidable.
There has been discussion for decades
about the “Builder of the Model” (BOM)
rule in CL Aerobatics—some like it and
some don’t. Those who like it and want to
keep it a part of the Stunt event cite that this
is how the founders of the event wanted it to
be, and so it should always remain that way.
They also feel that there is an inherent
artistic and craftsmanship aspect to this
event and if the BOM rule were to be
eliminated, the quality of the models entered
would diminish and the event would lose
much of its mystique and exclusiveness.
Their view is that building, finishing, and
flying are all part of the event. Hey, those
are all valid points and concerns.
Those who would like to see the BOM
There’s validity to these viewpoints, too.
I’m sure that many will chime in with
other concerns and comments on all sides of
this issue after they read this column. We
need to open this up to mature and logical
discussion on all points of view in order to
find common ground on which we can all
agree.
The BOM debate has simmered for a
long time in Stunt, but it has been brought to
a full boil recently by the introduction of
ready-to-fly, high-end performance,
commercially available CL Aerobatic
models from a few sources worldwide.
The models that really brought this into
focus are the Shark and the Classic designs
made and sold by the Yatsenko brothers—
Yuriy and Andrey—who hail from the
Ukraine. They run a model business there
rule removed from CL Stunt cite the fact
that FAI F2B rules have not had a BOM
rule for many years, and the quality of the
models at FAI events has not diminished. It
has allowed for increased participation by
those who might not be able to build their
own models for whatever reason (time,
space, health, etc.).
They also point to the many competitive
sports in which a participant does not have
to build his or her own equipment. (Dorothy
Hamill didn’t have to make her own ice
skates and Jeff Gordon doesn’t have to build
his own race cars.) Some in this group also
feel that the BOM rule is stifling
participation in what they consider to be
mainly a sporting event, and it may be
discouraging the development of new
construction techniques and processes.
Right: The Discovery Models’ Sharks Phase 3
model. Phase 1 and 2 models require construction,
alignment, and finishing. Above are the parts for
the Phase 1 Shark ready for assembly. Note the
neat workmanship and thoughtful engineering.
Photos by Jose Modesto.
Using Jose Modesto’s composite
construction molds, Will DeMauro
built this electric-powered SV-22
and qualified for the 2010 Nats
Advanced Class CL Aerobatic
Finals. DeMauro photo.
called Discovery Aeromodels. The models
that they have designed and engineered for
sale use aerospace thinking—mainly
because the brothers are engineers who
work for the Antonov Aeronautical
Scientist/Technical Complex (the
company that designs and builds the
Antonov aircraft in the Ukraine).
The Yatsenko brothers’ models fly
well and have scored highly at World
events. In the hands of Orestes Hernandez,
they have won the US Nationals on two
occasions.
It is important to point out that Orestes
provided documentation to the Nats Event
Director on both of those occasions to
verify that he indeed constructed the
model he used from parts supplied by the
Yatsenkos to be compliant with the thenand
now-current BOM rule. In other
words, they supplied Orestes with an
actual “kit” for the Shark.
Currently, the Yatsenkos are providing
their models in three phases of
construction to allow the models to
comply with current AMA BOM rules.
One of these phases is an all-balsa model
kit that must be assembled, aligned, and
completely finished by the modeler.
Those models are examples of some
advanced thinking in terms of design and
construction. In fact, much of the
construction of the Yatsenko brothers’
models is done in hyper-accurate molds
and incorporates aerospace-type materials
and concepts.
To paraphrase Robert Preston’s
character in the movie, Music Man: We’ve
got trouble, right here in River City, and
that starts with “T” and that rhymes with
“C” and that stands for Composites!
It is a fact of life that technology will
advance when competitors are trying to
achieve performance gains. Composite
construction is here, and it is here to stay.
Unfortunately most composite parts come
out of their molds with some
attributes/properties that may render them
illegal for use in CL Stunt under the
current interpretation of BOM rules, if
they are purchased by a flier/constructor.
Lately the thinking is to interpret the
BOM rule to disallow any component that
is purchased and used in the building of a
competition model if that component has
the surface finish (paint or “gelcoat”)
already applied. Since many composite
parts do come out of the mold with a
smooth surface finish, there is some
difference of opinion about how that rule
should be interpreted and/or applied.
There is no argument about the fact
that if a builder makes his or her own
molds and then in turn produces molded
composite parts for personal use, the
BOM has not been violated. The concern
is that if these parts are sold to others,
then the resulting models are illegal for
use in our event because the builder did
not apply the surface finish.
Not everyone will be able to, or be
willing to, produce homemade composite
parts. The high cost of the required molds
and learning techniques to achieve useable
parts can take a lot of time and resources.
There is certainly a steep learning curve
associated with this technology. It can be
mastered, however, if the requisite time and
money is invested.
My good friend, Jose Modesto, has been
investing both the required time and money
to develop his own line of composite
models and model components. His intent
was to produce composite models for sale
to the modeling public—just like the
Yatsenko brothers.
Several local modelers have obtained
parts from Jose and have crafted some very
nice-looking and good-flying airplanes.
However, with the announcement of the
interpretation of the BOM rule that was to
be used at this year’s Nats, those fliers were
concerned that their models would be found
illegal for use at the event. The same held
true for those who intended to fly the
Yatsenko models.
Jose found a very creative and unselfish
way to enable a few of his local modeling
friends to use composite parts in their
airplanes with certainty that they were not
in violation of the BOM. He invited those
who were interested to come to his home
and lay up their own composite parts in his
molds. Brilliant!
One flier who took advantage of Jose’s
gracious offer was Will DeMauro. Will is
an up-and-coming Advanced-class flier on
the East Coast who has studied the
advantages of composite construction and
wanted to make his own model using this
technology.
Will made several trips to Jose’s house,
and under Jose’s watchful eye built a new
SV-22 Nats model in only a few weeks’
time. The result was the best-flying aircraft
that Will has ever owned, and with it he
placed higher at the Nats than he ever had
before. He credits the accuracy of the
component composite parts and Jose’s
alignment procedures in large part for his
sudden improvement.
Perhaps Jose has shown the way to
integrating composite construction for the
masses in an acceptable manner … but not
everyone can travel to Jose’s house to
build! Those who want to try this type of
construction in a given geographical region
could get together and pool their resources
to develop and construct the required
tooling (molds) and then share that tooling
to generate BOM-legal models. Of course
they would all have to agree on a specific
design. Good luck with that …
In checking with Jose to ensure that the
above was accurate, he told me that just as
are the Yatsenko brothers, he is now
producing “kit” versions of his models that
are totally BOM-compliant and will soon
have information available for those who
are interested.
This still does not address the legality
of many of the premolded component
models that are being sold around the
world. At this time they are still legal for
FAI competition, but not for use at our Nats.
I guess at this point I should declare my
position in this debate. I’ve always
contended that we should adopt the same
rules that are being used by the rest of the
world if we intend to be fully competitive at
FAI events. To fly under those rules just
once each year—once at the Team Trials
and once at the World Championships—
seems silly to me, especially when all the
other world competitors use those rules all
the time. Not many agree with me on that
point …
There are a number of people who want
the BOM eliminated entirely in this country,
just as there are many who want to make it
even more restrictive than it is now. I’m
fairly confident that we will end up retaining
a BOM rule of some kind, but I’m certain
that it will take a lot of give-and-take to
come up with one that is acceptable to all
concerned.
Let’s try to make that happen. Please
send in your thoughts on this subject and we
will print some of your comments here.
Perhaps a more in-depth discussion on this
can and should take place in the pages of
Stunt News, the official newsletter of the
Precision Aerobatics Model Pilot’s
Association (PAMPA).
To be fair in this discussion I should
mention that the BOM rule applies to our
rules in two instances:
1) At our Nats, for the age category CL
Precision Aerobatics (CLPA) competition
(Junior, Senior, and Open), the BOM rule
applies to be eligible to compete. The age
category competition is normally only found
at our Nats.
2) At all other CLPA contests in this
country, the AMA skill classes are used
where the BOM rule is not required in order
to be able to compete. However, if the
competitor did not build the model, he or
she can still fly in the skill class
competition, but will not receive appearance
points. And, if organizers of a skill class
CLPA event choose to do so, they can forgo
the appearance point/BOM matter and
announce beforehand that the BOM is not
required and that appearance points will not
be awarded. This approach is used for any
number of contests around the country.
My thanks to Keith Trostle for his help in
clarifying the actual implementation of the
BOM rule in competition. Keith and I agree
on some of the points that I made above and
not at all on others, but we are able and
willing to work together to find the common
ground. Hopefully all BOM discussions and
forums to come can be conducted in the
same manner.
Spray adhesives … again: I’ve written in
the recent past about 3M spray adhesives
and their applications for model building.
Some of our readers have chimed in with
personal experiences with these and other
adhesives.
Well, I received another contribution
from a reader about this subject. C.J. Sasso
wrote the following about an adhesive that
he has found useful. Take it away, C.J!
“Hi Bob: I am writing this in reference to
your recent column on 3M adhesives in
Model Aviation magazine. I was a user of
3M #77 adhesive to adhere balsa to my
white foam Sailplane wing cores. But this
was several years ago and there has been a
considerable time lapse before I discovered
the need for spray adhesive again.
“During the interim I had heard some
vague stories that the #77 formulation had
changed. I was therefore on guard when
about a year ago I was perusing the shelves
for a fresh can of #77 with which to adhere
the sheeting to the foam wing cores of a
scale plane I was building.
“In doing a shelf comparison of products,
I came across a Loctite product entitled
‘High Performance Spray Adhesive.’ The
label said it was safe for foam. I don’t trust
labels when there is the possibility to ruin a
good set of foam cores, but the price was
right (being a lot less expensive than #77) so
it was worth the risk to test it on some scrap
foam and evaluate the results.
“Typically I use ¾-ounce cloth in the
building process. Besides attaching balsa to
foam core wings, one of my construction
techniques is to epoxy the glass directly
November 2011 141
onto foam tail surfaces. In this latter
situation, the spray adhesive is lightly used
to hold the glass in place.
“I can now relate from testing and much
experience in building that the Loctite product
works very well and is perfectly safe for use on
expanded polystyrene foam. In fact, I think it
works better than the old formulation of 3M
#77.
“One reason is that the Loctite tack is not
quite as aggressive as the #77. This attribute
makes it easier to position adhesive coated
pieces in place with less of an issue in having
the piece stick to you or to itself in the process.
It also allows you—for a time before complete
setting—to lift and reposition the sheeting.
“I found the Loctite spray adhesive to be
available at Lowe’s and at Walmart in my area.
After reading your column I thought it might
be worthwhile to share this info with you and
with your readers.”
Thanks, C.J. It’s great to know that we have
yet one more tool in our building arsenal.
Till next time, fly Stunt! MA
Sources:
Discovery Aeromodels
http://discovery-aeromodels.com
PAMPA
www.control-line.org