Leroy Black’s Blohm und Voss Bv 138 flying boat
has Norvel .061 engines. Photo by Ted Kraver.
Correction: The 2014 Nats coverage in the December 2014 “Control Line Scale” column incorrectly
reported that Bob Whitney’s 1/2A Scale
pond racer used . 61 engines. The model was
actually flown with .061 engines. That would have
been one fast aircraft with a pair of . 61 engines!
Bv 138 Flying Boat
Leroy Black’s model of the Blohm und Voss
Bv 138 flying boat has three Norvel .061 engines.
The 42-inch wingspan aircraft was entered in the
Tucson 1/2A Scale contest in October 2014. The event
was hosted by the Cholla Choppers Model Airplane Club.
Flying boats are challenging because the full-scale aircraft has no wheels. One
method for building a model flying boat that can fly from a hard surface is to bury
half of the wheel in the fuselage, as shown in the photograph. The wheels allow the
model to tip from side to side, so a small wheel on each wingtip is necessary to use
throttle control to perform a taxi option.
CL Scale Rules Have Changed
If you plan to fly in an AMA-sanctioned Control Line (CL) Scale contest this year,
you will need to read the updated 2015-2016 rules on the AMA website. If you are
a contest director (CD), you also need to read the updated rules. If you don’t have
Internet access, find someone to print them for you.
The CL Scale rules were completely rewritten. It is worth reading the entire set of
rules so you know what to expect at the next contest.
We have several events that include Fun, Sport, Profile, and Team Scale. Designer
Scale has been eliminated. Authentic Scale and 1/2A Scale have been added as official
AMA events. The 1/2A Scale event has run for many years using club rules. If your
club decides to continue to use club rules, make this clear on your contest sanction
The 1/2A Scale event is judged 5 feet from the model. All other events are judged
from a distance of 15 feet. The one exception is Authentic Scale, which is judged
at 15 feet for outline and then up close for the details. Authentic Scale will require
judges who have experience with Scale modeling and will require extra time for the
The maximum number of allowable documentation pages has also changed.
Remember, the three-view only counts as one page regardless of how many pages it
takes. Fun and 1/2A Scale allow a maximum of four pages. Sport, Profile, and Team
can have up to eight pages of documentation, and Authentic Scale can have up to 12
pages of documentation.
It has long been unclear what weight should be used to calculate the pull-test
requirements for electric-powered aircraft. The updated rules now require that
the weight of the batteries be included in the weight of the model for pull-test
Many changes in the 2015-2016
CL Scale rule book
by Fred Cronenwett
The minimum line diameters have
also been revised, which will require
most of us to make a new set of flying
lines. The rule book has a diagram with
line diameters based on the model
weight and the number of lines. For
a model flown with two multistrand
lines in the 4- to 8-pound range, the
line diameter for this class was changed
from .018 to .021 diameters. For aircraft
weighing more than 12 pounds, the
line diameter is now .027 with two
Also, look at the line length
requirements. Any model that weighs 8
pounds or more needs to use 65- to 70-
foot lines. Bulk line material is available
from MBS Model Supply. Brodak
Manufacturing has lines available by
length and diameter.
The taxi option can only be
performed after the landing is complete
under the new rules. Some CDs
have allowed the taxi option to be
accomplished before takeoff. The rules
were written such that the model must
come to a complete stop with the engine
or motor idling before takeoff without
The rules also clarify that Profile Scale
models can be entered in any event, but
be prepared for outline downgrades if
127 Model Aviation APRIL 2015 www.ModelAviation.com
CONTROL LINE SCALE