Modeling Spoken Here continued on page 143
othing in the aeromodeling world
is more intriguing and exciting
than the sight and sound of a
multiengine model airplane flying. Perhaps
it’s the fact that not too many of them are
seen on a regular basis. More likely it’s
simply an acknowledgement of the effort
and thinking that goes into making a “multi”
work correctly.
Whatever the reason, whenever a model
with more than one power source gets ready
to fly, there are usually many interested
spectators watching with great anticipation.
In this issue we have several articles
dedicated to twins. If you are considering a
multiengine model, the first step will
probably be (and should be) a twin. Not too
many will attempt a trimotor or fourengined
airplane as their first foray into this
realm.
Making two power sources work reliably
and in unison is far more involved than
making just one engine/motor work
properly. Making three or more behave
properly is even more of a challenge.
I’ve always liked twins. I’ve sketched
dozens of them through the years but have
never had the time or courage to actually
design and build one. That is, until recently.
With the advent of more powerful
electric motor/battery combinations, a twin
is far less daunting than before. Making two
electric motors run together properly may
not be a cinch, but it appears to be easier
than getting two glow engines to operate
consistently.
Because of this I’ve started building a
new electric twin CL Aerobatics (Stunt)
design I’ve named “Ohm’s Outlaw.” I’ll let
you know how it works when it’s done.
One of the articles in this issue is a
construction feature by the prolific Dick
Sarpolus. Dick is no stranger to twins; he
has produced many of them for publication
as construction articles through the years.
Some of these were RC models and a few
were for CL use.
For this new airplane Dick wanted a
large twin sport/aerobatic model and he
wanted it to be electric powered. The result
is his Lotsa Watts design. I was honored to
be asked by Dick to visit him at his home
field in Monmouth County, New Jersey, and
get some stick time on his behemoth twin.
Dick displayed the big twin’s impressive
power by pushing the throttle full on in one
sudden movement. The model literally
leaped into the air, and Dick proceeded to
pull it into a straight-up climb, rolling it as it
shot upward. I got the feeling that he could
have let the model climb like that until it
was a speck in the sky if he wanted to.
Dick performed most of the aerobatic
maneuvers effortlessly with the Lotsa Watts
and then gave me a shot at the sticks. I
found the model to be smooth, predictable,
and easy to fly through maneuvers.
Aeromodeling Editor Bob Hunt
N
I had anticipated that a twin would have
an entirely different feel and that I would
have to work more to keep it tracking in
maneuvers. I was surprised to find that this
airplane felt just like a single-engine model
in flight. I highly recommend it as a first
built-up twin project.
Perhaps an easier route to getting a twin
into the air quickly would be to do what Jim
Feldmann did and modify an existing ARF.
His Sport Utility Twin (SUT) started life as
a Hobbistar 60 ARF.
Jim designed nacelles and grafted them
to the wing, opening up space in the main
fuselage to allow the resulting model to be
used as a camera airplane if desired. The
powerful SUT can also be used to tow up a
glider or perhaps even a banner. Jim makes
it a point to mention that other 60-size ARFs
can be modified in this manner.
He supplied complete plans for the
Hobbistar 60 conversion, and they are now
available through MA’s plans service.
Another article presented in this twin
theme issue is a technical piece by Eric
Henderson about tuning twins, and it deals
with all aspects of setting up twin glow
engines for reliable operation. Eric’s article
focuses on proper break-in of the individual
engines and getting them to be predictable in
operation.
Then he moves on to a step-by-step
cookbook procedure for getting the engines
to work together properly in a model. This
section includes an in-depth section on radio
programming.
Eric has done an excellent job of
covering all possible aspects of twin tuning.
If you are considering a glow twin setup,
Modeling Spoken Here
Published by The Academy of Model Aeronautics
Rob Kurek
Director of Publications
Editorial offices: (765) 287-1256, extension
224 (8 a.m.-5 p.m. weekdays); Fax: (765)
281-7907
Contributing Editors
Dave Brown
President
Doug Holland
Executive Vice President
Staff
(765) 287-1256 | www.modelaircraft.org
Fax: (765) 289-4248
Advertising Representative
Mark Lanterman, Airborne Media, 7414
Burton Dr., Liberty Township OH 45044
(513) 755-7494 | Fax: (513) 755-7495
Executive Director Jim Cherry
Model Aviation is an official publication of The Academy
of Model Aeronautics, Inc., an associate member of the
National Aeronautic Association (NAA). NAA is the official
U.S. representative of the Fédération Aéronautique
Internationale (FAI), the world governing body for sport
aviation, and represents the U.S. at FAI meetings. NAA
delegated to the AMA supervision of FAI-related
aeromodeling activities such as record attempts,
competition sanctions, and selection of U.S. teams for
World Championships. (ISSN 0744-5059, USPS 087-930
Publications Agreement No. 40688541) is owned
exclusively by The Academy of Model Aeronautics, Inc., a
nonprofit organization, and published monthly at 5161
East Memorial Drive, Muncie IN 47302. Periodical rate
postage paid at Muncie IN and at additional mailing
offices. Canadian return address: Station A, PO Box 54,
Windsor ON N9A 615
Account Executive Angela Martin
Administrative Assistant Yolanda Jones
Aeromodeling Editor Bob Hunt
Associate Editor Michael Ramsey
Director of Design/Production Carla Kunz
Executive Editor Elizabeth Helms
Graphic Designer Sarah Shaw
Managing Editor Shelia Ames Webb
Production Associate Jennifer Orebaugh
Stan Alexander
Bob Angel
Darwin Barrie
Bill Boss
Paul Bradley
Sal Calvagna
Mark Fadely
Dave Garwood
Dave Gee
Greg Gimlick
Jim T. Graham
Eric Henderson
Jim Hiller
James Holland
Louis Joyner
John Kagan
Rich Lopez
Dave Mark
D.B. Mathews
Dennis Norman
Dean Pappas
Richard L. Perry
Greg Rose
Red Scholefield
Gene Smith
Joe Wagner
Technical Editor Bob Aberle
If you are considering a
multiengine model, the
first step will probably be
(and should be) a twin.
6 MODEL AVIATION
08sig1.QXD 6/22/07 12:29 PM Page 6
Edition: Model Aviation - 2007/08
Page Numbers: 6