Free Flight Duration - 2011/05

News about the unofficial E-36 event
[[email protected]]
Free Flight Duration Louis Joyner
Also included in this column:
• 2010 America’s Cup results
• Lighten up with F1G Coupes
• Carbon-fiber pultrusions
John Oldenkamp designed his Joule Box for the new E-36 rules, which allow any type of motor and nickel or Lithium cells. This model
was featured in a recent issue of the NFFS Digest, Free Flight. Plans courtesy NFFS Digest.
Junior flier Brian Pacelli had a good 2010,
with a first in the multicontest America’s
Cup and a second at the Junior World
Championships in F1B Wakefield. Winding
rubber motors is done outside the model,
and then the wound motor is installed. Lisa
Pacelli photo.
Brian flies F1B models by Stephan
Stefanchuk of Ukraine. As do most
modern F1B aircraft, they feature
extensive use of carbon fiber in wing and
tail structures and timer-operated auto
surfaces. Pacelli photo.
THEE-
36EVENT
began as an
inexpensive introductory class for electric
FF, much as P-30 has served as a gateway
event for rubber power. The original E-36
rules limited projected wingspan to 36
inches and restricted power to four nickelbased
cells and a brush-type motor.
With the power thus limited, E-36
performance was closer to that of an
underpowered Rubber model—hardly the
exciting stuff needed to draw large numbers
of modelers to a new event.
A year ago, the National Free Flight
Society (NFFS) formed a committee to
investigate ways to improve performance,
take advantage of technological advances in
motors and batteries, and make E-36 more
attractive to both beginners and experienced
modelers. The Electric Power Subcommittee,
chaired by David Mills with members Jim
Jennings Jr., Dick Ivers, Bernie Crowe,
and Mark Covington, came up with new
rules.
But it wasn’t a backroom deal. Instead,
the committee solicited comments on the
NFFS forum and discussed suggestions on
the Internet. In addition, committee
members and other modelers built and
tested models to fit the new rules.
Because E-36 is not an official AMA
event, the committee was able to avoid the
take-it-or-leave-it system of rules changes
May 2011 119
05sig4.QXD_00MSTRPG.QXD 3/23/11 11:09 AM Page 119
On this 2.5-gram stabilizer, thin carbon-fiber strips glued to the
top and bottom of a full-depth balsa spar markedly increase
strength while keeping weight low. The TE is a trapezoid-shaped
carbon pultrusion. Column contains weight-saving tips and sources
for carbon-fiber pultrusions.
Printed circuit board provides an alternative to plywood for
stabilizer mounts. A slight reduction in the size of the mount
saved approximately 10% in weight.
The incidence adjustment screw for the new model (foreground) is
made from a small VIT adjuster button; the old fitting is a 2-56 nylon
screw in a threaded block of basswood. Booms are carbon-fiber kite
spars from A2Z Corp.
used for AMA events. The group’s approach allowed people who
actually fly the event to participate in developing and voting on
the rules.
“At some point an effort will be made to make E-36 into an
official AMA class,” said David Mills. “Hopefully we’ll have a
couple of years experience to finalize the rules.”
The new rules keep the original 36-inch-span limit but allow
any type of motor and permit the use of either six nickel cells or
two Lithium cells. Geared and folding propellers are allowed, but
auto surfaces are not.
The minimum flying weight is 120 grams. The motor run for
the first three flights has been reduced from 25 to 15 seconds.
The max remains at 120 seconds for all flights. The first flyoff
flight is made with a 10-second motor run; after that it drops to 5
seconds.
You can find more detailed information about the new rules
on the NFFS Web site. In addition, the Electric Power
Subcommittee is making a determined effort to support the event
with articles, plans, and technical information.
Bernie Crowe wrote an article about his Slick Willie E-36
design for the January 2011 Free Flight Quarterly. The piece
includes detailed drawings of the model, construction tips, and a
rundown of all of the electrical components needed.
David Mills said:
“I suspect E-36 will function much like P-30 has, as a good
entry-level class. We can give credit for this stair step approach
in cost and complexity up through the electric classes (E-36, A
Electric, B Electric and F1Q) mainly to Jim Jennings.
“Maybe we’ll look back on 2011 as the year electric power in
free flight really took off.”
120 MODEL AVIATION
05sig4.QXD_00MSTRPG.QXD 3/23/11 10:27 AM Page 120
May 2011 121
John Oldenkamp, one of the fathers of the
popular P-30 Rubber event, has been very
active with electric power. His Joule Box
design, recently featured in the NFFS Digest,
offers an easy entry into electric.
The all-balsa model features full-depth
spars and diagonal ribs to stiffen both wing
and stabilizer. Flat-bottomed airfoils and
squared-off lines should make it quick to
build. The wing area is approximately 190
square inches.
The America’s Cup, which the Southern
California Aero Team created and Jim
Parker administers, offers a multicontest
format that encourages modelers from the
US, Canada, and Mexico to compete in FAI
FF events.
Points are awarded at each contest, with a
first receiving 25, second 20, third 15, fourth
10, and fifth 5 points. Additional points are
awarded depending on the number of
contestants flying in the event. The best
results from four contests are counted.
To encourage travel, only two contests at
any one site can be counted; the other two
results must be from two other sites. In case
of a tie, results from more contests are
counted. You can find detailed rules for the
America’s Cup on the NFFS Web site.
The winners for 2010 are:
• F1A Towline Glider: Jim Parker
• F1B Wakefield Rubber: Brian Pacelli
• F1C Power: Don Chesson
• F1P Power: Bob Hanford
• F1G Coupe: Ed Vanlandingham
• F1H Towline Glider: Brian Van Nest
• F1J Power: Austin Gunder
• F1Q Electric: Julie Parker
• F1E Glider: Peter Brocks
In addition to winning F1B, Brian Pacelli
placed second in F1P. He is a three-time
member of the US Junior FF team and, at age
17, is eligible to try for a fourth team spot for
the 2012 Junior World Championships.
At the 2010 Junior World
Championships, Brian placed second in F1B
and third in F1P.
“Not bad for a kid who picked the event
[F1B] simply to ensure a full US Junior
Team in Romania,” said his mother, Lisa.
“All I had to do was drive and fly him
around the world for competitions, time him,
and be proud, so it wasn’t that much of an
effort for me.”
Flying a pair of Stefanchuk F1B models,
Brian scored four firsts and a third to garner
109 America’s Cup points, edging out Open
flier Blake Jensen by 2 points.
Other recent members of the US Junior
team did well in the America’s Cup, with
Timothy Barron placing second in F1A and
Taron Malkhasyan earning fifth in F1P.
Former Junior World Champion Austin
Gunder, who has graduated from Stanford
and is working at AeroVironment, placed
second in F1C in addition to his F1J win.
Lightening Up: After years of building F1B
Wakefield models, I started working on
some F1G Coupes. Sizewise, they aren’t too
different. A typical F1B has approximately
250 square inches of wing area; a typical
Coupe’s is roughly 170-210 square inches.
But the minimum airframe weight for an
F1B is almost triple the 70-gram minimum
weight for a Coupe. It has been a challenge
for me to build down to that weight, but I
have learned a few things.
• Begin with a budget. Weigh all purchased
parts first. In my case that’s the front end,
motor tube, tailboom, timer, and tracking
transmitter. Be sure to include the small bits
such as the bobbin, rear peg, timer mounting
screws, and hold-down rubber bands.
Total those numbers and subtract from
the required minimum weight to find how
many grams you have to spend on the rest of
the model.
Many AMA events have no minimum
weight. However, you shouldn’t use that as
an excuse to pay no attention to weight.
Look at suggested weights for similar aircraft
and use that for a guide.
• Use your scale. Weigh each sheet of balsa
and write the number in grams, along with
the density in pounds per cubic foot, on the
label. (On the Internet you can find
convenient charts for converting sheet
weight to density.)
You should weigh each piece of your
model before it goes on. Is it the lightest
piece of wood you could use? Is it strong
enough but not too strong?
History Preserved
Discover the evolution of the AMA logo, read
excerpts from the  rst issue of Model Aviation, or
kick back and laugh at aviation comics dating back
to 1916. To celebrate the Academy’s 75th anniversary
this year, the AMA Web site is featuring snippets of
organizational and aeromodeling history, covering a
wide array of topics.
Posted each ! ursday, these vignettes are
complemented by plenty of photos and quotes.
To view these features, click on “AMA and Model
Aviation History Moments” on the National Model
Aviation Museum Web page—www.modelaircra" .org/
museum—or go directly to www.modelaircra" .org/
museum/factoids.aspx. MA
www.modelaircraft.org/museum www.ama75.com
The Cover of Model Aviation, vol. 1, no. 1, May 1936.
05sig4.QXD_00MSTRPG.QXD 3/23/11 10:29 AM Page 121
Use lighter wood for wingtips, tails, and
other extremities and heavier wood for more
highly stressed areas.
• Keep notes. If you weigh as you go and keep
accurate, detailed records, in time you will
develop a database. This information can be
invaluable in designing and building
subsequent aircraft.
I wanted to use a carbon-fiber D-box for
two Coupes. (See the February Duration
column.) By carefully weighing the F1B Dbox
skins I had, I was able to calculate the
weight of 1 square mm. In that case it was
.000307 gram. Then I could calculate the
weight of the D-box skins for the size I wanted
to use for the Coupe.
I found that reducing the chord of the Dbox
by 1mm saved 0.7 gram. I ended up
cutting the D-box chord from 25% of the wing
chord to 20%, saving almost 7 grams.
• Easy on the glue. There is no need for a
heavy fillet of glue with a perfectly fitted joint.
When working with epoxy or Titebond, I
apply a coat to the surface and then blot off
excess. Although a folded paper towel will
work, I prefer wedge-shaped foam makeup
sponges.
• Consider the alternatives. A 36-inch-long
piece of 8-pound-per-cubic-foot 1/2-inch TE
stock weighs approximately 3.6 grams. A
similar length of 1.6mm trapezoid-shaped
carbon-fiber pultrusion weighs 1.2 grams.
For full-depth spars and ribs, you can build
with extremely light balsa and add thin
carbon-fiber caps top and bottom. The result
will be both lighter and stiffer than a
conventional all-balsa structure.
• Think small. Don’t make things bigger or
heavier than they need to be.
For stabilizer mounts I use printed circuit
board; it is stiffer than plywood and just as
easy to work. Reducing the size from 11 x 30
mm to 7 x 26 mm saved 1/10 gram.
The stabilizer adjustment screw went from
2-56 nylon to a much smaller steel version in
an aluminum fitting, saving an additional 1/10.
The fitting is actually a VIT (variableincidence
tailplane) fitting I repurposed from
one I purchased from Mike Woodhouse’s Free
Flight Supplies some years back.
• Sand and then sand some more. Keep a scale
handy while you are sanding; you’ll be
amazed by how much all that dust weighs.
• Choose coverings carefully. Typical choices
for smaller models can range from
approximately 2 grams per square meter to
more than 30 grams. On a 200-square-inch
wing (with a total area of 400 square inches),
that can mean a weight range of roughly 1/2
gram to more than 7 grams.
122 MODEL AVIATION
Remember that covering weight can
include adhesive and dope, as well as the
weight of the covering material. It’s easy to
find lists of coverings on the Internet, but
make sure you compare like units.
I find grams per square meter easiest to
work with, but you might prefer grams per
square foot. There are 10.7639 square feet in a
square meter and 0.0929 square meter in a
square foot.
Carbon Pultrusions: Tim Goldstein’s A2Z
Corp offers a large selection of carbon-fiber
pultrusions from Van Dijk Pultrusion
Products in the Netherlands. The most useful
shapes for FF are rectangle and trapezoid.
Rectangular shapes come in thicknesses
ranging from 0.12mm to 1.1mm and in widths
from 1.0mm to 8.0mm. Most pieces come in
1-meter strips.
However, the thinnest stock—0.12mm
thick—comes in 10-meter (33 foot) rolls in
1.0mm, 1.5mm, 2.0mm, and 3.0mm widths.
Those are useful for rib caps or for spar caps
on small models such as P-30s.
The trapezoid-shaped pieces come in 1-
meter lengths and widths of 1.6mm, 3.0mm,
and 3.8mm. They are perfect for TEs.
The 2005 NFFS Symposium featured a
piece by Maarten Van Dijk about the
manufacturing process. The Van Dijk
Pultrusion Products Web site contains
information about both process and product.
Free Flight Supplies also sells Van Dijk
pultrusions. MA
Sources:
Free Flight Quarterly
www.freeflightquarterly.com
National Free Flight Society
www.freeflight.org
Free Flight Supplies
www.freeflightsupplies.co.uk
A2Z Corp.
(877) 754-7465
www.a2zcorp.us
Van Dijk Pultrusion Products
www.dpp-pultrusion.com
AMA Academy of Model
Aeronautics
ARF Almost Ready to Fly
BEC Battery Eliminator Circuit
CA cyanoacrylate glue
CAD computer-aided design
cc cubic centimeter
CD contest director or
compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted (noise
power calculated in dB
[decibel])
DT dethermalizer
EAA Experimental Aircraft
Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed Control
EPS expanded polystyrene foam
FAA Federal Aviation
Administration
FAI Fédération Aéronautique
Internationale
FCC Federal Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000 volts)
LCD Liquid Crystal Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal Hydride
OD outside diameter
RC Radio Control
rpm revolutions per minute
RTF Ready to Fly
SASE self-addressed, stamped
envelope
SIG Special Interest Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations /Acronyms
05sig4.QXD_00MSTRPG.QXD 3/23/11 10:51 AM Page 122