Free Flight Duration-2011/08

The 2011 Symposium is available
[[email protected]]
Free Flight Duration Louis Joyner
Also included in this column:
• FF World Championships
• Britain’s Free Flight Forum
• Phil Ball’s Waif Mk3
• Dihedral sanding jig
Made from plastic-covered shelf material, this jig is used for sanding rib
ends to the correct angle to give the desired dihedral. Thick carbon-capped
ribs on this Coupe wing can be butt-glued together.
Left: Phil Ball’s Open Rubber model makes extensive use of carbon-fiber
components including the tubular fuselage and molded D-box for the wing’s LE.
The model is featured in the 2011 Free Flight Forum.
2011 FREE FLIGHT World
Championships: In F1A Glider, Russia
scored a team first and team member Yury
Titov took the individual first. The
highest-placing American was Brian Van
Nest at 12th.
In F1B Wakefield Rubber, Russia’s
Alexander Milyutkin placed first and
Alexander Andriukov of the US was
second. Team first went to Israel and the
US placed third.
Ukraine’s Eugene Verbitsky placed
first in F1C Power. Faust Parker was the
highest-placed American at eighth. The
team prize went to Ukraine and the US
placed second.
The National Free Flight Society’s
(NFFS) 2011 Symposium is out. This
year’s Sympo editor, David Lacey, is
focusing on the needs of the average FF
modeler. “I have a number of authors
writing tips and personal experiences to
help the intermediate advance to a higher
stage,” says David.
Some of the topics covered include
trimming gas models, Discus Launch and
Catapult Gliders, electric power for Flying
Aces Scale, electric power and helicopters
for Science Olympiad, selecting covering
material and applied weights, engine
balancing, and information for FF
newcomers.
Subjects with a more technical focus
include an explanation of the relationship
between CG and tail volume coefficient, 3-
D analysis of F1A Towline Gliders, and
Hand-Launch gliding.
An exploration of the effects of aspect
ratio and flight times points out that
increased wing-aspect ratio and the use of
folding propellers are responsible for the
dramatic increases in glide time for F1C
power models.
Surprisingly, the altitude gained in the
climb has remained relatively constant
throughout the last 60 years as the
increasing power of engines has been
canceled out by shortening of engine runs
by the rules makers. Cuts throughout the
years have reduced motor runs from
20 seconds to the current five seconds.
Models of the Year chairman, Mike
Fedor, along with committee members
Rob Romash, Dick Mathis, and Don
DeLoach, have selected 11 models for
2011. Two will be familiar to many
modelers. Wally Simmers’ Gollywock
Rubber model dates back to the 1930s and
has been built by tens of thousands of
modelers. It is still a competitive design
for Old-Timer events.
Tom Hallman’s Peanut Scale
Mitsubishi 1MF1 biplane graced the
February 2011 cover of MA. Other models
selected include Tony Mathews’ F1B
Wakefield with the Brian Eggleston (BE)
low-drag airfoil (LDA) wing; Artem
Babenko’s F1C Folder; Evgeny Gorban’s
F1G Model 2010 Coupe; and Jim Buxton’s
record-breaking Amalgam 6 Indoor Hand-
Launch Glider (featured in the January
2011 issue of MA).
Two other indoor designs selected were
Bill Gowen’s A-6 and Tom Iacobellis’
Limited Pennyplane. Jean Pailet’s Genie
Redux 1/2A F1J design and the F1Q
Electric model by Matti Lihtamo and Serei
Vorihvost round out the selections.
Modelers selected for the Free Flight
Hall of Fame include Larry Coslick, Larry
Davidson, David Linstrum, John
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130 MODEL AVIATION
Above: A digital angle meter is used to set the desired angle.
Shims can be added or removed for coarse angle adjustments.
Right: The top is attached to the fixed-base block with a piano
hinge. The adjustable base block supports a piece of half-round
molding.
O’Donnell, and Bill Vanderbeek. The late
father-and-son team of Bob and Bill
Hunter, who gave us the Satellite Gas
design and Hot Stuff adhesive, was also
honored. Rex Hinson chaired the Hall of
Fame selection committee which included
Fred Terzian, Jim Juhl Sr., Abram
VanDover, and Don DeLoach.
The 2011 Symposium is available from
NFFS Publications; ordering information
can be found on the NFFS website.
The British counterpart of the NFFS
Symposium is the Free Flight Forum, now
in its 27th year. The latest offering, edited
by Mike Evatt, includes a rich mix of
articles focused on construction and the
more practical aspects of FF. There’s
precious little theory in this year’s
publication.
Ian Kaynes, longtime editor of Free
Flight News and chairman of the
International Aeromodeling Committee
(CIAM) FF subcommittee, has put
together a thorough account of F1E Slope
Soaring Gliders.
Ian included a number of graphs
showing the calculated affects of model
weight and size on performance in
different wind conditions. Of more general
interest is his detailed description of the
foam-wing construction for his windyweather
model.
Chris Edge offers an interesting method
for constructing an undercambered wing
without the use of the usual lower-surface
jig. He uses an idea developed by Peter
Allnutt that utilizes laser-cut ribs, each
with a “border frame.” (Imagine a wing rib
centered in a rectangular piece of balsa.)
The border frames serve as jigs,
precisely positioning each rib above a flat
building board while spar, D-box shell,
and TE are attached. The big advantage of
this method is that it allows construction
of a one-off wing without the trouble of
building a lower-surface jig that might be
used only once. It also permits building a
wing with an airfoil that changes from root
to tip. You can read more on the FlyQuiet
forum listed in “Sources.”
Mick Lester offers a technique for
rolling your own tubular carbon-fiber spars
as well as an interesting idea for cutting
carbon cap strips using a small circular
saw.
Neil Cliff explores a variety of
innovative construction techniques
including tubular spar construction using
carbon-fiber stock and an unusual
technique for molding balsa D-boxes. He
also explains several clever ways of
making traditional stick-and-tissue
fuselages for Rubber models.
Bryan Spooner’s “Laminated Propeller
Blades” explains the use of a spreadsheet
to lay out a mold for Rubber model
propellers. Ray Elliott also deals with
propellers—single-bladers for F1B.
Peter Halman explains the design
evolution of the Irvine 15R-HS and HS15
engines. It’s fascinating.
But even the best model needs to be
launched into good air. In separate articles,
Roy Vaughn and Peter Brown explain their
approaches to electronic air-picking
devices.
As with the 2010 Forum, this edition
includes a gallery of the most successful
British models from the previous year,
including Ray Hall’s modified version of a
1959 semiscale Gas model that won the
Bowden Trophy, an event that scores not
only duration but also flight realism and
the style and quality of the model.
Peter Brown’s Coupe features delayed
propeller release (DPR), variableincidence
tailplane (VIT), wing wiggler,
and larger-than-usual propeller of 520mm
diameter (roughly 20.4 inches). Phil Ball’s
Waif Mk3 Rubber model is designed for
the British Open Rubber.
Mark Benns’ latest iteration of his
Spin-Up series of Discus-Launched
Gliders is also honored. Designed to
handle wind and turbulence, the models
feature composite wings of carbon cloth
vacuum-bagged over a Rohacell foam
core.
Clive King’s Chuckit is a low-ceiling
indoor hand-launched glider that uses
flexible wing flaps that deflect on launch
for minimum drag; they bend back down
for the glide. The 15-inch-span model
weighs 2.5 grams.
At the other end of the size spectrum is
Mike Smith’s electric-powered scale
model of the de Havilland D.H.10c
biplane bomber with a 66-inch wingspan
and more than three pounds in weight.
Needless to say it was a multiyear project.
You can see other examples of his work
on the Free Flight Scale website listed in
“Sources.”
Copies of the 2011 Free Flight Forum
can be ordered from Martin Dilly or from
NFFS Publications.
Waif Mk3: One of the models detailed in
the 2011 Free Flight Forum is Phil Ball’s
Rubber model built to the British rules
introduced a few years back. Unlike the
unrestricted American Mulvihill rules,
British rules limit Rubber weight to 50
grams (roughly 1.7 ounces).
Phil’s model makes considerable use of
carbon fiber to produce a model that is
stiff and light; airframe weight is 77
grams with roughly 250 sq. in. of wing
area. The motor tube is made from two
layers of 100-gram-per-square-meter
carbon cloth. It measures 32.5 inches and
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August 2011 133
weighs 22 grams.
The wing uses a carbon-fiber D-tube
from Szabo in Hungary. Each tube weighs
approximately 3.5 grams and is roughly
520mm (20.5 inches) long. Originally
intended for F1A stabilizers, the D-tube
provides both torsional and bending
strength for the 22-gram wing. The TE is
carbon fiber and the ribs are carbon
capped.
The 25-inch-diameter, 30-inch-pitch
propeller is carved from ½-inch sheet
balsa. The rubber motor is 27 inches long
and takes between 900 and 1,000 turns; the
propeller run is more than two minutes.
Dihedral sanding jig: After years of
makeshift arrangements, I finally made a
dedicated jig for sanding the angled
dihedral joints for wings. Previous
methods had included the old standby of
propping up the wing half at the edge of a
table and sanding in the dihedral and the
table.
Another approach used a fine-tooth
blade in a table saw, but that method
required a sacrificial piece of wood
underneath the wing to prevent tear-out.
The new jig consists of a base to guide
the square sanding block, a hinged section
to hold the wing, and an adjustable block
to set the angle. Borrowing an idea from
sine blocks used in machine shops, I used a
piece of half-round molding on top of the
adjustable block. For small angle
adjustments the adjustable block can be
moved closer or farther away from the
hinge. To extend the range, I made a
couple of extra shims that can be added to
raise the adjustable block.
Most of the jig is made from readymade
shelving available at most big-box
home centers. The shelf I used was 12 x 24
inches. It’s plastic-covered particle board
that cuts easily with a table saw. The base
measures 8 x 14½ inches; the hinged top
plate is 6 x 11½ inches (be sure to cut this
piece so one short end has a finished
edge).
There are two other pieces, each 3 x 8
inches. One is attached permanently to the
base 2 inches from the end with a finished
edge facing the narrow edge of the base.
Glue doesn’t work well with the shelf
material, but screws do. To attach the top
plate to the base block I used a short
section of piano hinge.
The second 3 x 8 piece serves as the
bottom of the adjustable block. I cut several
8-inch-long pieces of 3/8 x 1½-inch pine for
spacers. One is topped with a 6-inch-long
piece of ½-inch half-round molding. The
spacers can be added or removed for gross
adjustments, and the adjustable block
moved for fine adjustments.
To set the angle I use a digital angle
gauge; mine is from Woodcraft, but some
of the discount tool and supply places also
carry them. First, set the gauge on the base
to zero, then place on top of the hinged
piece and move the adjustable block until
the desired angle is reached. Then, clamp
or screw the adjustable block down.
Remember that the angle should be half
the desired dihedral angle since you will
be sanding both panels. Sanding only one
would result in unequal heights at the joint.
For sanding, I use a piece of 2 x 2
hardwood from a big-box store. Take an
accurate square with you to check that the
piece you buy is square. Attach medium
sandpaper to one face. Add a 1 x 2 pine
strip to the bottom of the 2 x 2, offsetting
the 1 x 2 slightly so it is flush with the
surface of the sandpaper. The 2 x 2 will
ride against the finished edge of the first 3
x 8 block.
Dimensions are not critical so make the jig
any size you like. The important thing is to
make sure that both the fixed and adjustable
blocks are square to the base. MA
Sources:
National Free Flight Society Symposium
http://bit.ly/lzhQdZ
National Free Flight Society
www.freeflight.org
FlyQuiet FF Forum
www.flyquiet.co.uk
Martin Dilly
[email protected]
Free Flight Scale
www.freeflightscale.com
Szabo
Vasas Gyorgy
[email protected]
Woodcraft
(800) 225-1153
www.woodcraft.com
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