Free Flight Duration - 2008/08

152 MODEL AVIATION
An overview of the 41st NFFS Symposium Report
[[email protected]]
Free Flight Duration Louis Joyner
Also included in this column:
• British Free Flight Forum 2008
• Trimming the Dixielander
• Smoothie timers
• Instead of balsa ...
• Witch Hawk
• AMA Gas info
George Fuller’s Dixielander is now legal for NFFS Nostalgia Gas. Three-views from a
1959 Aeromodeller show built-in adjustments that allowed the 350-square-inch model to
handle a .15.
Based on George Fuller’s Dixielander, the author’s 36-inch-span
1/2A from the early 1960s flew right off the board.
FF Hall of Famer Reid Simpson’s R60 A/B Gas airplane is a Model of
the Year. Based on F1C technology, the 110-inch-span design uses a
six-panel wing and carbon-aluminum boom. Power is a B&B 3.5.
THE NATIONAL FREE Flight Society’s
(NFFS’s) annual Symposium Report, better
known as the Sympo, serves as a source of
the latest technical information and provides
a historical record of the evolution of FF.
For the 41st edition, editor Rick Pangell
pulled together articles covering a wide
range of FF topics.
Daniel Petcu continues his F1E Sympo
series with a piece about bunting. The F1E
class, long popular in Europe, has gained
interest in this country. The models are
large, Nordic-size Gliders that are handlaunched,
much like RC Slope Soaring
aircraft. But F1E models use a forwardmounted
fin fitted with a magnet for
steering.
Peter McQuade explores the effect of
bank angle on towing stability of F1A
Gliders. Brian Eggleston and Peter Allnut
teamed up to prepare a paper about the use
of Internet tools to design an F1A airfoil.
Brian did the theoretical work and Peter
built the test model. Rubber guru Fred
Pearce looks at the effects of stress-induced
crystallization on rubber strip.
George Mansfield’s “Systems Approach
to Design and Build an FAC Scale Model”
offers suggestions for optimizing
construction methods and material selection.
Although geared toward the popular Flying
Aces Club Scale models, the information
should be helpful for nonscale-model types.
Texas Timers owner Hank Nystrom looks at
the mechanical timer’s history and future.
The 2008 Models of the Year, selected
by Bill Booth and committee, include Mark
Benn’s Spin-Up 36 tip-launch glider, Tim
Batiuk’s record-holding Turn-Up tip-launch
glider, and Reid Simpson’s R60 A/B Gas
model.
In addition, special awards go to Roger
Morrell for the Southern California Aero
Team Electronic News (SEN), to Ray
Harlan for his extensive line of Indoor tools
and supplies, and to Jim Parker, Walt Ghio,
and others for the Junior F1P Program. See
the May 2008 Duration column for more
about this worthwhile endeavor.
Free Flight Hall of Fame inductees for
2008 are Alexander Andriukov, Rex
Hinson, Herb Kothe, Reid Simpson, Roger
Simpson, and the late Walt Rozelle.
You can order your copy of the Sympo
from NFFS Publication Services. The price
is $30 for NFFS members and $35 for
nonmembers. Postage is $5 within the US.
Postage for orders from Mexico or Canada
is $9. Only check or money order will be
accepted for domestic orders.
For more information, contact NFFS
Publications Coordinator Bob Stalick or
visit the NFFS Web site.
British Free Flight Forum 2008: In the last
quarter century, the annual Free Flight
Forum has provided a useful mix of the
practical and theoretical, all with a
delightful touch of British humor. The 2008
version, chaired by Mike Evatt and edited
by Martin Dilly, includes more than a dozen
articles.
Peter King’s “Beyond Rubber Stretch
Testing” factors the traditional rubberenergy
test into a computer analysis of
model performance. He also looks at the
optimum VIT (variable incidence tailplane)
timing for F1B models.
Bob Bailey’s “Selection and Testing of
Balsa Wood for Indoor Duration Models”
illustrates test methods that assure both
adequate strength and light weight. In
“Measuring Success,” Mike Woodhouse
shows a variety of special fixtures he uses to
set up his F1B models with accuracy and
repeatability.
Phil Ball looks at the new British Rubber
class that was introduced last year to replace
Open Rubber. The new category limits
rubber weight to 50 grams. For many
contests, the new class is combined with
Vintage models (100 grams of rubber) and
Classic models (75 grams). “A Review of
the 2007 BMFA and Combined Rubber
Contest Season” illustrates typical models
and explores the best options for contest
flying.
Chris Strachan’s “Small Rubber Models
as an Introduction to Free Flight” suggests
both the P-30 class and the popular 25-inchspan
British kits from the past, such as the
Keil Kraft Achilles, as good starting points.
In “The Lottery of Winning” George
Seyfang looks at the variables of contest
flying. His conclusion is that the more
skilled flier with the better model is usually
unbeatable. That’s no surprise, but the
methodology is interesting.
In a second article, “Transportable Wind
Tunnels,” George proposes two wind-tunnel
designs: a small garage-size version with an
800 x 400mm test section and a trailermounted
tunnel that would accommodate
models exceeding 8 feet in span.
For the F1A Towline Glider fliers, Chris
Edge presented “Aborted Launch
Solutions,” to deal with the problem of a
premature hook unlatch. His solution is to
modify the circle tow and timer hardware
and software to allow relatching. If you
think the modern F1A is simple, you need to
take a look at this article.
Indoor flier Nick Aikman looks at new
Lightweight foam building techniques in “Lutz Schramm’s
F1D.” Instead of bent balsa, Lutz uses
Kevlar thread wetted with epoxy resin and
formed in a fixture to create the propellerblade
outline. The latest versions use carbon
fiber instead of Kevlar.
British F1C team member Alan Jack
explores thermistors and the difficulty of
finding good air in “Comments on Thermal
Picking and Related Matters in Odessa ’07.”
“Balsa for Indoor Models” by Mark
Benns explains the difficulty of selecting the
best wood and cutting it accurately. After
reading this, you’ll understand why Indoor
wood is the most expensive lumber in the
world.
For electric FF, Jonathan Crossley offers
“The Zombie Flight Profiler: Advanced
Motor Control for Electric Free Flight.” The
Atomic Workshop Zombie Flight Profiler is
a lightweight electronic module that
functions as a motor-run timer and voltagecutoff
device.
In “Safety and You!”, Manny
Williamson focuses on what the individual
can do to reduce the chance of both property
damage and personal injury. Roger Morrell’s
“Electronic Timers” takes a look at this
increasingly popular means of flight control.
He includes practical tips for installing,
setting up, and caring for electronic timers.
The 2008 Forum report is available from
Martin Dilly. The price, including airmail
postage to the US, is £14.00. (£14.00 is
approximately $30, but the exchange rate
fluctuates daily.) Make out checks to
“BMFA F/F Team Support Fund.” Since
checks must be in pounds sterling only and
drawn on a bank with a branch in the UK,
it’s much easier to pay by credit card.
Contact Martin by fax or E-mail. Back
issues of previous Forums are also available.
The 2008 Forum is also available from
NFFS Publications (Bob Stalick). The price
is $25 plus $5 postage. Checks or money
orders only on US orders; international
orders can pay by credit card, but a service
fee is charged.
Dixielander Trim: The NFFS’s Nostalgia
committee recently approved George
Fuller’s Dixielander for use in the Nostalgia
Gas event. The original design was a
compact, 350-square-inch model with an
undercambered wing airfoil based on the
NACA 6409, a high pylon, and an aftmounted
rudder. Power was a 2.5cc engine,
and the flying weight was roughly 15
ounces.
The design, kitted by Yeoman, was
among the most popular Power models in
Great Britain during the late 1950s, but it
was seldom flown in this country. The only
one I ever saw was George Fuller’s own EType
Dixielander, which he flew at the 1961
Nats in Willow Grove, Pennsylvania.
The E-Type was a stretched Dixielander
powered by an ETA .29. The wingspan was
almost 60 inches, compared to the standard
Dixielander’s 50 inches, producing a wing
area that just exceeded 400 square inches.
Before you get too excited, George
developed the E-Type Dixielander in
1959—well past the 1956 cutoff for
Nostalgia Gas. Only the original Dixielander
is legal for Nostalgia.
After witnessing the incredible climb of
George’s model at the Nats, I decided to try
my own 1/2A variation, on the “smaller is
better” theme. I came up with, essentially, a
scaled-down Dixielander with a flat-bottom
airfoil and rudder on the bottom.
The wing measured 6 x 36 inches, giving
it an area of slightly less than 200 square
inches, which was considerably less than the
typical 1/2As of the early 1960s. Power was a
Cox TD. This design is also too late for the
Nostalgia event.
Luckily I had a copy of George’s
Aeromodeller article about trimming Power
models. I followed his suggestions
religiously. The secret to the Dixielander’s
success was the built-in settings. The wing
and stabilizer are both set at plus 3°, both
wingtips are washed out 2°, and the right
main panel is washed in 3°.
The stabilizer is set parallel to the right
inboard wing panel, to give right glide turn.
The CG is located at roughly the wing TE.
Glide adjustments are made by slightly
shifting the CG—never by shimming the
stabilizer. If necessary, adjust power trim by
slightly shimming the wing LE or TE.
My model flew right off the board, with
no adjustments whatsoever. With an all-up weight of approximately 5 ounces and less
than 200 square inches of wing area, the
climb was very fast, yet surprisingly safe. I
credit all this to George Fuller’s trim system
and recommend it without reservation if you
do try a Dixielander for Nostalgia.
Full-size plans for the Yeoman-kit
version of the Dixielander are available
from Whit Russell at NFFS Plans. The
price, including postage, is $8 for NFFS
members and $9 for nonmembers. Rolled
plans in a mailing tube are $5 extra. See the
NFFS Web site for information about
Canadian and overseas orders.
If you are an NFFS member, be sure to
read Bob Stalick’s article about the
Dixielander in the December 2007 Digest.
You can also take a look at the NFFS plans
in the January-February 2008 Digest.
Smoothie Timers: Tim Goldstein has
upgraded the Smoothie DT timer in his
Sting Aero line of Hand-Launched and
Catapult Gliders.
As do other viscous timers, the Smoothie
utilizes a rotary damper. Line tension slowly
turns an arm while a thick liquid sealed
inside the timer case offers resistance. But
line tension is critical. If there is too little,
the timer won’t rotate at all; If there is too
much, the timer turns too quickly.
Now the Smoothie timers come with an
assortment of sleeves that fit over the
rotating hub, allowing you to adjust the
leverage and rotational speed. Timers are
$9.95 each plus shipping. Also available are
the stock viscous rotary dampers for $3.95
each. These require drilling and fitting a pin
(not supplied).
Visit the Sting Aero section of the Peck-
Polymers Web site for more information
about Smoothie timers.
Instead of Balsa: For some reason, plastic
foam, which was introduced a half century
ago, has found surprisingly little use by the
FF community. I was pleasantly surprised
to see Junior flier Miles Johnson with a
foam-winged Catapult Glider at the 2007
Nats.
His model has a wing cut from blue
insulation foam using the hot-wire method.
Since hot wiring works only with straight
tapers, the wing had to be cut in four
sections and then hand-sanded with 320-grit
paper to shape the curved tips.
Then the wing was covered top and
bottom with lightweight fiberglass cloth
wetted out with epoxy resin. The assembly
was vacuum-bagged while the epoxy set.
Foam is approximately half the weight
of balsa, and it requires a surface skin for
stiffness.
“The foam by itself isn’t that strong,”
said Miles.
The fiberglass cloth that he used is the
most popular skin choice for light models,
but there are other options.
Some years back, Ramrod designer Ron
St. Jean developed a simple system using
tissue applied to foam with diluted white
glue. Larger RC models often use foam
August 2008 155
skinned with balsa sheet or even hardwood
veneer.
If you are interested in giving foam a try,
there is a wealth of information in back
issues of both the Free Flight Forum and the
Sympo. An excellent place to begin is Len
Surtees’ “Composite Wings for Outdoor and
Indoor HLG” in the 2002 Sympo, available
from NFFS Publications.
One method Len describes uses stacked
phone books instead of a vacuum bag to
attach the fiberglass skin. You can’t get
much easier than that.
Witch Hawk: In the May column, I
mistakenly credited Ralph Prey as the
designer of the Witch Hawk. Bob Watson,
who has a fleet of five Witch Hawks, Emailed
to let me know that Jim Clem
designed the model.
Ralph Prey is the author of an excellent
two-part series, “How to Adjust that High-
Powered AMA Gas Free Flight,” which was
published in the July and August 1979 MAs.
AMA Gas Info: AMA Life Member Huston
Gruen E-mailed me requesting information
about getting started in AMA Gas.
Since I haven’t touched a Power model in
more than 30 years, I did an Internet search
that turned up an excellent piece by Don
DeLoach entitled “Beginning Free Flight
Power.” You can find it on Bob Beecroft’s
Web site, which contains several other
interesting articles and dozens of links to
other FF sites. MA
Sources:
NFFS
www.freeflight.org
NFFS Publication Services/Bob Stalick
Box 1775
Albany OR 97321
[email protected]
The Atomic Workshop
(44)(0)1493 369317
www.atomicworkshop.co.uk
Martin Dilly 20, Links Rd.
West Wickham, Kent BR4 OQW
UK
Fax: (44)(0)20-8777-5533
[email protected]
Whit Russell at NFFS Plans
1375 Ridgefield Dr.
Roswell GA 30075
Peck-Polymers
(720) 833-9300
www.peck-polymers.com/store
Bob Beecroft
www.theaerosmith.com