FREE FLIGHT SPORT - 2004/08

ONE OF MY favorite model designers of the
late 1950s was Keith Laumer. His sport FF
designs were unique and downright cute. The
ones that keep popping into my head are the
Twin Lizzie, the Zoomerang, the Curvette, the
Dan’l Boom, the Dub-L Dek-R, and the V
Girl.
These models were powered by the 1⁄2A
engines of the day: the Atwood and Cub
.049s. Appropriate power plants today would
be the Cox Pee Wee .020 or a motor such as
the HiLine Dual Mini 6. I never built one of
Keith’s models as a kid, but I will remedy that
this year.
While checking out FF sites on the
Internet, I found an airplane that looked
similar to Keith’s Dan’l Boom. The builder
was James Caley—the man behind JCI tissue.
He sent me the following information on the
model.
“I am flattered that you would take an interest in my Boombox,
and would be honored and delighted to have it shown in Model
Aviation. I loved the designs of Keith Laumer also, and I am a fan of
his excellent science fiction stories.
“I built the original Dan’l Boom first and it was a fun airplane to
build and fly. It finally flew away while flying in a small field
surrounded by a residential area. I decided to build another, but made
some modifications.
“The Dan’l Boom had polyhedral; I decided to make it just
dihedral. The wing planform was changed to a straight taper of 33
inch span. The original ‘boom’ was solid balsa. I slightly enlarged the
cross-section and made it with a ‘keel’ of 3⁄32 inch balsa with a couple
formers and 1⁄32 inch sheet wrapped around to give the cross-section a
sort of ‘football’ shape. The fuselage is sheet balsa, and the entire
airframe is covered with JCI Japanese tissue, clear doped only.
“The Boombox weighs 7 ounces ready for flight. The DT is just
the old fuse type, with the snuffer tube sticking out the back of the
boom. The vertical stabilizer is attached to the horizontal stabilizer.
134 MODEL AVIATION
Gene Smith, 1401 N. Husband St., Stillwater OK 74075; E-mail: [email protected]
FREE FLIGHT SPORT
James Caley’s Boombox is modified from Keith Laumer’s Dan’l Boom. This version was
lost to a thermal despite a DT. Kits are available from James for $45.
Bob Schlosberg’s CO2-powered Twin Lizzie. Its high-drag
fuselage helps keep it out of the clutches of thermals.
Al Lawton’s great-flying Greyhawk Embryo features the wheel
pants and windshield necessary to garner bonus points.
The Easy Built Luscombe Phantom is a cutie and a good flier. Fly
it for fun or in FAC Dime or Old Time Kit Scale.
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“After the usual test glides, and with the propeller on backward for
decreased power, the model flew great from the first flight. The model
flies left in power and glide and uses a little down and left thrust.
“I used to fly in a small field. I never went for much power, speed
or altitude and always used a slightly larger propeller than the one that
comes with the Pee Wee. The model flew slowly and was very stable.
Kylie with Dennydart. If you shrink or dope the tissue on these
light models, they will warp like potato chips.
Raven is one in a series of six 18-inch-span rubber-powered
designs once sold by Frog model kit company in England.
With a full tank it got up about 300 feet, in left turning circles of
perhaps 100 feet. The Boombox pictured flew OOS [out of sight] one
windy day at my small field! I shall build another soon.”
James makes a kit of the Dan’l Boom, which includes Japanese
tissue and turned balsa wheels. He sells it for $45 plus $5 shipping.
For the kit and JCI tissue, contact James at JC Industries International,
655 State College #19, Fullerton CA 92831, or on the Web site:
www.jcimodels.com.
More Sig Cub Fans: Ohioan David Narance has built eight or nine
Sig Cubs because they are great for experimenting. He has found that
the following changes help his models.
1) Add a second 1⁄8-inch square spar down the main wing, along
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136 MODEL AVIATION
check out the site. Many libraries can help
you with computer services.
The tail surfaces are 1⁄16 sheet balsa. One
problem with this type of construction is its
tendency to warp, but one of the builders in
the cookup reminded me of a simple
technique to prevent that problem.
Cut a circular piece of balsa from one side
of the stabilizer that is approximately twothirds
the width of the stabilizer. Rotate the
cutout 90° and glue it back in place. Now the
grain of the body of the stabilizer is along its
length and the grain of the circle is along its
width; this stiffens the stabilizer and helps
prevent warps.
Check out the FFCU at www.smallflying
arts.com/index.htm. Click on Flying Model
Forum. Then under SFA Forum, click on F/F
Sport Builds. Go to Frog Senior Series, and
you will find the Frog series thread complete
with many building and flying tips.
The following is a brief flight report on my
Raven, which I built to the 18-inch span. I
used a 6-inch Peck-Polymers propeller with a
15-inch loop of 1⁄8-inch rubber, which I
anticipated would be a bit weak.
Trimming started with 3° of right thrust
and 3° of downthrust. With 300 winds, the
model flew straight away roughly 50 feet. I
added a shim for more right thrust to get a
right turn. Then 500 winds got a nice right
turn until the power ran down, and then the
right turn tightened. I tweaked a small amount
of left rudder. Then 800 winds gave a nice
right turn and a slightly nose-down glide.
I will conduct the next tests with a
stronger motor, which should move the CG
back a bit and give a better climb and glide.
The model is diving a bit after launch and
may fly better with less downthrust. Your
results may vary.
Grandkid’s Corner: If you are looking for
simple models for the grandkids, check out
www.luminet.net/~bkuhl/Dart.htm. In
addition to the Delta Dart, the site shows
some helpful conversions for improving the
Guillow’s Strato Streak.
The site also plans for a flying wing and
the Dennydart, which is a great-flying stick
model designed by Neil Dennis, 7940
Cadwell Rd., Bliss NY 14024. He is selling a
bundle of three Dennydart kits for $12
postpaid Priority Mail. Pay by money order
or PayPal. To contact Neil or to order with
PayPal, E-mail [email protected].
Easy Built Models has relocated to Alabama
and is actively producing kits, including
several new additions. A couple of those are
the Jimmie Allen Blue Flash Racer, which is
a laser-cut kit, and the Luscombe Phantom,
which is a print wood kit. Both are eligible
for Society of Antique Modelers competition
and a few of the Flying Aces Club events.
A color catalog is $3 or free with an
order. You can order online at www.easy
builtmodels.com, and most orders ship the
next business day. Easy Built Models’
mailing address is Box 681744, Prattville
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the bottom of the panels, and located
approximately 1 inch back from the top spar
to resist wing warps.
2) Add extra 1⁄8- or 3⁄32-inch square
diagonals on tail sections to resist warps.
3) Use the provided wing pylon pieces as
a template, but recut and add 1⁄4 inch more to
allow the pylon to extend down the side of
the solid-balsa fuselage. This helps prevent
the wind from moving the wing off-center.
4) Instead of using the provided brass or
aluminum tubing “bearing,” build a beefedup
front end to accept a Peck-Polymers
(large) nylon thrust bearing. This allows for
smooth power transmission.
David has learned that the Cubs seem to
hold up better with these modifications.
A couple of his Cubs have been powered
with motors, three have been powered with
Telco, Brown, and Modela CO2 motors, and
one has been highly strengthened and
enlarged to accept a Pee Wee .20 engine. All
have flown well.
For more information about the Sig Cub,
see this column in the August 2003 MA.
Go for the Silver: There are a variety of
ways to obtain silver tissue for that Mustang
or similar project. I have seen good results
with aluminum powder in clear nitrate dope
and with silver Floquil/nitrate mix.
Hal Schwan advised me of a method I had
not seen. He uses Testors Metalizer paints.
Made for plastic models, these paints must be
airbrushed, but Hal says they cover quickly
and are the lightest he has found. They are
thin enough to airbrush right out of the bottle.
There are “Buffing” and “Non-Buffing”
varieties. When applied to a smooth, hard
surface, such as a finished cowl, the Buffing
variety can be polished to a high gloss. Seal
the silver with clear nitrate. You would use
the “Non-Buffing” type for tissue over open
framework. Hal sent me a small patch of
silver tissue he had painted. It really looks
good.
Greyhawk Embryo: Al Lawton designed a
birdlike Embryo, and it has been a reliable
performer. Keep in mind that bonus points
are awarded for wheel pants, simulated
exhaust, and a cockpit.
This model uses a Silly Putty/cocktail
straw timer for the DT. Because of the
stabilizer’s location, it would have been
difficult to raise the entire stabilizer. Instead,
Al pops up the elevator and gets an effective
DT.
Flying Frogs: The Free Flight Cookup
(FFCU) group had a group build of the Frog
simple series this spring. The models are cute
as can be and go together relatively easily.
They are all variations on a central theme and
include biplane, shoulder-wing, and twin-tail
designs.
You can find the plans on Mike Stuart’s
Web page: www.thestuarts.eclipse.co.uk/. If
you do not have a computer, ask a friend to
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