Radio Control Giants-2011/08

104 MODEL AVIATION
[[email protected]]
Radio Control Giants Sal Calvagna
Jack Clemens builds his final Macon
WELCOME BACK.We’re smack in the
middle of summer. That means warm days,
barbecues, ice cream, and lots of RC activity.
Plan to attend one of the Giant Scale
events in your area. If gas prices are giving
you second thoughts, grab a couple of friends
and share the expense. Not all aircraft have
wings or rotors. In this month’s column there
are three fantastic models: one with three
wings, one with two wings, and one with no
wings at all.
The first model is a Glenn Torrance
Models (GTM) ¼-scale Fokker Dr.I, built by
Rudy Vinalet of Hialeah, Florida, and flown
by owner John “Chip” Koenig of Boca
Raton, Florida. The airplane received a
respectable static score of 95.898 in its first
Top Gun competition early this year.
The kit is scale in outline and appearance,
as are all GTM models. The Dr.I is powered
by an O.S. Gemini FT-160 twin-cylinder
glow engine swinging an 18 x 6 Xoar World
War I-style propeller. Rudy installed a Sonic-
Tronics/McDaniel R/C onboard glow driver.
The model is covered with Solartex
material and painted with WarbirdColors
water-based urethane. The radio is a Futaba
2.4 GHz FAAST system utilizing digital
servos. Please visit GTM’s website listed
in “Sources.”
Heyward Macdonald of
Charlottesville, Virginia,
scratch-built this nicelooking,
self-designed
Royal Aircraft Factory
S.E.5a. It took him nine
months to draw the plans
and construct the model.
The S.E.5a spans 60
inches, weighs 8.8
Above left: Look at
the amazing inner
structure of the 20-
foot rigid dirigible
USS Macon model.
Above right: Note the
balanced elevators
and rudders on the
completed rigid
airframe.
Preparing for some
limited flight testing,
Jack is leading the
airship Macon by its
tether.
Heyward Macdonald
displays his latest
creation: an electricpowered
RAF S.E.5a
with a 60-inch
wingspan. A 900-
watt outrunner
motor spins the
16-inch APC
propeller.
Also included in this column:
• Glenn Torrance Models
¼-scale Fokker Dr.I
• Heyward Macdonald’s
scratch-built S.E.5a
08sig4xx_00MSTRPG.QXD 6/23/11 1:21 PM Page 104
August 2011 105
Check out all the details in this
nice side view of the Fokker.
(L-R) Crew Chief Andy Koenig, dad and
pilot Chip Koenig, and builder Rudy
Vinalet with their Glenn Torrance Models
¼-scale Fokker Dr.I at Top Gun 2011.
pounds, and is powered by a 900-watt
outrunner electric motor. Heyward states that
he could have reduced the weight further;
however, he built the wings with the scale
number of ribs—224 to be exact.
Current wing loading is a mere 17 ounces
per square foot. Finishing touches include
homemade wheels and a sprung
undercarriage. The rudder servo is connected
through a gyro to improve ground handling
and the model has an FMA Co-Pilot II
installed in case Heyward gets into trouble in
the air. (Author’s note: I’ve seen Heyward fly
and I doubt that he’ll ever make use of the
FMA Co-Pilot.)
Nice work Heyward!
Jack Clemens of Brentwood, California,
writes that in the 1940s he did a lot of
modeling, but that family and work kept him
away from any serious projects until his
retirement in 2002.
A photo from the 1930s shows that
Hangar One at Moffett Field in Sunnyvale,
California, housed one of the Navy’s giant
flying aircraft carriers: the rigid dirigible USS
Macon (ZRS-5). The hangar, off of Highway
101, is now nothing more than an oddity for
the thousands of people who pass by on their
daily commute.
Jack believes that building a scale model
of the Macon and one day flying it in the giant
hangar would be a fitting tribute. Here’s what
Jack has written:
“The history of the Macon is welldocumented,
but in summary it was a giant
dirigible capable of carrying, launching, and
retrieving scouting aircraft to serve as the preradar
‘eyes of the fleet.’
“Distinguished from blimps that were
shaped like balloons that dangerously
distorted when flown at high speeds, the
Macon employed a rigid exterior airframe
which held its aerodynamic shape at any
operating speed. First flown in April 1932, the
Macon operated out of Moffett Field in
support of the Pacific Fleet until it was lost in
a weather-related accident off the Monterey,
California, coast in February 1935.
“The airship contained 12 gasbags for
buoyancy, a hangar deck housing up to five
Curtiss Sparrow Hawk airplanes, a trapeze
device for launching and retrieving the
aircraft, crew quarters for 50 men, eight
directed-thrust motors, and an underslung
command control cabin.
“The airframe was constructed from
lightweight duralumin girders running the
length of the cigar-shaped hull with 12 main
frames forming the circular cross sections.
The airship was immense at 785 feet in length
and over 130 feet in diameter. Six million,
five hundred thousand cubic feet of helium
filled the 12 gasbags to provide lift.
“Construction: A request to the Smithsonian
resulted in many archived photos and an
overall drawing of the airship’s interior.
Construction that matched the original seemed
the best approach using balsa wood as the
structural material for light weight. Very thin,
50 micro-inch metalized Mylar was selected
as the lightest material available to contain the
helium.
“Computer modeling allowed some fairly
decent estimates of weight and lift. In airships,
the weight increases as the square of the
dimensions whereas the lift increases as the
cube of the dimensions, so bigger tends to be
better.
“My calculations showed a size of at least
20 feet in length would be necessary for the
model to achieve buoyancy. A scale of 1 inch
to 1 meter provided the required size, which
would just fit diagonally in our two-car
garage. Patterns for the gasbags just fit onto
the available 4-foot-wide rolls of Mylar.
“Construction of the main frames (rings)
consisted of building 36 pyramids from 3/32 x
1/16-inch balsa for each of the 12 frames. The
largest of the main frames measured just over
40 inches and weighed just over an ounce.
Longerons of 1/16 x 3/16 balsa run the length of
the hull and space the main and intermediate
rings.
“A cradle consisting of a long beam and
12 Y-shaped supports was constructed to
support the hull during assembly. Each main
frame was clipped to a foam spider support
with a circular hole at the center. A piece of
plastic irrigation pipe served as mandrel to
align the rings during assembly. Two laser
levels helped keep things aligned during the
assembly. Silver Coverite MicroLite was used
to cover the hull.
“The fins were built on bench-top support
fixtures and attached to the hull individually.
Because of the concern over the weight of the
large-area fins, they were covered with 5
micron Risteen MicroLite film. Window
frames in the hull form the attachment point
for each of the small ‘Firefly’ electric motors.
Where the prototype housed the motors in the
hull and drove the propellers through shafts
and bearings, the model houses the motors on
outriggers and drives the propellers directly.
“While scale in size and proportion, the
model lacks some details of the original. The
additional weight of the launching apparatus
and aircraft were felt to be beyond the payload
of the original design.
“The control car houses the radio
electronics. Three motors on each side
provide primary propulsion while one
independently throttled motor swivels from
horizontal to vertical to provide downthrust to
aid in maneuvering during landing. Rudder
and elevator controls are actuated through a
cable and pulley system.
“Small hatches allow the deflated gasbags
to be inserted into the hull. Each bag has a
filler tube for filling with helium and a dump
vale to speed emptying spent gas. As each
gasbag is filled, the airship becomes
noticeably lighter. The ship becomes buoyant
with each bag filled to 80-90% capacity.
Weights are added to the nose or tail to bring
the model into horizontal balance.
“Flight: The original dream of flying in
Hangar One will not be possible. Since the
start of this project, the hangar at Moffett has
been declared off-limits because of
contamination from years of aircraft
maintenance in the building and deterioration
of the asbestos siding originally applied as a
fire preventative. Personnel at the Moffett
Museum are working with NASA on a plan to
fly the model in one of the two smaller
hangars at Moffett Field built to house antisub
patrol blimps during WWII.
(Editor’s note: On April 21, 2011, workers
began to dismantle and demolish the historic
former home of the USS Macon. NASA has
plans to restore the structure, but a request
08sig4xx_00MSTRPG.QXD 6/23/11 1:22 PM Page 105
for approval has yet to make it through
Congress. See the “Sources” listings for a
link to a newspaper article about the
demolition.)
“The current model is my third attempt to
finish a flying model of the Macon. I began
work on Macon I in 2003 and finished it in
early 2006. I had made a lot of mistakes and it
was on the heavy side.
“I had inflated the airship several times in
my garage to test the buoyancy and balance
and was waiting for a calm evening to test-fly
it. My wife and I went out one night only to
find the hull on the floor with a giant hole in
it. Apparently, our cat decided to use the
model as an intermediate platform when
jumping down from a high shelf where he
loved to sleep.
“While the entry hole appeared repairable,
the exit hole had destroyed the majority of the
hull. I had no idea how to jig and fixture the
remnants for repair so I stuffed the remains of
this ‘Cat-a-clysmic’ event into two shopping
bags and started on an improved (and lighter)
Macon II.
“Macon II was finished in October 2008. I
flew a number of short test flights and found
the eight motors to be more than adequate to
move the ship at a brisk speed. A calm
afternoon led to a longer flight which scared a
couple of people sunbathing by the pool.
“Later that week, the local forecast called
for calm early-morning winds. An early start
was not adequate for the several hours it took
to fill and balance the airship, so there was a
slight wind by the time I got it launched. A
gust carried the Macon over the house and by
the time I could get around back, it had
drifted quite a way off.
“My inexperience showed when I found I
could not get the model to come back and I
lost sight of it over a grove of trees. A couple
of hours of searching orchards and fields
turned up nothing. I pretty much gave it up for
lost.
“The Macon had come to roost about 5
miles away in a prune orchard. A trip to the
farm in a rental truck found only the
collapsed rear two-thirds of the hull. Again
the remains neatly fit in two grocery bags and
I considered it the end of the story.
“Of all people, my wife encouraged me to
give it one more shot and so, Macon III was
born. More care and lightening culminated in
the current model. I am extremely wind shy
and am waiting for favorable weather before
doing more tests on a tether. For sure, this is
the last rigid airship in my garage.”
What a great story and fantastic model!
You know what they say, Jack. The third
time’s a charm. The very best to you with
your upcoming flights.
That’s all for now. Remember, check those
onboard battery systems. Cycle test and
replace as necessary. If your battery packs are
a few years old, just replace them; it’s not
worth the risk. MA
Sources:
International Miniature Aircraft Association
www.fly-imaa.org
Glenn Torrance Models
(919) 562-0403
www.flygtm.com
O.S. Engines
(800) 637-7660
www.osengines.com
Xoar Propellers
(626) 679-1158
www.xoarintl.com
Solartex
[email protected]
www.solarfilm.co.uk
WarbirdColors
[email protected]
www.warbirdcolors.com
Futaba
(800) 637-7660
www.futaba-rc.com
FMA Direct
(800) 343-2934
www.fmadirect.com
USS Macon (ZRS-5)
http://1.usa.gov/9lvNVJ
Hangar One Demolition
http://www.mercurynews.com/sunnyvale/ci_
17954157