102 MODEL AVIATION
Flying for Fun D.B. Mathews | [email protected]
Correcting previous information about an Airtronics receiver
Also included in this column:
• The Pterodactyl
• Stearman-Hammond revisited
Above: Is this a stealth design from 1931?
Long before radar was in use, Geoffrey Hill
developed this configuration.
Left: Alan Brown’s Westland Pterodactyl
model passes by at a low level. It is an
unusual choice for a scale model.
Above: The Westland Pterodactyl is an
attention grabber.
Left: Notice the Pterodactyl’s tiny vertical
stabilizers, bicycle undercart, and
outriggers with skids.
OOPS! In the February 2007 column I wrote some erroneous
information. In an effort to correct that, I’ll try again.
Old-style Airtronics receivers will run satisfactorily on any
negative-shift transmitter, and some of the newer Futaba and Hitec
transmitters have the capability of changing shifts. Thus old-style
(and new style for that matter) Airtronics receivers can be run with
any transmitter that is capable of changing shift.
Back when transmitters were either positive or negative shift,
Airtronics receivers would only respond to Airtronics or JR
transmitters. Now that many transmitters come with the ability to be
set for either shift, this is no longer a problem.
If you have an old Airtronics transmitter and want the
advantages of programmability, etc., you can purchase a modern
06sig4.QXD 4/20/07 1:51 PM Page 102
Airtronics transmitter to get what you want. Airtronics may have
transmitters that are capable of selecting frequencies or soon will.
However, there is a catch. The leads from old Airtronics servos
are wired differently. To work with modern Airtronics and other
servos the leads must be changed or a suitable “jumper” must be
installed.
The JR9303 transmitter I mentioned is still a good alternative
since the frequency can be changed to match the various Airtronics
receivers you want to use. One transmitter can run all the various
frequencies of your old Airtronics flight packs.
I hope this clarifies what I wrote. I have never owned Airtronics
equipment and was repeating what the only local flier who is using
it told me, but the story wasn’t straight.
The incompatibility of the servos somehow got twisted around to
an incompatibility of the whole system. I made the error of repeating
an old wives’ tale without checking the facts.
More Odd Aircraft: The highly gratifying reader response to my
seeking out how much interest there is in prototypes that have been
rarely, if ever, modeled leads me to base another column on that
subject. It has become obvious that many of us enjoy playing “Do
you know this airplane?” with our friends.
The Internet provides us with access to a nearly unlimited supply
of information about aircraft prototypes that fall into the “What on
earth is that thing?” classification. Nearly all people are driven
throughout their lives to add to their funds of knowledge, whether
practical or trivial. The Internet is a hyperfast research tool compared
to the old-fashioned encyclopedia and library-card searches.
Named for its resemblance to the prehistoric flying reptiles, the
tailless Pterodactyl aircraft was designed by Captain Geoffrey Hill.
He was Handley Page’s chief test pilot in 1918 and advanced to
work on the famous Handley Page wing slots.
On his own Hill had designed and constructed a tailless glider he
first flew at Devils Rest Bottom on the Sussex Downs in December
1924. It was a study in maintaining control of tailless aircraft when
stalled. The Pterodactyl and subsequent versions were highly
successful; they could not be stalled.
The Air Ministry and the Royal Aircraft Establishment were
impressed and funded an order for a version to be powered with a
35-horsepower Bristol Cherub engine. And although Hill was on the
Handley Page staff, Westland was chosen to take over the project.
During the ensuing eight years Westland and Hill designed and
built several additional Pterodactyl prototypes, including a tractorengined
two-seat fighter with a machine gun turret in the back.
The model I present this month is an RC electric-powered 1931
Pterodactyl IV developed by Alan Brown of Watsonville, California.
The IV was a three-seater powered with an inverted four-cylinder,
120-horsepower de Havilland Gipsy III.
Intended to compete with other civilian
three-place aircraft such as the de Havilland
Puss Moth, the Pterodactyl’s takeoff roll was
unacceptable, as was its cruising speed.
Nothing was done with the design after the
prototype, but the full-scale aircraft caused
quite a stir whenever it was flown at air shows.
One of the Pterodactyl’s astounding
features was the first adjustable set of swing
wings that really flew. They were swept 5°
aft when the aircraft was flown as a single
place and forward if carrying passengers.
This feature was used to essentially move the
balance point as required by various loading
configurations.
Alan originally powered his model with a
.40 glow engine. In that configuration it
required nose weight and was never
successful. Conversion to AXI electric power
allowed him to balance it without nose
weight, resulting in markedly reduced overall
weight. The model has had several
successful flights.
According to Alan, the Pterodactyl is
June 2007 103
I will give you two months to identify this airplane. It is one of a kind and still flies.
Don Robinson has this vanity tag on his minivan.
Richard Franco’s Stearman-Hammond. For construction he uses
drawings that were often included with old solid-model kits.
06sig4.QXD 4/20/07 1:56 PM Page 103
horrible on takeoff. If you use too little
throttle, one of the wingtip fin/skids will
dig in and cause it to ground loop. If you
give it too much power, the high thrustline
combined with the short longitudinal track
bicycle gear causes it to nose over.
Alan’s model is 1/6 scale, which gives it
an 88-inch wingspan. Construction is
conventional stick and sheet.
He has no workable drawings for his
model but is willing to advise anyone who
would like to enlarge the three-views in
Westland Aircraft Since 1925 by Derek N.
James and build a Pterodactyl IV. Several
FF rubber-power Pterodactyl designs have
been published through the years.
If you have the urge to develop such a
strange model, consider the three-views
and information about the Pterodactyl IB in
The Book of Westland Aircraft by A.H.
Lukens, published by Harborough
Publishing Ltd.
Neither of these books was in file at my
local library, but the staff used an
interlibrary loan on the Internet to get them
from other libraries.
Stearman-Hammond Revisited: When I
featured the Ariel in the December 2006
column I mentioned that someone had to
have built a flyable model of this
interesting prototype since a large number
of photos and articles about it are available
from various sources. But there is not much
in the way of three-views.
Shortly after the column was published I
heard from Richard Franco of Fremont,
California. He addressed a lifelong
fascination with the aircraft by researching
it and building a flying model. He wrote:
“As a young child I had firsthand
experience with the Stearman-Hammond.
When I was 12 or 13 (1937 or 1938) I was
visiting my sister and her husband who
lived at the entrance to the Niles,
California, steel mill. Their house was next
to a large vacant field, and parked next to
its fence was the Stearman-Hammond.
“It was a sight to behold; the fuselage
was polished aluminum, and the twin
booms were something I had never seen
before. I climbed over the fence for a good
look, being careful not to touch anything. I
never saw a takeoff or landing, but it did
fly over once in awhile.
“This experience stayed with me over
the years until I happened upon another
example (or perhaps the same one) painted
white with green trim on display at the
Flying Lady Restaurant in Morgan Hill
many years later. I was allowed to
photograph and measure the airplane. At
that time we were having RC competitions
at the Flying Lady and I decided to build a
model.
“Paul Matt (yes, that Paul Matt)
supplied me with whatever info he could
dig up, and fellow club member Jeff
Whitney plotted the wing ribs, making the
job real simple.
“Being a retired art teacher, sculpting
the compound curves out of blue foam was
easy for me. It flew well and even will do
some simple aerobatics.”
The fuselage is a balsa box to which
blue foam blocks are adhered with aliphatic
cement. Balsa formers are located at
strategic spots to serve as sanding/cutting
guides. The foam is shaped to contour
following the patterns found from an
ancient Comet solid model.
The window frames are wood, adhered
into appropriated cutouts in the foam. The
air scoop is open in the front to allow air to
flow back through a hole in the firewall for
engine cooling.
After the foam had been shaped and
sanded, a thin coat of epoxy and 3/4-ounce
fiberglass was applied to the fuselage and
booms. Richard didn’t mention how the
wings were constructed, but I’d suspect
they are hot-wire-cut foam with balsa skins.
Many of you readers may not know how
solid models were created. The drawings
included with the kit were of front, side,
and top views, with cross-sectional
drawings of key points.
One would cut a rough outline of all
sections and then use the template (usually
adhered to cardboard or wood) to create
cross-sections while carving the wood. The
wings and empennage also illustrated
proper cross-sections keyed to marked
areas.
I’ve written this rough outline to make
the point that by creating a box, marking
the cross-section locations on it, cutting
formers using the inside of the section
drawings, and then filling in the spaces
between the formers with blue foam, one
can create and shape the model.
Such a technique makes it possible to
re-create almost any model from good
three-views. This method opens up many
interesting possibilities for creating scale
models for which no kits are available.
Richard’s model spans 60 inches,
weighs 5.5 pounds, is powered with an O.S.
.26 four-stroke engine turning a 9 x 6 APC
propeller, and has servos on the aileron,
elevator, throttle, and nose wheel. No
rudder is used.
Richard has no working drawings
available, but he offers his help to anyone
who is interested in creating a Stearman-
Hammond. His address is 41040 Amapola
Ct., Fremont CA 94539. MA
SCALE FLIGHT MODEL CO.
Repro Rubber Power Kits, Comet, Megow, Burd,
Scientific, Jasco, also available - Campbell,
Diels, Dumas, Florio Flyer, Guillow’s,
Golden Age Repro, Herr, Micro-X, Peck, Sig.
Send $2.00 for Model Airplane Catalog
Penn Valley Hobby Center
837-A W. Main St., Lansdale, PA 19446
www.pennvalleyhobbycenter.com
104 MODEL AVIATION
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