Radio Control Slope Soaring - 2004/02

BALSA LIVES! If God had intended man to build model
airplanes with fiberglass, there would be fiberglass trees. In this
time when EPP (expanded polypropylene)-foam sailplanes take
the lion’s share of the market and molded fiberglass sailplanes
define one extreme of speed, strength, and craftsmanship, balsa
bashers are still out there designing, modifying, and flying stickbuilt
Slope jets.
Remembering that designing and building are major
components of the hobby and that some glider fliers prefer
working with wood rather than resin, I’m pleased to report that
wooden Slope sailplanes are still being designed and built, and
they look good and fly well.
Eric Molestead ([email protected]) of Vancouver,
Washington, sent photos and an enthusiastic description of his
early flights with his Lear Jet, modified from the Great Planes
power kit. Eric explains his kit modifications in the following.
Dave Garwood, 5 Birch Ln., Scotia NY 12302; E-mail: [email protected]
RADIO CONTROL SLOPE SOARING
Walt Bub’s original-design balsa-frame F9F Panther Slope jet
flies gracefully over Lake Ontario in upstate New York.
Eric Molestead at controls. Bryan Robbins gives Eric’s Lear Jet a
heave-ho on maiden voyage. Travis Schafer photo.
Bill Griggs (Canastota NY) flew Walt Bub’s Panther for 45
minutes at Lake Ontario and learned that it flies well.
Eric Molestead (Vancouver WA) holds the Lear Jet he modified
from the Great Planes balsa kit. Schafer photo.
132 MODEL AVIATION
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February 2004 133
“The Lear spans 69 inches with tip tanks and weighs in at
about 61⁄2 pounds. The tip tanks are removable, and are held in
place with small magnets and springs. Wing area is in the
neighborhood of 600 square inches. The wing is pink foam
covered with 1⁄64 plywood, and covered with UltraCote.
“The fuselage is basically stock, except for the nose of course.
I just stuck a chunk of pink foam on the firewall and sanded the
foam to shape. Then I fiberglassed the entire fuselage. The belly
has an extra layer of fiberglass; you know how slope landings
are.
“I fiberglassed the fuselage and painted it with Krylon. The
nacelles are hair mousse cans with the ends cut off. (It’s amazing
how much mousse is in one of those cans!) I built a foam-core
horizontal stabilizer with a thin symmetrical airfoil section and
slightly more area than the original. The vertical stabilizer and
rudder are stock. The rudder is operational but it doesn’t do
much. It wags the tail back and forth some, but that’s about it.”
Photos show Eric’s first flying day with the Lear Jet, and he
wrote:
“The first flight of the Lear was at Bald Butte, which is about
10 miles south of Hood River, Oregon. The site has an awesome
view and great lift. Even though the airplane is a bit heavy, it
seems to fly quite nicely. Very smooth and stable, and it looks
extremely realistic in flight.
“Several people told me the open nacelles would be too
draggy, but the airplane doesn’t seem to care. And the air flowing
through the nacelles makes kind of a cool whooshing sound in
flight.”
Eric’s next project is to convert a Great Planes F-14 Tomcat
kit for Slope. He’s thinking of implementing the swing-wing
feature of the prototype. We’ll be watching this Sierra Hotel
builder.
On my last trip to Lake Ontario I flew with Bill Griggs
([email protected]), who was flying a Walt Bub
([email protected]) Grumman F9F Panther—a Korean War-era,
Navy carrier-borne jet.
The fuselage is built from balsa sticks with a carved-balsa
nose block. The wings are white foam core sheeted with 1⁄16
balsa, and the whole airframe is covered with Oracover. The
Panther has a span of 60 inches, a wing area of approximately
480 square inches, and a flying weight of roughly 24 ounces.
Walt makes his own construction drawings, and with this
model he started with the three-view drawings in the
Squadron/Signal F9F Panther/Cougar in Action book, which is
available from www.squadron.com.
Bill flew the Panther effortlessly for approximately 45
minutes. “The Panther flies like a giant Sig Ninja,” he said about
its flight performance. “Very predictable and super stable but not
particularly jetlike. The airplane has one speed: majestic.”
Walt is an active designer, and some of his designs are
available through Northeast Aero Design at www.northeastaero
design.com. Walt is in love with airplanes from the Grumman
Iron Works. I have built and flown his Grumman A-6 Intruder
design (shown in the February 2003 Slope Soaring column). The
A-6 also flies like a “giant Sig Ninja”; it’s extremely gentle and
stable but kinda slow for a jet.
Walt’s Intruder’s fuselage is made from vacuum-formed
styrene. Why molded styrene instead of the more common
molded fiberglass? It’s because Walt developed allergylike
symptoms after working with epoxy for many years.
Cumulative Epoxy Allergy: One of the most diabolical
conditions that can befall a modeler is what I’ll call a
“Cumulative Epoxy Allergy.” My knowledge of this comes from
the experiences of four friends who each happen to be kit makers
and who, after working with epoxy for decades, suddenly
developed severe symptoms and can no longer work with the
material.
The symptoms are most often skin reactions and may include
respiratory symptoms. Some feel that latex gloves are not enough
to prevent skin symptoms, and some report that vinyl gloves give
a measure of protection. Most believe that barrier creams are
ineffective at preventing a skin reaction to uncured epoxy resin.
As far as I know, when you get symptoms, you have to flat-out
quit working with epoxy.
Joe Hahn ([email protected]) of DJ Aerotech,
www.djaerotech.com, explained:
“It’s tough to get folks to fully appreciate the problem until
it’s too late. I can’t even be in a room in which laminating resin
(which seems to be the only type of epoxy that really attacks me)
is being used without [experiencing] some symptom.
“I’ve seen people with bad cases of poison ivy; my symptoms
are very similar to that in many ways. Open, bleeding cracks in
my skin were the really no-fun stuff. Severe itching and swelling
in affected areas together with lots of pain with any contact at all
in the affected areas is a common symptom for me.
“I haven’t experienced the respiratory problems, but a buildup
of vapors, such as you get when you’re working in one place,
huddled over a lay-up job of some kind, tends to attack areas such
as under my chin and around my ears. Use of masks didn’t seem
to help with this problem.”
Don Stackhouse ([email protected]), Joe’s partner at DJ
Aerotech, added:
Bill Griggs and the Panther. You can see the stick-built fuselage
and tail parts and the balsa-sheeted foam-core wing.
Finishing method on Eric’s Lear Jet is fiberglass and paint over
balsa fuselage; Oracover on wing. Schafer photo.
02sig5.QXD 11/25/03 9:51 am Page 133
134 MODEL AVIATION
“Once Joe was sensitized, it wasn’t just
wet resin and its fumes that would set off
the reaction; it was also the sanding dust.
He could barely tolerate the sawdust from
sawing the dihedral bevels on the roots of
bagged wings, but sanding the leading and
trailing edges after they came out of the
vacuum bag and Mylars was an absolute
no-no. Somebody else had to do that, and
that was usually me.
“Apparently there are enough active
chemicals in the resin of a ‘cured’ wing
panel that it could trigger the reaction. He
couldn’t even be in the same room when I
was sanding.
“Presumably the initial sensitization
was from contact, but after that the
reaction could be triggered via many
routes. Breathing the vapors could trigger
the reaction in the skin of his hands, even
if he wore gloves.
“Touching a phone that someone had
carelessly answered with wet hands, long
after the resin vapors had been cleared out
of the room, could trigger the reaction not
only in his hands, but also the areas such
as under his chin that had been sensitized
originally by vapors. Apparently an area
gets sensitized by whatever means, but
after that, any mode that gets the
chemicals into his circulatory system could
trigger the reaction in any and all of the
sensitized areas.
“One epoxy resin maker told me that
barrier creams are nearly worthless, and
that latex gloves are good for bacteria and
other microbes, but are permeable for the
chemicals in epoxy, and therefore are not
much better than barrier creams. They
recommended vinyl gloves.
“Barrier creams can be helpful in
addition to vinyl gloves, for protecting
exposed areas such as forearms from
exposure to vapors, but are very little help
for protection against direct physical
contact with the resin.
“Everyone is different. I’ve been
working with epoxies for longer than Joe
(although Joe was probably getting it in
larger and steadier doses during the time
he became sensitized than the typical
average frequency of exposure I’ve had),
and I do not have the allergic reaction yet.
“However, given enough exposure (and
apparently it is cumulative in nature)
everyone will eventually develop an
allergy to epoxy; it just takes some people
longer than others. When it does happen, it
tends to happen very suddenly; one day
you’re fine and the next day the problems
rapidly start to escalate.”
Regarding prevention, we know far too
little. Joe said:
“I suspect that it’s hard to get enough
air circulation in any lay-up area. It’s
probably tough to get enough skin
protection of any kind, also. I understand
that vinyl gloves are much more effective
as a barrier than latex, although at this
point it makes no difference for me.
Barrier creams didn’t work either.
“I’m guessing that I might be able to
work with the stuff in a full HAZMAT suit
and separate air supply. The dermatologist
essentially was no help—there does not
seem to be a way of ‘blocking’ the effects
with any treatment either internal or
external.”
What do the Material Safety Data
Sheets (MSDSs) say? An Internet search
on October 8, 2003, using http://msds.pdc.
cornell.edu/msdssrch.asp returned “7312
MSDS sheets found containing epoxy
resin.”
Reviewing several of the sheets, I
learned that some manufacturers write in
general terms about the hazards, warning
against skin contact and breathing vapors,
but I have not seen an MSDS that clearly
warns of the severity of symptoms that my
four friends have experienced.
This is strange to me because when I
picked up some zip-close plastic bags at
Grainger, I saw that the invoice came with
an MSDS (which essentially said not to put
plastic bags over your head). I have not
received an MSDS with any epoxy I have
purchased at a hobby shop or a hardware
store, nor have I seen an expression of the
potential hazard mentioned on a hobbyrelated
Web site. I did read in October on
R/C Soaring Exchange (an Internet
newsgroup) that the United Parcel Service
charges composite materials suppliers a
$25-per-can HAZMAT shipping fee.
My four friends have related that they
have not found effective treatments, even
though some have worked extensively with
dermatologists. Another afflicted friend
summarized his search for effective medical
treatment as follows.
“Over the years, with different doctors,
they have changed the diagnosis from one
thing to another, and back again. They’ve
tested positive on poison oak, but changed
the diagnosis to spider bite. The next visit, it
was a snake bite. Then, psoriasis, then
eczema.”
He believes that latex gloves may
contribute to his anguish.
For most of us it would be a tragedy to
not be able to work with epoxy. I’m not a
materials specialist, nor am I a physician,
and I’ve told you basically everything I
know about the problem in this column. My
advice is to treat epoxy resin as a hazardous
material; avoid skin contact and avoid
breathing vapors as much as you can.
A crackerjack Web site for researching
paint schemes for Slope jets is
www.jetphotos.net. The last time I visited
the site, it claimed: “Now with over
146,000 photos online! 561 added
yesterday; 3,088 in last week; 17,783 in
last month.” MA
The Mount Rainier Radio Control Society announces the 24th
Western Washington Fairgrounds, Puyallup WA
Saturday, January 31, 2004, 9 AM to 5 PM
Sunday, February 1, 2004, 9 AM to 4 PM
Daily admission $7.00 at the gate - FREE PARKING
$6.00 advance by mail - see: www.nwmodelexpo.com
Youth age 12 and under with an adult - free
General Info - Bob Brownell, 253-847-5721
[email protected]
Swap meet reservations - Don Sweasy, 253-445-4763
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