March 2001 127
bEdFord rEPriSE: In the last column, I
noted that the gymnasium at the Bedford
Boy’s Ranch in Bedford, Texas was no longer
used for Indoor flying, because of the blowers
running continuously.
Actually, heavy Scale models and electricpowered
models are still flown there during
weekly sessions.
Science olympiad help: The Cleveland
Clowns, a very active model club in the
Cleveland, Ohio area, is conducting active
training for entrants and adult mentors. The
club is also staging what sounds like practice
competition.
Contact Dr. Vernon Hacker (Hack) via Email
at [email protected] (or call [216] 486-
4990) to get in on the fun.
Guerrilla Fliers in Penn Station (New York
City): Don Ross, a columnist for Flying
Models magazine, recently reported that some
people had been flying Indoor Scale models
in New York’s Penn Station.
The basic idea was to show Indoor models
to a large number of people. Subsequent
discussions, especially with regard to safety,
led Don to discourage the idea.
He feels that we might get some really
good publicity if the effort could be restricted
to Limited Pennyplane and lighter models.
Without strict control of the activity, those
who would try heavier or faster models could
get us all into trouble.
Certainly, no club should miss
opportunities to fly demonstrations using safe
models, such as Pennyplanes. The best
possible outcome would be that the club gets
a member or two, regular access to a site it
proved during the demonstration(s), and
sometimes even a short newspaper article or
30 seconds on television.
I am an advisor member of a personal
robot club; sometimes television coverage
comes out really well and sometimes it
doesn’t. We have friends at the Dallas
Morning News, so no problem!
Where are the Juniors? Darryl Stevens
([email protected]) sent me an
Bud tenny, Box 830545, richardson tX 75083
FREE FLIGHT INDOOR
This simple run-down stand depends on a good fit between the clamp and the
motorstick, to hold the model steady. Text had details of stands. Tenny photo.
Dual-clamp run-down stand does a great job of holding model steady for repairs.
Combining a heavy base with a radio antenna
makes a run-down stand that collapses
into small dimensions. Tenny photo.
E-mail after noting that four European countries
fielded full Junior teams, and the US had only
Nick Leonard Jr. entered in Junior competition.
More E-mail in the thread follows.
Darryl: This is almost embarrassing in the way
that we have only one Junior listed, and quite
possibly Nick may be the only one who is flying
F1D in the US. I can’t think of any others.
Bud: Good to hear from you! What do you
suggest?
Darryl: Unless you have a father who is
involved with modeling, you just can’t drive
yourself to Idaho to fly. Hobby shops do not
support Indoor because there isn’t much money
in it, and flying sites are hard to come by.
I’ve two RC [Radio Control] fields within 10
miles of my home here in Seattle. On weekends
there are many more spectators than fliers. The
following week some of the spectators have new
[Almost Ready-to-Flys] to fly.
I even have trouble myself keeping
motivated knowing that Moscow may be my
only real Indoor flying opportunity for the year.
No real suggestions—it’s sad, but already
Indoor is becoming “Indoor RC” for most.
rubber Test reprise: The swing-arm rubber
test rig (photos and commentary in previous
column) is sufficiently operational to allow
preliminary testing. The shakedown test-runs
used a 10-inch loop made from 0.093-inch-wide
Tan II of unknown pedigree (most likely 5-94).
Test runs continued until I became
familiar with the rig, and had some level of
confidence in the measurement equipment.
The next step is to learn to make
standardized test motors, so direct comparison
between different batches of Tan II can be made.
building Test motors—Measuring
Techniques: I make all test motors 0.6
grams in weight; this will help me develop
skills I can use in F1D competition.
Making a new motor before had been
simple. I decided on a strip width and
made a loop a bit longer than I expected to
use. Then I used a test windup to prove the
knot was sound and the motor was free of
major flaws.
However, 0.6-gram motors are different!
Since the motor weight in F1D55 competition
can’t exceed 0.6 grams, changing the model’s
power must be done by changing the rubber
cross-section.
Therefore, each motor will be a different
length, to use the maximum allowable
amount of rubber.
cross-section and Length Measurement: I
measure a test sample of rubber using a
yardstick clamped in a vise, so it stands
vertical. I hold the end of the strip even with
the top of the yardstick, with the rubber strip
hanging by its own weight.
If the sample is to be longer than three feet, I
use sharp tweezers to grip the rubber exactly at
the end of the yardstick, and I move the tweezers
to the top of the yardstick. For a five-foot-long
sample, I cut the strip at the 24-inch mark.
I use one-inch machinist’s micrometer
calipers for cross-section measurement. Many
fliers use spring-loaded calipers to measure
rubber strip; regardless of how much the
spring tension has been relieved, the rubber
will be compressed to some degree.
I avoid the compression by carefully
closing the micrometer while sliding the
rubber strip back and forth. I take the reading
at the calipers setting where the rubber barely
begins to drag between the jaws of the
calipers, avoiding compression of the rubber.
Maybe that seems to be too much of a
perfectionist’s approach, but any undefined
compression of the rubber affects the
accuracy of a cross-section calculation.
I don’t mean to imply that the spring
calipers shouldn’t be used to check motors at
the flying field—nearly accurate measurements
made with the same calipers are quite
satisfactory for choosing the next motor.
Preparation of Test Motors: Some
preliminary tests indicated that useful 0.6-
gram motors would have a strip width
between 0.065 inch and 0.052 inch.
All test motors will be evaluated on the
basis of weight/unit length. The rubber strip
of nominal 0.065-inch width is actually
logged as 0.0404 grams/inch. A 0.6-gram
motor made from this strip will be a loop
approximately 7.5 inches long.
The other end of the useful range (my guess)
is 0.031 grams/inch (0.052-inch width nominal);
a 0.6-gram motor from this strip would make a
loop approximately 9.7 inches long.
Test-motor identification: Each glassine
envelope (available at stamp-collector supply
stores) will be marked with the following: a
unique name; initial strip size (0.0404
grams/inch); weight of motor; initial loop length;
and length of loop after test-wind (before rest).
The loop will settle to a rested length after
several test runs. The length will be checked
immediately after each test; this will be
compared to the rest length.
run-down Stands: Throughout the years, I
have collected photos of all kinds of fieldsupport
equipment. The run-down stand is
used to support the model between flights.
Each flier makes his or her own; the variety
is endless. The photos show examples I’ve
seen, but I’ve lost track of who did which one.
One photo shows a stand that collapses,
folds, etc., to small dimensions for easy
storage. The black base comes from the
“helping hands” fixture, commonly available
for electronics experimenters.
Another photo shows a different style of
stand. This one typically has a post 12
inches long or longer, which plugs into a
wood base large enough to provide stability
with the model in it.
This type of model clamp is ideally
custom-fit to the diameter of the motorstick,
to provide just enough friction to hold the
model steady. The wood in the clamp should
be waterproofed, to avoid humidity changes
in slot width.
The other photo shows a dual-clamp
stand, which provides outstanding support
for field repair or installing wing bracing.
Very soft foam should be used inside the
clamps. The fixture should not be used to
hold the model for long periods of time, to
avoid deforming the motorstick. MA
