An AMA Gold Leader Club
November, 2004
No. 450
THE PRESIDENT'S CORNER
by Russ O'Brien
Recalling October 2003
It was a year ago that the VFSS club was invited to
demonstrate R/C flying
to a large group of Boy Scouts during their weekend
campout in the Chester
County Park at St. Peter's Village area. Joe Saporito
recalled flying at
the site with the Alpha Squadron in the early 90's.
A check of the location
revealed a large field, a quasi-promise that the grass
might be mowed
shorter, and lots of big trees which are a hazard to
fly into and cause
turbulent air horizontally for a distance equal to seven
times their height.
On the show day, VFSS volunteers found the large field
packed with rows of
parked vehicles. The only open space was on a slope
with ankle high grass,
adjacent to playground equipment, which was cleared
of children for the
show. Some found plywood, and 4x4's were pushed together
to form a
launching ramp. Joe Pasquini flew a plane around in
the confined area and
handed it over to Joe Saporito, who cut the engine and
safely glided it down
to a landing in tall grass. Joe Saporito flew a ZAGI
electric and a
glow-powered helicopter to complete the show. Several
other models were
left on the ground for a static display, as their owners
wisely decided that
was the best thing to do.
Defensive Flying
We have all heard the term "defensive driving,"
such as being prepared near
exit ramps for a driver who suddenly cuts across in
front of you to get to
his exit, or the similarly selfish one who tries to
enter the traffic stream
not by going ahead of you or behind you but by making
it a tie at the merge
point. Junkyards are full of cars whose drivers tried
to put two cars in
one place. Similar situations occur while flying R/C
model airplanes, with
the added complexity of three dimensions instead of
two, and the difficulty
of judging separation distances while standing up to
300 yards away. The
following is a discussion of six types of turns, four
of which can be
applied in an emergency to avoid accidents.
Basic Turns - Clockwise and Counter-clockwise
A student learns how to make slow turns, clockwise and
counter-clockwise,
using ailerons, rudder and elevator to make a turn of
15 to 30 degrees bank
without losing altitude. This is a required skill which
is useful in
non-emergency situations. Due to the nature of R/C
flying, planes spend
almost half their flying time making turns.
Emergency Situations - Quick Action Required
Numerous emergency situations arise which require the
R/C pilot to reverse
direction and vacate the zone pronto. Slow, banked
turns take up too much
space and too much time in these situations. Examples
of emergencies are as
follows:
Four Emergency Quick Turns
Immelman Turn: This is essentially half of an inside
loop with a rollout at
the top. During this maneuver, the plane reverses direction,
gains altitude
but loses speed.
Split-S: Roll to inverted and pull back on the elevator
stick. The plane
does a half loop downward and is quickly on reciprocal
heading, right side
up and at high speed. During the maneuver, the plane
loses altitude and
gains speed. A slight nose up prior to rolling inverted
will compensate for
lost altitude. Air show performers, including The Blue
Angels, use this
maneuver at high altitude and slow speed for turn-arounds
at both ends of
the performance box.
Pylon Turns, Left or Right: Roll one quarter turn to
knife edge and
immediately pull back on the elevator stick. In the
knife edge attitude,
the elevator temporarily acts as a big rudder. This
is the quickest turn of
all; usually over and done in two seconds, depending
on entry speed and
control surface throws.
Note: Split-S and Pylon turns put high stress on the
airframe. For planes
with wings held on with rubber bands, use the HOBBICO
rule of thumb of two
#64 rubber bands for each airplane pound, with the last
two applied
diagonally.
Conclusion: Using these quick turn-around techniques
can not only save your
plane in an emergency but can also add pizzazz to an
otherwise routine
flying session.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CAD DESIGN / LASER CUTTING FOR MODEL AIRCRAFT PARTS
by Robert J. Caso
Being able to use a CAD program is almost a must when
using a laser for
model making. Although just mentioning "CAD"
sounds scary, it's really not
difficult to learn if you just start drawing lines and
making boxes. It's
also not very expensive. ModelCAD and DesignCAD are
very good packages and
both retail for under $100. Once you have a good working
knowledge of a CAD
package, there is no limit to the things that can be
produced. I started
painting all my scale markings, using shelf paper masks
cut with a laser. I
make a lot of fiberglass molds and plugs for vacuum-forming
- all supported
with CAD-drawn, laser-cut parts. I can cut intricate
CAD drawn designs out
of Trim Monokote - without piercing the backing! You're
limited only by
your imagination - not by what airplane subjects are
commercially available.
You can send the files to a cutting service and have
them cut the parts for
you. But first, you must have the parts ready in CAD.
There are basically two ways to design the parts for
a model. The first is
to start with a set of paper plans; the printed parts
being scanned in using
a tabletop scanner and then imported into a CAD package
(to drive the laser)
and laboriously retraced by hand since the resulting
outlines of the scanned
bit-mapped image are not precise enough to cut from.
CAD packages produce
vector (zero width) lines which are much more precise.
A bit mapped image
is a series of small blocks forming the outline of an
object. There is
also an issue with retracing - where do you draw your
line against a thick,
bit mapped line? This is especially an issue where
parts contain a slot,
such as slot in a rib both with its size and exact location.
If you're off
a couple of thousandths either way, the slot may not
fit and not line up
with others. Only by making some test cuts or by redrawing
the entire wing
plan form in CAD and comparing this against the ribs
will ferret out these
issues. We're also assuming here - a big assumption
- that the parts shown
on the hand drawn paper plans are correct.
The second way to make a model is to start from scratch
right in CAD. If
you're considering a scale subject, a good way to start
is to get a clearly
drawn three-view, scan it in and import it into CAD.
While you still have
to do some tracing of the subject's outlines, this will
give you a
vectorized outline of the aircraft to which you can
add its infrastructure.
Here is where it pays to have built a few model airplanes
and to have had
experience with a few other designs. Before you start
drawing away however,
you first have to scale the model - how big do you want
it? The
infrastructure for an 80-inch Mosquito would differ
greatly from a 30-inch
model in terms of wood sizes, rib and bulkhead spacing,
materials and the
complexity of the parts. How accurate do you want the
model to be? Gas or
electric? Flaps? All these questions play a part in
the basic design.
Referencing proven designs helps immensely in solving
these
model-engineering problems. After awhile, you will
begin to acquire design
experience; for example you will find that rib spacing
is 2" to 3",
regardless of the size of the model.
OK, so you have the three view of the model scanned
and scaled, now what?
Start at the beginning - for the fuselage side view,
put a line in for the
thrust line of the model and trace over the lines corresponding
to its
outline. As an aside, always work off a center or other
datum line when
plotting things out and keep scanned images in a different
layer than your
drawing. Determine your bulkhead spacing and draw vertical
lines up and
down through the thrust line to the outlines of the
aircraft. Do the same
for the top view. The vertical lines on the side view
corresponding with
those in the top view represent a 2D overall boundary
of a given bulkhead -
its overall height and width. Put them together and
you have the front view
of a rectangular bulkhead. Any curves are then lofted
in and slots and
lightening holes are added. There's a bulkhead. I
am oversimplifying a bit
here but this is the general 2D CAD procedure.
For the plan view of the wing, draw the outlines of
the wing and put in
centerlines for the spars and ribs. Import a rib from
the CAD library and
lay it against one of the rib's centerlines on the plan
view. If the rib is
too big or small, adjust it by squeezing or stretching
it with the
appropriate CAD function. Import a pre-drawn slot
from your library and
place it on your rib where it intersects the spar centerlines
- always
working off center. Cut off the front and back of the
rib to allow for
leading and trailing edge structure and the rib is complete.
Parts
requiring certain wood thicknesses or types should be
cut and pasted in a
file together with other parts sharing the same size
and type of material -
a "cut file."
There are other design considerations including mounting
systems for the
wing, empennage, servos, landing gear and engine, all
of which must be
incorporated in your design. Same goes for any doublers,
stringers or other
parts that support flight loads.
Summary
It's always a thrill and a sense of accomplishment for
me to start with a
box of wood and in a matter of weeks have it in controlled
flight. I know
that once you start drawing your dream design, you'll
be hooked. I was.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
VFSS BOG MEETING
Submitted by Steve Kolet, Secretary
October 5, 2004
Members present: 11 BOG, President, Vice President,
Treasurer; no quorum.
Meeting opened at 7:00 PM at the field by President
Russ O'Brien.
OLD BUSINESS
Item 1: We discussed our club obligation to actively
remind members to
follow VFSS rules for hand carrying or hand guiding
our aircraft to and from
the runway - no exceptions. All members agreed that
this must be done.
Steve Kolet will write an article for the club newsletter
detailing this and
explaining the rationale for the "L" shaped
cut path for runway access.
Item 2: BOG members made suggestions for the Bylaws
update, changing the
BOG meeting date to the 3rd Tuesday of the month, and
using a telephone
recall pyramid to notify BOG members of meeting cancellations,
etc.
NEW BUSINESS
Item 1: Treasurer Carl Sutton briefed the state of
our 2004 budget and
disbursements. With the projected expenses to year-end,
it looks like 2004
will be about even.
Item 2: Treasurer Sutton then briefed the 2005 budget.
We have a potential
shortfall if all budgeted funds are disbursed. We then
discussed options to
handle this projected shortfall. Some of the options
are to cut the fun fly
to one, cut some funding for items like newsletter,
printing the bylaws
update, more use of email and increasing yearly dues.
All business was concluded with no action, as we had no quorum.
~~~~~~~~~~~~~~~~~~~~~~~~~~~
BOG ELECTION RESULTS
by Steve Kolet
Congratulations to the newly elected members of the
BOG for 2005. They are
Warren Barrick
Andrew Berg
Miles Bowman
Al Campana
Rob Caso
John Matt
John Powell
Alex Primas
Bob Sudermann
Bill Sunick
Carl Sutton
The two alternates for the next year are Sean Merle
and Larry Scaggs. We
thank you all for volunteering to serve our club.
The new members should attend the December 7, 2004,
BOG Meeting for the
election of officers.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GETTING OUT AND BACK
by Steve Kolet
It seems that there is some confusion about how to get
from the pits to the
runway and back. I hope this will help clear it up.
First of all, the
Field Management Guide has a safety item which covers
it:
6. All aircraft must be physically restrained (i.e.,
carried or guided by
hand on the plane) while moving from the pit area to
the runway edge for
takeoff and return from the runway to the pits after
flight. Taxiing is
positively prohibited.
After starting your aircraft and releasing the restraint,
you have two
options to get your plane to the runway. You may pick
up the plane and
carry it from the pits to the access lane beyond the
piloting positions and
set it down. Or, you may put a hand on the plane and
push/guide it from
your position in the pits out the access lane to beyond
the piloting
positions and then release it from your control.
After flying, you reverse these two options above to
get your plane back to
the pits. But, there is a potentially dangerous situation
lurking here. I
recently heard about a wild event which occurred at
a club. After flying
and taxiing back to the edge of the runway, the pilot
was ready to shut down
his engine and retrieve his plane. As the pilot left
the flying position to
go out to the plane, which still had engine running,
the engine suddenly
went to full throttle and the plane jumped forward,
nearly hitting its
pilot, who jumped clear. The wing tip hit the barrier
at the runway edge
and the plane turned into the access lane, which gave
it a direct shot at
the pits and spectators beyond. The plane hit another
pilot's flight box
and a roll of paper towels and stopped before doing
any more damage. The
flight box had several deep gouges and was knocked out
of square. Paper
towels were shredded. This club was very lucky no one
was severely injured.
After hearing about this event, your BOG looked at our
field layout and
discussed what we could do to make it safer. The AMA
field guidelines
recommend a 25-foot minimum distance from runway edge
to the pits and
barriers to prevent a runaway plane from direct access
from runway to the
pits, etc. VFSS has the 25-foot minimum distance covered.
The barriers are
another problem. We, the BOG, thought about a permanent
fence - yeah,
right, we really thought the park would go for that
one. So we thought
about a portable fence which would be stored at the
field put up every time
anyone flew. We thought all VFSS members would just
jump at that one. So
we looked at methods which would increase safety and
require no action by
any pilots. A full grass barrier was determined to
be the answer. We
thought about making the pit entry to the access at
a 45-degree angle to the
current lane. This would work, but it could allow a
runaway plane to hit a
wingtip and make a turn, as we had just heard about.
So we decided that an
"L" shaped path to the current lane and allowing
the grass to fill in the
block by the pits was the best solution. We hope to
have the field mowing
crew get on board with this, cut the lanes, and allow
the block to fill in
with tall grass. We will roll the new "L"
and keep it trimmed short until
the grass takes hold in the spring of 2005!
Oh yeah, there is one more thing we can do to be safer
on shut down. After
flying, taxi to the edge of the runway near an access
lane. Do not point
the nose into the access lane. Keep the nose of the
plane pointed parallel
to the runway or pointed at the tall grass, shut down
your engine, check
runway clear, call, "On the runway!" and then
get your plane.
~~~~~~~~~~~~~~~~~~~~~~~~~~
CLUB CALENDAR
Tuesday, November 2
BOG Meeting: 7:00 PM at the church annex. Agenda:
Bylaws, Awards Banquet.
Saturday, November 6
R/C Auction and Swap Meet, Schue Middle School, 1500
Capital Trail, Kirkwood
Highway, Newark, DE (North of Newark Center at Red Mill
Rd.) Delaware R/C
Club. Doors open 9:00 AM. Auction 11:00 AM-2:00 PM.
Refreshments, raffle.
Tuesday, November 9
General Membership Meeting: 8:00 PM at the church.
Speaker: Harry Charnock,
"World War Two Electronics and Radar Technology."
Nominations for Club
Awards.
Friday, November 12
31st Year R/C Auction. Delaware Valley Federation of
Model Airplane Clubs.
Maple Point Middle School, Langhorne-Yardley Road, Langhorne
PA. Doors open
6:00 PM. Auction 7:00 PM. Door Prizes. Super Selection.
Wednesday, November 24
Thanksgiving eve R/C Auction. Levittown Aerobugs, 7PM,
Gallagher Community
Center, Bath Rd., Bristol, PA (Behind Twp. Municipal
Bldg.) Food, Drinks,
Door Prizes, 50/50. Info. 215-945-0829.
Tuesday, December 7
BOG Meeting: election of officers.
Friday, December 10
Doylestown PA Flea Market. Moved from Lenape Middle
School to bigger
quarters across State Rd. to CB West High School. Setup
6:00 PM. Sales
6:30-9:00 PM. Admission $3. Food, Drinks. Known for
new old stock (NOS)
2S and 4S O.S. engines. Info 215-348-1496.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FOR SALE
YS-53 supercharged 4 stk, run twice. Complete in box
and like new $225
Super Tigre S-2000 New in box - $100
Rob Caso, 610-564-9529
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TIDBIT
As the plane landed and was coming to a stop, a lone
voice came over the
loudspeaker: "Whoa, big fella. WHOA!"
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