An AMA Gold Leader Club
August, 2003
No. 435
FROM THE PREZ
by Bob Sudermann
The wet spring weather continued on into June and put
a slight damper on our
Memorial Fun Fly, which had to be postponed to Sunday
the 22nd of June.
Although attendance was down from previous years, I'm
sure due to conflicts
with the switch of days, we still had a great turnout
and a whole lot of
Fun. Mike Estock did a great job coordinating everyone's
efforts even with
the switch. We had 4 or 5 candy drops by Rom Boutin
with Mike Estock's
assistance. No matter how many times Rom drops candy,
the kids just love
it. Out thanks goes out to the Alpha Squadron for their
participation, and
as always they put on a great show. Hopefully the fall
weather will
corporate and those who missed the June Fun Fly will
be around in September.
Bob Dolan did it again at the July meeting with some,
how can I put this,
'Interesting Prizes' for his Spot Landing contest.
Participation was a bit
light, with Carl Sutton and Bob being the only participants.
For the August meeting we are going to have an 'Instruction
Night.' So,
students, bring your aircraft and we'll get a couple
of flights in.
On Saturday, August 30, Eric Henderson will put on an
Aerobatic Clinic.
This was originally scheduled for May 24th. If you
want some expert
assistance in setup, radio programming, flight trimming
and aerobatic
execution, just show up. It does not matter what kind
of craft you are
flying, the tips and guidance will make any aircraft
fly better and make all
of us better pilots.
So - see you at the field.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
POTENTIAL RADIO INTERFERENCE AT THE VFSS FIELD,
VALLEY FORGE PARK
by Phil Staas
During June, I observed a number of flight maneuvers
that experienced pilots
suspected were caused by radio interference on their
channels. The most
frequent spot for interference seemed to be the northwest
corner of the
field in a line-of-sight with a "telephone"
pole just off Rt. 252.
Using the VFSS scanning receiver, a Yaesu Communications
Receiver Model FRG
9600, I listened with these results:
July 8 from 1000 to 1030 with a whip antenna:
1. At 72.420 MHz there was an intermittent source of
signals that sounded
very much like telephone switching signals. The signals
were strong for 15
to 20 seconds and off for 5 seconds, approximately,
repeating constantly.
2. When the 72.420 MHz signal was present, I listened
at 72.410 MHz (RC
Channel 31) and at 72.430 MHz (RC Channel 32) and heard
the same signals
with somewhat less strength than at 72.420 MHz. (Note
that my method of
signal sensing was to set the squelch level on the Yaesu
receiver to produce
audio at signals from RC transmitters on the field in
use by pilots.)
3. Similar "telephone" signals were heard
at 72.880 MHz with less frequency
of occurrence, e.g., every 30 seconds or so. A lower
amplitude signal was
often present at 72. 890 (RC Channel 55), but nothing
at Channel 54.
4. For reference, RC transmitter signals are heard as
a constant buzzing
with good strength at designated RC Channels. Similar
to the "telephone"
signals, there are often RC signals in adjacent frequencies
on the Yaesu
receiver. For example, an RC transmitter on at RC Channel
32 will have its
buzzing signal heard at 72.420 MHz and 72.440 MHz at
lesser signal strength.
July 8 from 1930 to 2000 (after the VFSS meeting):
5. After the meeting, I mounted a directional antenna
on a mast some four
feet off the ground. The usual 72.420 MHz and 72.880
MHz "telephone"
signals were there in strength with signals at RC Channels
31, 32, and 55.
In addition, a "telephone" sounding signal
was also heard at 72.700 MHz this
evening giving the same signals at RC Channels 45 and
46.
6. Using the directional antenna, I found the 72.420
MHz signal most strong
in the direction of the "telephone" pole at
10 degrees from magnetic north.
The 72.880 MHz and 72.700 MHz signals seemed most strong
at 90 degrees and
210 degrees from magnetic north.
July 9 from 1200 to 1230 with the whip antenna:
7. A quick check on this date showed "telephone"
signals at the usual 72.420
MHz and 72.880 MHz, but no signal at 72.700 MHz. Instead,
a new "telephone"
signal was heard at 72.060 MHz with weaker signals at
72.050 MHz (RC Channel
13) and 72.070 MHz (RC Channel 14).
Preliminary Conclusions
A. As 72 MHz signals most likely travel "line-of-sight"
with reflections,
too, the source of signals in the 10 degrees direction
(northwest of the
field) is probably through the gap in the hills and
not the "telephone" pole
on Rt. 252.
B. Strong signals will most likely be sensed in adjacent
channels in a
typical receiver due to the nature of receiver selectivity.
I would expect
crystal-controlled receivers used in RC are quite good
in selectivity, but a
strong signal in an adjacent frequency could over-power
a weak RC
transmitter.
C. Considering the distances the model airplane can
be from its RC
transmitter and the relative angles that form between
the RC receiver's
antenna (essentially a whip antenna, too) and the RC
transmitter antenna
near the ground, it is possible that momentarily a "foreign"
signal could be
the strongest at the airplane receiver. (I will research
this further.)
D I will continue to monitor signals at the field in
the band of frequencies
used for RC. In addition to keeping batteries well-charged,
I would say
avoid RC Channels 31, 32, and 55.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FOR WHAT IT'S WORTH
by Harold J. Harrison
I would like to share an experience at the field in
the hope that some of
you might benefit from it.
Saturday, July 5: Weather clear but hot, humid and
breezy - maybe a 20 mph
wind.
I arrived at the field just before noon, and from an
earlier crowd there
were still about five or six guys with their airplanes
on the flight line.
Some of them were sitting in chairs under umbrellas.
I got my trusty, modified stick ready to fly. I have
been flying this 50"
wingspan, 46 cubic-inch, two-stroke engine airplane
for a good ten years and
know pretty much what it can and cannot do.
Lately, the engine has not responded very well in the
low range, choosing to
quit, especially in hot and humid weather. Adjusting
high and low needle
valve settings and changing the plug did not seem to
help much. This day I
changed from a 10-8 to a 10-7 pitch prop to see if unloading
the engine a
little might help.
While I was changing the prop, fueling up, and getting
ready, the wind was
getting noticeably stronger. One umbrella blew over,
and my chair nearly
collapsed. Not to worry; I had flown in windy conditions
many times before.
The airplane had good penetration with its low frontal
and side areas.
Radio on, engine running, full throttle holding nose
up, slight needle
adjustment for different prop. Good transition from
low to high throttle.
Every thing looked good.
The plane was a little slow getting off. There was
a crosswind over the
field about 45o, coming from the west and blowing toward
the flight line.
In the air the plane handled about the same, not much
different with the
prop change.
After flying around for about five minutes, being careful
not to throttle
back till ready to land, the engine quit suddenly at
high RPM while heading
west, which it had never done before. It wasn't too
bad a position, but not
very high and about one third of the way in from the
west end of the field,
and out beyond the north edge of the field.
Simple - nose down, a shallow 180o turn and back onto
the field - only it
didn't work that way. By the time the 180 was completed,
the wind had blown
it way downwind in the direction of the flight line.
In the turn the flying
surfaces were exposed to the wind, giving much more
area for the wind to
push against.
After the turn the wings were straight and level. Rudder
input was unable
to make the airplane turn. It just would not turn and
continued in a direct
line toward the parked airplanes and the guys in the
chairs. All I could do
was yell, "Headache! Headache!" and hope
for the best.
Here is what happens. Going downwind with a dead engine,
your ground speed
might be 20-30 MPH, but your airplane relative to the
wind it is flying in
might only be 5 or 10 MPH. A rudder deflection at low
speed will not give
the desired response; in fact, it will give just the
opposite.
To illustrate this phenomenon, take the venerable Piper
J5 Cub or any
full-scale tail dragger. When taxiing downwind, you
push the stick forward,
deflecting the elevator down. Normally this would raise
the tail, but since
there isn't enough prop wash over the surfaces for this
to happen, the wind
blowing from behind will push down on the exposed upper
surface of the
elevator, pushing the tail wheel firmly on the ground.
Reverse this and see
what happens. Elevator up normally pushes the tail
down, but the wind will
now push on the exposed bottom surface and lift the
tail up off the ground,
causing unwanted damage up front. So when flying downwind
with a dead
engine, don't be surprised if you find you have no control
over your
airplane.
Fortunately, I was first in line on the flight line
from this direction, and
the airplane hit my starting stand, stopping it dead.
You remember my
safety starting stand? I wrote an article about it
a couple years ago
extolling the virtue of having one. Don't laugh. Now
there is another good
reason to have one - they make great runaway airplane
stoppers.
Everything stopped except the engine, which rolled up
to Ed Moore sitting in
his chair. He said, "Here." I said, "What's
this?" He said, "It's your
engine." The prop wasn't even broken!
What should I have done? Simple. I should have kept
it into the wind, nose
down, and headed for the tall grass.
In the real airplane world this attitude has a name.
It is called
complacency. Watch out; it can reach out and bite you.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
STUDENT UPDATE
by Bob Sudermann
This past month we have two new certified pilots. Ken
Reimund and Michael
Koeugh successfully passed our rigorous exam. Instructor
Steve Kolet
assisted Ken, and Michael started last fall with (I
think this is correct)
Tris Colket. Congrats!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLUB CALENDAR
Tuesday, August 5th -
BOG meeting at the field, 6:30 PM.
Tuesday, August 12th -
General Membership meeting at the field, 6:30 PM.
Saturday, August 30th -
Aerobatic Clinic with Eric Henderson.
Saturday, September 13th -
Fall Fun Fly
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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