skranish
Apr 01, 1997, 01:00 AM
<p><font size="4"><b>Weight Reduction by Electrostatic Discharge</b></font> </p>
<p>Have you ever walked across a rug on a dry winter day, and received a shock when you
touched a metal object, such as a doorknob? The rug is providing you with a static charge
- basically an excess of electrons - and you receive a shock when you touch an object that
provides a low impedance discharge path (essentially a quick escape route) for those extra
electrons. </p>
<p>Our electric powered airplanes can experience the same thing, and the excess electrons
- the static charge - can seriously degrade performance of the motor system and plane. How
does the plane pick up a static charge? Well, you do not have to drag it across
a wool rug. The motor itself is a great source of loose electrons, which come spewing
out of every opening and may even leak from damaged wiring. Brush arcing and armature
friction both cause electrons to loosen. Mechanical vibration can actually shake them
loose. </p>
<p>The airframe itself can pick up extra electrons because a plastic covered wing slicing
through the air will cut electrons free from the air molecules. Don't believe it? Have you
ever noticed how difficult it is to keep dust off plastic covering while applying it to
the airframe? The problem is that the covering attracts a static charge, and the static
charge attracts dust. (Actually, it is a fairly basic law of physics that ANYTHING that
you want to keep clean will attract dust in a way that you cannot reasonably circumvent,
but that is another topic) The plane flies much faster than you are likely to move your
covering iron, so the static charge problem is much worse in flight that it would be on
the ground. </p>
<table border="0" cellpadding="3" width="100%">
<tr>
<td width="50%"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass2.jpg" width="388" height="268"></td>
<td width="50%">The first photograph shows the static charge on my "Today's Hobbies
Skyvolt" while simply sitting still on the ground. This photograph was
taken with the patented (and classified) View-A-Charge adapter attached to a very
high speed 35mm camera. The View-A-Charge is essentially a Electron Macroscope (well, OK,
a filter) that allows one to see electrons in addition to the usual boring photons. I
can't show you a picture of the top-secret classified View-A-Charge, because,
well, then I would have to shoot you, which is fairly hard to do over the Web.
Notice how the charge is distributed evenly all over the plane. Note also that the plane
is sitting on 3 rubber wheels, which act as insulators, so the static charge does not
discharge, even though the plane is sitting on the ground. </td>
</tr>
</table>
<p>The presence of the static charge can present several problems. The most obvious is the
weight of these additional and totally unnecessary electrons. Another is the aerodynamic
drag that the electrons create by disrupting the otherwise smooth flow of air over the
wing. Yet another problem, that is often overlooked, is that the negative charge on the
plane actually repels it from the normally negatively charged ground, making it very
difficult, if not impossible to land the plane. </p>
<p>What can we do to discharge the plane? Well, we have to provide a good, solid ground
path for the electrons to flow on. A heavy duty jumper cable (the kind used to 'jump
start' a car) would make a great temporary ground strap, but they tend to be rather heavy,
and usually are not available in very long lengths. You may be old enough to remember when
heating oil delivery trucks used a heavy chain as a ground strap for the same reason we
want to - for electrostatic discharge. For some unknown reason, oil delivery trucks no
longer have these grounding chains (it may have something to do with the sparks generated
when the chain bounces on the pavement being <i>more </i>of a fire hazard than the static
charge, but I am not an authority on oil trucks). Anyway, we <i>do </i>want to have a
grounding chain, so we can discharge the static charge on the plane by dragging the chain
along the ground while doing low passes over the landing strip. </p>
<table border="0" cellpadding="3" cellspacing="1" width="100%">
<tr>
<td width="50%"><p align="center"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass5.jpg" width="367" height="214"></p>
<p align="center"><strong>The grounding chain is being used to release unnecessary
electrons during a low fly-by</strong></td>
<td width="50%">The next picture is a remarkable photograph taken by the View-A-Charge
with a very long zoom lens mounted onto a Track-A-Plane radar controlled gyro stabilized
camera positioning system. The Track-A-Plane is patented and classified, so I can't show
you a picture....oh, skip it. Anyway, the photo clearly shows the grounding chain
(attached to the plane near the tailwheel) in action - as it is dragged across the ground,
it provides a low impedance path to ground for the static charge on the plane, and the
electrons can be seen trailing behind the plane, where they have been deposited onto the
ground. You can even see how the remaining charge on the plane has moved towards the low
impedance path to ground, as there are no longer many extra electrons on the forward part
of the plane. </td>
</tr>
</table>
<p> </p>
<p align="center"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass4.jpg" width="340" height="228"></p>
<p align="center"><strong>A close-up view of the grounding chain in action. The
View-A-Charge filter allows us to see the actual electrons as they flow off the airframe
to the ground.</strong></p>
<p align="left"> </p>
<table border="0" cellpadding="3" width="100%">
<tr>
<td width="50%">If merely doing low passes is not your style, and you prefer the 'hovering
airplane' mode of flight that is all the rage in 'fun fly' planes, you can simply hover
near the ground to discharge the plane. For this photo, I replaced the Astro 05 and 7 cell
1700SCR pack in the Skyvolt with a geared Astro 90 and 36 N500AR cells, which actually
allowed the plane to do a near-vertical hover, at least when I could stop it from doing
torque rolls. This combination did seem a little overpowered, with a propeller only
slightly smaller than the wing, and it was often difficult to tell which was which,
considering the roll rate. </td>
<td width="50%"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass3.jpg" width="372" height="263"></td>
</tr>
</table>
<p>OK, now that we have established how to discharge the electrons from a plane, what did
we accomplish? A lot, actually. The electrons that were discharged from the Skyvolt were
collected in a Catch-A-Charge Electron Containment System (they aren't hard to find in the
grass when looking though the View-A-Charge) and then weighed. The Catch-A-Charge jar is
necessary because electrons don't like to stick together - objects with the same polarity
charge tend to repel each other, and if you simply make a pile of
electrons, they tend to go shooting all over the place as soon as you let go of them. </p>
<table border="0" cellpadding="3" width="100%">
<tr>
<td width="50%"><p align="center"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass.jpg" width="170" height="267"></td>
<td width="50%">This photo shows the patented (and classified, if you haven't guessed)
Electro-Mass weighing the electrons captured in the Catch-A-Charge. The electrons weighed
about 12.2 oz, which is about 25% of the weight of the plane. This weight reduction
provides a remarkable improvement in performance, provided you are willing to spend
most of the flight doing low passes dragging the grounding chain along the ground, and
have sufficient piloting skill to not damage the airframe while spending so much time in
ground effect. </td>
</tr>
</table>
<p> </p>
<hr>
<p><font size="4"><b>Problems with Electron Soaked Structures</b></font> </p>
<p>If you have ever built a (yeech!) slimer, you know that it is necessary to seal all
of the exposed wood surfaces to that they will not soak up the gunk that comes out of
the engine exhaust. Many of the articles and books about electric planes point out that
with an electric powered plane, this is not necessary. And like many supposed truths, it
turns out this is not true. While we do not need to worry about petroleum distillates, we
do need to worry about our own special type of fuel - electrons. Electrons can sneak
into any sort of opening, and if they get into the grain of wood, they can expand the
grain, weakening the wood and making it brittle.
Interestingly, electrons do not soak into plastic coverings, because they would rather
hang around on the surface and attract dust. Anyway, electrons soaking into exposed wood
can be a serious problem. </p>
<p>I have conducted some airframe structural integrity experiments that unfortunately were
not well documented, and frankly I do not care to duplicate. What I found was that when a
moving plastic fuselage (which is largely impervious to electron soaking) is abruptly
stopped by an immovable object such as the ground, it breaks into a small number of large
pieces, while a balsa fuselage (which has exposed surfaces and edges that can soak up
electrons) under the same circumstances will break into a large number of small pieces,
obviously because the wood has become more brittle under constant exposure to electrons. </p>
<p>The obvious solution to this problem is not to stop your airplanes with the ground,
unless of course you find it more effective to simply seal all of the exposed edges and
hope for the best. </p>
<hr>
<p><font size="4"><b>Using Gravity to Improve Electron Flow and Improve System Performance</b></font>
</p>
<p>You may remember from high school physics that freely flowing electrons move at about
about 3E8 meters per second. This may sound really fast, but in the world of electronics
it is not fast enough, because it means that an electron will move only about 0.30 meters
in a nanoSecond (1 billionth of a second). This turns out to be significant, because a lot
of high speed electronics tries to operate this fast, and the physical limitation of 0.30m
in a nanoSecond gets in the way. If you have ever seen a SuperComputer, such as a
Cray, the physical layout of the computer is dictated by this physical constraint. </p>
<p>Less than freely flowing electrons, such as those in a metal wire or a large pipe, flow
somewhat slower. What can we do about it? Well, there is a physical force available that
is often ignored in laying out the arrangement of an electric power system - gravity.
Yes, good old gravity - as Isaac Newton pointed out, <i>it's not just a good idea, it's
the law!</i> Gravity in the general neighborhood of the Earth provides an acceleration (an
increase in speed) of about 9.8 meters per second, per second (gravity in other
locations, like the vicinity of Jupiter, may be a little different, so check your
current location on a map). This means that for each second the electron spends being
accelerated downward by gravity, its speed will increase by 9.8m/S. If you place the
battery about 3E8 meters directly above the motor, and connect it with
zero-weight-zero-resistance superconducting wire (such as Radio Shack part #555-1212),
gravitational acceleration will increase the speed of the electrons by 9.8m/S, or about
3.3E-6%. Faster electronics means lower effective resistance, so this is a rather
impressive improvement for simply adjusting the position of the battery and adding a
little bit of wire. </p>
<hr>
<h2>COPYRIGHT </h2>
<p>This document is copyrighted (c) 1997 by Steven Kranish, and may not be copied or used
in other forms of publication (electronic or paper) without written permission from the
author, although I am not sure there is any <i>reason</i> to want do so. If
you actually find this humorous, I will gladly grant permission, but I would
like to know about it, so go ahead and ask. </p>
<hr>
<h2>CONTACTS </h2>
<p>If you have any questions, please re-read the column and think about it <i>real</i>
hard. If you must, contact me at <a href="http://rcgroups.com/shared/nospam.php?u=skranish&d=ezonemag.com">skranish(at)ezonemag.com</a>
<p>Have you ever walked across a rug on a dry winter day, and received a shock when you
touched a metal object, such as a doorknob? The rug is providing you with a static charge
- basically an excess of electrons - and you receive a shock when you touch an object that
provides a low impedance discharge path (essentially a quick escape route) for those extra
electrons. </p>
<p>Our electric powered airplanes can experience the same thing, and the excess electrons
- the static charge - can seriously degrade performance of the motor system and plane. How
does the plane pick up a static charge? Well, you do not have to drag it across
a wool rug. The motor itself is a great source of loose electrons, which come spewing
out of every opening and may even leak from damaged wiring. Brush arcing and armature
friction both cause electrons to loosen. Mechanical vibration can actually shake them
loose. </p>
<p>The airframe itself can pick up extra electrons because a plastic covered wing slicing
through the air will cut electrons free from the air molecules. Don't believe it? Have you
ever noticed how difficult it is to keep dust off plastic covering while applying it to
the airframe? The problem is that the covering attracts a static charge, and the static
charge attracts dust. (Actually, it is a fairly basic law of physics that ANYTHING that
you want to keep clean will attract dust in a way that you cannot reasonably circumvent,
but that is another topic) The plane flies much faster than you are likely to move your
covering iron, so the static charge problem is much worse in flight that it would be on
the ground. </p>
<table border="0" cellpadding="3" width="100%">
<tr>
<td width="50%"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass2.jpg" width="388" height="268"></td>
<td width="50%">The first photograph shows the static charge on my "Today's Hobbies
Skyvolt" while simply sitting still on the ground. This photograph was
taken with the patented (and classified) View-A-Charge adapter attached to a very
high speed 35mm camera. The View-A-Charge is essentially a Electron Macroscope (well, OK,
a filter) that allows one to see electrons in addition to the usual boring photons. I
can't show you a picture of the top-secret classified View-A-Charge, because,
well, then I would have to shoot you, which is fairly hard to do over the Web.
Notice how the charge is distributed evenly all over the plane. Note also that the plane
is sitting on 3 rubber wheels, which act as insulators, so the static charge does not
discharge, even though the plane is sitting on the ground. </td>
</tr>
</table>
<p>The presence of the static charge can present several problems. The most obvious is the
weight of these additional and totally unnecessary electrons. Another is the aerodynamic
drag that the electrons create by disrupting the otherwise smooth flow of air over the
wing. Yet another problem, that is often overlooked, is that the negative charge on the
plane actually repels it from the normally negatively charged ground, making it very
difficult, if not impossible to land the plane. </p>
<p>What can we do to discharge the plane? Well, we have to provide a good, solid ground
path for the electrons to flow on. A heavy duty jumper cable (the kind used to 'jump
start' a car) would make a great temporary ground strap, but they tend to be rather heavy,
and usually are not available in very long lengths. You may be old enough to remember when
heating oil delivery trucks used a heavy chain as a ground strap for the same reason we
want to - for electrostatic discharge. For some unknown reason, oil delivery trucks no
longer have these grounding chains (it may have something to do with the sparks generated
when the chain bounces on the pavement being <i>more </i>of a fire hazard than the static
charge, but I am not an authority on oil trucks). Anyway, we <i>do </i>want to have a
grounding chain, so we can discharge the static charge on the plane by dragging the chain
along the ground while doing low passes over the landing strip. </p>
<table border="0" cellpadding="3" cellspacing="1" width="100%">
<tr>
<td width="50%"><p align="center"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass5.jpg" width="367" height="214"></p>
<p align="center"><strong>The grounding chain is being used to release unnecessary
electrons during a low fly-by</strong></td>
<td width="50%">The next picture is a remarkable photograph taken by the View-A-Charge
with a very long zoom lens mounted onto a Track-A-Plane radar controlled gyro stabilized
camera positioning system. The Track-A-Plane is patented and classified, so I can't show
you a picture....oh, skip it. Anyway, the photo clearly shows the grounding chain
(attached to the plane near the tailwheel) in action - as it is dragged across the ground,
it provides a low impedance path to ground for the static charge on the plane, and the
electrons can be seen trailing behind the plane, where they have been deposited onto the
ground. You can even see how the remaining charge on the plane has moved towards the low
impedance path to ground, as there are no longer many extra electrons on the forward part
of the plane. </td>
</tr>
</table>
<p> </p>
<p align="center"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass4.jpg" width="340" height="228"></p>
<p align="center"><strong>A close-up view of the grounding chain in action. The
View-A-Charge filter allows us to see the actual electrons as they flow off the airframe
to the ground.</strong></p>
<p align="left"> </p>
<table border="0" cellpadding="3" width="100%">
<tr>
<td width="50%">If merely doing low passes is not your style, and you prefer the 'hovering
airplane' mode of flight that is all the rage in 'fun fly' planes, you can simply hover
near the ground to discharge the plane. For this photo, I replaced the Astro 05 and 7 cell
1700SCR pack in the Skyvolt with a geared Astro 90 and 36 N500AR cells, which actually
allowed the plane to do a near-vertical hover, at least when I could stop it from doing
torque rolls. This combination did seem a little overpowered, with a propeller only
slightly smaller than the wing, and it was often difficult to tell which was which,
considering the roll rate. </td>
<td width="50%"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass3.jpg" width="372" height="263"></td>
</tr>
</table>
<p>OK, now that we have established how to discharge the electrons from a plane, what did
we accomplish? A lot, actually. The electrons that were discharged from the Skyvolt were
collected in a Catch-A-Charge Electron Containment System (they aren't hard to find in the
grass when looking though the View-A-Charge) and then weighed. The Catch-A-Charge jar is
necessary because electrons don't like to stick together - objects with the same polarity
charge tend to repel each other, and if you simply make a pile of
electrons, they tend to go shooting all over the place as soon as you let go of them. </p>
<table border="0" cellpadding="3" width="100%">
<tr>
<td width="50%"><p align="center"><img src="http://static.rcgroups.com/articles/ezonemag/fromlab/../../images/emass.jpg" width="170" height="267"></td>
<td width="50%">This photo shows the patented (and classified, if you haven't guessed)
Electro-Mass weighing the electrons captured in the Catch-A-Charge. The electrons weighed
about 12.2 oz, which is about 25% of the weight of the plane. This weight reduction
provides a remarkable improvement in performance, provided you are willing to spend
most of the flight doing low passes dragging the grounding chain along the ground, and
have sufficient piloting skill to not damage the airframe while spending so much time in
ground effect. </td>
</tr>
</table>
<p> </p>
<hr>
<p><font size="4"><b>Problems with Electron Soaked Structures</b></font> </p>
<p>If you have ever built a (yeech!) slimer, you know that it is necessary to seal all
of the exposed wood surfaces to that they will not soak up the gunk that comes out of
the engine exhaust. Many of the articles and books about electric planes point out that
with an electric powered plane, this is not necessary. And like many supposed truths, it
turns out this is not true. While we do not need to worry about petroleum distillates, we
do need to worry about our own special type of fuel - electrons. Electrons can sneak
into any sort of opening, and if they get into the grain of wood, they can expand the
grain, weakening the wood and making it brittle.
Interestingly, electrons do not soak into plastic coverings, because they would rather
hang around on the surface and attract dust. Anyway, electrons soaking into exposed wood
can be a serious problem. </p>
<p>I have conducted some airframe structural integrity experiments that unfortunately were
not well documented, and frankly I do not care to duplicate. What I found was that when a
moving plastic fuselage (which is largely impervious to electron soaking) is abruptly
stopped by an immovable object such as the ground, it breaks into a small number of large
pieces, while a balsa fuselage (which has exposed surfaces and edges that can soak up
electrons) under the same circumstances will break into a large number of small pieces,
obviously because the wood has become more brittle under constant exposure to electrons. </p>
<p>The obvious solution to this problem is not to stop your airplanes with the ground,
unless of course you find it more effective to simply seal all of the exposed edges and
hope for the best. </p>
<hr>
<p><font size="4"><b>Using Gravity to Improve Electron Flow and Improve System Performance</b></font>
</p>
<p>You may remember from high school physics that freely flowing electrons move at about
about 3E8 meters per second. This may sound really fast, but in the world of electronics
it is not fast enough, because it means that an electron will move only about 0.30 meters
in a nanoSecond (1 billionth of a second). This turns out to be significant, because a lot
of high speed electronics tries to operate this fast, and the physical limitation of 0.30m
in a nanoSecond gets in the way. If you have ever seen a SuperComputer, such as a
Cray, the physical layout of the computer is dictated by this physical constraint. </p>
<p>Less than freely flowing electrons, such as those in a metal wire or a large pipe, flow
somewhat slower. What can we do about it? Well, there is a physical force available that
is often ignored in laying out the arrangement of an electric power system - gravity.
Yes, good old gravity - as Isaac Newton pointed out, <i>it's not just a good idea, it's
the law!</i> Gravity in the general neighborhood of the Earth provides an acceleration (an
increase in speed) of about 9.8 meters per second, per second (gravity in other
locations, like the vicinity of Jupiter, may be a little different, so check your
current location on a map). This means that for each second the electron spends being
accelerated downward by gravity, its speed will increase by 9.8m/S. If you place the
battery about 3E8 meters directly above the motor, and connect it with
zero-weight-zero-resistance superconducting wire (such as Radio Shack part #555-1212),
gravitational acceleration will increase the speed of the electrons by 9.8m/S, or about
3.3E-6%. Faster electronics means lower effective resistance, so this is a rather
impressive improvement for simply adjusting the position of the battery and adding a
little bit of wire. </p>
<hr>
<h2>COPYRIGHT </h2>
<p>This document is copyrighted (c) 1997 by Steven Kranish, and may not be copied or used
in other forms of publication (electronic or paper) without written permission from the
author, although I am not sure there is any <i>reason</i> to want do so. If
you actually find this humorous, I will gladly grant permission, but I would
like to know about it, so go ahead and ask. </p>
<hr>
<h2>CONTACTS </h2>
<p>If you have any questions, please re-read the column and think about it <i>real</i>
hard. If you must, contact me at <a href="http://rcgroups.com/shared/nospam.php?u=skranish&d=ezonemag.com">skranish(at)ezonemag.com</a>