Dennis Weatherly
May 01, 1996, 01:00 AM
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<title>The Electric Aircraft Design Analysis Program, version 2.0</title>
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<pre>Electric Aircraft Design Analysis V2.00
program by Roger Jaffe
review by Dennis Weatherly dennis_weatherly(at)mentorg.com
Have you ever wondered what size electric motor to use in
your latest project? Have you ever wanted to design your
own electric powered aircraft but weren't sure if the
model/size/motor combination you had in mind would perform
as you intended? Have you ever thought about adding a
couple of cells to the motor battery pack and wondered what
that would do to the duration and performance of your model?
All of these kinds of questions can be addressed by Roger
Jaffe's Electric Aircraft Design Analysis program. This
Windows-based computer program provides electric powered
aircraft performance prediction using a variety of
mathematical models.
Roger authors the Electric Power column in Model Builder
magazine. Over the years he has accumulated a large number
of performance prediction formulae that he has shared in his
writings. In this program he has combined these formulae
into an easy-to-use tool for the modeler.
The program runs under Windows 3.x or Windows 95. It
requires about 450K of disk space. You don't need an
extremely powerful PC; I originally ran the 1.03 version on
a 16 MHz 386SX system with 4 Mb of RAM. Installation is
simple. A small user's manual is provided that explains how
to use the program as well as the mathematic formulae in
action behind-the-scenes. I don't know the current price
but I believe it is around $25 US.
Version 2.00 is the latest release and represents a complete
rewrite of the program. Ease of use has been enhanced from
previous versions and more information is displayed at a
glance.
There are three main "Windows" in the program:
The Full Scale window allows you to record the aircraft
name, wingspan (in feet), wing area (in square feet), number
of motors and comments about a full-size aircraft. The
program arrives with a variety of Full Scale aircraft
pre-defined.
The Motor window allows you to record the motor name, weight
(in ounces), propeller information (diameter, pitch, rpm and
efficiency percentage), battery pack information (volts per
cell, cell count, current draw, weight, capacity), power
consumption (volts x amps or Abbot method), motor
efficiency, static thrust and comments. Motor output power
(in watts) and estimated duration are automatically
calculated for you based on this information. Most of the
AstroFlight line is already set up for you.
The Model window is where you do the bulk of the work. You
can select a Full Scale entry and provide a scaling factor
or enter the model name, wingspan (in inches), wing area (in
square inches), number of motors and ready to fly weight (in
ounces) about the model you want to study. Several popular
electric power models and some proposed scale models are
pre-defined for you.
Once all of the Model data has been entered and a Motor
definition has been imported a variety of performance
calculations are performed automatically to provide the
following information:
Wing Loading (ounces/square foot)
Wing Cube Loading (ounces/cubic foot - Francis Reynolds'
approach to wing loading that takes airfoil affects into
account)
Aircraft Performance Ratio (in two forms, based on Wing
Loading and based on Wing Cube Loading).
Rod Moore Performance Factor
Power to Weight Ratio (watts/pound)
These calculations each result in a decimal number (the
calculated value) and a textual "rating". For example, the
Rod Moore Performance Factor is set up to provide
"Marginal", "Adequate" or "Excellent" textual ratings based
on the decimal number that is calculated. The program comes
with the labels and their ranges pre-defined. You can edit
these textual labels and assign your own words, define the
number of steps and map a given range of calculated values
to a label. So far I have not had any need to modify the
pre-defined ranges.
Once the Model is defined in the Model window it is easy to
check out the affects of various changes. What if the model
weighs more than estimated? Just plug in the new weight and
all the performance figures are re-calculated automatically.
Want to try a geared 15 instead of a direct drive 25?
Import a different motor definition and see the results.
Want to add more cells to a given power system? Define the
new battery configuration in the Motor window (if it doesn't
already exist) and then import it into the Model window.
You can have multiple Aircraft, Motor and Model windows open
at one time. Each window can be saved for later use or
copied to use as a template for a new definition.
I have used this program to check out proposed electric
conversions and to help design new aircraft from scratch. I
have also run all of my existing prop-driven electric fleet
through the program to verify that the performance I see is
what the program will predict. I have been very pleased
with the accuracy of the predictions.
There are a few limitations to the program at this point.
It does not handle ducted fan applications. It also does
not easily handle multi-wing aircraft, although you could
estimate the effective wing area and use that value. The
program might also have some problems estimating performance
for unusual configurations, such as flying wings or canards,
but I have not tried any of these situations.
All in all this has proven to be a most useful tool for my
electric power projects. It has given me the confidence to
tackle some projects that I might have skipped otherwise,
due to lack of experience or similar models to study.
The software can be ordered via the following address:
Roger Jaffe
6462 Sunny Brae Drive
San Diego, CA 92119
74164.3237(at)compuserve.com
---
Dennis Weatherly (503) 685-1176
Mentor Graphics Corporation <a href="http://rcgroups.com/shared/nospam.php?u=dennis_weatherly&d=mentorg.com">dennis_weatherly(at)mentorg.com</a>
Wilsonville, Oregon U.S.A.</pre>
</body>
</html>
<head>
<title>The Electric Aircraft Design Analysis Program, version 2.0</title>
</head>
<body bgcolor="#FFFFFF">
<pre>Electric Aircraft Design Analysis V2.00
program by Roger Jaffe
review by Dennis Weatherly dennis_weatherly(at)mentorg.com
Have you ever wondered what size electric motor to use in
your latest project? Have you ever wanted to design your
own electric powered aircraft but weren't sure if the
model/size/motor combination you had in mind would perform
as you intended? Have you ever thought about adding a
couple of cells to the motor battery pack and wondered what
that would do to the duration and performance of your model?
All of these kinds of questions can be addressed by Roger
Jaffe's Electric Aircraft Design Analysis program. This
Windows-based computer program provides electric powered
aircraft performance prediction using a variety of
mathematical models.
Roger authors the Electric Power column in Model Builder
magazine. Over the years he has accumulated a large number
of performance prediction formulae that he has shared in his
writings. In this program he has combined these formulae
into an easy-to-use tool for the modeler.
The program runs under Windows 3.x or Windows 95. It
requires about 450K of disk space. You don't need an
extremely powerful PC; I originally ran the 1.03 version on
a 16 MHz 386SX system with 4 Mb of RAM. Installation is
simple. A small user's manual is provided that explains how
to use the program as well as the mathematic formulae in
action behind-the-scenes. I don't know the current price
but I believe it is around $25 US.
Version 2.00 is the latest release and represents a complete
rewrite of the program. Ease of use has been enhanced from
previous versions and more information is displayed at a
glance.
There are three main "Windows" in the program:
The Full Scale window allows you to record the aircraft
name, wingspan (in feet), wing area (in square feet), number
of motors and comments about a full-size aircraft. The
program arrives with a variety of Full Scale aircraft
pre-defined.
The Motor window allows you to record the motor name, weight
(in ounces), propeller information (diameter, pitch, rpm and
efficiency percentage), battery pack information (volts per
cell, cell count, current draw, weight, capacity), power
consumption (volts x amps or Abbot method), motor
efficiency, static thrust and comments. Motor output power
(in watts) and estimated duration are automatically
calculated for you based on this information. Most of the
AstroFlight line is already set up for you.
The Model window is where you do the bulk of the work. You
can select a Full Scale entry and provide a scaling factor
or enter the model name, wingspan (in inches), wing area (in
square inches), number of motors and ready to fly weight (in
ounces) about the model you want to study. Several popular
electric power models and some proposed scale models are
pre-defined for you.
Once all of the Model data has been entered and a Motor
definition has been imported a variety of performance
calculations are performed automatically to provide the
following information:
Wing Loading (ounces/square foot)
Wing Cube Loading (ounces/cubic foot - Francis Reynolds'
approach to wing loading that takes airfoil affects into
account)
Aircraft Performance Ratio (in two forms, based on Wing
Loading and based on Wing Cube Loading).
Rod Moore Performance Factor
Power to Weight Ratio (watts/pound)
These calculations each result in a decimal number (the
calculated value) and a textual "rating". For example, the
Rod Moore Performance Factor is set up to provide
"Marginal", "Adequate" or "Excellent" textual ratings based
on the decimal number that is calculated. The program comes
with the labels and their ranges pre-defined. You can edit
these textual labels and assign your own words, define the
number of steps and map a given range of calculated values
to a label. So far I have not had any need to modify the
pre-defined ranges.
Once the Model is defined in the Model window it is easy to
check out the affects of various changes. What if the model
weighs more than estimated? Just plug in the new weight and
all the performance figures are re-calculated automatically.
Want to try a geared 15 instead of a direct drive 25?
Import a different motor definition and see the results.
Want to add more cells to a given power system? Define the
new battery configuration in the Motor window (if it doesn't
already exist) and then import it into the Model window.
You can have multiple Aircraft, Motor and Model windows open
at one time. Each window can be saved for later use or
copied to use as a template for a new definition.
I have used this program to check out proposed electric
conversions and to help design new aircraft from scratch. I
have also run all of my existing prop-driven electric fleet
through the program to verify that the performance I see is
what the program will predict. I have been very pleased
with the accuracy of the predictions.
There are a few limitations to the program at this point.
It does not handle ducted fan applications. It also does
not easily handle multi-wing aircraft, although you could
estimate the effective wing area and use that value. The
program might also have some problems estimating performance
for unusual configurations, such as flying wings or canards,
but I have not tried any of these situations.
All in all this has proven to be a most useful tool for my
electric power projects. It has given me the confidence to
tackle some projects that I might have skipped otherwise,
due to lack of experience or similar models to study.
The software can be ordered via the following address:
Roger Jaffe
6462 Sunny Brae Drive
San Diego, CA 92119
74164.3237(at)compuserve.com
---
Dennis Weatherly (503) 685-1176
Mentor Graphics Corporation <a href="http://rcgroups.com/shared/nospam.php?u=dennis_weatherly&d=mentorg.com">dennis_weatherly(at)mentorg.com</a>
Wilsonville, Oregon U.S.A.</pre>
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