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<title>Motor Testing: Static and In-Flight Motor Performance Testing</title>
<div class="details">
<span id="author" class="author">Bdale Garbee</span><br>
<span id="email" class="email"><a href="mailto:bdale@gag.com">bdale@gag.com</a></span><br>
-<span id="revnumber">version v1.9.9,</span>
-<span id="revdate">06 Oct 2021</span>
+<span id="revnumber">version v1.9.18,</span>
+<span id="revdate">28 Apr 2024</span>
</div>
<div id="toc" class="toc">
<div id="toctitle">Table of Contents</div>
</li>
<li><a href="#_installation">3. Installation</a>
<ul class="sectlevel2">
-<li><a href="#_power_switch_and_battery">3.1. Power Switch and Battery</a></li>
-<li><a href="#_pressure_sensor">3.2. Pressure Sensor</a></li>
+<li><a href="#_trigger_to_start_recording">3.1. Trigger to Start Recording</a></li>
+<li><a href="#_power_switch_and_battery">3.2. Power Switch and Battery</a></li>
+<li><a href="#_pressure_sensor">3.3. Pressure Sensor</a></li>
</ul>
</li>
<li><a href="#_operation">4. Operation</a></li>
<h2 id="_license">License</h2>
<div class="sectionbody">
<div class="paragraph">
-<p>Copyright © 2021 Bdale Garbee and Keith Packard</p>
+<p>Copyright © 2024 Bdale Garbee and Keith Packard</p>
</div>
<div class="paragraph">
<p>This document is released under the terms of the <a href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons ShareAlike 3.0 License</a></p>
can always be improved… If you have questions that aren’t answered in this
manual, or just need a little help figuring things out, we strongly suggest
joining the Altus Metrum user email list, which you can do by visiting
-<a href="https://lists.gag.com/mailman/listinfo/altusmetrum" class="bare">https://lists.gag.com/mailman/listinfo/altusmetrum</a>.</p>
+<a href="https://lists.gag.com/mailman3" class="bare">https://lists.gag.com/mailman3</a>.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_installation">3. Installation</h2>
<div class="sectionbody">
+<div class="admonitionblock warning">
+<table>
+<tr>
+<td class="icon">
+<img src="./images/icons/warning.svg" alt="Warning">
+</td>
+<td class="content">
+Firmware versions prior to 1.9.13 used acceleration to detect
+launch. Starting with 1.9.13, the firmware switched to using
+pressure to trigger recording. Altus Metrum strongly recommends
+upgrading all EasyMotor boards to current firmware, the
+behavior of which is described here.
+</td>
+</tr>
+</table>
+</div>
<div class="paragraph">
-<p>EasyMotor needs to be rigidly attached in the airframe, and the
-long axis of the circuit board needs to be aligned with the axis
-of flight. By default, the round beeper on the board should be
-“up” towards the nose cone, and the screw terminal strips should
-be “down” towards the fins and motor nozzle end of the rocket.</p>
+<p>EasyMotor needs to be rigidly attached in the airframe, in any
+convenient orientation.</p>
</div>
<div class="sect2">
-<h3 id="_power_switch_and_battery">3.1. Power Switch and Battery</h3>
+<h3 id="_trigger_to_start_recording">3.1. Trigger to Start Recording</h3>
+<div class="paragraph">
+<p>Starting with firmware version 1.9.13, a pressure sensor must
+be attached, and pressure change is used to initiate and conclude
+data recording. Pressure and 3 axes of acceleration are recorded
+for later analysis.</p>
+</div>
+<div class="paragraph">
+<p>EasyMotor looks for a 50 psi rise in pressure from ambient to
+start recording. Recording stops when the pressure drops
+below 50 psi and shows variation of less than 30 psi for at
+least 10 seconds. These conditions are intended to capture all
+actual burn data including anomalies such as "chuffs".</p>
+</div>
+</div>
+<div class="sect2">
+<h3 id="_power_switch_and_battery">3.2. Power Switch and Battery</h3>
<div class="paragraph">
<p>In addition to the circuit board itself, EasyMotor needs
-a power switch and battery to operate. Unlike most other
-Altus Metrum products, EasyMotor does not work with
-single-cell LiPo batteries. That’s because commonly
-available inexpensive pressure sensors need 5V, which is
-more than a single-cell LiPo provides. Any battery that
-provides from 6.5 to about 15 volts should work. Good
-choices are the common 9V alkaline battery, or the very
-small and light A23 12V alkaline batteries.</p>
+a power switch and battery to operate. Like many Altus
+Metrum products, EasyMotor requires a single-cell LiPo
+battery, and has an on-board charging circuit. The 5V
+needed for inexpensive pressure sensors is generated
+onboard using a switching regulator to boost the voltage.</p>
</div>
<div class="paragraph">
<p>Because he often mounts EasyMotor to the motor’s forward
</div>
</div>
<div class="sect2">
-<h3 id="_pressure_sensor">3.2. Pressure Sensor</h3>
+<h3 id="_pressure_sensor">3.3. Pressure Sensor</h3>
<div class="paragraph">
<p>The primary motivation for designing EasyMotor was to have
a reliable way of recording motor chamber pressure during
by the sensor. Very inexpensive sensors that have a
“1/8 NPT” threaded input, a “Buick-style” 3-pin connector,
and typically ship with a short cable and mating
-connector, are readily available on eBay and AliExpress.</p>
+connector, are readily available through various vendors
+including Amazon, eBay, and AliExpress.</p>
+</div>
+<div class="paragraph">
+<p>These pressure sensors have three wires and sometimes a
+shield around those wires. The colors of the wires can vary,
+but typically are red for power, black for ground, and green
+for the analog output. Hook red to '+5', green to 'PRES', and
+black to one of the two 'GND' screws on the board. The other
+'GND' screw is available for connecting the shield if one is
+present. This is mostly relevant if you’re using the product
+for static testing on the ground with a longer than usual
+cable.</p>
</div>
<div class="paragraph">
<p>To log in-flight chamber pressure, a typical approach
the pressure sensor, and attach the sensor leads to
EasyMotor.</p>
</div>
+<div class="paragraph">
+<p>If you aren’t up for machining closures yourself,
+<a href="http://lokiresearch.com">Loki Research</a> sells
+54mm and 75mm "experimental bulkheads" with threaded
+sensor ports that can be used with snap ring cases,
+and other related mechanical bits and pieces.</p>
+</div>
</div>
</div>
</div>
</div>
<div class="paragraph">
<p>After flight, AltosUI can be used to download the flight data,
-then export it to a comma separated values (CSV) file. Such a
-file can easily be loaded into a spreadsheet for analysis.</p>
+view a quick graph of acceleration and pressure with pan and
+zoom capabilities, then export it to a comma separated values
+(CSV) file. Such a file can easily be loaded into a spreadsheet
+for analysis.</p>
</div>
</div>
</div>
</div>
<div id="footer">
<div id="footer-text">
-Version v1.9.9<br>
-Last updated 2021-10-07 00:16:13 -0600
+Version v1.9.18<br>
+Last updated 2024-04-28 20:36:09 -0600
</div>
</div>
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projects / web / altusmetrum / blobdiff