<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Friends,</div><div><br></div><div>Even if you know the history, you might not have seen the actual blueprints, and you still have to find it in the blueprints. <br><br>Regards,<div>Douglas</div></div><div><br>On Jun 11, 2018, at 6:59 AM, Michelle Thompson via Ground-Station <<a href="mailto:ground-station@lists.openresearch.institute">ground-station@lists.openresearch.institute</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="auto">Good question - post with a generous spoiler alert style header. Cc Phil for a faster reply.</div><br><div class="gmail_quote"><div dir="ltr">On Mon, Jun 11, 2018, 04:52 Zach Leffke via Ground-Station <<a href="mailto:ground-station@lists.openresearch.institute">ground-station@lists.openresearch.institute</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p>Do you want answers (or attempts at answers) on the list or
direct to you?</p>
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<p>-Zach, KJ4QLP<br>
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<pre class="m_6306829133418286794moz-signature" cols="72">Research Associate
Aerospace Systems Lab
Ted & Karyn Hume Center for National Security & Technology
Virginia Polytechnic Institute & State University
Work Phone: 540-231-4174
Cell Phone: 540-808-6305</pre>
<div class="m_6306829133418286794moz-cite-prefix">On 6/8/2018 10:36 PM, Michelle Thompson
via Ground-Station wrote:<br>
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<div>Phil Karn KA9Q has been working on
something fun for us. If you enjoy this
quiz, please feel free to share it and let
him know!</div>
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<div>Given the documents that you can find at:
<a href="https://github.com/phase4space/AO-10-blueprints" target="_blank" rel="noreferrer">https://github.com/phase4space/AO-10-blueprints</a></div>
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<div>Quiz for fans of the AMSAT Phase
IIIB/AO-10 blueprints</div>
<div>Phil Karn, KA9Q</div>
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<div>Question 1: AO-10 carried a 400-newton
kick (rocket) motor that used hypergolic
propellants. It was fired only once, but the
burn duration was 1.68 times longer than
planned. Why? (Note: the burn did *not* end
because of propellant depletion.)</div>
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<div>The cause can be discerned from the
prints; i.e., it was a hardware problem, not
a software bug or operational mistake.</div>
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<div>Optional hint 1: The burn was timed in
hardware.</div>
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<div>Question 2: The ground test of the
hardware consisted of successfully executing
a maximal length burn. What tests could have
revealed it?</div>
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<div>Question 3: Although the first burn did
not deplete the propellants, it was not
possible to fire the engine again because of
insufficient helium pressure. Why? (Hint:
the cause was not insufficient helium
loading before launch.)</div>
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