-<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Goblin 10</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a name="id2560049"></a>Goblin 10</h1></div><div><h2 class="subtitle">A NAR L3 Certification Rocket</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Bdale</span> <span class="surname">Garbee</span></h3></div></div><div><p class="copyright">Copyright © 2008 Bdale Garbee</p></div><div><div class="legalnotice"><a name="id2815458"></a><p>
+<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Goblin 10</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a name="id2481338"></a>Goblin 10</h1></div><div><h2 class="subtitle">A NAR L3 Certification Rocket</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Bdale</span> <span class="surname">Garbee</span></h3></div></div><div><p class="copyright">Copyright © 2008 Bdale Garbee</p></div><div><div class="legalnotice"><a name="id2736747"></a><p>
This document is released under the terms of the
<a class="ulink" href="http://creativecommons.org/licenses/by-sa/3.0/" target="_top">
Creative Commons ShareAlike 3.0
</a>
license.
- </p></div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 1.0</td><td align="left">15 November 2008</td></tr><tr><td align="left" colspan="2">Successful certification flight at Hudson Ranch</td></tr><tr><td align="left">Revision 0.2</td><td align="left">28 October 2008</td></tr><tr><td align="left" colspan="2">Revising during flight to DC</td></tr><tr><td align="left">Revision 0.1</td><td align="left">23 October 2008</td></tr><tr><td align="left" colspan="2">Initial content, derived from YikStik</td></tr></table></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="chapter"><a href="#id2822757">1. Introduction</a></span></dt><dt><span class="chapter"><a href="#id2828645">2. Design</a></span></dt><dd><dl><dt><span class="section"><a href="#id2838502">Overview</a></span></dt><dt><span class="section"><a href="#id2815988">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2842401">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2823397">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2833680">Nose Cone Electronics Bay</a></span></dt><dt><span class="section"><a href="#id2812400">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2842095">Avionics</a></span></dt><dt><span class="section"><a href="#id2819216">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2826797">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2845875">Recovery System</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#id2847645">3. Construction Details</a></span></dt><dd><dl><dt><span class="section"><a href="#id2845740">Airframe</a></span></dt><dt><span class="section"><a href="#id2813144">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2834138">Avionics Bay</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2831717">4. Recovery Systems Package</a></span></dt><dd><dl><dt><span class="section"><a href="#id2847622">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2830883">Recovery Initiation Control Components</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2846528">5. Checklists </a></span></dt><dt><span class="chapter"><a href="#id2842033">6. Flight Summary</a></span></dt><dt><span class="chapter"><a href="#id2842161">7. Analysis and Conclusions</a></span></dt></dl></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2822757"></a>Chapter 1. Introduction</h2></div></div></div><p>
+ </p></div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 1.0</td><td align="left">15 November 2008</td></tr><tr><td align="left" colspan="2">Successful certification flight at Hudson Ranch</td></tr><tr><td align="left">Revision 0.2</td><td align="left">28 October 2008</td></tr><tr><td align="left" colspan="2">Revising during flight to DC</td></tr><tr><td align="left">Revision 0.1</td><td align="left">23 October 2008</td></tr><tr><td align="left" colspan="2">Initial content, derived from YikStik</td></tr></table></div></div></div><hr></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="chapter"><a href="#id2744045">1. Introduction</a></span></dt><dt><span class="chapter"><a href="#id2749934">2. Design</a></span></dt><dd><dl><dt><span class="section"><a href="#id2759790">Overview</a></span></dt><dt><span class="section"><a href="#id2737277">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2763689">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2744686">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2754969">Nose Cone Electronics Bay</a></span></dt><dt><span class="section"><a href="#id2733689">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2763384">Avionics</a></span></dt><dt><span class="section"><a href="#id2740504">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2748086">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2767164">Recovery System</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#id2768933">3. Construction Details</a></span></dt><dd><dl><dt><span class="section"><a href="#id2749141">Airframe</a></span></dt><dt><span class="section"><a href="#id2754017">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2771414">Avionics Bay</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2745741">4. Recovery Systems Package</a></span></dt><dd><dl><dt><span class="section"><a href="#id2740673">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2752914">Recovery Initiation Control Components</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2748101">5. Checklists </a></span></dt><dt><span class="chapter"><a href="#id2750187">6. Flight Summary</a></span></dt><dt><span class="chapter"><a href="#id2764884">7. Analysis and Conclusions</a></span></dt></dl></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2744045"></a>Chapter 1. Introduction</h2></div></div></div><p>
This is a rocket I'm building for my second attempt at a NAR Level 3
certification flight. It's basically a Polecat Aerospace Goblin 10 kit
augmented with an additional electronics bay in the nose cone, some
NCR launch sites under their standing waivers.
The smallest reasonable motor for this rocket would be a Cesaroni
K445 or equivalent, which would yield an apogee of about 2300 feet.
- </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2828645"></a>Chapter 2. Design</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2838502">Overview</a></span></dt><dt><span class="section"><a href="#id2815988">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2842401">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2823397">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2833680">Nose Cone Electronics Bay</a></span></dt><dt><span class="section"><a href="#id2812400">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2842095">Avionics</a></span></dt><dt><span class="section"><a href="#id2819216">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2826797">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2845875">Recovery System</a></span></dt></dl></dd></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2838502"></a>Overview</h2></div></div></div><p>
+ </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2749934"></a>Chapter 2. Design</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2759790">Overview</a></span></dt><dt><span class="section"><a href="#id2737277">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2763689">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2744686">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2754969">Nose Cone Electronics Bay</a></span></dt><dt><span class="section"><a href="#id2733689">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2763384">Avionics</a></span></dt><dt><span class="section"><a href="#id2740504">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2748086">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2767164">Recovery System</a></span></dt></dl></dd></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2759790"></a>Overview</h2></div></div></div><p>
The Goblin 10 kit is a simple "four fins and a nose cone" rocket
that is short and squat, with a 98mm motor mount.
It supports dual-deploy by
centering rings, accessed by a side hatch. An additional payload bay
will be built inside the nose cone to carry experimental altimeters,
a tracking beacon, and possibly a GPS position reporting system.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2815988"></a>Rocksim File</h2></div></div></div>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2737277"></a>Rocksim File</h2></div></div></div>
This is the current working design in Rocksim format:
- <a class="ulink" href="Polecat_Goblin_10.rkt" target="_top"> Polecat_Goblin_10.rkt </a></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2842401"></a>Drawing from Rocksim</h2></div></div></div><span class="inlinemediaobject"><img src="Polecat_Goblin_10.jpg" height="450"></span></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2823397"></a>Motor Retention</h2></div></div></div><p>
+ <a class="ulink" href="Polecat_Goblin_10.rkt" target="_top"> Polecat_Goblin_10.rkt </a></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2763689"></a>Drawing from Rocksim</h2></div></div></div><span class="inlinemediaobject"><img src="Polecat_Goblin_10.jpg" height="450"></span></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2744686"></a>Motor Retention</h2></div></div></div><p>
I will include 8-24 T-nuts in the aft centering ring spaced to allow
the use of an Aeropack 98mm retainer and associated 75mm adapter.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2833680"></a>Nose Cone Electronics Bay</h2></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2754969"></a>Nose Cone Electronics Bay</h2></div></div></div><p>
Instead of using the supplied nose cone bulkhead, I intend to cut a
custom one that would support installing a length of 98mm motor mount
from the tip of the nose to the bulkhead. With a plate cut to cover
the aft end of the airframe tube, this would form an electronics bay
capable of holding a beacon transmitter, GPS system, or other custom
electronics.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2812400"></a>Electronics</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2842095"></a>Avionics</h3></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2733689"></a>Electronics</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2763384"></a>Avionics</h3></div></div></div><p>
The recovery system will feature dual redundant barometric altimeters
in the main avionics bay between the two forward motor mount
centering rings.
A third rotary switch will be used as a SAFE/ARM switch configured
to interrupt connectivity to all ejection charges in accordance with
NAR certification requirements.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2819216"></a>Stability Evaluation</h3></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2740504"></a>Stability Evaluation</h3></div></div></div><p>
The Goblin 10 kit designers indicate
that the rocket is unconditionally stable with all motors that fit
the motor mount geometry. Since we're adding mass at both ends, by
I also note that the simulated margin of stability
in my as-built configuration is fairly close to the margin of
stability of the as-designed model.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2826797"></a>Expected Performance</h3></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2748086"></a>Expected Performance</h3></div></div></div><p>
The Aerotech M1297W reload should carry this vehicle to just under
7000 feet AGL from Colorado Front Range launch sites. It
should reach just over 2 miles on a Cesaroni M795 moon burner
or equivalent.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2845875"></a>Recovery System</h3></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2767164"></a>Recovery System</h3></div></div></div><p>
The recovery system will use dual redundant barometric altimeters
firing 4F black powder charges using commercial e-matches.
At apogee, a drogue chute will deploy with separation of the nose
</p><p>
The recovery system attachment points will all use 1/4 inch u-bolts
with nuts, washers, and backing plates through bulkheads.
- </p></div></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2847645"></a>Chapter 3. Construction Details</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2845740">Airframe</a></span></dt><dt><span class="section"><a href="#id2813144">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2834138">Avionics Bay</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2845740"></a>Airframe</h2></div></div></div><p>
+ </p></div></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2768933"></a>Chapter 3. Construction Details</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2749141">Airframe</a></span></dt><dt><span class="section"><a href="#id2754017">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2771414">Avionics Bay</a></span></dt></dl></div><p>
+ I have collected all of my
+ <a class="ulink" href="http://gallery.gag.com/rockets/goblin10" target="_top">
+ build photos
+ </a>
+ in one place, they may show better than I can explain how various
+ aspects of the Goblin went together.
+ </p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2749141"></a>Airframe</h2></div></div></div><p>
The airframe tubing provided in the Polecat kit is thick cardboard tube
with a thin exterior fiberglass wrap. To increase airframe strength,
and particularly to prevent zippers, additional reinforcement seemed
curing by an inflatable child's bounce toy inside a plastic garbage
bag. The result is a substantially strengthened tube, with carbon
fiber lining from the leading edge back past the first centering ring.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2813144"></a>Nose Cone</h2></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2754017"></a>Nose Cone</h2></div></div></div><p>
The provided nose cone bulkhead was replaced by a custom centering
ring cut from 3/8 inch birch plywood. The ring's outer diameter was
adjusted put place the ring approximately an inch forward of the end
the piece of airframe tubing. After the epoxies cured, a rotary tool
was used to cut the airframe tubing off flush with the aft surface of
the centering ring.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2834138"></a>Avionics Bay</h2></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2771414"></a>Avionics Bay</h2></div></div></div><p>
The avionics bay walls were installed approximately 90 degrees apart
prior to installation of the motor mount assembly in the airframe.
The airframe wall was marked for a 3.5 x 6.5" access hatch centered
A suitably sized avionics sled should be possible to install and remove
through the avionics bay hatch allowing for possible future experiments
with alternative avionics.
- </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2831717"></a>Chapter 4. Recovery Systems Package</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2847622">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2830883">Recovery Initiation Control Components</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2847622"></a>Recovery System Description</h2></div></div></div><p>
+ </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2745741"></a>Chapter 4. Recovery Systems Package</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2740673">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2752914">Recovery Initiation Control Components</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2740673"></a>Recovery System Description</h2></div></div></div><p>
This rocket uses dual deployment.
</p><p>
The apogee event separates the nose cone from the
chute apex, with a smaller drogue chute deployed to pull off the bag
and cleanly deploy the main. The primary motivation for this is to
prevent the main chute shrouds from tangling during ejection.
- </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2830883"></a>Recovery Initiation Control Components</h2></div></div></div><p>
+ </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2752914"></a>Recovery Initiation Control Components</h2></div></div></div><p>
The main avionics bay between the forward two centering rings is
populated with two commercial altimeters, a PerfectFlite MAWD
and a Missile Works miniRRC2.
With a 10 foot Team Vatsaas design parachute and our
anticipated build weight, the descent rate under main
should be just over 20 feet per second.
- </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2846528"></a>Chapter 5. Checklists </h2></div></div></div><div class="orderedlist"><ol type="1"><li>
+ </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2748101"></a>Chapter 5. Checklists </h2></div></div></div><div class="orderedlist"><ol type="1"><li>
Planning
<div class="orderedlist"><ol type="1"><li>
Pick a club launch with suitable waiver and facilities to
flight line
</li><li>
bring the rocket to observers for post-flight inspection
- </li></ol></div></li></ol></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2842033"></a>Chapter 6. Flight Summary</h2></div></div></div><p>
+ </li></ol></div></li></ol></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2750187"></a>Chapter 6. Flight Summary</h2></div></div></div><p>
A successful level 3 certification flight occurred on 15 November 2008
at the SCORE Hudson Ranch launch facility. The motor was an Aerotech
M1297W provided by Tim Thomas of Giant Leap Motors, the igniter was
Video of the launch taken by Jeff Lane
</a></li><li><a class="ulink" href="http://www.youtube.com/watch?v=xaJnl89wfWU" target="_top">
Video of the launch taken by Jason Unwin
- </a></li></ul></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2842161"></a>Chapter 7. Analysis and Conclusions</h2></div></div></div><p>
+ </a></li></ul></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2764884"></a>Chapter 7. Analysis and Conclusions</h2></div></div></div><p>
The ascent was straighter than expected... very smooth during
the motor burn, then a couple slow rolls during coast. The two
altimeters agreed within 4 feet on the apogee. The max