1 <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 V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book"><div class="titlepage"><div><div><h1 class="title"><a name="idm15495832"></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="idp109064"></a><p>
2 This document is released under the terms of the
3 <a class="ulink" href="http://creativecommons.org/licenses/by-sa/3.0/" target="_top">
4 Creative Commons ShareAlike 3.0
7 </p></div></div><div><div class="revhistory"><table style="border-style:solid; 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 class="toc"><dt><span class="chapter"><a href="#idp112680">1. Introduction</a></span></dt><dt><span class="chapter"><a href="#idp2161264">2. Design</a></span></dt><dd><dl><dt><span class="section"><a href="#idp1850344">Overview</a></span></dt><dt><span class="section"><a href="#idp2704224">Rocksim File</a></span></dt><dt><span class="section"><a href="#idp2161528">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#idp2305928">Motor Retention</a></span></dt><dt><span class="section"><a href="#idp2452064">Nose Cone Electronics Bay</a></span></dt><dt><span class="section"><a href="#idp2439640">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#idp2461808">Avionics</a></span></dt><dt><span class="section"><a href="#idp3312136">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#idp2033792">Expected Performance</a></span></dt><dt><span class="section"><a href="#idp3384200">Recovery System</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#idp1515616">3. Construction Details</a></span></dt><dd><dl><dt><span class="section"><a href="#idp2928992">Airframe</a></span></dt><dt><span class="section"><a href="#idp1978904">Nose Cone</a></span></dt><dt><span class="section"><a href="#idp47048">Avionics Bay</a></span></dt></dl></dd><dt><span class="chapter"><a href="#idp48792">4. Recovery Systems Package</a></span></dt><dd><dl><dt><span class="section"><a href="#idp49112">Recovery System Description</a></span></dt><dt><span class="section"><a href="#idp52136">Recovery Initiation Control Components</a></span></dt></dl></dd><dt><span class="chapter"><a href="#idp749288">5. Checklists </a></span></dt><dt><span class="chapter"><a href="#idp201568">6. Flight Summary</a></span></dt><dt><span class="chapter"><a href="#idp58192">7. Analysis and Conclusions</a></span></dt></dl></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp112680"></a>Chapter 1. Introduction</h1></div></div></div><p>
8 This is a rocket I'm building for my second attempt at a NAR Level 3
9 certification flight. It's basically a Polecat Aerospace Goblin 10 kit
10 augmented with an additional electronics bay in the nose cone, some
11 structural reinforcement, and incorporating a few personal build
14 Preliminary analysis suggests that it should reach just under 7k feet
15 on the Aerotech M1297W reload, and could break two miles on the
16 Cesaroni M795W moon-burner. This means that a certification flight can
17 be supported at Hudson Ranch with the standing 8k waiver, at the Tripoli
18 Colorado site under their higher-altitude window, or at either of the
19 NCR launch sites under their standing waivers.
20 The smallest reasonable motor for this rocket would be a Cesaroni
21 K445 or equivalent, which would yield an apogee of about 2300 feet.
22 </p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp2161264"></a>Chapter 2. Design</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp1850344">Overview</a></span></dt><dt><span class="section"><a href="#idp2704224">Rocksim File</a></span></dt><dt><span class="section"><a href="#idp2161528">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#idp2305928">Motor Retention</a></span></dt><dt><span class="section"><a href="#idp2452064">Nose Cone Electronics Bay</a></span></dt><dt><span class="section"><a href="#idp2439640">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#idp2461808">Avionics</a></span></dt><dt><span class="section"><a href="#idp3312136">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#idp2033792">Expected Performance</a></span></dt><dt><span class="section"><a href="#idp3384200">Recovery System</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1850344"></a>Overview</h2></div></div></div><p>
23 The Goblin 10 kit is a simple "four fins and a nose cone" rocket
24 that is short and squat, with a 98mm motor mount.
25 It supports dual-deploy by
26 using the forward end of the long motor mount tube to hold the main.
27 The primary electronics bay is between the forward two motor mount
28 centering rings, accessed by a side hatch. An additional payload bay
29 will be built inside the nose cone to carry experimental altimeters,
30 a tracking beacon, and possibly a GPS position reporting system.
31 </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2704224"></a>Rocksim File</h2></div></div></div>
32 This is the original working design in Rocksim format,
33 <a class="ulink" href="Polecat_Goblin_10.rkt" target="_top"> Polecat_Goblin_10.rkt </a>,
34 and this is the final design file as the airframe existed before
35 burning up with our house in June of 2013:
36 <a class="ulink" href="Polecat_Goblin_10+MonkeyBay+ARRD.rkt" target="_top"> Polecat_Goblin_10+MonkeyBay+ARRD.rkt </a></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2161528"></a>Drawing from Rocksim</h2></div></div></div><span class="inlinemediaobject"><img src="Polecat_Goblin_10.jpg" height="450"></span></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2305928"></a>Motor Retention</h2></div></div></div><p>
37 I will include 8-24 T-nuts in the aft centering ring spaced to allow
38 the use of an Aeropack 98mm retainer and associated 75mm adapter.
39 </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2452064"></a>Nose Cone Electronics Bay</h2></div></div></div><p>
40 Instead of using the supplied nose cone bulkhead, I intend to cut a
41 custom one that would support installing a length of 98mm motor mount
42 from the tip of the nose to the bulkhead. With a plate cut to cover
43 the aft end of the airframe tube, this would form an electronics bay
44 capable of holding a beacon transmitter, GPS system, or other custom
46 </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2439640"></a>Electronics</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp2461808"></a>Avionics</h3></div></div></div><p>
47 The recovery system will feature dual redundant barometric altimeters
48 in the main avionics bay between the two forward motor mount
51 A PerfectFlite MAWD will be flown as the primary altimeter and to
52 record the flight altitude profile.
53 A MissileWorks Mini-RRC2 will fly as backup altimeter and to
54 directly capture max velocity.
56 Each altimeter will have a separate battery and rotary power switch.
57 A third rotary switch will be used as a SAFE/ARM switch configured
58 to interrupt connectivity to all ejection charges in accordance with
59 NAR certification requirements.
60 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp3312136"></a>Stability Evaluation</h3></div></div></div><p>
61 The Goblin 10 kit designers indicate
62 that the rocket is unconditionally stable with all motors that fit
63 the motor mount geometry. Since we're adding mass at both ends, by
64 putting a payload in the nose cone and by glassing the fins, the
65 overall stability of the design should be retained, but simulation
66 to confirm that seems prudent.
68 Thorough analysis using
69 <a class="ulink" href="http://www.apogeerockets.com/rocksim.asp" target="_top">
72 with various motors ranging from the Cesaroni K445 through the
73 Aerotech M1939W always shows the stability as marginal.
74 This is typical of short fat rockets that don't meet normal length
75 to airframe diameter ratio expectations.
76 Given this, I take the fact that RockSim shows the stability as
77 marginal instead of unstable as strong evidence that the rocket
78 will in fact be stable in flight.
79 I also note that the simulated margin of stability
80 in my as-built configuration is fairly close to the margin of
81 stability of the as-designed model.
82 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp2033792"></a>Expected Performance</h3></div></div></div><p>
83 The Aerotech M1297W reload should carry this vehicle to just under
84 7000 feet AGL from Colorado Front Range launch sites. It
85 should reach just over 2 miles on a Cesaroni M795 moon burner
87 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp3384200"></a>Recovery System</h3></div></div></div><p>
88 The recovery system will use dual redundant barometric altimeters
89 firing 4F black powder charges using commercial e-matches.
90 At apogee, a drogue chute will deploy with separation of the nose
91 cone. A Giant Leap TAC-1 36 inch chute already in hand will serve
93 At a preset altitude, a main chute will be deployed from the forward
94 end of the motor mount tube to achieve recovery of the bulk of the
95 rocket at approximately 20 ft/sec.
97 I intend to sew the main parachute from scratch with my wife's help
98 using a design documented by
99 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
102 using 1.9oz rip-stop nylon and 550 lb parachute cord. The anticipated
103 build weight implies that a 10 foot parachute would be appropriately
106 The recovery system attachment points will all use 1/4 inch u-bolts
107 with nuts, washers, and backing plates through bulkheads.
108 </p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp1515616"></a>Chapter 3. Construction Details</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp2928992">Airframe</a></span></dt><dt><span class="section"><a href="#idp1978904">Nose Cone</a></span></dt><dt><span class="section"><a href="#idp47048">Avionics Bay</a></span></dt></dl></div><p>
109 I have collected all of my
110 <a class="ulink" href="http://gallery.gag.com/rockets/goblin10" target="_top">
113 in one place, they may show better than I can explain how various
114 aspects of the Goblin went together.
115 </p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2928992"></a>Airframe</h2></div></div></div><p>
116 The airframe tubing provided in the Polecat kit is thick cardboard tube
117 with a thin exterior fiberglass wrap. To increase airframe strength,
118 and particularly to prevent zippers, additional reinforcement seemed
121 The inner layer of paper was removed from the front 9" or
122 so of the tube. The tube was soaked with West Systems epoxy diluted
123 with about 20% by volume with acetone, and then a carbon fiber wrap was
124 applied to the interior front of the tube and held in place during
125 curing by an inflatable child's bounce toy inside a plastic garbage
126 bag. The result is a substantially strengthened tube, with carbon
127 fiber lining from the leading edge back past the first centering ring.
128 </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1978904"></a>Nose Cone</h2></div></div></div><p>
129 The provided nose cone bulkhead was replaced by a custom centering
130 ring cut from 3/8 inch birch plywood. The ring's outer diameter was
131 adjusted put place the ring approximately an inch forward of the end
132 of the motor mount tube, and the inner diameter was cut to fit Giant
133 Leap 98mm phenolic airframe tubing. A length of such tubing was cut
134 to fit inside the nose cone and extend back to flush with the trailing
135 edge of the ring. The centering ring was drilled and fitted with two
136 u-bolts for recovery system attachment and four 6-32 T-nuts to hold
137 a payload mounting plate in place over the aft end of the 98mm tube.
139 The airframe tubing was glued into the tip of the nose cone with West
140 Systems epoxy using both milled glass and microlite filler to thicken
141 the mix. The centering ring was then epoxied in place using a similar
142 mix around the outer edge to form a heavy fillet and 5-minute epoxy to
143 the piece of airframe tubing. After the epoxies cured, a rotary tool
144 was used to cut the airframe tubing off flush with the aft surface of
146 </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp47048"></a>Avionics Bay</h2></div></div></div><p>
147 The avionics bay walls were installed approximately 90 degrees apart
148 prior to installation of the motor mount assembly in the airframe.
149 The airframe wall was marked for a 3.5 x 6.5" access hatch centered
150 over the bay 90 degrees from the rail button line. This allows
151 sufficient room to install the switches on one side of the hatch yet
152 still inside the bay, and to place the static vent on the other side
153 of the hatch so that there will be minimal effect from air disturbed
154 by movement over the hatch cover edges.
156 Rails were fabricated from 3/8" birch plywood and 6-32 blind nuts to
157 allow for a removable avionics sled, rectangular, with 4 screws to
158 hold the sled in place.
159 A suitably sized avionics sled should be possible to install and remove
160 through the avionics bay hatch allowing for possible future experiments
161 with alternative avionics.
162 </p></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp48792"></a>Chapter 4. Recovery Systems Package</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp49112">Recovery System Description</a></span></dt><dt><span class="section"><a href="#idp52136">Recovery Initiation Control Components</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp49112"></a>Recovery System Description</h2></div></div></div><p>
163 This rocket uses dual deployment.
165 The apogee event separates the nose cone from the
166 airframe. The nose cone is attached to the airframe with a length
167 of heavy-duty tubular nylon shock cord. A drogue chute protected
168 during ejection by a kevlar blanket is attached to the shock cord
169 close to the nose cone end.
171 The main is a 10 foot chute sewn from the design documented by
172 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
175 It is held in place prior to ejection by a layer of paper taped over
176 the front of the motor mount tube. At ejection, a piston pushes the
177 chute forward through the paper and ejects it from the rocket.
178 This chute is attached to the airframe through an additional length of
179 heavy-duty tubular nylon shock cord.
181 Depending on the results of ground testing, the main chute may be
182 packed in a Giant Leap kevlar deployment bag attached at the main
183 chute apex, with a smaller drogue chute deployed to pull off the bag
184 and cleanly deploy the main. The primary motivation for this is to
185 prevent the main chute shrouds from tangling during ejection.
186 </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp52136"></a>Recovery Initiation Control Components</h2></div></div></div><p>
187 The main avionics bay between the forward two centering rings is
188 populated with two commercial altimeters, a PerfectFlite MAWD
189 and a Missile Works miniRRC2.
190 Each is powered by a dedicated 9V alkaline battery, and has a
191 dedicated on/off power switch mounted for access from outside the
192 rocket. Additionally, a single safe/arm switch with two poles is used
193 to interrupt the return circuits from the igniters to each altimeter.
194 See the attached schematic of the avionics bay contents for more
197 Details of ejection charge design goes here.
200 <a class="ulink" href="http://www.info-central.org/recovery_powder.shtml" target="_top">
201 Info Central Black Powder Sizing
203 page is the most authoritative site I've found on this topic.
204 The formula they suggest is diameter in inches squared times
205 length in inches times a coefficient in grams of black powder.
206 For the main charge, which will be in the 98mm motor mount tube, a
207 pressure of 15psi is appropriate giving a coefficient of 0.006.
208 For the drogue charge, which will be in the main airframe, a
209 pressure of 5psi is more appropriate, leading to a coefficient
212 The drogue bay is 10 inches ID at the widest point, but contains
213 the protrusion of the main bay and a decreasing radius in the
214 nose cone. Thus some fudging on the length is appropriate, and
215 we will use 18 inches. That works out to 3.6 grams of BP. This
216 rocket will not fly high enough for there to be a significant
217 effect on BP burn characteristics, so no special compensation
220 The main bay is 3.9 inches ID and perhaps as much as 24 inches long
221 depending on which motor is selected.
222 That works out to 2.2 grams of BP.
224 Ground testing yielded 3.5 grams for the apogee charge and 1.5 grams
226 Backup charges will contain additional BP in accordance
227 with the "blow it off or blow it up" philosophy.
229 With a 10 foot Team Vatsaas design parachute and our
230 anticipated build weight, the descent rate under main
231 should be just over 20 feet per second.
232 </p></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp749288"></a>Chapter 5. Checklists </h1></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
234 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>1.1.</td><td>
235 Pick a club launch with suitable waiver and facilities to
237 </td></tr><tr><td>1.2.</td><td>
238 Confirm L3CC member(s) available to attend selected launch.
239 </td></tr><tr><td>1.3.</td><td>
240 Confirm that required loaner motor hardware will be available at launch.
241 </td></tr><tr><td>1.4.</td><td>
242 Notify launch sponsor (club president) of intended flight.
243 </td></tr><tr><td>1.5.</td><td>
244 Notify interested friends of intended flight.
245 </td></tr><tr><td>1.6.</td><td>
246 Perform final pre-flight simulation with as-built masses, etc.
247 </td></tr><tr><td>1.7.</td><td>
248 Gather consummables and tools required to support flight
249 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>1.7.1.</td><td>
251 </td></tr><tr><td>1.7.2.</td><td>
253 </td></tr><tr><td>1.7.3.</td><td>
255 </td></tr><tr><td>1.7.4.</td><td>
256 motor retainer and adapter parts
257 </td></tr><tr><td>1.7.5.</td><td>
258 small nylon wire ties
259 </td></tr><tr><td>1.7.6.</td><td>
260 cellulose wadding material
261 </td></tr><tr><td>1.7.7.</td><td>
263 </td></tr><tr><td>1.7.8.</td><td>
264 screwdriver for phillips-head avionics bay screws
265 </td></tr><tr><td>1.7.9.</td><td>
266 small straight-blade screwdriver for power switches
267 </td></tr><tr><td>1.7.10.</td><td>
268 motor reload kit (or arrangements to procure at launch)
269 </td></tr><tr><td>1.7.11.</td><td>
270 high temperature grease
271 </td></tr><tr><td>1.7.12.</td><td>
272 long small diameter dowels for igniter insertion
273 </td></tr></tbody></table></div></td></tr></tbody></table></div></li><li class="listitem">
275 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>2.1.</td><td>
276 program altimeters for suitable mach delay and recovery deployment
277 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
279 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">
281 </li><li class="listitem">
282 1300 foot main deploy
283 </li></ul></div></li><li class="listitem">
286 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">
288 </li><li class="listitem">
289 1000 foot main deploy
290 </li><li class="listitem">
291 2 seconds apogee delay
292 </li><li class="listitem">
294 </li><li class="listitem">
296 </li><li class="listitem">
297 ops mode 16 (default)
298 </li></ul></div></li></ul></div></td></tr><tr><td>2.2.</td><td>
299 assemble all recovery system components and ensure everything fits
300 </td></tr><tr><td>2.3.</td><td>
301 confirm wiring and operation of altimeter power and safe/arm
303 </td></tr><tr><td>2.4.</td><td>
304 Ground test recovery system to confirm suitable black powder
306 </td></tr></tbody></table></div></li><li class="listitem">
308 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>3.1.</td><td>
309 confirm payload batteries in good condition, bay loaded,
311 </td></tr><tr><td>3.2.</td><td>
312 confirm reception of signals from transmitter(s)
313 </td></tr><tr><td>3.3.</td><td>
314 install fresh 9V batteries for altimeters on avionics bay sled
315 </td></tr><tr><td>3.4.</td><td>
316 inspect altimeters and associated avionics bay wiring for
318 </td></tr><tr><td>3.5.</td><td>
319 close up avionics bay
320 </td></tr><tr><td>3.6.</td><td>
321 build and install BP charges
322 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>3.6.1.</td><td>
323 Drogue Primary Charge - 3.5 grams 4F BP
324 </td></tr><tr><td>3.6.2.</td><td>
325 Drogue Backup Charge - 4.0 grams 4F BP
326 </td></tr><tr><td>3.6.3.</td><td>
327 Main Primary Charge - 1.5 grams 4F BP
328 </td></tr><tr><td>3.6.4.</td><td>
329 Main Backup Charge - 2.0 grams 4F BP
330 </td></tr></tbody></table></div></td></tr><tr><td>3.7.</td><td>
331 fold main chute, connect recovery harness to piston and airframe,
332 install in MMT and tape paper over the front end
333 </td></tr><tr><td>3.8.</td><td>
334 fold drogue chute into a kevlar pad, connect recovery harness to
335 nose cone and airframe, install in airframe
336 </td></tr><tr><td>3.9.</td><td>
337 power up payload using switch on base plate in nose cone, then
338 install nose cone, using masking tape to adjust fit as required
339 </td></tr><tr><td>3.10.</td><td>
340 safely power up altimeters, operate safe/arm switch,
341 and confirm e-match continuity
342 </td></tr><tr><td>3.11.</td><td>
343 safe and power-down the altimeters
344 </td></tr><tr><td>3.12.</td><td>
345 load motor per manufacturer instructions
346 </td></tr><tr><td>3.13.</td><td>
347 install motor in motor mount
348 </td></tr><tr><td>3.14.</td><td>
349 install motor retention
350 </td></tr><tr><td>3.15.</td><td>
351 prepare igniter using e-matches, 1/8 inch dowel
352 </td></tr><tr><td>3.16.</td><td>
353 confirm all screws in place, avionics off and safe
354 </td></tr><tr><td>3.17.</td><td>
355 fill out a launch card
356 </td></tr><tr><td>3.18.</td><td>
357 notify RSO/LCO of readiness for inspection and launch, obtain
358 a rail assignment and permission to move rocket to launch pad for
360 </td></tr><tr><td>3.19.</td><td>
361 coordinate readiness with support team members, photographers,
363 </td></tr></tbody></table></div></li><li class="listitem">
365 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>4.1.</td><td>
366 move rocket to launch area
367 </td></tr><tr><td>4.2.</td><td>
368 clean and lubricate launch rail if necessary
369 </td></tr><tr><td>4.3.</td><td>
370 confirm reception of signals from payload transmitter(s)
371 </td></tr><tr><td>4.4.</td><td>
372 mount rocket on launch rail, rotate to vertical
373 </td></tr><tr><td>4.5.</td><td>
374 power up primary altimeter, confirm expected beep pattern
375 </td></tr><tr><td>4.6.</td><td>
376 power up backup altimeter, confirm expected beep pattern
377 </td></tr><tr><td>4.7.</td><td>
379 </td></tr><tr><td>4.8.</td><td>
380 confirm altimeters both giving expected beep patterns for
382 </td></tr><tr><td>4.9.</td><td>
383 install igniter and connect to launch control system
384 </td></tr><tr><td>4.10.</td><td>
385 capture GPS waypoint for rail location
386 </td></tr><tr><td>4.11.</td><td>
387 smile for the cameras, make sure we have enough "foil Murphy!"
389 </td></tr><tr><td>4.12.</td><td>
390 retreat to safe area behind LCO
391 </td></tr><tr><td>4.13.</td><td>
392 confirm continued reception of transmitter signal(s) from
394 </td></tr><tr><td>4.14.</td><td>
395 confirm photographers and observers are ready and know what to
397 </td></tr><tr><td>4.15.</td><td>
398 make sure binoculars and backpack with water and recovery tools
400 </td></tr><tr><td>4.16.</td><td>
401 tell RSO and LCO we're ready to launch
402 </td></tr><tr><td>4.17.</td><td>
403 try to relax and enjoy watching the flight!
404 </td></tr></tbody></table></div></li><li class="listitem">
406 <div class="orderedlist"><table border="0" class="orderedlist"><colgroup><col align="left" valign="top"><col></colgroup><tbody><tr><td>5.1.</td><td>
407 track rocket to landing site
408 </td></tr><tr><td>5.2.</td><td>
409 capture GPS waypoint of landing site, take lots of photos
410 </td></tr><tr><td>5.3.</td><td>
412 </td></tr><tr><td>5.4.</td><td>
413 gather up and roughly re-pack recovery system for return to
415 </td></tr><tr><td>5.5.</td><td>
416 bring the rocket to observers for post-flight inspection
417 </td></tr></tbody></table></div></li></ol></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp201568"></a>Chapter 6. Flight Summary</h1></div></div></div><p>
418 A successful level 3 certification flight occurred on 15 November 2008
419 at the SCORE Hudson Ranch launch facility. The motor was an Aerotech
420 M1297W provided by Tim Thomas of Giant Leap Motors, the igniter was
421 assembled by James Russell using his special thermite mixture, and
422 numerious SCORE, COSROCS, and NCR members were present to assist with
423 the launch! Great weather for November... mostly clear and sunny,
424 light winds, dry ground, temps above freezing.
426 The motor came up to pressure very quickly and the rocket leapt off
427 the pad, climbing smoothly under power and then doing about two slow
428 rolls during the coast phase. Deployment of the nose cone and drogue
429 occurred as planned when the primary apogee charge fired.
430 Unfortunately, the main deployed around the time the backup apogee
431 charge fired, so the descent was under main from apogee. Fortunately,
432 the winds were low enough and the descent rate high enough that the
433 rocket touched down without damage within the waiver area for a
434 successful certification!
436 The rocket weighed 25.2 pounds prepared for launch without the motor.
437 The motor weighed about 10.25 pounds, which included about 6 pounds
438 of propellant. Thus the descent mass under chute was just over 29
440 The miniRRC2 altimeter reported 5949 feet apogee, 980 feet per second
441 max velocity, and 19 seconds to apogee. The MAWD reported 5953 feet
443 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://picasaweb.google.com/jamesr2/StealeyMemorialLaunchSiteHudsonRanch" target="_top">
444 Photos of the launch taken by James Russell
445 </a></li><li class="listitem"><a class="ulink" href="http://cosrocs.org/all%20other%20videos/2008videos/11-15hudson/bdale_L3.mov" target="_top">
446 Video of the launch taken by Jeff Lane
447 </a></li><li class="listitem"><a class="ulink" href="http://www.youtube.com/watch?v=xaJnl89wfWU" target="_top">
448 Video of the launch taken by Jason Unwin
449 </a></li></ul></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp58192"></a>Chapter 7. Analysis and Conclusions</h1></div></div></div><p>
450 The ascent was straighter than expected... very smooth during
451 the motor burn, then a couple slow rolls during coast. The two
452 altimeters agreed within 4 feet on the apogee. The max
453 velocity recorded is a little higher than predicted by simulation,
454 but the accuracy of that measurement is likely limited since it is
455 based on pressure data.
457 I was able to watch the apogee events through binoculars, and could
458 clearly see the main deploy as the backup apogee charge fired. I saw
459 some evidence of tearing of the paper taped over the motor mount to
460 retain the main chute during ground testing, so assume this was the
461 root cause of the early deployment. When the backup apogee charge
462 fired, the shock cord was not yet in tension, and thus the charge
463 probably kicked the airframe backwards hard enough to allow the main
464 chute to slide out through the torn paper and deploy. The best fix
466 to fabricate a second piston to use as a cap and retain it with two
467 shear pins. This would be much less likely to prematurely deploy than
468 the current taped paper approach.
470 The most significant variance from expectation was the descent rate.
471 The spreadsheet provided by the Team Vatsaas folks for their design
472 suggested we'd see around 21 feet per second. Analysis of the flight
473 profile from the MAWD shows that our actual descent rate was about
474 32 feet per second. There are three possible sources of error to
476 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
477 The first is descent mass. Pre-flight calculations used
479 The actual flight weight was 25.2 pounds plus the burn-out
480 weight of the M1297W, which should be about 4.5 pounds.
481 That yields 29.5 pounds total. All pre-flight calculations
482 were done using 25 lbs, with the thought that the motor mass
483 might cancel out against the drag provided by the drogue.
484 In flight, it appeared the drogue supported the nose and the
485 main supported the fin can with very little interaction between
487 </li><li class="listitem">
488 Second, the dimensions given by Team Vatsaas' spreadsheet
489 for the pattern grid seem small. For a 10 foot chute, they
490 suggest a grid size of 5 inches, which looks more like an 8.5
491 foot finished chute size to me.
492 </li><li class="listitem">
493 Finally, the Cd in the spreadsheet is 1.5, which may be overly
496 My calculations show that if we assume a chute size of 8.5 feet and
497 a Cd closer to 1, we can get to a descent rate of 32 feet per second.
499 So, overall, this was a successful flight, but with three things to
500 change before we fly the airframe again...
501 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
502 the main chute may be too small
503 </li><li class="listitem">
504 switch to a piston to cap the main chute bay
505 </li><li class="listitem">
506 beef up the battery retention on the avionics sled
508 </p></div></div></body></html>
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