1 <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>YikStik</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="id2391886"></a>YikStik</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="id2647249"></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 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">28 October 2008</td></tr><tr><td align="left" colspan="2">
8 Recording results of first, and only, flight attempt.
9 </td></tr><tr><td align="left">Revision 0.5</td><td align="left">27 September 2008</td></tr><tr><td align="left" colspan="2">
11 </td></tr><tr><td align="left">Revision 0.4</td><td align="left">17 September 2008</td></tr><tr><td align="left" colspan="2">
12 Documenting the build process as it happens
13 </td></tr><tr><td align="left">Revision 0.3</td><td align="left">29 March 2008</td></tr><tr><td align="left" colspan="2">
14 Incorporate ideas from James Russell during initial L3CC review
15 </td></tr><tr><td align="left">Revision 0.2</td><td align="left">27 March 2008</td></tr><tr><td align="left" colspan="2">Cleaned up for initial review</td></tr><tr><td align="left">Revision 0.1</td><td align="left">16 March 2008</td></tr><tr><td align="left" colspan="2">Initial content</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="#id2634993">1. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#id2635039">Why "YikStik"?</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2626705">2. Design</a></span></dt><dd><dl><dt><span class="section"><a href="#id2626711">Overview</a></span></dt><dt><span class="section"><a href="#id2626729">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2626743">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2626762">Airframe Tubing</a></span></dt><dt><span class="section"><a href="#id2626778">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2626789">Fins</a></span></dt><dt><span class="section"><a href="#id2678165">Centering Rings and Bulkheads </a></span></dt><dt><span class="section"><a href="#id2666934">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2669027">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2682045">Avionics</a></span></dt><dt><span class="section"><a href="#id2658585">Payload</a></span></dt></dl></dd><dt><span class="section"><a href="#id2651147">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2650942">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2668569">Recovery System</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2661729">3. Construction Details</a></span></dt><dd><dl><dt><span class="section"><a href="#id2662660">Airframe and Couplers</a></span></dt><dt><span class="section"><a href="#id2664980">Fins</a></span></dt><dt><span class="section"><a href="#id2649782">Centering Rings and Bulkheads</a></span></dt><dt><span class="section"><a href="#id2643385">Assembling the Booster Section</a></span></dt><dt><span class="section"><a href="#id2656462">Avionics Bay</a></span></dt><dt><span class="section"><a href="#id2670911">Payload Bay</a></span></dt><dt><span class="section"><a href="#id2670213">Recovery System</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2656789">4. Recovery Systems Package</a></span></dt><dd><dl><dt><span class="section"><a href="#id2656948">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2659169">Recovery Initiation Control Components</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2673956">5. Stability Evaluation</a></span></dt><dt><span class="chapter"><a href="#id2656157">6. Expected Performance</a></span></dt><dt><span class="chapter"><a href="#id2675455">7. Checklists </a></span></dt><dt><span class="chapter"><a href="#id2678315">8. Flight Summary</a></span></dt><dt><span class="chapter"><a href="#id2672899">9. Analysis and Conclusions</a></span></dt></dl></div><p>
16 Please note that I stopped adding photos to this document at some
17 point. I have many more photos of the YikStik build, but haven't
18 decided how best to present them yet... update coming someday!
19 </p><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2634993"></a>Chapter 1. Introduction</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#id2635039">Why "YikStik"?</a></span></dt></dl></div><p>
20 This is the rocket I'm designing for my NAR Level 3 certification flight.
21 The general idea is to build a fairly cheap rocket capable of reliably
22 flying this year's Aerotech level 3 special, which is an M1297W reload.
23 I'd like to be able to fly the prototype of my own altimeter design, and
24 to be able to fly it often on smaller / cheaper reloads at launch sites
25 with modest waivers like Hudson Ranch.
27 I want to experiment with vacuum bagging carbon fiber reinforcements, and
28 intend to use my CNC milling machine to cut all the centering rings, etc.
29 The new Giant Leap "Dynawind" tubing feels like a good choice, and if we
30 stick to the 4 inch version we can use a cheap plastic nosecone to keep
33 Preliminary analysis suggests that a roughly 8 foot rocket made from 4 inch
34 airframe with a 75mm mount and three fins should fly to something around
35 14k feet on the M1297W, could break three miles on the M1850W, and yet
36 could safely fly on reloads as small as a J for economical fun. Those
37 altitudes mean the certification flight will need to be at a site with a
38 high-altitude waiver like the NCR north site.
39 </p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2635039"></a>Why "YikStik"?</h2></div></div></div><p>
40 I've always thought the high-gloss red paint job on one of my son's rockets
41 when out on a launch rod in the sun looks a lot like glistening wet
44 Combine that with the fact that my wife who isn't fond of the stuff
45 refers to lipstick as "yik stick"... and the rest should be obvious.
46 </p><span class="inlinemediaobject"><img src="images/lilnuke.jpg" width="338"></span><span class="inlinemediaobject"><img src="images/lipstick.jpg" width="338"></span><p>
47 My planned paint scheme is a bright red nosecone, gold tube, and black fin
48 can, which is the mental image I have of what lipstick applicators look
49 like, most likely from a stick my mother or one of my grandmothers had
50 when I was a child. Something like the image by Calliope1 that I found
52 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2626705"></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="#id2626711">Overview</a></span></dt><dt><span class="section"><a href="#id2626729">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2626743">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2626762">Airframe Tubing</a></span></dt><dt><span class="section"><a href="#id2626778">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2626789">Fins</a></span></dt><dt><span class="section"><a href="#id2678165">Centering Rings and Bulkheads </a></span></dt><dt><span class="section"><a href="#id2666934">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2669027">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2682045">Avionics</a></span></dt><dt><span class="section"><a href="#id2658585">Payload</a></span></dt></dl></dd><dt><span class="section"><a href="#id2651147">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2650942">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2668569">Recovery System</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2626711"></a>Overview</h2></div></div></div><p>
53 YikStik is a fairly simple "three fins and a nose cone" dual-deploy
54 rocket using a 75mm motor mount, 4 inch glass-wrapped phenolic airframe
55 with zipperless fin can, plastic nose cone, plywood fins,
56 and lots of glass and carbon fiber reinforcing.
57 The primary electronics bay will be designed to
58 hold two altimeters, and a distinct payload bay may carry an
59 experimental altimeter, GPS receiver, and downlink transmitter.
60 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2626729"></a>Rocksim File</h2></div></div></div>
61 This is the current working design in Rocksim format:
62 <a class="ulink" href="YikStik.rkt" target="_top"> YikStik.rkt </a></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2626743"></a>Drawing from Rocksim</h2></div></div></div><span class="inlinemediaobject"><img src="images/YikStik.jpg"></span></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2626762"></a>Airframe Tubing</h2></div></div></div><p>
63 I intend to cut the airframe components from two 48 inch lengths of
64 98mm Giant Leap Dynawind tubing. The 30 inch main bay and 18 inch drogue
65 bay will be cut from one length, while the 33 inches of fin can, 2 inches
66 of electronics bay, and 8 inches of payload bay will be cut from the
68 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2626778"></a>Nose Cone</h2></div></div></div><p>
69 I intend to use a Giant Leap "Pinnacle" 3.9 inch nose cone.
70 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2626789"></a>Fins</h2></div></div></div><p>
71 The fins are designed from scratch, and I intend to build them up from
72 two layers of 1/8 inch birch plywood, three layers of carbon fiber, and
73 two layers of 6 oz glass. The stack will be glass, carbon fiber,
74 plywood, carbon fiber, plywood, carbon fiber, glass. The edges of the
75 plywood will be routed to give a modified airfoil shape to the finished
76 fins. The stack will be laminated using West Systems epoxy products
78 The shape is a compromise between mass, surviving Mach-transition stress,
79 optimal stability margin, and avoiding damage during handling and on
80 contact with the ground during recovery.
82 The fins will be locked in to milled slots in two of the centering rings,
83 and will be epoxied to the motor mount with glass reinforcing tape.
84 The airframe will be slotted to allow the completed motor mount / fin
85 assembly to be inserted from the rear, with fillets of epoxy applied
86 inside and outside the airframe after insertion.
87 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2678165"></a>Centering Rings and Bulkheads </h2></div></div></div><p>
88 All centering rings and bulkheads will be custom machined from 3/8 inch
89 birch plywood using my 3-axis CNC milling machine. Some rings will use
90 laminated pairs of 3/4 inch total thickness to enable use of threaded
91 inserts for 1/4-20 rail button screws or deep routing for fin alignment
93 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2666934"></a>Motor Retention</h2></div></div></div><p>
94 I will embed three 8-24 T-nuts in the aft centering ring spaced to allow
95 the use of home-made Kaplow clips to retain 75mm motors.
96 The same holes may be used to attach custom motor mount adapters for
97 smaller diameter motors.
98 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2669027"></a>Electronics</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2682045"></a>Avionics</h3></div></div></div><p>
99 The recovery system will feature dual redundant barometric altimeters
100 in an electronics bay similar to the LOC design located between the
101 drogue and main parachute bays.
103 A PerfectFlite MAWD will be flown as the primary altimeter and to
104 record the flight altitude profile.
105 A MissileWorks Mini-RRC2 will fly as backup altimeter and to
106 directly capture max velocity.
108 Each altimeter will have a separate battery and power switch. A 4PDT
109 slide switch will be used as a SAFE/ARM switch configured to interrupt
110 connectivity to the ejection charges.
111 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2658585"></a>Payload</h3></div></div></div><p>
113 <a class="ulink" href="http://altusmetrum.org/" target="_top">
114 my own altimeter design
116 as a payload in a short payload section just behind the nose cone.
117 I have acquired the pieces to add a GPS receiver and RF downlink using
118 ham radio frequencies to the payload to track the rocket's position
120 This is not essential to fly,
121 but could make recovery simpler and would just be fun to fly if I can
122 get it all working and suitably ground and/or flight tested in time.
123 </p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2651147"></a>Stability Evaluation</h2></div></div></div><p>
124 This design has been thoroughly analyzed using
125 <a class="ulink" href="http://www.apogeerockets.com/rocksim.asp" target="_top">
128 with motors ranging from the
129 Cesaroni J285 through the Aerotech M1850W and appears to be
130 unconditionally stable across that range. The lowest margin is around
131 1.2 seen with the M1297W planned for my level 3 certification flight,
132 albeit with many masses still only roughly estimated.
134 These simulations will be refined as the build proceeds and as-built
135 stability verified before flight.
136 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2650942"></a>Expected Performance</h2></div></div></div><p>
137 The Aerotech M1297W reload should carry this vehicle without ballast
138 to just over 14 thousand feet AGL. It should make over 16 thousand
139 feet AGL on an M1850W, and should fly stably to roughly 2.5k feet AGL
142 Hitting optimal mass on the largest motors may require
143 ballast, depending on final build weight.
144 My plan is to fly without ballast on the certification flight,
145 trading some altitude for a slower and softer recovery.
146 If the cert succeeds, then I might try an optimal mass
147 flight sometime later on an M1850W or equivalent "bigger M"
148 reload to join the "three mile club".
149 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2668569"></a>Recovery System</h2></div></div></div><p>
150 The recovery system will use dual redundant barometric altimeters firing
151 black powder charges.
152 At apogee, a drogue chute will deploy from just forward of the fin can,
153 with size selected for an approximately 100 ft/sec descent rate.
154 At a preset altitude, a main chute will be deployed to achieve recovery
155 of the bulk of the rocket at under 20 ft/sec.
156 The main chute will be packed in a deployment bag, configured as a
157 "freebag" and pulled out of the airframe by a second drogue chute. This
158 drogue will recover the nosecone and deployment bag separately from the
159 remainder of the rocket which will recover under the main.
161 I intend to sew the parachutes from scratch using a design documented by
162 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
165 using 1.9oz rip-stop nylon and 550 lb parachute cord.
166 If time runs short, equivalent chutes from SkyAngle,
167 Rocketman, or Giant Leap could be substituted (at significantly higher
170 The deployment bag will probably be purchased from Giant Leap. The
171 recovery harness will probably use tubular kevlar, also from Giant Leap.
173 The recovery system attachment points will all use 1/4 inch u-bolts with
174 nuts, washers, and backing plates through bulkheads except for the fin
175 can. The fin can has insufficient room between the motor mount and
176 the airframe inner wall for nuts and washers, so an alternative means of
177 recovery system attachment is required. The fin can will be equipped
178 with either a 3/16 inch stainless steel aircraft cable loop, or a loop
179 of 1/2 inch tubular kevlar, bonded to the motor mount.
180 If available, a screw-eye attached to the forward motor closure may be
181 used instead of or in addition to this recovery attachment loop.
182 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2661729"></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="#id2662660">Airframe and Couplers</a></span></dt><dt><span class="section"><a href="#id2664980">Fins</a></span></dt><dt><span class="section"><a href="#id2649782">Centering Rings and Bulkheads</a></span></dt><dt><span class="section"><a href="#id2643385">Assembling the Booster Section</a></span></dt><dt><span class="section"><a href="#id2656462">Avionics Bay</a></span></dt><dt><span class="section"><a href="#id2670911">Payload Bay</a></span></dt><dt><span class="section"><a href="#id2670213">Recovery System</a></span></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2662660"></a>Airframe and Couplers</h2></div></div></div><p>
183 The tubing for the airframe, couplers, and motor mount was all cut
184 using a carefully aligned and adjusted power mitre saw, and the ends
185 lightly sanded to remove rough spots.
186 The main and drogue bays were cut from one 48 inch length of Giant
187 Leap 98mm Dynawind tubing, the fin can, electronics bay, and payload
188 bay were cut from the second. The three couplers for the fin can,
189 electronics bay, and payload bay were cut from Giant Leap 98mm phenolic
190 coupler stock. And the motor mount was cut from Giant Leap 75mm
191 phenolic airframe stock. This photo shows the airframe tube on the
192 left, the motor mount in the middle, and the coupler sections on the
193 right. Note that the motor mount is the longest piece because of
194 the zipperless design with full-length motor mount.
195 </p><span class="inlinemediaobject"><img src="images/hpim2719.jpg" width="405"></span><p>
196 The airframe tubing selected includes a wrap of 10oz glass in epoxy
197 over the base phenolic tubing (visible in the previous photo as a
198 shine on the outside of the tubing), but the coupler stock is unreinforced.
199 To ensure the couplers can handle the anticipated loading, I reinforced
200 each with one layer of interior carbon fiber, using the "kitchen
201 vacuum bagging" technique documented by
202 <a class="ulink" href="http://www.jcrocket.com/kitchenbagging.shtml" target="_top">
206 This was my first hands-on experience working with carbon fiber. The
207 end of the coupler nearest the unit during bagging experienced some
208 crushing of the fibers right at the end. It doesn't matter for this
209 project because each of the couplers will have at least one end fitted
210 with a bulkhead or centering ring, but in the future I'll be tempted
211 to cut the coupler stock a bit long before bagging and trim to length
212 after reinforcing to get "perfect" ends. The technique worked
213 marvelously otherwise, and the resulting couplers look and should work
215 </p><span class="inlinemediaobject"><img src="images/hpim2723.jpg" width="495"></span><p>
216 </p><span class="inlinemediaobject"><img src="images/hpim2757.jpg" width="495"></span></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2664980"></a>Fins</h2></div></div></div><p>
217 Six pieces of 1/8 inch birch plywood were stacked, edge-aligned on what
218 would be the fin root edge, and clamped. The outline of the fin design
219 was marked in pencil, and three 1/8 inch holes drilled through the
220 stack inside the fins to allow using 4-40 screws and nuts to hold the
221 blanks together while making the initial cuts, so that they would all be
222 matched in size. The clamps were removed to avoid interference
223 during cutting. The fin outline was then cut using a radial arm saw.
224 </p><span class="inlinemediaobject"><img src="images/hpim2691.jpg" width="495"></span><p>
225 A router table with 1/8
226 in roundover bit was then used to round over the outer edge, 3 blanks on
227 one side and three on the other. This edge might have been left square,
228 but I prefer the look and feel of rounding. The router table with a 1/2
229 inch diameter straight cutting bit and a fin beveling jig was used
230 to impart a 10-degree bevel on the leading and trailing edge of each fin
231 blank, again 3 on one side and three on the other. The resulting 6
232 blanks thus form 3 pairs of fin components with a modified airfoil shape.
233 </p><span class="inlinemediaobject"><img src="images/hpim2700.jpg" width="495"></span><p>
234 </p><span class="inlinemediaobject"><img src="images/hpim2704.jpg" width="495"></span><p>
235 The fin assembly started with a simple lamination of two layers of ply
236 sandwiching a layer of carbon fiber. Each fin used "one pump" of West
237 Systems epoxy and the stack was vacuum bagged using the Foodsaver with
238 wide bagging material. To keep everything flat while the epoxy cured,
239 the stack of fins was sandwiched between two unused extra shelves for
240 a storage cabinet I had on hand (particle board covered in laminate, very
241 flat and smooth, nearly inflexible at this loading), and stacked with
242 about 75 lbs of loose barbell weights.
244 On one of the three fins, the plywood layers are out of alignment by
245 1-2mm in the longest axis. The other two are nearly perfect. Light
246 sanding should allow me to match them before laminating the outer layers
247 of carbon fiber and glass.
248 </p><span class="inlinemediaobject"><img src="images/hpim2803.jpg" width="495"></span><p>
249 </p><span class="inlinemediaobject"><img src="images/hpim2805.jpg" width="495"></span><p>
250 </p><span class="inlinemediaobject"><img src="images/hpim2811.jpg" width="495"></span><p>
251 </p><span class="inlinemediaobject"><img src="images/hpim2816.jpg" width="495"></span><p>
252 After the fins cured, they were bulk sanded with medium and fine
253 sandpaper and an electric palm sander. Final sanding of the leading
254 and trailing edges was done using 400 grit paper on a flat surface,
255 holding the fin the way you'd sharpen a knife against a stone. The
256 results seem good, all three fins match pretty closely.
258 A fin holding jig was cut from 1/8" hardboard using my rotary tool
259 with a fiber cutoff wheel. The fin slots were made to be a snug fit.
260 A small batch of epoxy was used to apply a bead to the root edge and
261 tab at the leading edge, then the fins were installed against the
262 motor mount and locked into place with the jig to cure. The centering
263 ring that locks the aft edge of the fins was dry-fit during this
264 operation to ensure proper alignment, but was not glued yet. It will
265 go on after the airframe and internal fin filets are installed.
267 The fins were reinforced with fiberglass and epoxy. Masking tape was
268 used to carefully delineate where the airframe ID will be, then 6oz
269 glass 14.25" by 3.5" was epoxied fin-fin across the MMT. Strips of
270 8.6oz "boat tape" fiberglass were worked into the joints with more
271 epoxy, and a sheet of plastic covered by ziplog bags of water were
272 used to hold things in place during the initial curing. The three
273 sides were done one at a time and allowed to cure before proceeding.
274 The results look good, and in combination with internal and external
275 airframe filets should yield a super-strong fin can.
276 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2649782"></a>Centering Rings and Bulkheads</h2></div></div></div><p>
277 Pairs of 3/8 inch birch plywood blanks were laminated using Titebond
278 wood glue and clamped while curing to form 3/4 inch blanks for centering
279 rings. From a strength perspective, 3/8 inch should suffice, but there
280 are two reasons for going with thicker blanks in some places. The first
281 is that the rail buttons chosen use 1/4-20 mounting screws, and threaded
282 inserts in that size are nearly 3/8 inch outside diameter (and thus would
283 tear up a ring only 3/8 inch thick on insertion). The second is that I
284 like to mill slots in the centering rings on each end of the fins to
285 "lock" the fins into position. Doubling the blanks used to cut those
286 rings will allow me to cut 1/4 inch deep fin slots and still have a half
287 inch of unmolested wood in the rings for strength.
288 </p><span class="inlinemediaobject"><img src="images/hpim2689.jpg" width="495"></span><p>
289 </p><span class="inlinemediaobject"><img src="images/hpim2690.jpg" width="495"></span><p>
290 The aft centering ring and the one just aft of the zipperless
291 coupler section were edge-drilled for the installation of brass
292 1/4-20 threaded inserts to hold rail buttons. The inserts were
293 locked in place with epoxy, then ground down until nothing protruded
294 beyond the OD of the ring.
295 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2643385"></a>Assembling the Booster Section</h2></div></div></div><p>
296 The forward two centering rings were installed on the MMT using
297 JB Weld high-temperature epoxy, and incorporating an aircraft cable
298 loop for recovery system retention since there just wasn't room for
301 The ring at the leading edge of the fins was initially installed
302 assuming the aft ring would be nearly flush with the rear of the MMT
303 and equipped with Kaplow-clip style retainers, but before the fins
304 were installed a Giant Leap Slimline Tailcone Retainer for 75mm motor
305 in 98mm airframe became available thanks to Tim Thomas, and so this
306 ring was cut out and replaced with another one inch farther forward
307 to allow installation of the tailcone at the rear of the MMT. I
308 really like the tailcone on my Vertical Assault kit, and think it'll
309 work out to be a great addition for this rocket!
311 An alignment jig for the fins was carefully marked out and then cut
312 from 1/8 inch hardboard using my rotary tool and abrasive cutoff wheel.
313 The fins were then epoxied at the root and short leading edge to the
314 motor mount tube and into the slots in the forward centering ring,
315 and held rigidly aligned by the jig until the epoxy set. The fins
316 were then masked at what would be the ID of the airframe tube, and
317 reinforced with 6oz glass fin-fin across the motor mount tube between
318 each fin pair, further reinforced with strips of 1 inch glass "boat
319 tape" at each fin root joint.
321 The airframe tubing section was carefully marked for fin slots, which
322 were then cut using my rotary tool with abrasive cutoff wheel. Epoxy
323 was applied ahead of the center two rings as the frame was slid into
324 place, and the frame left standing upright until the epoxy set to
325 hopefully form ring-fin fillets on those two rings. The interior
326 fin to airframe joints were reinforced one fin at a time using West
327 Systems epoxy will milled glass as a filler. A long 3/8" dowel was
328 used to place and smooth these interior filets. The aft centering ring
329 was installed by pouring West Systems epoxy in the three fin-fin gaps,
330 placing the ring, then standing the airframe up to allow the epoxy to
331 flow over the forward surface of the ring and into the gaps between it,
332 the motor mount, and the airframe tubing. After it set, the booster
333 was placed nose-down, the airframe gaps behind the fins were taped,
334 and more epoxy was applied to seal the aft of the ring to the tubes.
335 Before this epoxy set, JB Weld was used to glue the tail cone retainer
339 airframe joints were filleted using 5-minute epoxy thickened with
340 baby powder and smoothed with the tip of a plastic spoon, which I
341 learned about building the Vertical Assault kit. Gives great results,
342 and allowed all 6 joints to be done in one session. The space
343 above the top surface of the forward centering ring and between the
344 motor mount and zipperless-design coupler tubing was filled with epoxy
345 and milled glass. Minor gaps in the airframe behind each fin were
346 filled with epoxy clay.
347 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2656462"></a>Avionics Bay</h2></div></div></div><p>
348 The avionics bay contains the two commercial altimeters used to
349 record information about the flight and deploy the drogue and main
350 recovery systems. It is constructed of a piece of Giant Leap 98mm
351 coupler tubing reinforced with an interior wrap of vacuum-bagged
352 carbon fiber, and a 2 inch length of Giant Leap 98mm DynaWind airframe
355 The bulkheads are custom-milled from 3/8 inch birch plywood
356 milled so that about 3/16" fits inside the coupler and the remainder
357 seals the end of the coupler and just fits inside the airframe. Each
358 bulkhead has a u-bolt for attaching the recovery harnesses, and dual
359 CPVC end caps as ejection charge holders with screw terminal blocks
360 from Missile Works to attach the igniters. Two lengths of 1/4 inch
361 all-thread with nuts and washers tie the bulkheads together, with
362 wing-nuts used on one end to allow for easy disassembly.
364 A sled was fabricated to hold the altimeters and batteries. It
365 consists of 1/8 inch birch ply laminated with 6oz fiberglass on each
366 side, epoxied to cardboard tubes taken from the packaging for Aerotech
367 igniters that slide over the all-thread, further reinforced with nylon
368 ties at each end. The tubes are staggered one on either side so that
369 the sled goes right up the center of the airframe tubing.
371 Two "centering rings" containing three each 6-32 threaded inserts are
372 epoxied inside the bay to provide hard points for attaching the
373 airframe tubes for the drogue and main recovery bays. The inside
374 diameter of these rings is notched for the avionics sled, and thus
375 these rings also provide physical support for the sled.
377 Three rotary switches from Missile Works are installed through the
378 short airframe tubing section, drilled such that they end up
379 essentially flush with the outside of the airframe, clamp the coupler
380 tubing, and project inside the bay. Two are wired as SPST switches
381 for power to the two altimeters, the third is wired as a DPST switch
382 that open-circuits the igniters for the required "safe/arm" function
383 called for in the NAR L3 certification requirements.
385 The wiring of the avionics bay is documented in the attached
386 schematic diagram. Connectors were used to allow each bulkhead and
387 the switches in the housing to be quickly detached from the sled.
388 The connectors are 9-pin D shells for the switch wiring, and 4-pin
389 Molex connectors like those used on older PC hard drive power cables
390 for the bulkheads. To allow use of a single switch pole for the
391 safe/arm function for each altimeter, the two igniters attached to
392 each altimeter are safed by interrupting the common return lines as
393 shown in the schematic.
395 Sizing the static port for the avionics bay was done by applying the
396 formulas suggested by PerfectFlite and Missile Works for their
397 respective altimeter products, then comparing the results with each
398 other and with information found on the web. I've personally had
399 better luck with single ports than with multiple holes, perhaps because
400 I've been working with relatively small rockets. Regardless, I'm
401 sticking with what I know and will use a single static port hole here.
403 The measured dimensions
404 of the avionics bay as constructed are 95mm ID and approximately 250mm
405 between bulkheads. This works out to 108.73 cubic inches before
406 accounting for the volume of the sled, electronics, and wiring and
407 other components inside the bay. By the PerfectFlight formula, the
408 static port should be 0.221 inches in diameter. By the Missile Works
409 formula for a bay over 100 cubic inches the answer is 0.261 inches.
410 The closest standard drill size, which happens to split the difference,
411 is 0.250 inches. Easy enough!
412 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2670911"></a>Payload Bay</h2></div></div></div><p>
413 The construction of the payload bay is very similar to the avionics
414 bay, except that there is a hard-epoxied rear bulkhead, and only one
415 screw ring to hard-mount the nose cone. The forward end of the
416 payload bay is open to the open interior volume of the nose cone in
417 anticipation of extending downlink antennas above the carbon fiber
418 reinforcement in the coupler and into the nose cone, since carbon
419 fiber is opaque to RF.
420 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2670213"></a>Recovery System</h2></div></div></div><p>
421 Pre-sewn 1/4 inch tubular kevlar harness sections were purchased
422 from Giant Leap, along with a small kevlar deployment bag and two
423 kevlar chute protectors.
425 For an apogee drogue, I plan to fly a Public Missiles 4 x 144 inch
426 nylon streamer. It will be protected with one of the kevlar blankets
427 and attached to one of the kevlar harness sections holding the booster
430 The main parachute will be sewn from 1.9 oz rip-stop nylon purchased
432 <a class="ulink" href="http://creativecommons.org/licenses/by-sa/3.0/" target="_top">
433 Mill Outlet Fabric Shop
435 in Colorado Springs. Using the spreadsheet from
436 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
439 I calculate that we want an 8 foot chute to keep the airframe less
440 nose cone and payload bay below 20 feet per second at touch-down.
442 To extract the main chute and recover the nose cone and payload bay,
443 a 3 foot parachute from BSD Rocketry will be packed in a kevlar
444 blanket ahead of the main chute deployment bag, attached by kevlar
445 harness to the nose cone and payload bay assembly, and to the top of
446 the deployment bag. This assembly will recover separately from the
449 The altimeters are programmed such that the MAWD fires its drogue
450 charge at apogee and its main charge at 1100 feet. The miniRRC2
451 is programmed to fire its drogue charge two seconds past apogee,
452 and its main charge at 900 feet. Thus the MAWD is primary and the
453 miniRRC2 is the backup. Since the M1297W has a burn time of about
454 5 seconds, mach inhibit is programmed on both altimeters to 8 seconds.
455 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2656789"></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="#id2656948">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2659169">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="id2656948"></a>Recovery System Description</h2></div></div></div><p>
456 This rocket uses dual deployment.
458 The apogee event separates the
459 airframe between the zipperless-design booster section and the
460 drogue bay. These two sections are linked by a Giant Leap 20 foot
461 pre-sewn 1/4 inch tubular kevlar assembly, attached to which is a
462 Public Missiles 4 x 144 inch red nylon streamer packed in a Giant Leap
463 kevlar chute protection pad.
465 The main event separates the airframe between the forward payload bay
466 and the main bay. Attached to the nose cone and payload bay assembly
467 is a Giant Leap 15 foot pre-sewn 1/4 inch tubular kevlar assembly,
468 attached "free bag" style to the top of a Giant Leap deployment bag
469 containing the main chute. A 36 inch BSD Rocketry nylon parachute
470 packed in a Giant Leap kevlar chute protection pad serves to pull the
471 deployment bag off the main chute, after which it allows for safe
472 recovery of the nose cone and payload assembly at just under 20 feet
475 The 8 foot main chute is home-made from 1.9 oz rip-stop nylon using
476 the design documented by
477 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
480 It is attached to the remainder of the rocket using another Giant Leap
481 pre-sewn 1/4 inch tubular kevlar assembly.
483 The anchor points are all 5/16 inch u-bolts, except for on the booster
484 which is equipped with an embedded loop of 3/16 inch stainless aircraft
485 cable. All connections are made with suitable quick-links.
486 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2659169"></a>Recovery Initiation Control Components</h2></div></div></div><p>
487 The LOC-style avionics bay between the main and drogue bays is
488 populated with two commercial altimeters, a PerfectFlite MAWD
489 and a Missile Works miniRRC2.
490 Each is powered by a dedicated 9V battery, and has a
491 dedicated on/off power switch mounted for access from outside the
492 rocket. Additionally, a single safe/arm switch with two poles is used
493 to interrupt the return circuits from the igniters to each altimeter.
494 See the attached schematic of the avionics bay contents for more
497 The bulkheads at each end of the avionics bay have two CPVC end caps
498 for ejection charge holders, and two-terminal screw blocks for
499 attachment of electric matches purchase from Giant Leap used to ignite
500 Goex 4F black powder ejection charges. Each charge holder and terminal
501 block pair is labelled as to main or backup since the charges will be
505 <a class="ulink" href="http://www.info-central.org/recovery_powder.shtml" target="_top">
506 Info Central Black Powder Sizing
508 page is the most authoritative site I've found on this topic.
509 Each of the main and drogue bay interfaces will use 2 2-56 nylon screws
510 as shear pins, each of which needs 35 pounds of force or so to shear.
511 Designing for 15psi puts us between 150 and 200 pounds total force in
512 a 4 inch airframe. The formula is thus 0.006 grams times diameter
513 squared in inches times length in inches.
515 My drogue bay is 3.9 inches ID and 8 inches long, or 95.52 cubic
516 inches. That works out to about 0.73 grams. However, there will be
517 some volume in the motor mount tube above the motor that also must
518 be accounted for, enough to nearly double the total volume when flying
519 on the M1297W certification motor. Also, since this charge must fire
520 reliably at 15-18k feet above ground level of around 5k feet, such
521 that combustion is likely to be incomplete, we need to add some margin.
523 My main bay is 3.9 inches ID and about 25 inches between bulkheads,
524 or about 298.50 cubic inches. That works out to 2.28 grams.
526 Sanity checking, PerfectFlite recommends that a 4F black powder charge
527 be sized by multiplying the volume of the bay in cubic inches by 0.01
528 grams. That yields about 1.8 grams for the drogue bay and 3 grams for
531 That suggested to me that a good starting point for ground testing is
532 1.5 grams for the drogue bay and 2.5 grams for the main bay. Ground
533 tests were done using the PC interface cable for the MAWD routed in
534 through the static test port to manually trigger ejections. Testing
535 of the apogee bay showed that 1.5 grams was sufficient for deployment
536 and 1.8 grams was more authoritative. A single test of main deploy
537 with 2.5 grams gave a nearly perfect result.
538 Given the altitude of our expected apogee, we should be generous with
539 the apogee charge, perhaps using 2.0 grams for the primary. The main
540 will deploy at an altitude below where the tests were performed, so
541 no adjustment in charge size should be required.
543 Descent rate of the nose cone and payload bay which mass just under
544 1kg will be less than 20 feet per second with a 36 inch chute based
545 on manufacturer recommendations and Rocksim v8 simulation.
546 Descent rate of the remainder of the rocket under the 8 foot chute
547 should be about 18 feet per second by the spreadsheet provided by
548 the designers of this chute pattern, sanity checked using the descent
549 rate tables of similar commercial parachute designs, like those from
551 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2673956"></a>Chapter 5. Stability Evaluation</h2></div></div></div><p>
552 Simulation using Rocksim v8 with a variety of motors showed that the
553 rocket is unconditionally stable with all motors likely to be flown.
554 The worst-case stability among 75mm motors is actually with the
555 M1297W chosen for the certification flight, at margin 1.05. This is
556 because the front of this motor falls almost exactly at the CP. Using
557 a longer motor like the M1850W raises the initial stability margin to
558 1.10 because the front fuel grain is ahead of the CP, and lesser
559 motors also increase the stability because less mass is behind the CP.
560 The smallest motor I can conceive of flying in this rocket (a Cesaroni
561 J285) would leave us overstable with margin 3.79 on the way to about
563 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2656157"></a>Chapter 6. Expected Performance</h2></div></div></div><p>
564 On the certification flight, using an Aerotech M1297W reload and
565 associated hardware, the anticipated apogee is round 14,700 feet. This
566 is just under 75% of the NCR North Site standing waiver of 20,000 feet.
568 The highest altitude simulated would be achieved with an Aerotech
569 M1850W reload at nearly 18,000 feet. The lowest altitude simulated
570 is with a Cesaroni J285 and Slimline adapters to just over 1800 feet.
572 add description of anticipated flight profile here, including launch
573 weight, estimated drag coefficient, velocity leaving the rail, max
574 expected velocity, altitude, and acceleration
575 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2675455"></a>Chapter 7. Checklists </h2></div></div></div><div class="orderedlist"><ol type="1"><li>
577 <div class="orderedlist"><ol type="1"><li>
578 Pick a club launch with suitable waiver and facilities to
581 Confirm L3CC member(s) available to attend selected launch.
583 Confirm that required loaner motor hardware will be available at launch.
585 Notify launch sponsor (club president) of intended flight.
587 Notify interested friends of intended flight.
589 Perform final pre-flight simulation with as-built masses, etc.
591 Gather consummables and tools required to support flight
592 <div class="orderedlist"><ol type="1"><li>
599 motor retainer snap rings
601 small nylon wire ties
603 cellulose wadding material
607 screwdriver for phillips-head airframe screws
609 small straight-blade screwdriver for power switches
613 high temperature grease
615 long small diameter dowels for igniter insertion
616 </li></ol></div></li></ol></div></li><li>
618 <div class="orderedlist"><ol type="1"><li>
619 program altimeters for suitable mach delay and recovery deployment
620 <div class="itemizedlist"><ul type="disc"><li>
622 <div class="itemizedlist"><ul type="circle"><li>
625 1500 foot main deploy
626 </li></ul></div></li><li>
629 <div class="itemizedlist"><ul type="circle"><li>
632 1000 foot main deploy
634 2 seconds apogee delay
640 ops mode 16 (default)
641 </li></ul></div></li></ul></div></li><li>
642 assemble all recovery system components and ensure everything fits
644 confirm wiring and operation of altimeter power and safe/arm switches
646 Ground test recovery system to confirm suitable black powder
648 </li></ol></div></li><li>
650 <div class="orderedlist"><ol type="1"><li>
651 confirm payload batteries in good condition, bay loaded, power switch works
653 confirm reception of signals from transmitter(s) in payload bay
655 install fresh 9V batteries for altimeters on avionics bay sled
657 inspect altimeters and associated avionics bay wiring for visible faults
659 close up avionics bay
661 install e-matches, confirming resistance of 1-2 ohms and fit in charge cups
663 power up altimeters, operate safe/arm switch, and confirm e-match continuity
665 load BP charges into charge cups
666 <div class="orderedlist"><ol type="1"><li>
667 Drogue Primary Charge - 2.0 grams 4F BP
669 Drogue Backup Charge - 2.5 grams 4F BP
671 Main Primary Charge - 2.5 grams 4F BP
673 Main Backup Charge - 3.0 grams 4F BP
674 </li></ol></div></li><li>
675 connect recovery harnesses and install recovery bay airframe sections
677 power up altimeters, operate safe/arm switch, and confirm e-match continuity
679 safe and power-down the altimeters
681 load main recovery bay, attaching nosecone and payload bay assembly
683 install nylon 2-56 screws as shear pins between main bay and payload bay
685 load drogue recovery bay, feeding harness end through fin can motor tube
687 install nylon 2-56 screws as shear pins between drogue bay and fin can
689 load motor per manufacturer instructions
691 attach forged eye-bolt to forward closure if not already present
693 attach drogue harness to eye-bolt on forward motor closure
695 install motor in motor mount
697 install motor retention snap rings
699 prepare igniter for later installation by attaching to long 1/8" dowel
701 confirm all screws in place, avionics off and safe
703 fill out a launch card
705 notify RSO/LCO of readiness for inspection and launch, obtain a rail
706 assignment and permission to move rocket to launch pad for final prep
708 coordinate readiness with support team members, photographers, observers
709 </li></ol></div></li><li>
711 <div class="orderedlist"><ol type="1"><li>
712 move rocket to launch area
714 clean and lubricate launch rail if necessary
716 power up payload and confirm reception of signals from transmitter(s)
718 mount rocket on launch rail, rotate to vertical
720 power up primary altimeter, confirm expected beep pattern
722 power up backup altimeter, confirm expected beep pattern
726 confirm altimeters both giving expected beep patterns for igniter continuity
728 install igniter and connect to launch control system
730 capture GPS waypoint for rail location
732 smile for the cameras, make sure we have enough "foil Murphy!" shots taken
734 retreat to safe area behind LCO
736 confirm continued reception of transmitter signal(s) from payload bay
738 confirm photographers and observers are ready and know what to expect
740 make sure binoculars and backpack with water and recovery tools are at hand
742 tell RSO and LCO we're ready to launch
744 try to relax and enjoy watching the flight!
745 </li></ol></div></li><li>
747 <div class="orderedlist"><ol type="1"><li>
748 track rocket to landing site
750 capture GPS waypoint of landing site, take lots of photos
754 gather up and roughly re-pack recovery system for return to flight line
756 bring the rocket to observers for post-flight inspection
757 </li></ol></div></li></ol></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2678315"></a>Chapter 8. Flight Summary</h2></div></div></div><p>
758 YikStik was flown on an M1297W on Saturday morning at NCR's Oktoberfest
759 2008. The boost was beautiful. Unfortunately, we lost visual as the
760 rocket climbed into high clouds near apogee. Radio tracking signals
761 remained strong for several minutes, then disappeared. We were
762 confused by viewing what we thought was YikStik descending before
763 signals were lost in about the right direction, but now believe we
764 were actually watching a previously launched rocket and did not see
765 YikStik descend. This confusion prevented location of any of the
766 rocket until Sunday evening, after I had left the launch area.
768 After an extensive search, the nose cone assembly was finally found
769 with the Walston tracking gear nearly 3.5 miles down range. The
770 remainder of the rocket has not been found despite extensive searching
771 on the ground and from the air.
773 Reward if returned posters were placed in the area during the week
774 following the launch but have elicited no useful reponses yet.
775 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2672899"></a>Chapter 9. Analysis and Conclusions</h2></div></div></div><p>
776 Consideration of how the nose cone ended up where it did suggests
777 we may have had an apogee deployment of the main, perhaps due to
778 stress on the shear pins before launch, during boost, or during
779 apogee drogue deployment causing them to break early.
781 It is unfortunate that we were confused by seeing another rocket
782 descending about the expected amount of time after YikStik's launch
783 in approximately the right direction. This caused us to believe that
784 the rocket was much closer than the nose cone turned out to be, causing
785 us to waste a lot of time searching in an area too close to the launch
787 It also caused us to assume something really weird had happened to the
788 transmitters, such that the tracking signal was suddenly lost long
789 after the rocket was on the ground, instead of what seems to really
790 have happened, which is that the rocket was farther away descending
791 after a main deployment at apogee, and the loss of signal was simply
792 due to dropping below a ridge line a couple miles from the launch site.
793 I can't help but think that if we'd been
794 looking in the right area sooner after the launch that we might have
795 found the rocket before someone else apparently picked it up.
797 I regret the decision to use a "free bag" configuration of the
799 Since both tracking transmitters were in the payload bay behind
800 the nose cone, and we were eventually able to recover that portion
801 of the rocket, it is possible that if the deployment bag were tethered
802 to the main that we might have recovered the remainder of the rocket.
804 If the rocket is recovered and able to fly again, the two changes I
805 would like to make are to tether the deployment bag to the apex of the
806 main, and to move from 2-56 nylon screws to 4-40 nylon screws for the
807 main deployment shear pins, ensuring the holes through the airframe
808 are a loose enough fit to avoid stresses on the pins during boost. I
809 have no way to know what happened for sure, but believe this might
810 solve the assumed problem of main deployment at apogee.
812 All in all, the design and build process was educational, and a lot
813 of fun! I'm looking forward to fabricating more custom parts using
814 carbon fiber and vacuum bagging in the future.
815 The beautiful boost and obvious survival of the rocket airframe
816 through the expected mach transitions confirms my design and
817 construction skills are adequate to attain an L3 cert.
818 While I hope to recover the remainder of YikStik someday, I won't
819 waste any time before trying again with a new airframe!
820 </p></div></div></body></html>
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