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="id2322390"></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="id2577753"></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 1.2</td><td align="left">12 January 2009</td></tr><tr><td align="left" colspan="2">
8 Document firmware bug in miniRRC2 and possible impact on flight.
9 </td></tr><tr><td align="left">Revision 1.1</td><td align="left">5 December 2008</td></tr><tr><td align="left" colspan="2">
10 Remove embedded images in favor of references to gallery.gag.com
11 </td></tr><tr><td align="left">Revision 1.0</td><td align="left">28 October 2008</td></tr><tr><td align="left" colspan="2">
12 Recording results of first, and only, flight attempt.
13 </td></tr><tr><td align="left">Revision 0.5</td><td align="left">27 September 2008</td></tr><tr><td align="left" colspan="2">
15 </td></tr><tr><td align="left">Revision 0.4</td><td align="left">17 September 2008</td></tr><tr><td align="left" colspan="2">
16 Documenting the build process as it happens
17 </td></tr><tr><td align="left">Revision 0.3</td><td align="left">29 March 2008</td></tr><tr><td align="left" colspan="2">
18 Incorporate ideas from James Russell during initial L3CC review
19 </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="#id2565537">1. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#id2565574">Why "YikStik"?</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2557207">2. Design</a></span></dt><dd><dl><dt><span class="section"><a href="#id2557213">Overview</a></span></dt><dt><span class="section"><a href="#id2557231">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2557244">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2557261">Airframe Tubing</a></span></dt><dt><span class="section"><a href="#id2557277">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2557288">Fins</a></span></dt><dt><span class="section"><a href="#id2608670">Centering Rings and Bulkheads </a></span></dt><dt><span class="section"><a href="#id2597438">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2599532">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2612550">Avionics</a></span></dt><dt><span class="section"><a href="#id2589090">Payload</a></span></dt></dl></dd><dt><span class="section"><a href="#id2581651">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2581446">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2599074">Recovery System</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2592234">3. Construction Details</a></span></dt><dd><dl><dt><span class="section"><a href="#id2599259">Airframe and Couplers</a></span></dt><dt><span class="section"><a href="#id2596433">Fins</a></span></dt><dt><span class="section"><a href="#id2606804">Centering Rings and Bulkheads</a></span></dt><dt><span class="section"><a href="#id2588775">Assembling the Booster Section</a></span></dt><dt><span class="section"><a href="#id2584973">Avionics Bay</a></span></dt><dt><span class="section"><a href="#id2606384">Payload Bay</a></span></dt><dt><span class="section"><a href="#id2607348">Recovery System</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2600260">4. Recovery Systems Package</a></span></dt><dd><dl><dt><span class="section"><a href="#id2595964">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2609782">Recovery Initiation Control Components</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2585586">5. Stability Evaluation</a></span></dt><dt><span class="chapter"><a href="#id2606777">6. Expected Performance</a></span></dt><dt><span class="chapter"><a href="#id2611290">7. Checklists </a></span></dt><dt><span class="chapter"><a href="#id2610811">8. Flight Summary</a></span></dt><dt><span class="chapter"><a href="#id2607490">9. Analysis and Conclusions</a></span></dt></dl></div><p>
20 Please note that I stopped adding photos to this document at some
21 point. I have many more photos of the YikStik build, but haven't
22 decided how best to present them yet... update coming someday!
23 </p><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2565537"></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="#id2565574">Why "YikStik"?</a></span></dt></dl></div><p>
24 This is the rocket I'm designing for my NAR Level 3 certification flight.
25 The general idea is to build a fairly cheap rocket capable of reliably
26 flying this year's Aerotech level 3 special, which is an M1297W reload.
27 I'd like to be able to fly the prototype of my own altimeter design, and
28 to be able to fly it often on smaller / cheaper reloads at launch sites
29 with modest waivers like Hudson Ranch.
31 I want to experiment with vacuum bagging carbon fiber reinforcements, and
32 intend to use my CNC milling machine to cut all the centering rings, etc.
33 The new Giant Leap "Dynawind" tubing feels like a good choice, and if we
34 stick to the 4 inch version we can use a cheap plastic nosecone to keep
37 Preliminary analysis suggests that a roughly 8 foot rocket made from 4 inch
38 airframe with a 75mm mount and three fins should fly to something around
39 14k feet on the M1297W, could break three miles on the M1850W, and yet
40 could safely fly on reloads as small as a J for economical fun. Those
41 altitudes mean the certification flight will need to be at a site with a
42 high-altitude waiver like the NCR north site.
43 </p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2565574"></a>Why "YikStik"?</h2></div></div></div><p>
44 I've always thought the high-gloss red paint job on one of my son's rockets
45 when out on a launch rod in the sun looks a lot like glistening wet
48 Combine that with the fact that my wife who isn't fond of the stuff
49 refers to lipstick as "yik stick"... and the rest should be obvious.
51 My planned paint scheme is a bright red nosecone, gold tube, and black fin
52 can, which is the mental image I have of what lipstick applicators look
53 like, most likely from a stick my mother or one of my grandmothers had
55 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2557207"></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="#id2557213">Overview</a></span></dt><dt><span class="section"><a href="#id2557231">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2557244">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2557261">Airframe Tubing</a></span></dt><dt><span class="section"><a href="#id2557277">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2557288">Fins</a></span></dt><dt><span class="section"><a href="#id2608670">Centering Rings and Bulkheads </a></span></dt><dt><span class="section"><a href="#id2597438">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2599532">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2612550">Avionics</a></span></dt><dt><span class="section"><a href="#id2589090">Payload</a></span></dt></dl></dd><dt><span class="section"><a href="#id2581651">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2581446">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2599074">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="id2557213"></a>Overview</h2></div></div></div><p>
56 YikStik is a fairly simple "three fins and a nose cone" dual-deploy
57 rocket using a 75mm motor mount, 4 inch glass-wrapped phenolic airframe
58 with zipperless fin can, plastic nose cone, plywood fins,
59 and lots of glass and carbon fiber reinforcing.
60 The primary electronics bay will be designed to
61 hold two altimeters, and a distinct payload bay may carry an
62 experimental altimeter, GPS receiver, and downlink transmitter.
63 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2557231"></a>Rocksim File</h2></div></div></div>
64 This is the current working design in Rocksim format:
65 <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="id2557244"></a>Drawing from Rocksim</h2></div></div></div><span class="inlinemediaobject"><img src="YikStik.jpg"></span></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2557261"></a>Airframe Tubing</h2></div></div></div><p>
66 I intend to cut the airframe components from two 48 inch lengths of
67 98mm Giant Leap Dynawind tubing. The 30 inch main bay and 18 inch drogue
68 bay will be cut from one length, while the 33 inches of fin can, 2 inches
69 of electronics bay, and 8 inches of payload bay will be cut from the
71 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2557277"></a>Nose Cone</h2></div></div></div><p>
72 I intend to use a Giant Leap "Pinnacle" 3.9 inch nose cone.
73 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2557288"></a>Fins</h2></div></div></div><p>
74 The fins are designed from scratch, and I intend to build them up from
75 two layers of 1/8 inch birch plywood, three layers of carbon fiber, and
76 two layers of 6 oz glass. The stack will be glass, carbon fiber,
77 plywood, carbon fiber, plywood, carbon fiber, glass. The edges of the
78 plywood will be routed to give a modified airfoil shape to the finished
79 fins. The stack will be laminated using West Systems epoxy products
81 The shape is a compromise between mass, surviving Mach-transition stress,
82 optimal stability margin, and avoiding damage during handling and on
83 contact with the ground during recovery.
85 The fins will be locked in to milled slots in two of the centering rings,
86 and will be epoxied to the motor mount with glass reinforcing tape.
87 The airframe will be slotted to allow the completed motor mount / fin
88 assembly to be inserted from the rear, with fillets of epoxy applied
89 inside and outside the airframe after insertion.
90 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2608670"></a>Centering Rings and Bulkheads </h2></div></div></div><p>
91 All centering rings and bulkheads will be custom machined from 3/8 inch
92 birch plywood using my 3-axis CNC milling machine. Some rings will use
93 laminated pairs of 3/4 inch total thickness to enable use of threaded
94 inserts for 1/4-20 rail button screws or deep routing for fin alignment
96 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2597438"></a>Motor Retention</h2></div></div></div><p>
97 I will embed three 8-24 T-nuts in the aft centering ring spaced to allow
98 the use of home-made Kaplow clips to retain 75mm motors.
99 The same holes may be used to attach custom motor mount adapters for
100 smaller diameter motors.
101 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2599532"></a>Electronics</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2612550"></a>Avionics</h3></div></div></div><p>
102 The recovery system will feature dual redundant barometric altimeters
103 in an electronics bay similar to the LOC design located between the
104 drogue and main parachute bays.
106 A PerfectFlite MAWD will be flown as the primary altimeter and to
107 record the flight altitude profile.
108 A MissileWorks Mini-RRC2 will fly as backup altimeter and to
109 directly capture max velocity.
111 Each altimeter will have a separate battery and power switch. A 4PDT
112 slide switch will be used as a SAFE/ARM switch configured to interrupt
113 connectivity to the ejection charges.
114 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2589090"></a>Payload</h3></div></div></div><p>
116 <a class="ulink" href="http://altusmetrum.org/" target="_top">
117 my own altimeter design
119 as a payload in a short payload section just behind the nose cone.
120 I have acquired the pieces to add a GPS receiver and RF downlink using
121 ham radio frequencies to the payload to track the rocket's position
123 This is not essential to fly,
124 but could make recovery simpler and would just be fun to fly if I can
125 get it all working and suitably ground and/or flight tested in time.
126 </p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2581651"></a>Stability Evaluation</h2></div></div></div><p>
127 This design has been thoroughly analyzed using
128 <a class="ulink" href="http://www.apogeerockets.com/rocksim.asp" target="_top">
131 with motors ranging from the
132 Cesaroni J285 through the Aerotech M1850W and appears to be
133 unconditionally stable across that range. The lowest margin is around
134 1.2 seen with the M1297W planned for my level 3 certification flight,
135 albeit with many masses still only roughly estimated.
137 These simulations will be refined as the build proceeds and as-built
138 stability verified before flight.
139 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2581446"></a>Expected Performance</h2></div></div></div><p>
140 The Aerotech M1297W reload should carry this vehicle without ballast
141 to just over 14 thousand feet AGL. It should make over 16 thousand
142 feet AGL on an M1850W, and should fly stably to roughly 2.5k feet AGL
145 Hitting optimal mass on the largest motors may require
146 ballast, depending on final build weight.
147 My plan is to fly without ballast on the certification flight,
148 trading some altitude for a slower and softer recovery.
149 If the cert succeeds, then I might try an optimal mass
150 flight sometime later on an M1850W or equivalent "bigger M"
151 reload to join the "three mile club".
152 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2599074"></a>Recovery System</h2></div></div></div><p>
153 The recovery system will use dual redundant barometric altimeters firing
154 black powder charges.
155 At apogee, a drogue chute will deploy from just forward of the fin can,
156 with size selected for an approximately 100 ft/sec descent rate.
157 At a preset altitude, a main chute will be deployed to achieve recovery
158 of the bulk of the rocket at under 20 ft/sec.
159 The main chute will be packed in a deployment bag, configured as a
160 "freebag" and pulled out of the airframe by a second drogue chute. This
161 drogue will recover the nosecone and deployment bag separately from the
162 remainder of the rocket which will recover under the main.
164 I intend to sew the parachutes from scratch using a design documented by
165 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
168 using 1.9oz rip-stop nylon and 550 lb parachute cord.
169 If time runs short, equivalent chutes from SkyAngle,
170 Rocketman, or Giant Leap could be substituted (at significantly higher
173 The deployment bag will probably be purchased from Giant Leap. The
174 recovery harness will probably use tubular kevlar, also from Giant Leap.
176 The recovery system attachment points will all use 1/4 inch u-bolts with
177 nuts, washers, and backing plates through bulkheads except for the fin
178 can. The fin can has insufficient room between the motor mount and
179 the airframe inner wall for nuts and washers, so an alternative means of
180 recovery system attachment is required. The fin can will be equipped
181 with either a 3/16 inch stainless steel aircraft cable loop, or a loop
182 of 1/2 inch tubular kevlar, bonded to the motor mount.
183 If available, a screw-eye attached to the forward motor closure may be
184 used instead of or in addition to this recovery attachment loop.
185 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2592234"></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="#id2599259">Airframe and Couplers</a></span></dt><dt><span class="section"><a href="#id2596433">Fins</a></span></dt><dt><span class="section"><a href="#id2606804">Centering Rings and Bulkheads</a></span></dt><dt><span class="section"><a href="#id2588775">Assembling the Booster Section</a></span></dt><dt><span class="section"><a href="#id2584973">Avionics Bay</a></span></dt><dt><span class="section"><a href="#id2606384">Payload Bay</a></span></dt><dt><span class="section"><a href="#id2607348">Recovery System</a></span></dt></dl></div><p>
186 I have collected all of my
187 <a class="ulink" href="http://gallery.gag.com/rockets/yikstik" target="_top">
190 in one place, they may show better than I can explain how various
191 aspects of YikStik went together.
192 </p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2599259"></a>Airframe and Couplers</h2></div></div></div><p>
193 The tubing for the airframe, couplers, and motor mount was all cut
194 using a carefully aligned and adjusted power mitre saw, and the ends
195 lightly sanded to remove rough spots.
196 The main and drogue bays were cut from one 48 inch length of Giant
197 Leap 98mm Dynawind tubing, the fin can, electronics bay, and payload
198 bay were cut from the second. The three couplers for the fin can,
199 electronics bay, and payload bay were cut from Giant Leap 98mm phenolic
200 coupler stock. And the motor mount was cut from Giant Leap 75mm
201 phenolic airframe stock.
202 Note that the motor mount is the longest piece because of
203 the zipperless design with full-length motor mount.
205 The airframe tubing selected includes a wrap of 10oz glass in epoxy
206 over the base phenolic tubing (visible in some photos as a
207 shine on the outside of the tubing),
208 but the coupler stock is unreinforced.
209 To ensure the couplers can handle the anticipated loading, I reinforced
210 each with one layer of interior carbon fiber, using the "kitchen
211 vacuum bagging" technique documented by
212 <a class="ulink" href="http://www.jcrocket.com/kitchenbagging.shtml" target="_top">
216 This was my first hands-on experience working with carbon fiber. The
217 end of the coupler nearest the unit during bagging experienced some
218 crushing of the fibers right at the end. It doesn't matter for this
219 project because each of the couplers will have at least one end fitted
220 with a bulkhead or centering ring, but in the future I'll be tempted
221 to cut the coupler stock a bit long before bagging and trim to length
222 after reinforcing to get "perfect" ends. The technique worked
223 marvelously otherwise, and the resulting couplers look and should work
225 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2596433"></a>Fins</h2></div></div></div><p>
226 Six pieces of 1/8 inch birch plywood were stacked, edge-aligned on what
227 would be the fin root edge, and clamped. The outline of the fin design
228 was marked in pencil, and three 1/8 inch holes drilled through the
229 stack inside the fins to allow using 4-40 screws and nuts to hold the
230 blanks together while making the initial cuts, so that they would all be
231 matched in size. The clamps were removed to avoid interference
232 during cutting. The fin outline was then cut using a radial arm saw.
234 A router table with 1/8 inch
235 roundover bit was then used to round over the outer edge, 3 blanks on
236 one side and three on the other. This edge might have been left square,
237 but I prefer the look and feel of rounding. The router table with a 1/2
238 inch diameter straight cutting bit and a fin beveling jig was used
239 to impart a 10-degree bevel on the leading and trailing edge of each fin
240 blank, again 3 on one side and three on the other. The resulting 6
241 blanks thus form 3 pairs of fin components with a modified
244 The fin assembly started with a simple lamination of two layers of ply
245 sandwiching a layer of carbon fiber. Each fin used "one pump" of West
246 Systems epoxy and the stack was vacuum bagged using the Foodsaver with
247 wide bagging material. To keep everything flat while the epoxy cured,
248 the stack of fins was sandwiched between two unused extra shelves for
249 a storage cabinet I had on hand
250 (particle board covered in laminate, very
251 flat and smooth, nearly inflexible at this loading), and stacked with
252 about 75 lbs of loose barbell weights.
254 On one of the three fins, the plywood layers are out of alignment by
255 1-2mm in the longest axis. The other two are nearly perfect. Light
256 sanding should allow me to match them before laminating the outer layers
257 of carbon fiber and glass.
259 After the fins cured, they were bulk sanded with medium and fine
260 sandpaper and an electric palm sander. Final sanding of the leading
261 and trailing edges was done using 400 grit paper on a flat surface,
262 holding the fin the way you'd sharpen a knife against a stone. The
263 results seem good, all three fins match pretty closely.
265 A fin holding jig was cut from 1/8" hardboard using my rotary tool
266 with a fiber cutoff wheel. The fin slots were made to be a snug fit.
267 A small batch of epoxy was used to apply a bead to the root edge and
268 tab at the leading edge, then the fins were installed against the
269 motor mount and locked into place with the jig to cure. The centering
270 ring that locks the aft edge of the fins was dry-fit during this
271 operation to ensure proper alignment, but was not glued yet. It will
272 go on after the airframe and internal fin filets are installed.
274 The fins were reinforced with fiberglass and epoxy. Masking tape was
275 used to carefully delineate where the airframe ID will be, then 6oz
276 glass 14.25" by 3.5" was epoxied fin-fin across the MMT. Strips of
277 8.6oz "boat tape" fiberglass were worked into the joints with more
278 epoxy, and a sheet of plastic covered by ziplog bags of water were
279 used to hold things in place during the initial curing. The three
280 sides were done one at a time and allowed to cure before proceeding.
281 The results look good, and in combination with internal and external
282 airframe filets should yield a super-strong fin can.
283 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2606804"></a>Centering Rings and Bulkheads</h2></div></div></div><p>
284 Pairs of 3/8 inch birch plywood blanks were laminated using Titebond
285 wood glue and clamped while curing to form 3/4 inch blanks for centering
286 rings. From a strength perspective, 3/8 inch should suffice, but there
287 are two reasons for going with thicker blanks in some places. The first
288 is that the rail buttons chosen use 1/4-20 mounting screws, and threaded
289 inserts in that size are nearly 3/8 inch outside diameter
291 tear up a ring only 3/8 inch thick on insertion). The second is that I
292 like to mill slots in the centering rings on each end of the fins to
293 "lock" the fins into position. Doubling the blanks used to cut those
294 rings will allow me to cut 1/4 inch deep fin slots and still have a half
295 inch of unmolested wood in the rings for strength.
297 The aft centering ring and the one just aft of the zipperless
298 coupler section were edge-drilled for the installation of brass
299 1/4-20 threaded inserts to hold rail buttons. The inserts were
300 locked in place with epoxy, then ground down until nothing protruded
301 beyond the OD of the ring.
302 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2588775"></a>Assembling the Booster Section</h2></div></div></div><p>
303 The forward two centering rings were installed on the MMT using
304 JB Weld high-temperature epoxy, and incorporating an aircraft cable
305 loop for recovery system retention since there just wasn't room for
308 The ring at the leading edge of the fins was initially installed
309 assuming the aft ring would be nearly flush with the rear of the MMT
310 and equipped with Kaplow-clip style retainers, but before the fins
311 were installed a Giant Leap Slimline Tailcone Retainer for 75mm motor
312 in 98mm airframe became available thanks to Tim Thomas, and so this
313 ring was cut out and replaced with another one inch farther forward
314 to allow installation of the tailcone at the rear of the MMT. I
315 really like the tailcone on my Vertical Assault kit, and think it'll
316 work out to be a great addition for this rocket!
318 An alignment jig for the fins was carefully marked out and then cut
319 from 1/8 inch hardboard using my rotary tool and abrasive cutoff wheel.
320 The fins were then epoxied at the root and short leading edge to the
321 motor mount tube and into the slots in the forward centering ring,
322 and held rigidly aligned by the jig until the epoxy set. The fins
323 were then masked at what would be the ID of the airframe tube, and
324 reinforced with 6oz glass fin-fin across the motor mount tube between
325 each fin pair, further reinforced with strips of 1 inch glass "boat
326 tape" at each fin root joint.
328 The airframe tubing section was carefully marked for fin slots, which
329 were then cut using my rotary tool with abrasive cutoff wheel. Epoxy
330 was applied ahead of the center two rings as the frame was slid into
331 place, and the frame left standing upright until the epoxy set to
332 hopefully form ring-fin fillets on those two rings. The interior
333 fin to airframe joints were reinforced one fin at a time using West
334 Systems epoxy will milled glass as a filler. A long 3/8" dowel was
335 used to place and smooth these interior filets. The aft centering ring
336 was installed by pouring West Systems epoxy in the three fin-fin gaps,
337 placing the ring, then standing the airframe up to allow the epoxy to
338 flow over the forward surface of the ring and into the gaps between it,
339 the motor mount, and the airframe tubing. After it set, the booster
340 was placed nose-down, the airframe gaps behind the fins were taped,
341 and more epoxy was applied to seal the aft of the ring to the tubes.
342 Before this epoxy set, JB Weld was used to glue the tail cone retainer
346 airframe joints were filleted using 5-minute epoxy thickened with
347 baby powder and smoothed with the tip of a plastic spoon, which I
348 learned about building the Vertical Assault kit. Gives great results,
349 and allowed all 6 joints to be done in one session. The space
350 above the top surface of the forward centering ring and between the
351 motor mount and zipperless-design coupler tubing was filled with epoxy
352 and milled glass. Minor gaps in the airframe behind each fin were
353 filled with epoxy clay.
354 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2584973"></a>Avionics Bay</h2></div></div></div><p>
355 The avionics bay contains the two commercial altimeters used to
356 record information about the flight and deploy the drogue and main
357 recovery systems. It is constructed of a piece of Giant Leap 98mm
358 coupler tubing reinforced with an interior wrap of vacuum-bagged
359 carbon fiber, and a 2 inch length of Giant Leap 98mm DynaWind airframe
362 The bulkheads are custom-milled from 3/8 inch birch plywood
363 milled so that about 3/16" fits inside the coupler and the remainder
364 seals the end of the coupler and just fits inside the airframe. Each
365 bulkhead has a u-bolt for attaching the recovery harnesses, and dual
366 CPVC end caps as ejection charge holders with screw terminal blocks
367 from Missile Works to attach the igniters. Two lengths of 1/4 inch
368 all-thread with nuts and washers tie the bulkheads together, with
369 wing-nuts used on one end to allow for easy disassembly.
371 A sled was fabricated to hold the altimeters and batteries. It
372 consists of 1/8 inch birch ply laminated with 6oz fiberglass on each
373 side, epoxied to cardboard tubes taken from the packaging for Aerotech
374 igniters that slide over the all-thread, further reinforced with nylon
375 ties at each end. The tubes are staggered one on either side so that
376 the sled goes right up the center of the airframe tubing.
378 Two "centering rings" containing three each 6-32 threaded inserts are
379 epoxied inside the bay to provide hard points for attaching the
380 airframe tubes for the drogue and main recovery bays. The inside
381 diameter of these rings is notched for the avionics sled, and thus
382 these rings also provide physical support for the sled.
384 Three rotary switches from Missile Works are installed through the
385 short airframe tubing section, drilled such that they end up
386 essentially flush with the outside of the airframe, clamp the coupler
387 tubing, and project inside the bay. Two are wired as SPST switches
388 for power to the two altimeters, the third is wired as a DPST switch
389 that open-circuits the igniters for the required "safe/arm" function
390 called for in the NAR L3 certification requirements.
392 The wiring of the avionics bay is documented in the attached
393 schematic diagram. Connectors were used to allow each bulkhead and
394 the switches in the housing to be quickly detached from the sled.
395 The connectors are 9-pin D shells for the switch wiring, and 4-pin
396 Molex connectors like those used on older PC hard drive power cables
397 for the bulkheads. To allow use of a single switch pole for the
398 safe/arm function for each altimeter, the two igniters attached to
399 each altimeter are safed by interrupting the common return lines as
400 shown in the schematic.
402 Sizing the static port for the avionics bay was done by applying the
403 formulas suggested by PerfectFlite and Missile Works for their
404 respective altimeter products, then comparing the results with each
405 other and with information found on the web. I've personally had
406 better luck with single ports than with multiple holes, perhaps because
407 I've been working with relatively small rockets. Regardless, I'm
408 sticking with what I know and will use a single static port hole here.
410 The measured dimensions
411 of the avionics bay as constructed are 95mm ID and approximately 250mm
412 between bulkheads. This works out to 108.73 cubic inches before
413 accounting for the volume of the sled, electronics, and wiring and
414 other components inside the bay. By the PerfectFlight formula, the
415 static port should be 0.221 inches in diameter. By the Missile Works
416 formula for a bay over 100 cubic inches the answer is 0.261 inches.
417 The closest standard drill size, which happens to split the difference,
418 is 0.250 inches. Easy enough!
419 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2606384"></a>Payload Bay</h2></div></div></div><p>
420 The construction of the payload bay is very similar to the avionics
421 bay, except that there is a hard-epoxied rear bulkhead, and only one
422 screw ring to hard-mount the nose cone. The forward end of the
423 payload bay is open to the open interior volume of the nose cone in
424 anticipation of extending downlink antennas above the carbon fiber
425 reinforcement in the coupler and into the nose cone, since carbon
426 fiber is opaque to RF.
427 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2607348"></a>Recovery System</h2></div></div></div><p>
428 Pre-sewn 1/4 inch tubular kevlar harness sections were purchased
429 from Giant Leap, along with a small kevlar deployment bag and two
430 kevlar chute protectors.
432 For an apogee drogue, I plan to fly a Public Missiles 4 x 144 inch
433 nylon streamer. It will be protected with one of the kevlar blankets
434 and attached to one of the kevlar harness sections holding the booster
437 The main parachute will be sewn from 1.9 oz rip-stop nylon purchased
439 <a class="ulink" href="http://www.milloutletfabric.com/" target="_top">
440 Mill Outlet Fabric Shop
442 in Colorado Springs. Using the spreadsheet from
443 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
446 I calculate that we want an 8 foot chute to keep the airframe less
447 nose cone and payload bay below 20 feet per second at touch-down.
449 To extract the main chute and recover the nose cone and payload bay,
450 a 3 foot parachute from BSD Rocketry will be packed in a kevlar
451 blanket ahead of the main chute deployment bag, attached by kevlar
452 harness to the nose cone and payload bay assembly, and to the top of
453 the deployment bag. This assembly will recover separately from the
456 The altimeters are programmed such that the MAWD fires its drogue
457 charge at apogee and its main charge at 1100 feet. The miniRRC2
458 is programmed to fire its drogue charge two seconds past apogee,
459 and its main charge at 900 feet. Thus the MAWD is primary and the
460 miniRRC2 is the backup. Since the M1297W has a burn time of about
461 5 seconds, mach inhibit is programmed on both altimeters to 8 seconds.
462 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2600260"></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="#id2595964">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2609782">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="id2595964"></a>Recovery System Description</h2></div></div></div><p>
463 This rocket uses dual deployment.
465 The apogee event separates the
466 airframe between the zipperless-design booster section and the
467 drogue bay. These two sections are linked by a Giant Leap 20 foot
468 pre-sewn 1/4 inch tubular kevlar assembly, attached to which is a
469 Public Missiles 4 x 144 inch red nylon streamer packed in a Giant Leap
470 kevlar chute protection pad.
472 The main event separates the airframe between the forward payload bay
473 and the main bay. Attached to the nose cone and payload bay assembly
474 is a Giant Leap 15 foot pre-sewn 1/4 inch tubular kevlar assembly,
475 attached "free bag" style to the top of a Giant Leap deployment bag
476 containing the main chute. A 36 inch BSD Rocketry nylon parachute
477 packed in a Giant Leap kevlar chute protection pad serves to pull the
478 deployment bag off the main chute, after which it allows for safe
479 recovery of the nose cone and payload assembly at just under 20 feet
482 The 8 foot main chute is home-made from 1.9 oz rip-stop nylon using
483 the design documented by
484 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
487 It is attached to the remainder of the rocket using another Giant Leap
488 pre-sewn 1/4 inch tubular kevlar assembly.
490 The anchor points are all 5/16 inch u-bolts, except for on the booster
491 which is equipped with an embedded loop of 3/16 inch stainless aircraft
492 cable. All connections are made with suitable quick-links.
493 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2609782"></a>Recovery Initiation Control Components</h2></div></div></div><p>
494 The LOC-style avionics bay between the main and drogue bays is
495 populated with two commercial altimeters, a PerfectFlite MAWD
496 and a Missile Works miniRRC2.
497 Each is powered by a dedicated 9V battery, and has a
498 dedicated on/off power switch mounted for access from outside the
499 rocket. Additionally, a single safe/arm switch with two poles is used
500 to interrupt the return circuits from the igniters to each altimeter.
501 See the attached schematic of the avionics bay contents for more
504 The bulkheads at each end of the avionics bay have two CPVC end caps
505 for ejection charge holders, and two-terminal screw blocks for
506 attachment of electric matches purchase from Giant Leap used to ignite
507 Goex 4F black powder ejection charges. Each charge holder and terminal
508 block pair is labelled as to main or backup since the charges will be
512 <a class="ulink" href="http://www.info-central.org/recovery_powder.shtml" target="_top">
513 Info Central Black Powder Sizing
515 page is the most authoritative site I've found on this topic.
516 Each of the main and drogue bay interfaces will use 2 2-56 nylon screws
517 as shear pins, each of which needs 35 pounds of force or so to shear.
518 Designing for 15psi puts us between 150 and 200 pounds total force in
519 a 4 inch airframe. The formula is thus 0.006 grams times diameter
520 squared in inches times length in inches.
522 My drogue bay is 3.9 inches ID and 8 inches long, or 95.52 cubic
523 inches. That works out to about 0.73 grams. However, there will be
524 some volume in the motor mount tube above the motor that also must
525 be accounted for, enough to nearly double the total volume when flying
526 on the M1297W certification motor. Also, since this charge must fire
527 reliably at 15-18k feet above ground level of around 5k feet, such
528 that combustion is likely to be incomplete, we need to add some margin.
530 My main bay is 3.9 inches ID and about 25 inches between bulkheads,
531 or about 298.50 cubic inches. That works out to 2.28 grams.
533 Sanity checking, PerfectFlite recommends that a 4F black powder charge
534 be sized by multiplying the volume of the bay in cubic inches by 0.01
535 grams. That yields about 1.8 grams for the drogue bay and 3 grams for
538 That suggested to me that a good starting point for ground testing is
539 1.5 grams for the drogue bay and 2.5 grams for the main bay. Ground
540 tests were done using the PC interface cable for the MAWD routed in
541 through the static test port to manually trigger ejections. Testing
542 of the apogee bay showed that 1.5 grams was sufficient for deployment
543 and 1.8 grams was more authoritative. A single test of main deploy
544 with 2.5 grams gave a nearly perfect result.
545 Given the altitude of our expected apogee, we should be generous with
546 the apogee charge, perhaps using 2.0 grams for the primary. The main
547 will deploy at an altitude below where the tests were performed, so
548 no adjustment in charge size should be required.
550 Descent rate of the nose cone and payload bay which mass just under
551 1kg will be less than 20 feet per second with a 36 inch chute based
552 on manufacturer recommendations and Rocksim v8 simulation.
553 Descent rate of the remainder of the rocket under the 8 foot chute
554 should be about 18 feet per second by the spreadsheet provided by
555 the designers of this chute pattern, sanity checked using the descent
556 rate tables of similar commercial parachute designs, like those from
558 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2585586"></a>Chapter 5. Stability Evaluation</h2></div></div></div><p>
559 Simulation using Rocksim v8 with a variety of motors showed that the
560 rocket is unconditionally stable with all motors likely to be flown.
561 The worst-case stability among 75mm motors is actually with the
562 M1297W chosen for the certification flight, at margin 1.05. This is
563 because the front of this motor falls almost exactly at the CP. Using
564 a longer motor like the M1850W raises the initial stability margin to
565 1.10 because the front fuel grain is ahead of the CP, and lesser
566 motors also increase the stability because less mass is behind the CP.
567 The smallest motor I can conceive of flying in this rocket (a Cesaroni
568 J285) would leave us overstable with margin 3.79 on the way to about
570 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2606777"></a>Chapter 6. Expected Performance</h2></div></div></div><p>
571 On the certification flight, using an Aerotech M1297W reload and
572 associated hardware, the anticipated apogee is round 14,700 feet. This
573 is just under 75% of the NCR North Site standing waiver of 20,000 feet.
575 The highest altitude simulated would be achieved with an Aerotech
576 M1850W reload at nearly 18,000 feet. The lowest altitude simulated
577 is with a Cesaroni J285 and Slimline adapters to just over 1800 feet.
579 add description of anticipated flight profile here, including launch
580 weight, estimated drag coefficient, velocity leaving the rail, max
581 expected velocity, altitude, and acceleration
582 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2611290"></a>Chapter 7. Checklists </h2></div></div></div><div class="orderedlist"><ol type="1"><li>
584 <div class="orderedlist"><ol type="1"><li>
585 Pick a club launch with suitable waiver and facilities to
588 Confirm L3CC member(s) available to attend selected launch.
590 Confirm that required loaner motor hardware will be available at launch.
592 Notify launch sponsor (club president) of intended flight.
594 Notify interested friends of intended flight.
596 Perform final pre-flight simulation with as-built masses, etc.
598 Gather consummables and tools required to support flight
599 <div class="orderedlist"><ol type="1"><li>
606 motor retainer snap rings
608 small nylon wire ties
610 cellulose wadding material
614 screwdriver for phillips-head airframe screws
616 small straight-blade screwdriver for power switches
620 high temperature grease
622 long small diameter dowels for igniter insertion
623 </li></ol></div></li></ol></div></li><li>
625 <div class="orderedlist"><ol type="1"><li>
626 program altimeters for suitable mach delay and recovery deployment
627 <div class="itemizedlist"><ul type="disc"><li>
629 <div class="itemizedlist"><ul type="circle"><li>
632 1500 foot main deploy
633 </li></ul></div></li><li>
636 <div class="itemizedlist"><ul type="circle"><li>
639 1000 foot main deploy
641 2 seconds apogee delay
647 ops mode 16 (default)
648 </li></ul></div></li></ul></div></li><li>
649 assemble all recovery system components and ensure everything fits
651 confirm wiring and operation of altimeter power and safe/arm switches
653 Ground test recovery system to confirm suitable black powder
655 </li></ol></div></li><li>
657 <div class="orderedlist"><ol type="1"><li>
658 confirm payload batteries in good condition, bay loaded, power switch works
660 confirm reception of signals from transmitter(s) in payload bay
662 install fresh 9V batteries for altimeters on avionics bay sled
664 inspect altimeters and associated avionics bay wiring for visible faults
666 close up avionics bay
668 install e-matches, confirming resistance of 1-2 ohms and fit in charge cups
670 power up altimeters, operate safe/arm switch, and confirm e-match continuity
672 load BP charges into charge cups
673 <div class="orderedlist"><ol type="1"><li>
674 Drogue Primary Charge - 2.0 grams 4F BP
676 Drogue Backup Charge - 2.5 grams 4F BP
678 Main Primary Charge - 2.5 grams 4F BP
680 Main Backup Charge - 3.0 grams 4F BP
681 </li></ol></div></li><li>
682 connect recovery harnesses and install recovery bay airframe sections
684 power up altimeters, operate safe/arm switch, and confirm e-match continuity
686 safe and power-down the altimeters
688 load main recovery bay, attaching nosecone and payload bay assembly
690 install nylon 2-56 screws as shear pins between main bay and payload bay
692 load drogue recovery bay, feeding harness end through fin can motor tube
694 install nylon 2-56 screws as shear pins between drogue bay and fin can
696 load motor per manufacturer instructions
698 attach forged eye-bolt to forward closure if not already present
700 attach drogue harness to eye-bolt on forward motor closure
702 install motor in motor mount
704 install motor retention snap rings
706 prepare igniter for later installation by attaching to long 1/8" dowel
708 confirm all screws in place, avionics off and safe
710 fill out a launch card
712 notify RSO/LCO of readiness for inspection and launch, obtain a rail
713 assignment and permission to move rocket to launch pad for final prep
715 coordinate readiness with support team members, photographers, observers
716 </li></ol></div></li><li>
718 <div class="orderedlist"><ol type="1"><li>
719 move rocket to launch area
721 clean and lubricate launch rail if necessary
723 power up payload and confirm reception of signals from transmitter(s)
725 mount rocket on launch rail, rotate to vertical
727 power up primary altimeter, confirm expected beep pattern
729 power up backup altimeter, confirm expected beep pattern
733 confirm altimeters both giving expected beep patterns for igniter continuity
735 install igniter and connect to launch control system
737 capture GPS waypoint for rail location
739 smile for the cameras, make sure we have enough "foil Murphy!" shots taken
741 retreat to safe area behind LCO
743 confirm continued reception of transmitter signal(s) from payload bay
745 confirm photographers and observers are ready and know what to expect
747 make sure binoculars and backpack with water and recovery tools are at hand
749 tell RSO and LCO we're ready to launch
751 try to relax and enjoy watching the flight!
752 </li></ol></div></li><li>
754 <div class="orderedlist"><ol type="1"><li>
755 track rocket to landing site
757 capture GPS waypoint of landing site, take lots of photos
761 gather up and roughly re-pack recovery system for return to flight line
763 bring the rocket to observers for post-flight inspection
764 </li></ol></div></li></ol></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2610811"></a>Chapter 8. Flight Summary</h2></div></div></div><p>
765 YikStik was flown on an M1297W on Saturday morning at NCR's Oktoberfest
766 2008. The boost was beautiful. Unfortunately, we lost visual as the
767 rocket climbed into high clouds near apogee. Radio tracking signals
768 remained strong for several minutes, then disappeared. We were
769 confused by viewing what we thought was YikStik descending before
770 signals were lost in about the right direction, but now believe we
771 were actually watching a previously launched rocket and did not see
772 YikStik descend. This confusion prevented location of any of the
773 rocket until Sunday evening, after I had left the launch area.
775 After an extensive search, the nose cone assembly was finally found
776 with the Walston tracking gear nearly 3.5 miles down range. The
777 remainder of the rocket has not been found despite extensive searching
778 on the ground and from the air.
780 Reward if returned posters were placed in the area during the week
781 following the launch but have elicited no useful reponses yet.
782 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2607490"></a>Chapter 9. Analysis and Conclusions</h2></div></div></div><p>
783 Consideration of how the nose cone ended up where it did suggests
784 we may have had an apogee deployment of the main, perhaps due to
785 stress on the shear pins before launch, during boost, or during
786 apogee drogue deployment causing them to break early.
788 It is unfortunate that we were confused by seeing another rocket
789 descending about the expected amount of time after YikStik's launch
790 in approximately the right direction. This caused us to believe that
791 the rocket was much closer than the nose cone turned out to be, causing
792 us to waste a lot of time searching in an area too close to the launch
794 It also caused us to assume something really weird had happened to the
795 transmitters, such that the tracking signal was suddenly lost long
796 after the rocket was on the ground, instead of what seems to really
797 have happened, which is that the rocket was farther away descending
798 after a main deployment at apogee, and the loss of signal was simply
799 due to dropping below a ridge line a couple miles from the launch site.
800 I can't help but think that if we'd been
801 looking in the right area sooner after the launch that we might have
802 found the rocket before someone else apparently picked it up.
804 I regret the decision to use a "free bag" configuration of the
806 Since both tracking transmitters were in the payload bay behind
807 the nose cone, and we were eventually able to recover that portion
808 of the rocket, it is possible that if the deployment bag were tethered
809 to the main that we might have recovered the remainder of the rocket.
811 If the rocket is recovered and able to fly again, the two changes I
812 would like to make are to tether the deployment bag to the apex of the
813 main, and to move from 2-56 nylon screws to 4-40 nylon screws for the
814 main deployment shear pins, ensuring the holes through the airframe
815 are a loose enough fit to avoid stresses on the pins during boost. I
816 have no way to know what happened for sure, but believe this might
817 solve the assumed problem of main deployment at apogee.
819 All in all, the design and build process was educational, and a lot
820 of fun! I'm looking forward to fabricating more custom parts using
821 carbon fiber and vacuum bagging in the future.
822 The beautiful boost and obvious survival of the rocket airframe
823 through the expected mach transitions confirms my design and
824 construction skills are adequate to attain an L3 cert.
825 While I hope to recover the remainder of YikStik someday, I won't
826 waste any time before trying again with a new airframe!
828 [update] We have learned that one of the altimeters used in this
829 flight, the Missile Works miniRRC2, was subject to a fault in
830 firmware that could cause premature ejection of the main
831 in flights above 10k feet. Thus, it now seems even more likely
832 that we sustained an apogee ejection of the main, but that it
833 may well have been through no fault of the rocket's design,
834 construction, or preparation. Frustrating!
835 </p></div></div></body></html>
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