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="id2286209"></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="id2541572"></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 1.1</td><td align="left">5 December 2008</td></tr><tr><td align="left" colspan="2">
8 Remove embedded images in favor of references to gallery.gag.com
9 </td></tr><tr><td align="left">Revision 1.0</td><td align="left">28 October 2008</td></tr><tr><td align="left" colspan="2">
10 Recording results of first, and only, flight attempt.
11 </td></tr><tr><td align="left">Revision 0.5</td><td align="left">27 September 2008</td></tr><tr><td align="left" colspan="2">
13 </td></tr><tr><td align="left">Revision 0.4</td><td align="left">17 September 2008</td></tr><tr><td align="left" colspan="2">
14 Documenting the build process as it happens
15 </td></tr><tr><td align="left">Revision 0.3</td><td align="left">29 March 2008</td></tr><tr><td align="left" colspan="2">
16 Incorporate ideas from James Russell during initial L3CC review
17 </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="#id2529342">1. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#id2529378">Why "YikStik"?</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2521011">2. Design</a></span></dt><dd><dl><dt><span class="section"><a href="#id2521016">Overview</a></span></dt><dt><span class="section"><a href="#id2521034">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2521047">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2521064">Airframe Tubing</a></span></dt><dt><span class="section"><a href="#id2521080">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2521091">Fins</a></span></dt><dt><span class="section"><a href="#id2572489">Centering Rings and Bulkheads </a></span></dt><dt><span class="section"><a href="#id2561257">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2563350">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2576368">Avionics</a></span></dt><dt><span class="section"><a href="#id2552908">Payload</a></span></dt></dl></dd><dt><span class="section"><a href="#id2545470">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2545265">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2562893">Recovery System</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2556052">3. Construction Details</a></span></dt><dd><dl><dt><span class="section"><a href="#id2574743">Airframe and Couplers</a></span></dt><dt><span class="section"><a href="#id2552221">Fins</a></span></dt><dt><span class="section"><a href="#id2574331">Centering Rings and Bulkheads</a></span></dt><dt><span class="section"><a href="#id2556996">Assembling the Booster Section</a></span></dt><dt><span class="section"><a href="#id2541017">Avionics Bay</a></span></dt><dt><span class="section"><a href="#id2555429">Payload Bay</a></span></dt><dt><span class="section"><a href="#id2557458">Recovery System</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2552535">4. Recovery Systems Package</a></span></dt><dd><dl><dt><span class="section"><a href="#id2566288">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2569516">Recovery Initiation Control Components</a></span></dt></dl></dd><dt><span class="chapter"><a href="#id2571153">5. Stability Evaluation</a></span></dt><dt><span class="chapter"><a href="#id2571969">6. Expected Performance</a></span></dt><dt><span class="chapter"><a href="#id2576111">7. Checklists </a></span></dt><dt><span class="chapter"><a href="#id2542552">8. Flight Summary</a></span></dt><dt><span class="chapter"><a href="#id2567211">9. Analysis and Conclusions</a></span></dt></dl></div><p>
18 Please note that I stopped adding photos to this document at some
19 point. I have many more photos of the YikStik build, but haven't
20 decided how best to present them yet... update coming someday!
21 </p><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2529342"></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="#id2529378">Why "YikStik"?</a></span></dt></dl></div><p>
22 This is the rocket I'm designing for my NAR Level 3 certification flight.
23 The general idea is to build a fairly cheap rocket capable of reliably
24 flying this year's Aerotech level 3 special, which is an M1297W reload.
25 I'd like to be able to fly the prototype of my own altimeter design, and
26 to be able to fly it often on smaller / cheaper reloads at launch sites
27 with modest waivers like Hudson Ranch.
29 I want to experiment with vacuum bagging carbon fiber reinforcements, and
30 intend to use my CNC milling machine to cut all the centering rings, etc.
31 The new Giant Leap "Dynawind" tubing feels like a good choice, and if we
32 stick to the 4 inch version we can use a cheap plastic nosecone to keep
35 Preliminary analysis suggests that a roughly 8 foot rocket made from 4 inch
36 airframe with a 75mm mount and three fins should fly to something around
37 14k feet on the M1297W, could break three miles on the M1850W, and yet
38 could safely fly on reloads as small as a J for economical fun. Those
39 altitudes mean the certification flight will need to be at a site with a
40 high-altitude waiver like the NCR north site.
41 </p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2529378"></a>Why "YikStik"?</h2></div></div></div><p>
42 I've always thought the high-gloss red paint job on one of my son's rockets
43 when out on a launch rod in the sun looks a lot like glistening wet
46 Combine that with the fact that my wife who isn't fond of the stuff
47 refers to lipstick as "yik stick"... and the rest should be obvious.
49 My planned paint scheme is a bright red nosecone, gold tube, and black fin
50 can, which is the mental image I have of what lipstick applicators look
51 like, most likely from a stick my mother or one of my grandmothers had
53 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2521011"></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="#id2521016">Overview</a></span></dt><dt><span class="section"><a href="#id2521034">Rocksim File</a></span></dt><dt><span class="section"><a href="#id2521047">Drawing from Rocksim</a></span></dt><dt><span class="section"><a href="#id2521064">Airframe Tubing</a></span></dt><dt><span class="section"><a href="#id2521080">Nose Cone</a></span></dt><dt><span class="section"><a href="#id2521091">Fins</a></span></dt><dt><span class="section"><a href="#id2572489">Centering Rings and Bulkheads </a></span></dt><dt><span class="section"><a href="#id2561257">Motor Retention</a></span></dt><dt><span class="section"><a href="#id2563350">Electronics</a></span></dt><dd><dl><dt><span class="section"><a href="#id2576368">Avionics</a></span></dt><dt><span class="section"><a href="#id2552908">Payload</a></span></dt></dl></dd><dt><span class="section"><a href="#id2545470">Stability Evaluation</a></span></dt><dt><span class="section"><a href="#id2545265">Expected Performance</a></span></dt><dt><span class="section"><a href="#id2562893">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="id2521016"></a>Overview</h2></div></div></div><p>
54 YikStik is a fairly simple "three fins and a nose cone" dual-deploy
55 rocket using a 75mm motor mount, 4 inch glass-wrapped phenolic airframe
56 with zipperless fin can, plastic nose cone, plywood fins,
57 and lots of glass and carbon fiber reinforcing.
58 The primary electronics bay will be designed to
59 hold two altimeters, and a distinct payload bay may carry an
60 experimental altimeter, GPS receiver, and downlink transmitter.
61 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2521034"></a>Rocksim File</h2></div></div></div>
62 This is the current working design in Rocksim format:
63 <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="id2521047"></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="id2521064"></a>Airframe Tubing</h2></div></div></div><p>
64 I intend to cut the airframe components from two 48 inch lengths of
65 98mm Giant Leap Dynawind tubing. The 30 inch main bay and 18 inch drogue
66 bay will be cut from one length, while the 33 inches of fin can, 2 inches
67 of electronics bay, and 8 inches of payload bay will be cut from the
69 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2521080"></a>Nose Cone</h2></div></div></div><p>
70 I intend to use a Giant Leap "Pinnacle" 3.9 inch nose cone.
71 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2521091"></a>Fins</h2></div></div></div><p>
72 The fins are designed from scratch, and I intend to build them up from
73 two layers of 1/8 inch birch plywood, three layers of carbon fiber, and
74 two layers of 6 oz glass. The stack will be glass, carbon fiber,
75 plywood, carbon fiber, plywood, carbon fiber, glass. The edges of the
76 plywood will be routed to give a modified airfoil shape to the finished
77 fins. The stack will be laminated using West Systems epoxy products
79 The shape is a compromise between mass, surviving Mach-transition stress,
80 optimal stability margin, and avoiding damage during handling and on
81 contact with the ground during recovery.
83 The fins will be locked in to milled slots in two of the centering rings,
84 and will be epoxied to the motor mount with glass reinforcing tape.
85 The airframe will be slotted to allow the completed motor mount / fin
86 assembly to be inserted from the rear, with fillets of epoxy applied
87 inside and outside the airframe after insertion.
88 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2572489"></a>Centering Rings and Bulkheads </h2></div></div></div><p>
89 All centering rings and bulkheads will be custom machined from 3/8 inch
90 birch plywood using my 3-axis CNC milling machine. Some rings will use
91 laminated pairs of 3/4 inch total thickness to enable use of threaded
92 inserts for 1/4-20 rail button screws or deep routing for fin alignment
94 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2561257"></a>Motor Retention</h2></div></div></div><p>
95 I will embed three 8-24 T-nuts in the aft centering ring spaced to allow
96 the use of home-made Kaplow clips to retain 75mm motors.
97 The same holes may be used to attach custom motor mount adapters for
98 smaller diameter motors.
99 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2563350"></a>Electronics</h2></div></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2576368"></a>Avionics</h3></div></div></div><p>
100 The recovery system will feature dual redundant barometric altimeters
101 in an electronics bay similar to the LOC design located between the
102 drogue and main parachute bays.
104 A PerfectFlite MAWD will be flown as the primary altimeter and to
105 record the flight altitude profile.
106 A MissileWorks Mini-RRC2 will fly as backup altimeter and to
107 directly capture max velocity.
109 Each altimeter will have a separate battery and power switch. A 4PDT
110 slide switch will be used as a SAFE/ARM switch configured to interrupt
111 connectivity to the ejection charges.
112 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2552908"></a>Payload</h3></div></div></div><p>
114 <a class="ulink" href="http://altusmetrum.org/" target="_top">
115 my own altimeter design
117 as a payload in a short payload section just behind the nose cone.
118 I have acquired the pieces to add a GPS receiver and RF downlink using
119 ham radio frequencies to the payload to track the rocket's position
121 This is not essential to fly,
122 but could make recovery simpler and would just be fun to fly if I can
123 get it all working and suitably ground and/or flight tested in time.
124 </p></div></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2545470"></a>Stability Evaluation</h2></div></div></div><p>
125 This design has been thoroughly analyzed using
126 <a class="ulink" href="http://www.apogeerockets.com/rocksim.asp" target="_top">
129 with motors ranging from the
130 Cesaroni J285 through the Aerotech M1850W and appears to be
131 unconditionally stable across that range. The lowest margin is around
132 1.2 seen with the M1297W planned for my level 3 certification flight,
133 albeit with many masses still only roughly estimated.
135 These simulations will be refined as the build proceeds and as-built
136 stability verified before flight.
137 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2545265"></a>Expected Performance</h2></div></div></div><p>
138 The Aerotech M1297W reload should carry this vehicle without ballast
139 to just over 14 thousand feet AGL. It should make over 16 thousand
140 feet AGL on an M1850W, and should fly stably to roughly 2.5k feet AGL
143 Hitting optimal mass on the largest motors may require
144 ballast, depending on final build weight.
145 My plan is to fly without ballast on the certification flight,
146 trading some altitude for a slower and softer recovery.
147 If the cert succeeds, then I might try an optimal mass
148 flight sometime later on an M1850W or equivalent "bigger M"
149 reload to join the "three mile club".
150 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2562893"></a>Recovery System</h2></div></div></div><p>
151 The recovery system will use dual redundant barometric altimeters firing
152 black powder charges.
153 At apogee, a drogue chute will deploy from just forward of the fin can,
154 with size selected for an approximately 100 ft/sec descent rate.
155 At a preset altitude, a main chute will be deployed to achieve recovery
156 of the bulk of the rocket at under 20 ft/sec.
157 The main chute will be packed in a deployment bag, configured as a
158 "freebag" and pulled out of the airframe by a second drogue chute. This
159 drogue will recover the nosecone and deployment bag separately from the
160 remainder of the rocket which will recover under the main.
162 I intend to sew the parachutes from scratch using a design documented by
163 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
166 using 1.9oz rip-stop nylon and 550 lb parachute cord.
167 If time runs short, equivalent chutes from SkyAngle,
168 Rocketman, or Giant Leap could be substituted (at significantly higher
171 The deployment bag will probably be purchased from Giant Leap. The
172 recovery harness will probably use tubular kevlar, also from Giant Leap.
174 The recovery system attachment points will all use 1/4 inch u-bolts with
175 nuts, washers, and backing plates through bulkheads except for the fin
176 can. The fin can has insufficient room between the motor mount and
177 the airframe inner wall for nuts and washers, so an alternative means of
178 recovery system attachment is required. The fin can will be equipped
179 with either a 3/16 inch stainless steel aircraft cable loop, or a loop
180 of 1/2 inch tubular kevlar, bonded to the motor mount.
181 If available, a screw-eye attached to the forward motor closure may be
182 used instead of or in addition to this recovery attachment loop.
183 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2556052"></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="#id2574743">Airframe and Couplers</a></span></dt><dt><span class="section"><a href="#id2552221">Fins</a></span></dt><dt><span class="section"><a href="#id2574331">Centering Rings and Bulkheads</a></span></dt><dt><span class="section"><a href="#id2556996">Assembling the Booster Section</a></span></dt><dt><span class="section"><a href="#id2541017">Avionics Bay</a></span></dt><dt><span class="section"><a href="#id2555429">Payload Bay</a></span></dt><dt><span class="section"><a href="#id2557458">Recovery System</a></span></dt></dl></div><p>
184 I have collected all of my
185 <a class="ulink" href="http://gallery.gag.com/rockets/yikstik" target="_top">
188 in one place, they may show better than I can explain how various
189 aspects of YikStik went together.
190 </p><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2574743"></a>Airframe and Couplers</h2></div></div></div><p>
191 The tubing for the airframe, couplers, and motor mount was all cut
192 using a carefully aligned and adjusted power mitre saw, and the ends
193 lightly sanded to remove rough spots.
194 The main and drogue bays were cut from one 48 inch length of Giant
195 Leap 98mm Dynawind tubing, the fin can, electronics bay, and payload
196 bay were cut from the second. The three couplers for the fin can,
197 electronics bay, and payload bay were cut from Giant Leap 98mm phenolic
198 coupler stock. And the motor mount was cut from Giant Leap 75mm
199 phenolic airframe stock.
200 Note that the motor mount is the longest piece because of
201 the zipperless design with full-length motor mount.
203 The airframe tubing selected includes a wrap of 10oz glass in epoxy
204 over the base phenolic tubing (visible in some photos as a
205 shine on the outside of the tubing),
206 but the coupler stock is unreinforced.
207 To ensure the couplers can handle the anticipated loading, I reinforced
208 each with one layer of interior carbon fiber, using the "kitchen
209 vacuum bagging" technique documented by
210 <a class="ulink" href="http://www.jcrocket.com/kitchenbagging.shtml" target="_top">
214 This was my first hands-on experience working with carbon fiber. The
215 end of the coupler nearest the unit during bagging experienced some
216 crushing of the fibers right at the end. It doesn't matter for this
217 project because each of the couplers will have at least one end fitted
218 with a bulkhead or centering ring, but in the future I'll be tempted
219 to cut the coupler stock a bit long before bagging and trim to length
220 after reinforcing to get "perfect" ends. The technique worked
221 marvelously otherwise, and the resulting couplers look and should work
223 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2552221"></a>Fins</h2></div></div></div><p>
224 Six pieces of 1/8 inch birch plywood were stacked, edge-aligned on what
225 would be the fin root edge, and clamped. The outline of the fin design
226 was marked in pencil, and three 1/8 inch holes drilled through the
227 stack inside the fins to allow using 4-40 screws and nuts to hold the
228 blanks together while making the initial cuts, so that they would all be
229 matched in size. The clamps were removed to avoid interference
230 during cutting. The fin outline was then cut using a radial arm saw.
232 A router table with 1/8 inch
233 roundover bit was then used to round over the outer edge, 3 blanks on
234 one side and three on the other. This edge might have been left square,
235 but I prefer the look and feel of rounding. The router table with a 1/2
236 inch diameter straight cutting bit and a fin beveling jig was used
237 to impart a 10-degree bevel on the leading and trailing edge of each fin
238 blank, again 3 on one side and three on the other. The resulting 6
239 blanks thus form 3 pairs of fin components with a modified
242 The fin assembly started with a simple lamination of two layers of ply
243 sandwiching a layer of carbon fiber. Each fin used "one pump" of West
244 Systems epoxy and the stack was vacuum bagged using the Foodsaver with
245 wide bagging material. To keep everything flat while the epoxy cured,
246 the stack of fins was sandwiched between two unused extra shelves for
247 a storage cabinet I had on hand
248 (particle board covered in laminate, very
249 flat and smooth, nearly inflexible at this loading), and stacked with
250 about 75 lbs of loose barbell weights.
252 On one of the three fins, the plywood layers are out of alignment by
253 1-2mm in the longest axis. The other two are nearly perfect. Light
254 sanding should allow me to match them before laminating the outer layers
255 of carbon fiber and glass.
257 After the fins cured, they were bulk sanded with medium and fine
258 sandpaper and an electric palm sander. Final sanding of the leading
259 and trailing edges was done using 400 grit paper on a flat surface,
260 holding the fin the way you'd sharpen a knife against a stone. The
261 results seem good, all three fins match pretty closely.
263 A fin holding jig was cut from 1/8" hardboard using my rotary tool
264 with a fiber cutoff wheel. The fin slots were made to be a snug fit.
265 A small batch of epoxy was used to apply a bead to the root edge and
266 tab at the leading edge, then the fins were installed against the
267 motor mount and locked into place with the jig to cure. The centering
268 ring that locks the aft edge of the fins was dry-fit during this
269 operation to ensure proper alignment, but was not glued yet. It will
270 go on after the airframe and internal fin filets are installed.
272 The fins were reinforced with fiberglass and epoxy. Masking tape was
273 used to carefully delineate where the airframe ID will be, then 6oz
274 glass 14.25" by 3.5" was epoxied fin-fin across the MMT. Strips of
275 8.6oz "boat tape" fiberglass were worked into the joints with more
276 epoxy, and a sheet of plastic covered by ziplog bags of water were
277 used to hold things in place during the initial curing. The three
278 sides were done one at a time and allowed to cure before proceeding.
279 The results look good, and in combination with internal and external
280 airframe filets should yield a super-strong fin can.
281 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2574331"></a>Centering Rings and Bulkheads</h2></div></div></div><p>
282 Pairs of 3/8 inch birch plywood blanks were laminated using Titebond
283 wood glue and clamped while curing to form 3/4 inch blanks for centering
284 rings. From a strength perspective, 3/8 inch should suffice, but there
285 are two reasons for going with thicker blanks in some places. The first
286 is that the rail buttons chosen use 1/4-20 mounting screws, and threaded
287 inserts in that size are nearly 3/8 inch outside diameter
289 tear up a ring only 3/8 inch thick on insertion). The second is that I
290 like to mill slots in the centering rings on each end of the fins to
291 "lock" the fins into position. Doubling the blanks used to cut those
292 rings will allow me to cut 1/4 inch deep fin slots and still have a half
293 inch of unmolested wood in the rings for strength.
295 The aft centering ring and the one just aft of the zipperless
296 coupler section were edge-drilled for the installation of brass
297 1/4-20 threaded inserts to hold rail buttons. The inserts were
298 locked in place with epoxy, then ground down until nothing protruded
299 beyond the OD of the ring.
300 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2556996"></a>Assembling the Booster Section</h2></div></div></div><p>
301 The forward two centering rings were installed on the MMT using
302 JB Weld high-temperature epoxy, and incorporating an aircraft cable
303 loop for recovery system retention since there just wasn't room for
306 The ring at the leading edge of the fins was initially installed
307 assuming the aft ring would be nearly flush with the rear of the MMT
308 and equipped with Kaplow-clip style retainers, but before the fins
309 were installed a Giant Leap Slimline Tailcone Retainer for 75mm motor
310 in 98mm airframe became available thanks to Tim Thomas, and so this
311 ring was cut out and replaced with another one inch farther forward
312 to allow installation of the tailcone at the rear of the MMT. I
313 really like the tailcone on my Vertical Assault kit, and think it'll
314 work out to be a great addition for this rocket!
316 An alignment jig for the fins was carefully marked out and then cut
317 from 1/8 inch hardboard using my rotary tool and abrasive cutoff wheel.
318 The fins were then epoxied at the root and short leading edge to the
319 motor mount tube and into the slots in the forward centering ring,
320 and held rigidly aligned by the jig until the epoxy set. The fins
321 were then masked at what would be the ID of the airframe tube, and
322 reinforced with 6oz glass fin-fin across the motor mount tube between
323 each fin pair, further reinforced with strips of 1 inch glass "boat
324 tape" at each fin root joint.
326 The airframe tubing section was carefully marked for fin slots, which
327 were then cut using my rotary tool with abrasive cutoff wheel. Epoxy
328 was applied ahead of the center two rings as the frame was slid into
329 place, and the frame left standing upright until the epoxy set to
330 hopefully form ring-fin fillets on those two rings. The interior
331 fin to airframe joints were reinforced one fin at a time using West
332 Systems epoxy will milled glass as a filler. A long 3/8" dowel was
333 used to place and smooth these interior filets. The aft centering ring
334 was installed by pouring West Systems epoxy in the three fin-fin gaps,
335 placing the ring, then standing the airframe up to allow the epoxy to
336 flow over the forward surface of the ring and into the gaps between it,
337 the motor mount, and the airframe tubing. After it set, the booster
338 was placed nose-down, the airframe gaps behind the fins were taped,
339 and more epoxy was applied to seal the aft of the ring to the tubes.
340 Before this epoxy set, JB Weld was used to glue the tail cone retainer
344 airframe joints were filleted using 5-minute epoxy thickened with
345 baby powder and smoothed with the tip of a plastic spoon, which I
346 learned about building the Vertical Assault kit. Gives great results,
347 and allowed all 6 joints to be done in one session. The space
348 above the top surface of the forward centering ring and between the
349 motor mount and zipperless-design coupler tubing was filled with epoxy
350 and milled glass. Minor gaps in the airframe behind each fin were
351 filled with epoxy clay.
352 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2541017"></a>Avionics Bay</h2></div></div></div><p>
353 The avionics bay contains the two commercial altimeters used to
354 record information about the flight and deploy the drogue and main
355 recovery systems. It is constructed of a piece of Giant Leap 98mm
356 coupler tubing reinforced with an interior wrap of vacuum-bagged
357 carbon fiber, and a 2 inch length of Giant Leap 98mm DynaWind airframe
360 The bulkheads are custom-milled from 3/8 inch birch plywood
361 milled so that about 3/16" fits inside the coupler and the remainder
362 seals the end of the coupler and just fits inside the airframe. Each
363 bulkhead has a u-bolt for attaching the recovery harnesses, and dual
364 CPVC end caps as ejection charge holders with screw terminal blocks
365 from Missile Works to attach the igniters. Two lengths of 1/4 inch
366 all-thread with nuts and washers tie the bulkheads together, with
367 wing-nuts used on one end to allow for easy disassembly.
369 A sled was fabricated to hold the altimeters and batteries. It
370 consists of 1/8 inch birch ply laminated with 6oz fiberglass on each
371 side, epoxied to cardboard tubes taken from the packaging for Aerotech
372 igniters that slide over the all-thread, further reinforced with nylon
373 ties at each end. The tubes are staggered one on either side so that
374 the sled goes right up the center of the airframe tubing.
376 Two "centering rings" containing three each 6-32 threaded inserts are
377 epoxied inside the bay to provide hard points for attaching the
378 airframe tubes for the drogue and main recovery bays. The inside
379 diameter of these rings is notched for the avionics sled, and thus
380 these rings also provide physical support for the sled.
382 Three rotary switches from Missile Works are installed through the
383 short airframe tubing section, drilled such that they end up
384 essentially flush with the outside of the airframe, clamp the coupler
385 tubing, and project inside the bay. Two are wired as SPST switches
386 for power to the two altimeters, the third is wired as a DPST switch
387 that open-circuits the igniters for the required "safe/arm" function
388 called for in the NAR L3 certification requirements.
390 The wiring of the avionics bay is documented in the attached
391 schematic diagram. Connectors were used to allow each bulkhead and
392 the switches in the housing to be quickly detached from the sled.
393 The connectors are 9-pin D shells for the switch wiring, and 4-pin
394 Molex connectors like those used on older PC hard drive power cables
395 for the bulkheads. To allow use of a single switch pole for the
396 safe/arm function for each altimeter, the two igniters attached to
397 each altimeter are safed by interrupting the common return lines as
398 shown in the schematic.
400 Sizing the static port for the avionics bay was done by applying the
401 formulas suggested by PerfectFlite and Missile Works for their
402 respective altimeter products, then comparing the results with each
403 other and with information found on the web. I've personally had
404 better luck with single ports than with multiple holes, perhaps because
405 I've been working with relatively small rockets. Regardless, I'm
406 sticking with what I know and will use a single static port hole here.
408 The measured dimensions
409 of the avionics bay as constructed are 95mm ID and approximately 250mm
410 between bulkheads. This works out to 108.73 cubic inches before
411 accounting for the volume of the sled, electronics, and wiring and
412 other components inside the bay. By the PerfectFlight formula, the
413 static port should be 0.221 inches in diameter. By the Missile Works
414 formula for a bay over 100 cubic inches the answer is 0.261 inches.
415 The closest standard drill size, which happens to split the difference,
416 is 0.250 inches. Easy enough!
417 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2555429"></a>Payload Bay</h2></div></div></div><p>
418 The construction of the payload bay is very similar to the avionics
419 bay, except that there is a hard-epoxied rear bulkhead, and only one
420 screw ring to hard-mount the nose cone. The forward end of the
421 payload bay is open to the open interior volume of the nose cone in
422 anticipation of extending downlink antennas above the carbon fiber
423 reinforcement in the coupler and into the nose cone, since carbon
424 fiber is opaque to RF.
425 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2557458"></a>Recovery System</h2></div></div></div><p>
426 Pre-sewn 1/4 inch tubular kevlar harness sections were purchased
427 from Giant Leap, along with a small kevlar deployment bag and two
428 kevlar chute protectors.
430 For an apogee drogue, I plan to fly a Public Missiles 4 x 144 inch
431 nylon streamer. It will be protected with one of the kevlar blankets
432 and attached to one of the kevlar harness sections holding the booster
435 The main parachute will be sewn from 1.9 oz rip-stop nylon purchased
437 <a class="ulink" href="http://www.milloutletfabric.com/" target="_top">
438 Mill Outlet Fabric Shop
440 in Colorado Springs. Using the spreadsheet from
441 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
444 I calculate that we want an 8 foot chute to keep the airframe less
445 nose cone and payload bay below 20 feet per second at touch-down.
447 To extract the main chute and recover the nose cone and payload bay,
448 a 3 foot parachute from BSD Rocketry will be packed in a kevlar
449 blanket ahead of the main chute deployment bag, attached by kevlar
450 harness to the nose cone and payload bay assembly, and to the top of
451 the deployment bag. This assembly will recover separately from the
454 The altimeters are programmed such that the MAWD fires its drogue
455 charge at apogee and its main charge at 1100 feet. The miniRRC2
456 is programmed to fire its drogue charge two seconds past apogee,
457 and its main charge at 900 feet. Thus the MAWD is primary and the
458 miniRRC2 is the backup. Since the M1297W has a burn time of about
459 5 seconds, mach inhibit is programmed on both altimeters to 8 seconds.
460 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2552535"></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="#id2566288">Recovery System Description</a></span></dt><dt><span class="section"><a href="#id2569516">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="id2566288"></a>Recovery System Description</h2></div></div></div><p>
461 This rocket uses dual deployment.
463 The apogee event separates the
464 airframe between the zipperless-design booster section and the
465 drogue bay. These two sections are linked by a Giant Leap 20 foot
466 pre-sewn 1/4 inch tubular kevlar assembly, attached to which is a
467 Public Missiles 4 x 144 inch red nylon streamer packed in a Giant Leap
468 kevlar chute protection pad.
470 The main event separates the airframe between the forward payload bay
471 and the main bay. Attached to the nose cone and payload bay assembly
472 is a Giant Leap 15 foot pre-sewn 1/4 inch tubular kevlar assembly,
473 attached "free bag" style to the top of a Giant Leap deployment bag
474 containing the main chute. A 36 inch BSD Rocketry nylon parachute
475 packed in a Giant Leap kevlar chute protection pad serves to pull the
476 deployment bag off the main chute, after which it allows for safe
477 recovery of the nose cone and payload assembly at just under 20 feet
480 The 8 foot main chute is home-made from 1.9 oz rip-stop nylon using
481 the design documented by
482 <a class="ulink" href="http://www.vatsaas.org/rtv/systems/Parachutes/Chute.aspx" target="_top">
485 It is attached to the remainder of the rocket using another Giant Leap
486 pre-sewn 1/4 inch tubular kevlar assembly.
488 The anchor points are all 5/16 inch u-bolts, except for on the booster
489 which is equipped with an embedded loop of 3/16 inch stainless aircraft
490 cable. All connections are made with suitable quick-links.
491 </p></div><div class="section" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2569516"></a>Recovery Initiation Control Components</h2></div></div></div><p>
492 The LOC-style avionics bay between the main and drogue bays is
493 populated with two commercial altimeters, a PerfectFlite MAWD
494 and a Missile Works miniRRC2.
495 Each is powered by a dedicated 9V battery, and has a
496 dedicated on/off power switch mounted for access from outside the
497 rocket. Additionally, a single safe/arm switch with two poles is used
498 to interrupt the return circuits from the igniters to each altimeter.
499 See the attached schematic of the avionics bay contents for more
502 The bulkheads at each end of the avionics bay have two CPVC end caps
503 for ejection charge holders, and two-terminal screw blocks for
504 attachment of electric matches purchase from Giant Leap used to ignite
505 Goex 4F black powder ejection charges. Each charge holder and terminal
506 block pair is labelled as to main or backup since the charges will be
510 <a class="ulink" href="http://www.info-central.org/recovery_powder.shtml" target="_top">
511 Info Central Black Powder Sizing
513 page is the most authoritative site I've found on this topic.
514 Each of the main and drogue bay interfaces will use 2 2-56 nylon screws
515 as shear pins, each of which needs 35 pounds of force or so to shear.
516 Designing for 15psi puts us between 150 and 200 pounds total force in
517 a 4 inch airframe. The formula is thus 0.006 grams times diameter
518 squared in inches times length in inches.
520 My drogue bay is 3.9 inches ID and 8 inches long, or 95.52 cubic
521 inches. That works out to about 0.73 grams. However, there will be
522 some volume in the motor mount tube above the motor that also must
523 be accounted for, enough to nearly double the total volume when flying
524 on the M1297W certification motor. Also, since this charge must fire
525 reliably at 15-18k feet above ground level of around 5k feet, such
526 that combustion is likely to be incomplete, we need to add some margin.
528 My main bay is 3.9 inches ID and about 25 inches between bulkheads,
529 or about 298.50 cubic inches. That works out to 2.28 grams.
531 Sanity checking, PerfectFlite recommends that a 4F black powder charge
532 be sized by multiplying the volume of the bay in cubic inches by 0.01
533 grams. That yields about 1.8 grams for the drogue bay and 3 grams for
536 That suggested to me that a good starting point for ground testing is
537 1.5 grams for the drogue bay and 2.5 grams for the main bay. Ground
538 tests were done using the PC interface cable for the MAWD routed in
539 through the static test port to manually trigger ejections. Testing
540 of the apogee bay showed that 1.5 grams was sufficient for deployment
541 and 1.8 grams was more authoritative. A single test of main deploy
542 with 2.5 grams gave a nearly perfect result.
543 Given the altitude of our expected apogee, we should be generous with
544 the apogee charge, perhaps using 2.0 grams for the primary. The main
545 will deploy at an altitude below where the tests were performed, so
546 no adjustment in charge size should be required.
548 Descent rate of the nose cone and payload bay which mass just under
549 1kg will be less than 20 feet per second with a 36 inch chute based
550 on manufacturer recommendations and Rocksim v8 simulation.
551 Descent rate of the remainder of the rocket under the 8 foot chute
552 should be about 18 feet per second by the spreadsheet provided by
553 the designers of this chute pattern, sanity checked using the descent
554 rate tables of similar commercial parachute designs, like those from
556 </p></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2571153"></a>Chapter 5. Stability Evaluation</h2></div></div></div><p>
557 Simulation using Rocksim v8 with a variety of motors showed that the
558 rocket is unconditionally stable with all motors likely to be flown.
559 The worst-case stability among 75mm motors is actually with the
560 M1297W chosen for the certification flight, at margin 1.05. This is
561 because the front of this motor falls almost exactly at the CP. Using
562 a longer motor like the M1850W raises the initial stability margin to
563 1.10 because the front fuel grain is ahead of the CP, and lesser
564 motors also increase the stability because less mass is behind the CP.
565 The smallest motor I can conceive of flying in this rocket (a Cesaroni
566 J285) would leave us overstable with margin 3.79 on the way to about
568 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2571969"></a>Chapter 6. Expected Performance</h2></div></div></div><p>
569 On the certification flight, using an Aerotech M1297W reload and
570 associated hardware, the anticipated apogee is round 14,700 feet. This
571 is just under 75% of the NCR North Site standing waiver of 20,000 feet.
573 The highest altitude simulated would be achieved with an Aerotech
574 M1850W reload at nearly 18,000 feet. The lowest altitude simulated
575 is with a Cesaroni J285 and Slimline adapters to just over 1800 feet.
577 add description of anticipated flight profile here, including launch
578 weight, estimated drag coefficient, velocity leaving the rail, max
579 expected velocity, altitude, and acceleration
580 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2576111"></a>Chapter 7. Checklists </h2></div></div></div><div class="orderedlist"><ol type="1"><li>
582 <div class="orderedlist"><ol type="1"><li>
583 Pick a club launch with suitable waiver and facilities to
586 Confirm L3CC member(s) available to attend selected launch.
588 Confirm that required loaner motor hardware will be available at launch.
590 Notify launch sponsor (club president) of intended flight.
592 Notify interested friends of intended flight.
594 Perform final pre-flight simulation with as-built masses, etc.
596 Gather consummables and tools required to support flight
597 <div class="orderedlist"><ol type="1"><li>
604 motor retainer snap rings
606 small nylon wire ties
608 cellulose wadding material
612 screwdriver for phillips-head airframe screws
614 small straight-blade screwdriver for power switches
618 high temperature grease
620 long small diameter dowels for igniter insertion
621 </li></ol></div></li></ol></div></li><li>
623 <div class="orderedlist"><ol type="1"><li>
624 program altimeters for suitable mach delay and recovery deployment
625 <div class="itemizedlist"><ul type="disc"><li>
627 <div class="itemizedlist"><ul type="circle"><li>
630 1500 foot main deploy
631 </li></ul></div></li><li>
634 <div class="itemizedlist"><ul type="circle"><li>
637 1000 foot main deploy
639 2 seconds apogee delay
645 ops mode 16 (default)
646 </li></ul></div></li></ul></div></li><li>
647 assemble all recovery system components and ensure everything fits
649 confirm wiring and operation of altimeter power and safe/arm switches
651 Ground test recovery system to confirm suitable black powder
653 </li></ol></div></li><li>
655 <div class="orderedlist"><ol type="1"><li>
656 confirm payload batteries in good condition, bay loaded, power switch works
658 confirm reception of signals from transmitter(s) in payload bay
660 install fresh 9V batteries for altimeters on avionics bay sled
662 inspect altimeters and associated avionics bay wiring for visible faults
664 close up avionics bay
666 install e-matches, confirming resistance of 1-2 ohms and fit in charge cups
668 power up altimeters, operate safe/arm switch, and confirm e-match continuity
670 load BP charges into charge cups
671 <div class="orderedlist"><ol type="1"><li>
672 Drogue Primary Charge - 2.0 grams 4F BP
674 Drogue Backup Charge - 2.5 grams 4F BP
676 Main Primary Charge - 2.5 grams 4F BP
678 Main Backup Charge - 3.0 grams 4F BP
679 </li></ol></div></li><li>
680 connect recovery harnesses and install recovery bay airframe sections
682 power up altimeters, operate safe/arm switch, and confirm e-match continuity
684 safe and power-down the altimeters
686 load main recovery bay, attaching nosecone and payload bay assembly
688 install nylon 2-56 screws as shear pins between main bay and payload bay
690 load drogue recovery bay, feeding harness end through fin can motor tube
692 install nylon 2-56 screws as shear pins between drogue bay and fin can
694 load motor per manufacturer instructions
696 attach forged eye-bolt to forward closure if not already present
698 attach drogue harness to eye-bolt on forward motor closure
700 install motor in motor mount
702 install motor retention snap rings
704 prepare igniter for later installation by attaching to long 1/8" dowel
706 confirm all screws in place, avionics off and safe
708 fill out a launch card
710 notify RSO/LCO of readiness for inspection and launch, obtain a rail
711 assignment and permission to move rocket to launch pad for final prep
713 coordinate readiness with support team members, photographers, observers
714 </li></ol></div></li><li>
716 <div class="orderedlist"><ol type="1"><li>
717 move rocket to launch area
719 clean and lubricate launch rail if necessary
721 power up payload and confirm reception of signals from transmitter(s)
723 mount rocket on launch rail, rotate to vertical
725 power up primary altimeter, confirm expected beep pattern
727 power up backup altimeter, confirm expected beep pattern
731 confirm altimeters both giving expected beep patterns for igniter continuity
733 install igniter and connect to launch control system
735 capture GPS waypoint for rail location
737 smile for the cameras, make sure we have enough "foil Murphy!" shots taken
739 retreat to safe area behind LCO
741 confirm continued reception of transmitter signal(s) from payload bay
743 confirm photographers and observers are ready and know what to expect
745 make sure binoculars and backpack with water and recovery tools are at hand
747 tell RSO and LCO we're ready to launch
749 try to relax and enjoy watching the flight!
750 </li></ol></div></li><li>
752 <div class="orderedlist"><ol type="1"><li>
753 track rocket to landing site
755 capture GPS waypoint of landing site, take lots of photos
759 gather up and roughly re-pack recovery system for return to flight line
761 bring the rocket to observers for post-flight inspection
762 </li></ol></div></li></ol></div></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2542552"></a>Chapter 8. Flight Summary</h2></div></div></div><p>
763 YikStik was flown on an M1297W on Saturday morning at NCR's Oktoberfest
764 2008. The boost was beautiful. Unfortunately, we lost visual as the
765 rocket climbed into high clouds near apogee. Radio tracking signals
766 remained strong for several minutes, then disappeared. We were
767 confused by viewing what we thought was YikStik descending before
768 signals were lost in about the right direction, but now believe we
769 were actually watching a previously launched rocket and did not see
770 YikStik descend. This confusion prevented location of any of the
771 rocket until Sunday evening, after I had left the launch area.
773 After an extensive search, the nose cone assembly was finally found
774 with the Walston tracking gear nearly 3.5 miles down range. The
775 remainder of the rocket has not been found despite extensive searching
776 on the ground and from the air.
778 Reward if returned posters were placed in the area during the week
779 following the launch but have elicited no useful reponses yet.
780 </p></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="id2567211"></a>Chapter 9. Analysis and Conclusions</h2></div></div></div><p>
781 Consideration of how the nose cone ended up where it did suggests
782 we may have had an apogee deployment of the main, perhaps due to
783 stress on the shear pins before launch, during boost, or during
784 apogee drogue deployment causing them to break early.
786 It is unfortunate that we were confused by seeing another rocket
787 descending about the expected amount of time after YikStik's launch
788 in approximately the right direction. This caused us to believe that
789 the rocket was much closer than the nose cone turned out to be, causing
790 us to waste a lot of time searching in an area too close to the launch
792 It also caused us to assume something really weird had happened to the
793 transmitters, such that the tracking signal was suddenly lost long
794 after the rocket was on the ground, instead of what seems to really
795 have happened, which is that the rocket was farther away descending
796 after a main deployment at apogee, and the loss of signal was simply
797 due to dropping below a ridge line a couple miles from the launch site.
798 I can't help but think that if we'd been
799 looking in the right area sooner after the launch that we might have
800 found the rocket before someone else apparently picked it up.
802 I regret the decision to use a "free bag" configuration of the
804 Since both tracking transmitters were in the payload bay behind
805 the nose cone, and we were eventually able to recover that portion
806 of the rocket, it is possible that if the deployment bag were tethered
807 to the main that we might have recovered the remainder of the rocket.
809 If the rocket is recovered and able to fly again, the two changes I
810 would like to make are to tether the deployment bag to the apex of the
811 main, and to move from 2-56 nylon screws to 4-40 nylon screws for the
812 main deployment shear pins, ensuring the holes through the airframe
813 are a loose enough fit to avoid stresses on the pins during boost. I
814 have no way to know what happened for sure, but believe this might
815 solve the assumed problem of main deployment at apogee.
817 All in all, the design and build process was educational, and a lot
818 of fun! I'm looking forward to fabricating more custom parts using
819 carbon fiber and vacuum bagging in the future.
820 The beautiful boost and obvious survival of the rocket airframe
821 through the expected mach transitions confirms my design and
822 construction skills are adequate to attain an L3 cert.
823 While I hope to recover the remainder of YikStik someday, I won't
824 waste any time before trying again with a new airframe!
825 </p></div></div></body></html>
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