A NAR L3 Certification Rocket
Copyright © 2008 Bdale Garbee
+
A NAR L3 Certification Rocket
Copyright © 2008 Bdale Garbee
This document is released under the terms of the Creative Commons ShareAlike 3.0 license. -
| Revision History | |
|---|---|
| Revision 1.0 | 15 November 2008 |
| Successful certification flight at Hudson Ranch | |
| Revision 0.2 | 28 October 2008 |
| Revising during flight to DC | |
| Revision 0.1 | 23 October 2008 |
| Initial content, derived from YikStik | |
| Revision History | |
|---|---|
| Revision 1.0 | 15 November 2008 |
| Successful certification flight at Hudson Ranch | |
| Revision 0.2 | 28 October 2008 |
| Revising during flight to DC | |
| Revision 0.1 | 23 October 2008 |
| Initial content, derived from YikStik | |
Table of Contents
This is a rocket I'm building for my second attempt at a NAR Level 3 certification flight. It's basically a Polecat Aerospace Goblin 10 kit augmented with an additional electronics bay in the nose cone, some @@ -19,7 +19,7 @@ NCR launch sites under their standing waivers. The smallest reasonable motor for this rocket would be a Cesaroni K445 or equivalent, which would yield an apogee of about 2300 feet. -
Table of Contents
Table of Contents
The Goblin 10 kit is a simple "four fins and a nose cone" rocket that is short and squat, with a 98mm motor mount. It supports dual-deploy by @@ -28,19 +28,19 @@ centering rings, accessed by a side hatch. An additional payload bay will be built inside the nose cone to carry experimental altimeters, a tracking beacon, and possibly a GPS position reporting system. -
I will include 8-24 T-nuts in the aft centering ring spaced to allow the use of an Aeropack 98mm retainer and associated 75mm adapter. -
Instead of using the supplied nose cone bulkhead, I intend to cut a custom one that would support installing a length of 98mm motor mount from the tip of the nose to the bulkhead. With a plate cut to cover the aft end of the airframe tube, this would form an electronics bay capable of holding a beacon transmitter, GPS system, or other custom electronics. -
The recovery system will feature dual redundant barometric altimeters in the main avionics bay between the two forward motor mount centering rings. @@ -54,7 +54,7 @@ A third rotary switch will be used as a SAFE/ARM switch configured to interrupt connectivity to all ejection charges in accordance with NAR certification requirements. -
The Goblin 10 kit designers indicate that the rocket is unconditionally stable with all motors that fit the motor mount geometry. Since we're adding mass at both ends, by @@ -76,12 +76,12 @@ I also note that the simulated margin of stability in my as-built configuration is fairly close to the margin of stability of the as-designed model. -
The Aerotech M1297W reload should carry this vehicle to just under 7000 feet AGL from Colorado Front Range launch sites. It should reach just over 2 miles on a Cesaroni M795 moon burner or equivalent. -
The recovery system will use dual redundant barometric altimeters firing 4F black powder charges using commercial e-matches. At apogee, a drogue chute will deploy with separation of the nose @@ -102,7 +102,14 @@
The recovery system attachment points will all use 1/4 inch u-bolts with nuts, washers, and backing plates through bulkheads. -
Table of Contents
+ I have collected all of my + + build photos + + in one place, they may show better than I can explain how various + aspects of the Goblin went together. +
The airframe tubing provided in the Polecat kit is thick cardboard tube with a thin exterior fiberglass wrap. To increase airframe strength, and particularly to prevent zippers, additional reinforcement seemed @@ -115,7 +122,7 @@ curing by an inflatable child's bounce toy inside a plastic garbage bag. The result is a substantially strengthened tube, with carbon fiber lining from the leading edge back past the first centering ring. -
The provided nose cone bulkhead was replaced by a custom centering ring cut from 3/8 inch birch plywood. The ring's outer diameter was adjusted put place the ring approximately an inch forward of the end @@ -133,7 +140,7 @@ the piece of airframe tubing. After the epoxies cured, a rotary tool was used to cut the airframe tubing off flush with the aft surface of the centering ring. -
The avionics bay walls were installed approximately 90 degrees apart prior to installation of the motor mount assembly in the airframe. The airframe wall was marked for a 3.5 x 6.5" access hatch centered @@ -149,7 +156,7 @@ A suitably sized avionics sled should be possible to install and remove through the avionics bay hatch allowing for possible future experiments with alternative avionics. -
Table of Contents
Table of Contents
This rocket uses dual deployment.
The apogee event separates the nose cone from the @@ -173,7 +180,7 @@ chute apex, with a smaller drogue chute deployed to pull off the bag and cleanly deploy the main. The primary motivation for this is to prevent the main chute shrouds from tangling during ejection. -
The main avionics bay between the forward two centering rings is populated with two commercial altimeters, a PerfectFlite MAWD and a Missile Works miniRRC2. @@ -219,7 +226,7 @@ With a 10 foot Team Vatsaas design parachute and our anticipated build weight, the descent rate under main should be just over 20 feet per second. -
-
Planning
- Pick a club launch with suitable waiver and facilities to @@ -404,7 +411,7 @@ flight line
- bring the rocket to observers for post-flight inspection -
A successful level 3 certification flight occurred on 15 November 2008 at the SCORE Hudson Ranch launch facility. The motor was an Aerotech M1297W provided by Tim Thomas of Giant Leap Motors, the igniter was @@ -436,7 +443,7 @@ Video of the launch taken by Jeff Lane