X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=rockets%2Fairframes%2FGoblin10%2Findex.html;h=3bec14f2f8d28ffda5f760391b61eb0a42645e92;hb=96b64e92205c407c3d01166e51aa9c7b9e14c60a;hp=d4731417af7c920ec3e409a706dfe648ed3f96ff;hpb=4ae3b26a6ac33df700f9cd2fcc59abf85ce156a1;p=web%2Fgag.com diff --git a/rockets/airframes/Goblin10/index.html b/rockets/airframes/Goblin10/index.html index d473141..3bec14f 100644 --- a/rockets/airframes/Goblin10/index.html +++ b/rockets/airframes/Goblin10/index.html @@ -1,10 +1,10 @@ -
Copyright © 2008 Bdale Garbee
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Copyright © 2008 Bdale Garbee
This document is released under the terms of the Creative Commons ShareAlike 3.0 license. -
Revision History | |
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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 +28,22 @@ 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 +57,7 @@ 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 +79,12 @@ 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 @@ -102,14 +105,14 @@
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. -
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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 @@ -122,7 +125,7 @@ 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 @@ -140,7 +143,7 @@ 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 @@ -156,7 +159,7 @@ 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 @@ -180,7 +183,7 @@ 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. @@ -226,192 +229,192 @@ 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. -
1.1. |
Pick a club launch with suitable waiver and facilities to
support flight.
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1.2. |
Confirm L3CC member(s) available to attend selected launch.
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1.3. |
Confirm that required loaner motor hardware will be available at launch.
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1.4. |
Notify launch sponsor (club president) of intended flight.
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1.5. |
Notify interested friends of intended flight.
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1.6. |
Perform final pre-flight simulation with as-built masses, etc.
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1.7. |
Gather consummables and tools required to support flight
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2.1. |
program altimeters for suitable mach delay and recovery deployment
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2.2. |
assemble all recovery system components and ensure everything fits
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2.3. |
confirm wiring and operation of altimeter power and safe/arm
switches
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2.4. |
Ground test recovery system to confirm suitable black powder
charge sizing
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3.1. |
confirm payload batteries in good condition, bay loaded,
power switch works
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3.2. |
confirm reception of signals from transmitter(s)
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3.3. |
install fresh 9V batteries for altimeters on avionics bay sled
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3.4. |
inspect altimeters and associated avionics bay wiring for
visible faults
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3.5. |
close up avionics bay
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3.6. |
build and install BP charges
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3.7. |
fold main chute, connect recovery harness to piston and airframe,
install in MMT and tape paper over the front end
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3.8. |
fold drogue chute into a kevlar pad, connect recovery harness to
nose cone and airframe, install in airframe
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3.9. |
power up payload using switch on base plate in nose cone, then
install nose cone, using masking tape to adjust fit as required
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3.10. |
safely power up altimeters, operate safe/arm switch,
and confirm e-match continuity
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3.11. |
safe and power-down the altimeters
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3.12. |
load motor per manufacturer instructions
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3.13. |
install motor in motor mount
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3.14. |
install motor retention
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3.15. |
prepare igniter using e-matches, 1/8 inch dowel
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3.16. |
confirm all screws in place, avionics off and safe
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3.17. |
fill out a launch card
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3.18. |
notify RSO/LCO of readiness for inspection and launch, obtain
a rail assignment and permission to move rocket to launch pad for
final prep
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3.19. |
coordinate readiness with support team members, photographers,
observers
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4.1. |
move rocket to launch area
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4.2. |
clean and lubricate launch rail if necessary
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4.3. |
confirm reception of signals from payload transmitter(s)
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4.4. |
mount rocket on launch rail, rotate to vertical
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4.5. |
power up primary altimeter, confirm expected beep pattern
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4.6. |
power up backup altimeter, confirm expected beep pattern
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4.7. |
arm ejection charges
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4.8. |
confirm altimeters both giving expected beep patterns for
igniter continuity
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4.9. |
install igniter and connect to launch control system
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4.10. |
capture GPS waypoint for rail location
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4.11. |
smile for the cameras, make sure we have enough "foil Murphy!"
shots taken
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4.12. |
retreat to safe area behind LCO
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4.13. |
confirm continued reception of transmitter signal(s) from
payload bay
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4.14. |
confirm photographers and observers are ready and know what to
expect
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4.15. |
make sure binoculars and backpack with water and recovery tools
are at hand
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4.16. |
tell RSO and LCO we're ready to launch
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4.17. |
try to relax and enjoy watching the flight!
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5.1. |
track rocket to landing site
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5.2. |
capture GPS waypoint of landing site, take lots of photos
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5.3. |
note any damage
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5.4. |
gather up and roughly re-pack recovery system for return to
flight line
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5.5. | 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 @@ -437,13 +440,13 @@ The miniRRC2 altimeter reported 5949 feet apogee, 980 feet per second max velocity, and 19 seconds to apogee. The MAWD reported 5953 feet apogee. -
The ascent was straighter than expected... very smooth during the motor burn, then a couple slow rolls during coast. The two altimeters agreed within 4 feet on the apogee. The max @@ -470,7 +473,7 @@ profile from the MAWD shows that our actual descent rate was about 32 feet per second. There are three possible sources of error to consider. -
@@ -495,11 +498,11 @@
So, overall, this was a successful flight, but with three things to change before we fly the airframe again... -