Hi all,
I've lurked both TRF and the Australian rocketry forums for a while now, and only posted occasionally. Since our launch which would have been tomorrow got delayed, I figured I'd do a writeup of the rocket we've been working on the past few weeks. This is our first rocket truly built as a club. Conman13 and I started the club when I was a freshman and he was a senior. Since then we've grown to about 40 members, but 15 or so active. Towards the end of this semester, I figured it would be more prudent to just fly one big rocket as a club instead of having everyone fly a smaller L1. The larger rocket could be built cheaper, look more impressive to the university, and still give everyone a chance to learn about building high powered rockets. We're still looking for funding so money is tight, we need to maximize our return for each flight.
The Design:
The rocket was designed to fly on a range of high performance 54mm motors, while not breaking the 18k foot waiver at the Tripoli field nearest us (URRG). Both 3 and 4 inch airframes were considered, but 3 inch was settled on since it would use fewer consumables and perform better on the 54mm motors we would be flying. A simple 2-break dual deploy system was decided upon, since it's simple and reliable. The nosecone, airframe, coupler, and motor tube are all filament wound fiberglass from Wildman. The fins and centering rings were cut out of carbon fiber plate we made in our lab.
The first flight of the rocket is going to be on a CTI K1200 motor. It is a 5 grain motor, and produces 307 lbs of thrust for 1.7 seconds. Since this is a fairly aggressive motor for a rocket that weighs 4.4 lbs empty, I figured a thrust ring and flanged motor retainer would be appropriate. Anodized aluminum is also pretty so that's a plus.
Structures:
Fiberglass was a natural choice for the airframe of this rocket. It's strong enough for the velocities and accelerations we're expecting, RF transparent, and readily available. Our airframe, couplers, motor tube, and nosecone are all filament wound fiberglass from Wildman. The fins and centering rings were all cut from custom made carbon fiber plate on our university's waterjet. Lead-in's were drilled to avoid delamination of the carbon fiber. The plates were laminated from 13 layers of 0/45/0 2k plain weave cloth and HTR-212 laminating epoxy, and cured under vacuum for 12 hours. They came out to 0.091" thick, and ring like a sheet of metal. All the bonding on this rocket was done with either Hysol E120-HP or JB Weld 5-minute epoxy. The 5-minute epoxy was used for tacking the fins on, as well as the nuts to hold the thrust plate on. The E120-HP was used to bond the centering rings, the fillets, and couplers.
Avionics:
For our avionics, we decided to go with an all-in-one flight computer and tracker. We settled on the AIM XTRA since I'd used it in the past and had good results. The AIM can also do live telemetry, has a 200 G vertical accelerometer, and the GPS has proved to be fairly precise. We're not using a redundant altimeter, but have redundant ejection charges, and a backup CSI radio tracker. Power was originally supposed to be supplied by two 9v batteries, but we decided to use two 2s 200 mAh lipos instead. Switching will be handled by two screw switches mounted to the sled. I like the screw switches for their simplicity and reliability. The avionics will be mounted on a sled 3D printed on my Sovol SV-01 printer.
Recovery:
Recovery will be handled by a dual deployment system controlled by the AIM XTRA. The redundant ejection charges will be the surgical tubing type, to ensure that they function properly at any altitude. There's 20 feet of 7/16 Kevlar shock cord between both sections, connected with 1/4" quick links. The drogue is a Spherachutes small Apex, and the main is a standard 48" Spherachute. URRG is a fairly large field, but it's still easy to lose rockets out there, so I wanted to get it down as a fast as reasonably possible.
With all the specifics out of the way, here's the build so far:
The two orientations of carbon fiber cloth, peel ply, vacuum film, and breather cloth cut
The layup in the bag. My vacuum tape technique wasn't the greatest, but it's improved since
The finished plate. Came out to just a hair under 0.091"
The cut fins
All the parts washed and laid out
Bonding the coupler into the nosecone
Will continue in second post! Reached photo upload limit
I've lurked both TRF and the Australian rocketry forums for a while now, and only posted occasionally. Since our launch which would have been tomorrow got delayed, I figured I'd do a writeup of the rocket we've been working on the past few weeks. This is our first rocket truly built as a club. Conman13 and I started the club when I was a freshman and he was a senior. Since then we've grown to about 40 members, but 15 or so active. Towards the end of this semester, I figured it would be more prudent to just fly one big rocket as a club instead of having everyone fly a smaller L1. The larger rocket could be built cheaper, look more impressive to the university, and still give everyone a chance to learn about building high powered rockets. We're still looking for funding so money is tight, we need to maximize our return for each flight.
The Design:
The rocket was designed to fly on a range of high performance 54mm motors, while not breaking the 18k foot waiver at the Tripoli field nearest us (URRG). Both 3 and 4 inch airframes were considered, but 3 inch was settled on since it would use fewer consumables and perform better on the 54mm motors we would be flying. A simple 2-break dual deploy system was decided upon, since it's simple and reliable. The nosecone, airframe, coupler, and motor tube are all filament wound fiberglass from Wildman. The fins and centering rings were cut out of carbon fiber plate we made in our lab.
The first flight of the rocket is going to be on a CTI K1200 motor. It is a 5 grain motor, and produces 307 lbs of thrust for 1.7 seconds. Since this is a fairly aggressive motor for a rocket that weighs 4.4 lbs empty, I figured a thrust ring and flanged motor retainer would be appropriate. Anodized aluminum is also pretty so that's a plus.
Structures:
Fiberglass was a natural choice for the airframe of this rocket. It's strong enough for the velocities and accelerations we're expecting, RF transparent, and readily available. Our airframe, couplers, motor tube, and nosecone are all filament wound fiberglass from Wildman. The fins and centering rings were all cut from custom made carbon fiber plate on our university's waterjet. Lead-in's were drilled to avoid delamination of the carbon fiber. The plates were laminated from 13 layers of 0/45/0 2k plain weave cloth and HTR-212 laminating epoxy, and cured under vacuum for 12 hours. They came out to 0.091" thick, and ring like a sheet of metal. All the bonding on this rocket was done with either Hysol E120-HP or JB Weld 5-minute epoxy. The 5-minute epoxy was used for tacking the fins on, as well as the nuts to hold the thrust plate on. The E120-HP was used to bond the centering rings, the fillets, and couplers.
Avionics:
For our avionics, we decided to go with an all-in-one flight computer and tracker. We settled on the AIM XTRA since I'd used it in the past and had good results. The AIM can also do live telemetry, has a 200 G vertical accelerometer, and the GPS has proved to be fairly precise. We're not using a redundant altimeter, but have redundant ejection charges, and a backup CSI radio tracker. Power was originally supposed to be supplied by two 9v batteries, but we decided to use two 2s 200 mAh lipos instead. Switching will be handled by two screw switches mounted to the sled. I like the screw switches for their simplicity and reliability. The avionics will be mounted on a sled 3D printed on my Sovol SV-01 printer.
Recovery:
Recovery will be handled by a dual deployment system controlled by the AIM XTRA. The redundant ejection charges will be the surgical tubing type, to ensure that they function properly at any altitude. There's 20 feet of 7/16 Kevlar shock cord between both sections, connected with 1/4" quick links. The drogue is a Spherachutes small Apex, and the main is a standard 48" Spherachute. URRG is a fairly large field, but it's still easy to lose rockets out there, so I wanted to get it down as a fast as reasonably possible.
With all the specifics out of the way, here's the build so far:
The two orientations of carbon fiber cloth, peel ply, vacuum film, and breather cloth cut
The layup in the bag. My vacuum tape technique wasn't the greatest, but it's improved since
The finished plate. Came out to just a hair under 0.091"
The cut fins
All the parts washed and laid out
Bonding the coupler into the nosecone
Will continue in second post! Reached photo upload limit
