lavie154
Member
Time for my first build thread on here, except not really, as the rocket's mostly built and already made it to the pad once on a scrubbed flight. More on that and where the project is now further down.
Also, ahead of anything else, shoutout to @Neutron95 for allowing me to borrow his 54/1706 case as well as the tracker and EasyMini. This rocket would not exist without him.
This is Tritium 2.2, a 65mm (~2.55 in) diameter fully printed rocket I've been working on for the last month or so. It's flying on a K2050 from the Friends of Amateur Rocketry launch site in Mojave hopefully as soon as this weekend. OpenRocket says I'll hit about Mach 1.75 on this flight (590 m/s, 1320 mph) and an altitude of 9500 ft / 2.9 km.
The rocket's printed from primarily standard PETG on my (upgraded) Ender 3. The fin can is printed using a mix of carbon fiber/PETG blend filament for extra tensile strength as well as the standard white PETG. I'm using 5 fins with extremely wide fillets and diamond-shaped airfoils. I'm retaining the motor with a combination of a friction fit (this rocket uses a standard 54mm LOC motor mount tube, epoxied in) as well as head-end retention with a 5/16-18 eyebolt attached directly to the motor through a printed bulkhead and using the threaded plugged closure. The fin can and the first printed segment are epoxied together using RocketPoxy, while the second (blue) segment is held in using five #4 screws. The nosecone is a 7:1 VK printed in three parts—the first two are also epoxied together, while the tip is held in place using the eyebolt on the other side and a threaded insert embedded in the tip.
For recovery, I'm using drogueless head-end dual deploy. The "drogue" is about 12 feet of 1500-pound Kevlar cord, and the main is a 36" Apogee parachute. Motor-attached eyebolt aside, I'm using 1/4-20 hardware wherever possible, which while likely overkill for this rocket, is good practice for my future plans.
As far as avionics, I've got a Featherweight GPS for tracking, and originally planned to use a Raven 1 for primary deployments and Eggtimer Classic as backup. The Raven 1, however, refused to recognize any continuity after being installed. I'm replacing it with an EasyMini, and trying to see if I can keep the Raven as a datalogger. The avionics bay itself is printed with orange PETG and reinforced with two steel #6-32 threaded rods. The eyebolts attached to the avbay are both 1/4-20.
On that note, the Raven was the first of many hiccups with this build. Originally, I had planned to have the bottom end of the "drogue" shock cord attach to the printed body itself, as I was using the open floating forward closure. This worked relatively OK, but I was worried about a failure mode in which if that print tore, the entire fin can, casing and all, would tear off and fall on its own. Last weekend, after the third attempt that day to make it to the pad (first time, range closed before I was ready, 2nd time, installed a charge on the wrong computer), I dropped the nose of the rocket about 3 inches, and the print snapped right where that failure mode I expected would've been. Not great.
That brings me to today. After that attempt, I bought the threaded forward closure and worked to redesign the rocket to the current configuration, in which no printed parts should be under significant tension. It should be noted that printed parts can obviously handle some tension, however, if there's a defect in the part like the first attempt, that can cause an abrupt failure. I'm also adding the EasyMini, since @Neutron95 and I both felt pretty nervous about having an untested Eggtimer Classic handle deployments, and taking the motor apart to glue the grains just to be extra safe. I'll also likely look at making the rocket perhaps a bit prettier, since it's mostly unfinished right now and the FAR dust has left it looking pretty dirty.
The next flight attempt for this, again, should be as soon as 5 days from now (this Saturday) at FAR. I'll post about any progress from here, and glad to answer any questions folks have.
Also, ahead of anything else, shoutout to @Neutron95 for allowing me to borrow his 54/1706 case as well as the tracker and EasyMini. This rocket would not exist without him.
This is Tritium 2.2, a 65mm (~2.55 in) diameter fully printed rocket I've been working on for the last month or so. It's flying on a K2050 from the Friends of Amateur Rocketry launch site in Mojave hopefully as soon as this weekend. OpenRocket says I'll hit about Mach 1.75 on this flight (590 m/s, 1320 mph) and an altitude of 9500 ft / 2.9 km.
The rocket's printed from primarily standard PETG on my (upgraded) Ender 3. The fin can is printed using a mix of carbon fiber/PETG blend filament for extra tensile strength as well as the standard white PETG. I'm using 5 fins with extremely wide fillets and diamond-shaped airfoils. I'm retaining the motor with a combination of a friction fit (this rocket uses a standard 54mm LOC motor mount tube, epoxied in) as well as head-end retention with a 5/16-18 eyebolt attached directly to the motor through a printed bulkhead and using the threaded plugged closure. The fin can and the first printed segment are epoxied together using RocketPoxy, while the second (blue) segment is held in using five #4 screws. The nosecone is a 7:1 VK printed in three parts—the first two are also epoxied together, while the tip is held in place using the eyebolt on the other side and a threaded insert embedded in the tip.
For recovery, I'm using drogueless head-end dual deploy. The "drogue" is about 12 feet of 1500-pound Kevlar cord, and the main is a 36" Apogee parachute. Motor-attached eyebolt aside, I'm using 1/4-20 hardware wherever possible, which while likely overkill for this rocket, is good practice for my future plans.
As far as avionics, I've got a Featherweight GPS for tracking, and originally planned to use a Raven 1 for primary deployments and Eggtimer Classic as backup. The Raven 1, however, refused to recognize any continuity after being installed. I'm replacing it with an EasyMini, and trying to see if I can keep the Raven as a datalogger. The avionics bay itself is printed with orange PETG and reinforced with two steel #6-32 threaded rods. The eyebolts attached to the avbay are both 1/4-20.
On that note, the Raven was the first of many hiccups with this build. Originally, I had planned to have the bottom end of the "drogue" shock cord attach to the printed body itself, as I was using the open floating forward closure. This worked relatively OK, but I was worried about a failure mode in which if that print tore, the entire fin can, casing and all, would tear off and fall on its own. Last weekend, after the third attempt that day to make it to the pad (first time, range closed before I was ready, 2nd time, installed a charge on the wrong computer), I dropped the nose of the rocket about 3 inches, and the print snapped right where that failure mode I expected would've been. Not great.
That brings me to today. After that attempt, I bought the threaded forward closure and worked to redesign the rocket to the current configuration, in which no printed parts should be under significant tension. It should be noted that printed parts can obviously handle some tension, however, if there's a defect in the part like the first attempt, that can cause an abrupt failure. I'm also adding the EasyMini, since @Neutron95 and I both felt pretty nervous about having an untested Eggtimer Classic handle deployments, and taking the motor apart to glue the grains just to be extra safe. I'll also likely look at making the rocket perhaps a bit prettier, since it's mostly unfinished right now and the FAR dust has left it looking pretty dirty.
The next flight attempt for this, again, should be as soon as 5 days from now (this Saturday) at FAR. I'll post about any progress from here, and glad to answer any questions folks have.
