I recently got my L2. I flew a 4" Madcow DX3 that I fiberglassed all the tubes bar the coupler and set up for dual deploy. The motor was a J420 and the electronics were an EasyMini and a Quark.
There were a few things that I would describe as "abnormal" about the rocket - less so about the build but more about the flight configuration. First, the motor mount is 54mm and I used a 38 mm motor. That's not abnormal at all but I made a homemade adapter using a short section of homemade 38 mm tube and some 3d printed centering rings/thrust ring. The adapter was retained using a standard 54 mm aeropack retainer but the motor itself was retained in the adapter simply by wrapping a thick "retention ring" of sorts around the motor case right above the top of the adapter to prevent it from moving backwards out of the rocket. The second abnormal thing was my recovery blankets. I only had a couple small nomex blankets and don't have any raw stock of nomex fabric to cut some out of, so I just cut some out of denim from old jeans, covering the frayed edges using electrical tape. I'd seen it done somewhere on this forum and it seemed to work so I gave it a try on my ejection test and they did indeed work fine. I also had two protectors for each deployment event - one to wrap up the chute and a second to place right above the charge to protect most of the shock cord.
The flight was a complete success but there are still a few things that I liked and disliked about it.
Things I would do differently:
1. Do a better job on the solder joints in the avbay. One of the connections to the screw switch for the quark broke as I was hooking up the e-matches. I decided to just fly without the Quark enabled, using the EasyMini and motor eject for a backup on the drogue. The EasyMini worked perfectly but I would have liked to have flown the Quark as a backup at least to test and make sure of its functionality. In the future I might pot my solder joints in hot glue or epoxy, or even better, just wire the avionics bay such that there is always sufficient slack on the wires (but still containing them/tying them down so they don't get in the way).
2. Use kevlar shock cords. I used the nylon that came with the kit for the drogue side and another long nylon cord for the main side. It's what I had, but if possible on future projects I will always try to use kevlar - even with the double blankets I still got some singing and kevlar is easier to clean and doesn't melt like nylon does. The main side is easy to replace but the drogue side is of course epoxied to the motor mount which would make things difficult if I ever need to replace the shock cord on this rocket.
3. Add connectors to the outside of the avbay bulkheads for e-matches. I have done this before on my old school team's rockets and I am a big fan. I didn't have any connectors on hand for this one so I just had a hole in the bulkheads and ran the e-matches right into the altimeters. Prep at the launch site would be easier if I could fully button up the avbay the day before and only have to worry about plugging in the charges right at the end after I've tied the shock cords. Also means I spend less time with my hands right beside live charges.
4. In general I am not a fan of the molded plastic nosecones. The fit was quite loose and required a lot of tape to shim and the shear pins actually did not shear, just sort of bent out of place. It worked, but a proper fiberglass nosecone or at least a modified plastic one with a cardboard or fiberglass coupler would be nicer to work with.
5. Would have loved to have enough time to make a mount to stick a camera onboard.
Things I would do the same again:
1. 3d printed avionics sled. No reason not to do this. Easy mounting of batteries, channels for wiring to go in, built-in standoffs for boards and switches. Don't think I will ever fly a rocket with a flat wood or G10 plate in the avbay, like this kit was originally set up for.
2. Demin chute protectors. Worked great and cost me nothing. Might go ahead and try a demin deployment bag, would be pretty easy to make out of some pants!
3. Tape based motor retention in the homemade adapter. Same thing. Worked great and no cost.
4. The homemade adapter itself. Again, way cheaper than an aeropack one - just used an offcut of a 38 mm fiberglass tube I'd made for another project and a couple super small 3d printed parts.
5. Stick a gopro at the pad. Got a sick shot of the launch. Highly recommend putting a camera near the pad, really gives you a look you can't get from the flight line.
Anyways thanks to the organisers at URRG where I did the flight. Will definitely be back for more come next year.
There were a few things that I would describe as "abnormal" about the rocket - less so about the build but more about the flight configuration. First, the motor mount is 54mm and I used a 38 mm motor. That's not abnormal at all but I made a homemade adapter using a short section of homemade 38 mm tube and some 3d printed centering rings/thrust ring. The adapter was retained using a standard 54 mm aeropack retainer but the motor itself was retained in the adapter simply by wrapping a thick "retention ring" of sorts around the motor case right above the top of the adapter to prevent it from moving backwards out of the rocket. The second abnormal thing was my recovery blankets. I only had a couple small nomex blankets and don't have any raw stock of nomex fabric to cut some out of, so I just cut some out of denim from old jeans, covering the frayed edges using electrical tape. I'd seen it done somewhere on this forum and it seemed to work so I gave it a try on my ejection test and they did indeed work fine. I also had two protectors for each deployment event - one to wrap up the chute and a second to place right above the charge to protect most of the shock cord.
The flight was a complete success but there are still a few things that I liked and disliked about it.
Things I would do differently:
1. Do a better job on the solder joints in the avbay. One of the connections to the screw switch for the quark broke as I was hooking up the e-matches. I decided to just fly without the Quark enabled, using the EasyMini and motor eject for a backup on the drogue. The EasyMini worked perfectly but I would have liked to have flown the Quark as a backup at least to test and make sure of its functionality. In the future I might pot my solder joints in hot glue or epoxy, or even better, just wire the avionics bay such that there is always sufficient slack on the wires (but still containing them/tying them down so they don't get in the way).
2. Use kevlar shock cords. I used the nylon that came with the kit for the drogue side and another long nylon cord for the main side. It's what I had, but if possible on future projects I will always try to use kevlar - even with the double blankets I still got some singing and kevlar is easier to clean and doesn't melt like nylon does. The main side is easy to replace but the drogue side is of course epoxied to the motor mount which would make things difficult if I ever need to replace the shock cord on this rocket.
3. Add connectors to the outside of the avbay bulkheads for e-matches. I have done this before on my old school team's rockets and I am a big fan. I didn't have any connectors on hand for this one so I just had a hole in the bulkheads and ran the e-matches right into the altimeters. Prep at the launch site would be easier if I could fully button up the avbay the day before and only have to worry about plugging in the charges right at the end after I've tied the shock cords. Also means I spend less time with my hands right beside live charges.
4. In general I am not a fan of the molded plastic nosecones. The fit was quite loose and required a lot of tape to shim and the shear pins actually did not shear, just sort of bent out of place. It worked, but a proper fiberglass nosecone or at least a modified plastic one with a cardboard or fiberglass coupler would be nicer to work with.
5. Would have loved to have enough time to make a mount to stick a camera onboard.
Things I would do the same again:
1. 3d printed avionics sled. No reason not to do this. Easy mounting of batteries, channels for wiring to go in, built-in standoffs for boards and switches. Don't think I will ever fly a rocket with a flat wood or G10 plate in the avbay, like this kit was originally set up for.
2. Demin chute protectors. Worked great and cost me nothing. Might go ahead and try a demin deployment bag, would be pretty easy to make out of some pants!
3. Tape based motor retention in the homemade adapter. Same thing. Worked great and no cost.
4. The homemade adapter itself. Again, way cheaper than an aeropack one - just used an offcut of a 38 mm fiberglass tube I'd made for another project and a couple super small 3d printed parts.
5. Stick a gopro at the pad. Got a sick shot of the launch. Highly recommend putting a camera near the pad, really gives you a look you can't get from the flight line.
Anyways thanks to the organisers at URRG where I did the flight. Will definitely be back for more come next year.
