I bought this rocket from Wildman early this year and picked it up at Red Glare. I did some additional thinking, bought some longer parts, and then left it for months. I decided to make it one of my goals for 2023 to get it built. I'd love to stick a 75mm K from my Black Friday order in it at Red Glare 2023, but that's probably too optimistic given my work and family commitments over the next 4 months.
To start, here are the parts that make up my back end:
10" of 5" coupler tube (longer than the kit default, which I plan to use elsewhere)
5" slotted tailcone, forgot to measure the length (14"?)
24" of 3" motor mount (again longer than the default)
Fore CR that fits 5" airframe tube
Aft CR that fits 4" airframe tube
Giant Leap Slimline Retainer
Fins
I like to build my fin units sandwiched by centering rings on either end, with the motor retainer butting up against the aft CR. In my head, at least, this transfers thrust from the motor thrust ring to the retainer, to the CR, to the fins, to the airframe, without really relying on the strength of any glue joints. The trouble here is that the aft CR isn't the correct size to butt up against the rear fins while still contacting the tailcone. To deal with that, I'm going to laser cut a series of additional CRs from 1/4" (and one 1/8") ply to fill the 1.625" between the front size of the aft FG CR and the back of the fins. I'll sand them into a smoothish bevel so they fit nicely into the back end of the tailcone and bridge the aforementioned gap.
I want to extend the distance the coupler extends into the tailcone and the airframe, thus the extended 10" coupler. The sharpie marks show where I'm going to cut slots to allow the coupler to slide over (and bond tightly with) the fins and slide farther into the tailcone. I will use a CR tacked into the middle of the coupler when I install the motor mount into the tailcone to get alignment correct. The long motor mount extends just past the front of the coupler, allowing it to bookend the whole tail section. At on point I had considered attaching the airframe to this tail unit with a bunch of screws to allow for repairs, etc. but I think that's off the table (that was part of the inspiration for the longer coupler too, if I remember correctly). Question for readers: with what tools would you cut the slots in the coupler?
None of this touches at all on the front end of the rocket. My current plan is to reuse the sled and electronics from my 4" DD rocket, using the coupler and bulkheads from this kit and just requiring me to space the allthread the same. The terminals on my existing 4" av bay all have connectors between them and the electronics, which would allow me to just move the sled between av bays as necessary. I'll see when I get there if that plan survives contact with the build. Recovery attachment hasn't been determined yet. U-bolt on the fore CR will be inaccessible once the whole thing is built but is an option. My favorite option the last time I thought about this was a bulkhead installed up near the top of the airframe with a coupler piece to reinforce it, leaving just enough room for the one end of the av bay and the drogue part of the recovery package.
So my steps going forward:
1. Cut a bunch of ply CRs to fill the gap between the aft CR and the back end of the fins
2. Cut a CR to go (at least temporarily) in the coupler
3. Install the motor retainer and aft CRs onto the motor tube
4. Sand the ply CRs to shape so the assembly fits nicely in the tailcone
5. Tack the CR from #2 into the coupler
6. Prep the section of the motor tube that will be inaccessible for bonding the fins later
7. Install the motor mount into the tailcone, with the coupler/temporary CR slid in behind for alignment
8. Remove coupler
9. Cut short slots on coupler
10. Install fins
11. Do internal fin fillets
12. Do external fin fillets
13. Install coupler
14. Determine if recovery attachment needs to be included here and add it if so
15. Install fore CR(s)
I'm sure I've overlooked some things, so please point those out to me so I can fix them now. I'm also positive I've overthought this and am overbuilding it, but at this point I don't think you're going to talk me out of that part.
Thanks for reading, and I appreciate encouragement to keep working on this as it drags out over the next several months.
To start, here are the parts that make up my back end:
10" of 5" coupler tube (longer than the kit default, which I plan to use elsewhere)
5" slotted tailcone, forgot to measure the length (14"?)
24" of 3" motor mount (again longer than the default)
Fore CR that fits 5" airframe tube
Aft CR that fits 4" airframe tube
Giant Leap Slimline Retainer
Fins
I like to build my fin units sandwiched by centering rings on either end, with the motor retainer butting up against the aft CR. In my head, at least, this transfers thrust from the motor thrust ring to the retainer, to the CR, to the fins, to the airframe, without really relying on the strength of any glue joints. The trouble here is that the aft CR isn't the correct size to butt up against the rear fins while still contacting the tailcone. To deal with that, I'm going to laser cut a series of additional CRs from 1/4" (and one 1/8") ply to fill the 1.625" between the front size of the aft FG CR and the back of the fins. I'll sand them into a smoothish bevel so they fit nicely into the back end of the tailcone and bridge the aforementioned gap.
I want to extend the distance the coupler extends into the tailcone and the airframe, thus the extended 10" coupler. The sharpie marks show where I'm going to cut slots to allow the coupler to slide over (and bond tightly with) the fins and slide farther into the tailcone. I will use a CR tacked into the middle of the coupler when I install the motor mount into the tailcone to get alignment correct. The long motor mount extends just past the front of the coupler, allowing it to bookend the whole tail section. At on point I had considered attaching the airframe to this tail unit with a bunch of screws to allow for repairs, etc. but I think that's off the table (that was part of the inspiration for the longer coupler too, if I remember correctly). Question for readers: with what tools would you cut the slots in the coupler?
None of this touches at all on the front end of the rocket. My current plan is to reuse the sled and electronics from my 4" DD rocket, using the coupler and bulkheads from this kit and just requiring me to space the allthread the same. The terminals on my existing 4" av bay all have connectors between them and the electronics, which would allow me to just move the sled between av bays as necessary. I'll see when I get there if that plan survives contact with the build. Recovery attachment hasn't been determined yet. U-bolt on the fore CR will be inaccessible once the whole thing is built but is an option. My favorite option the last time I thought about this was a bulkhead installed up near the top of the airframe with a coupler piece to reinforce it, leaving just enough room for the one end of the av bay and the drogue part of the recovery package.
So my steps going forward:
1. Cut a bunch of ply CRs to fill the gap between the aft CR and the back end of the fins
2. Cut a CR to go (at least temporarily) in the coupler
3. Install the motor retainer and aft CRs onto the motor tube
4. Sand the ply CRs to shape so the assembly fits nicely in the tailcone
5. Tack the CR from #2 into the coupler
6. Prep the section of the motor tube that will be inaccessible for bonding the fins later
7. Install the motor mount into the tailcone, with the coupler/temporary CR slid in behind for alignment
8. Remove coupler
9. Cut short slots on coupler
10. Install fins
11. Do internal fin fillets
12. Do external fin fillets
13. Install coupler
14. Determine if recovery attachment needs to be included here and add it if so
15. Install fore CR(s)
I'm sure I've overlooked some things, so please point those out to me so I can fix them now. I'm also positive I've overthought this and am overbuilding it, but at this point I don't think you're going to talk me out of that part.
Thanks for reading, and I appreciate encouragement to keep working on this as it drags out over the next several months.
