Blackfish - L1 Super DX3 Build
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So I'm getting to the point of drilling shear pins. I think I'm more nervous about that and shims than anything else here. Anyway, I will hopefully get that done this week.
On another note, I getting much closer to final weight. It's currently right at 3kg (with generic weights for the parachutes and nose ballast). I'm spec'ing chutes and wanted to get an idea of what drogues others are using. As I said previously, I'm looking hard at spherachutes, but not sure about using their chutes as drogues. Which do you all like and use (or which would never touch again)? And any thoughts on sizing for drogues?
On another note, I getting much closer to final weight. It's currently right at 3kg (with generic weights for the parachutes and nose ballast). I'm spec'ing chutes and wanted to get an idea of what drogues others are using. As I said previously, I'm looking hard at spherachutes, but not sure about using their chutes as drogues. Which do you all like and use (or which would never touch again)? And any thoughts on sizing for drogues?
boatgeek
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I can't really comment on chute brands (I scratch build), but I'd look for something in the 12"-18" range with a spill hole. Ideal world descent rate under drogue is in the 80 fps range, but don't worry about 60-100 fps predictions if it gets you to a standard size. I tend to go a little high on speed under drogue because the body tubes will likely add some drag as well.
Also, if you choose a vendor, they should be able to give you a chute recommendation for drogue and main given weight at burnout and desired drogue/landing speeds.
As previously promised, a little peek inside the av-bay. I went all-in with Missileworks on this - RRC2Ls and their printed sled. The sled is pretty good but I felt that it could have been a little more thoughtfully laid out for wire management. It'll work for now, but I'm keeping my eyes open for better options.
Less apparent, I got Rocket Junkies charge wells. Saved me a bit of time building my own, and they look great, so I can justify the expense.
In other news, I've got just about everything drilled and prepped, so I'm about ready to get brass shims into the airframe. For those that have done it, do you do epoxy over the hole, then shim, then more epoxy? I'm thinking about laying some wax paper or mylar over the shim as it cures to try to keep it as smooth as possible. I'd like to hear what's worked for you (or not worth the time/effort).
Less apparent, I got Rocket Junkies charge wells. Saved me a bit of time building my own, and they look great, so I can justify the expense.
In other news, I've got just about everything drilled and prepped, so I'm about ready to get brass shims into the airframe. For those that have done it, do you do epoxy over the hole, then shim, then more epoxy? I'm thinking about laying some wax paper or mylar over the shim as it cures to try to keep it as smooth as possible. I'd like to hear what's worked for you (or not worth the time/effort).
My math with drag on the fin can gets me about ~75fps with a 12" flat sheet. I'm perfectly alright with that descent rate, but there is plenty of variation in drogue sizing and construction making it a less than straight forward research project. I appreciate the confirmation that I'm headed in the right direction though.
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That mounting bridge for the switches reminds me of:
I have not done it before, and what I have is a question, not advice. Don't the shims go in between the airframe and coupler? Keeping the sheer force from damaging those, and also cutting the pins like scissors? Doesn't that mean that they are flat against one another? If so, wouldn't that mean that you mustn't put anything like more epoxy on top of them?
Hi BudroO, all kind of depends on location of brass plate. If inside avbay, scuff brass and glue over already drill holed. Let dry and redrill. If plate is going in between NC shoulder and body tube, as in single deploy, then I will use a piece of baggie and clamp it down till dry. and again, redrill hole. Can send pics if you need. Dave.
That is what I'm tracking/planning. But you bring up a good point. I was not planning to go brass to brass... But to do brass on the inside of each - coupler and body tube. Now i'm questioning if I even have the right concept in mind.
What do you say, @David Schwantz? For a coupler/av-bay and airframe connection, where do you put shims?
1st 2 pics are the inside of a 1/5th V 2. They are on the inside of the sonotube, sonotube is glassed on outside. Located at the bottom of the NC shoulder. The screws will go through the shim plates and into a tapped aluminum bracket that is bolted to the base of the NC shoulder. Can take a pic of that tomorrow if you like as it is in the paint booth now with primer drying. The last 3 pics are LOCs 4" V 2. Again the brass plates are on the inside of the cardboard tube. With the last pic being the inside of the NC shoulder. I like to glue a plate with a blind nut in place. Just like the big V 2, by screwing into a threaded housing, it will hold the screw securely and does not allow it to roll over. They shear very cleanly. This also allows for very easy removal of the sheared off threaded portion.
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Awesome notes, thank you. I think I'll steal that blind nut idea too.
I gift it to you 
Quick update: First shim is in and curing with a large roll of butcher paper and a bit of mylar to keep everything smooth. I finally found some 2-56 blind nuts (Eugene Hobby for the win) which should be here on Saturday. If everything goes well, I could be testing charges on Sunday. Except I don't have any chutes yet. I'm still waiting to hear back from Spherachutes as they have a couple drogue chutes which could work and I asked their advice on which they'd recommend.
We are really dangerously close to painting - I need to start getting all the stencils cut out...
We are really dangerously close to painting - I need to start getting all the stencils cut out...
I have , in the past, substituted "old" bathroom towels for chutes. Only cause I like playing with BP
I finally got all the shims in and new Spherachutes showed up today. So I got a little ground testing done. Ended up needing a bit more oomph than the calculators suggested, but within safe limits. Video for proof:
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Jumping right into this build as I've been tinkering with the kit since I got it last week. I did the Coker nosecone mod to add the tracker bay. Nothing really fancy, but I did scratch build the sled. I used a 4x54 CR and 4" coupler bulkplate for the mount. I had to do a fair amount of sanding to get it all to fit, but it turned out nicely.
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I think I ended up using 6-32 screws and t-nuts because I had some extra lying around.
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The mock up of my sled base. I misjudged the 54mm when grabbing holesaws, but a little extra glue and it sorted out fine. I also used a chunk of 54mm tube to add a little extra rigidity to the base mount.
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After I got the poorly cut 54mm bulkplate glued up, I realized I forgot to cut a dado for the actual sled. Grabbed a coping saw and 10 minutes later it was fine.
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I opted for an Eggfinder Mini for tracking, not because I trust it, but because I had one for a 29mm MD build which I'd like to keep in the arsenal. I've never flown it though, mainly because I've never been able to get it to acquire satellites. I probably need to call up Cris and see what I'm doing wrong.
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My battery placement (sketched in pencil) worked out great until I mounted it in the 54mm tube. It sits pretty low in the tube. I will probably need to cut a bit of the tube to make it easier to fish zipties through.
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It's okay to be jealous of my joinery skills. Mounting up a battery tray to give some more support during liftoff.
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Lots of glue, some beer, and intermittently paying attention to my wife's TV show.
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Fortunately, as ugly as it all is, it will be hidden from view in the nosecone. After the epoxy cured, I decided I needed to widen the CR a bit to make it easier to slide the tracker bay in.
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So, you have a good fridge in your shop or your SO is suffering with a sub-standard kitchen.
Sorry for the delay, but you know, life and such. Anyway, I'm getting on with finishing (finally). The design and cutting of stencils is taking a bit, but I'm still pretty committed to the orca totem idea. We'll see how actual painting goes. For now, I'm priming and sanding and priming again. Enjoy my ad hoc paint booth and messy garage (rocket doesn't fit in my paint shelter).
Spent most of the weekend cutting stencils and getting the primer, sealer, and base coat on the Blackfish. Tonight, I got Createx UVLS on as an intercoat. This should be a better/stronger base for masking. I've had issues with 4030 peeling up (with paint) so I'm hopeful. Picture doesn't do the black pearl justice. With a good clear coat in the sun, it'll be gorgeous. Fingers crossed the white and red are too.
Finally getting some real paint on her. Only had a little snafu with tape releasing from paint, which you might be able to see in the red in the pic. I did figure out that the Frisket mask is not sticky enough for curved surfaces, so I'll likely have to recut the stencils. I am going to try to use them on the main body and fins still though.
Congratulations!
Just got the video finished and posted. I learned quite a bit from this build and flying dual deploy for the first time. The cert flight was single electronic deploy with motor back up and everything went beautifully. Unfortunately, I am going to have to retire my scratch built 2.1” rocket after a harness separation at 2500ft. Amazingly, I found the complete rocket, but I don't think I can get a new harness down in there.
Some notes from the build and flights in no particular order:
- FG sleeves are awesome, just wish Soller made a 4-5oz version
- Soller's heat shrink wrap is not great - I've had much better results on tube with a mylar wrap
- Spherachutes are pretty amazing, on the second or third flight this weekend I managed a complete inversion, but otherwise all the Spherachutes preformed flawlessly (I have three in the fleet now)
- Shear pins and brass plates were a lot less challenging than I made them out to be.
- In setting up redundant altimeters, remember to set the backup main at a different, lower altitude - fortunately caught this before I flew DD
- I kinda wish I'd built lighter/smaller rather than jump straight to something that can feasibly handle Js as is
I'm sure there are a ton more, but those are the ones I was thinking about this weekend. Anyway, thanks for all the help and support. Enjoy the video - we lost a lot of good footage to the heat...
Some notes from the build and flights in no particular order:
- FG sleeves are awesome, just wish Soller made a 4-5oz version
- Soller's heat shrink wrap is not great - I've had much better results on tube with a mylar wrap
- Spherachutes are pretty amazing, on the second or third flight this weekend I managed a complete inversion, but otherwise all the Spherachutes preformed flawlessly (I have three in the fleet now)
- Shear pins and brass plates were a lot less challenging than I made them out to be.
- In setting up redundant altimeters, remember to set the backup main at a different, lower altitude - fortunately caught this before I flew DD
- I kinda wish I'd built lighter/smaller rather than jump straight to something that can feasibly handle Js as is
I'm sure there are a ton more, but those are the ones I was thinking about this weekend. Anyway, thanks for all the help and support. Enjoy the video - we lost a lot of good footage to the heat...
Well, yeah. I can't stop now...Build more!
I picked up a 3" SBR Fusion this weekend that is begging for an I59 and definitely dual deploy.
