[ Edited the thread title to include build. Won't be super detailed, but enough... then once it flys, we'll compare predictions to actual, and note corrections. ]
Open rocket simulation of Barromean Rings. And build.
- Thread starter Tractionengines
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Did a little more on this today. Some filing to the slots, to get the shape better. Then sanded, and roughed up the glue areas. Used a short piece of body tube with CR's inside to keep it round. Then tacked the rings together with THICK CA, and a spay of Insta-Set.
Will give it the weekend to cure the CA used as "gap filler".
The slots on the rings.
#1 (bottom) gets all 4 slots open "UP".
#2 (middle) gets 2 slots open "DOWN" (go over #1) & 2 slots open "UP" (go under #3)
#3 (top) gets 4 slots open "DOWN".
tacked & gap-fill
Next week (hopefully) I will sand the "Top" and "Bottom" to even out the joints, and get consistent thickness. Then CLEAN WELL, to remove Insta-Set residue. Followed by "LOTS" of small epoxy fillets. (24 of them if I can count correctly.)
Will give it the weekend to cure the CA used as "gap filler".
The slots on the rings.
#1 (bottom) gets all 4 slots open "UP".
#2 (middle) gets 2 slots open "DOWN" (go over #1) & 2 slots open "UP" (go under #3)
#3 (top) gets 4 slots open "DOWN".
tacked & gap-fill
Next week (hopefully) I will sand the "Top" and "Bottom" to even out the joints, and get consistent thickness. Then CLEAN WELL, to remove Insta-Set residue. Followed by "LOTS" of small epoxy fillets. (24 of them if I can count correctly.)
Fillets, and more fillets, and... who's idea was this?
I figured out I can do up to 6 at once if I'm not to concerned about exactly bisecting each joint. So tape dams at the ends. Inject .5ml of 30min. epoxy each. Heat with hot-air gun so it flows easily, self levels, and bubbles pop. Then keep an eye for leaks, or lifting tape while it cools, and sets.
About 90-120min later, do the next ones. (Even though its 30 min epoxy, hitting it with heat at 60min will soften and allow to sag. At 2hrs, it won't do that.)
I figured out I can do up to 6 at once if I'm not to concerned about exactly bisecting each joint. So tape dams at the ends. Inject .5ml of 30min. epoxy each. Heat with hot-air gun so it flows easily, self levels, and bubbles pop. Then keep an eye for leaks, or lifting tape while it cools, and sets.
About 90-120min later, do the next ones. (Even though its 30 min epoxy, hitting it with heat at 60min will soften and allow to sag. At 2hrs, it won't do that.)
Nice. Painting should be even more fun. 
boatgeek
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I painted mine before even getting them to this stage. And that was hard-ish to get right.Nice. Painting should be even more fun.
Using Estes 4" Nosecone and body tube. (Mega Der Red Max parts they are selling) The Body tube is pre-slotted for 3 fins, so I'll need to fill them. Adding a section of LOC 4" coupler will do 3 things:
* Reinforce the body tube at the ring-fins. Thicker material for the rivets to bite into
* Backing so I can fill slots
* CR can push against it to transfer thrust to the body tube. (No TTW fin tabs.)
Using (2) LOC CR's and 38mm Motor Tube. A Launch Lab Rocketry 38mm motor retainer. Plus a 1/4" eye bolt. CR's were chamfered about 1/3 of the ring thickness to get a better bond without a big fillet.
More next week.
* Reinforce the body tube at the ring-fins. Thicker material for the rivets to bite into
* Backing so I can fill slots
* CR can push against it to transfer thrust to the body tube. (No TTW fin tabs.)
Using (2) LOC CR's and 38mm Motor Tube. A Launch Lab Rocketry 38mm motor retainer. Plus a 1/4" eye bolt. CR's were chamfered about 1/3 of the ring thickness to get a better bond without a big fillet.
More next week.
Forgot the photo of the front CR and Recovery anchor point.
Then used my "high power heatsink" to support the body while drilling a few holes. (Rail buttons and rivets)
Then used my "high power heatsink" to support the body while drilling a few holes. (Rail buttons and rivets)
Haven't been able to do any painting on the ring assembly, but wanted to keep this moving ahead.... so wrapped the body in Gold-Chrome sheet. Then temporarily mounted the rings, so I could cut out an area for epoxy to eventually bond the rings to body.
Decided to name it "RINGER" and add a few biohazard symbols, cut out of Red Holographic vinyl. Has more contrast in person, than what shows in the photo. Then added a wrap of clear vinyl, and cut out the epoxy areas again.
Need a nice day or preferably two, to get the rings and nose painted... got 15-18" of snow since Friday, but its supposed to be upper 40s a few days the end of this week. We'll see.
Decided to name it "RINGER" and add a few biohazard symbols, cut out of Red Holographic vinyl. Has more contrast in person, than what shows in the photo. Then added a wrap of clear vinyl, and cut out the epoxy areas again.
Need a nice day or preferably two, to get the rings and nose painted... got 15-18" of snow since Friday, but its supposed to be upper 40s a few days the end of this week. We'll see.
Ok...made some progress, so time to update the thread...
Nosecone painted. My son, Oliver, wanted it done Metallic Copper.
Then I built an Eggtimer Apogee with the quick mount system. Drilled appropriate holes, etc.
Amazingly. With careful measurements (checked many times), the screw switch access hole perfectly lines up with the center of the bio-hazard symbol. [I didn't say I was trying to do this, till now, in case it didn't work out.]
Nosecone painted. My son, Oliver, wanted it done Metallic Copper.
Then I built an Eggtimer Apogee with the quick mount system. Drilled appropriate holes, etc.
Amazingly. With careful measurements (checked many times), the screw switch access hole perfectly lines up with the center of the bio-hazard symbol. [I didn't say I was trying to do this, till now, in case it didn't work out.]
The rings were rough because of what we use the real parts for. I WAS going to smooth them, BUT just didn't feel like the time would be available. (I already said earlier, the finish of rings would be "rough" close up, and even worse on the insides...) SO, the rings were painted black. Then the outside was covered in Chrome Silver vinyl. That shows scratches easily, so clear Vinyl was put over it. To keep it from lifting I wrapped the clear over the top and bottom. It wrinkled a little on the inside, but oh well.
The unpainted areas on the innermost surface are the contact points for the main body. Epoxy will be "flowed" down there eventually to fully bond the rings to the body, where the gold cutouts were shown earlier.
Fin set was then attached with the 9 plastic rivets.
Full stack, need to get recovery system, and final weights, then were ready to test deployment charges, and fly this thing... when local launches get going.
I'll try to get a good photo outside in the next few days. All the reflections don't do it justice inside.
The unpainted areas on the innermost surface are the contact points for the main body. Epoxy will be "flowed" down there eventually to fully bond the rings to the body, where the gold cutouts were shown earlier.
Fin set was then attached with the 9 plastic rivets.
Full stack, need to get recovery system, and final weights, then were ready to test deployment charges, and fly this thing... when local launches get going.
I'll try to get a good photo outside in the next few days. All the reflections don't do it justice inside.
Last edited:
lakeroadster
When in doubt... build hell-for-stout!
That certainly is one beautiful rocket and your build techniques are second to none.
You're getting a huge stability increase from the ring fins, much of which are intertwined, meaning getting good airflow will be sub-optimal. Color me pessimistic. I'm doubting it will be as stable as the simulation estimates.
I'd try it 1st with a G80-4, but before that, if it were mine... I'd tie some twine to it and swing test it.
You're getting a huge stability increase from the ring fins, much of which are intertwined, meaning getting good airflow will be sub-optimal. Color me pessimistic. I'm doubting it will be as stable as the simulation estimates.
I'd try it 1st with a G80-4, but before that, if it were mine... I'd tie some twine to it and swing test it.
boatgeek
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Eh, having done this, I'm not at all concerned about stability. There's a lot of drag at the back where it belongs in the inner rings, plus a lot of fin way away from the body tube in the outer rings. You do want to drop the delay a bit since there is more drag than OR sees. I concur on a G80-4 first flight.That certainly is one beautiful rocket and your build techniques are second to none.
You're getting a huge stability increase from the ring fins, much of which are intertwined, meaning getting good airflow will be sub-optimal. Color me pessimistic. I'm doubting it will be as stable as the simulation estimates.
I'd try it 1st with a G80-4, but before that, if it were mine... I'd tie some twine to it and swing test it.
Thank you for the compliment on the build. I like to think and be "outside the box".
I am not worried about stability, the main part of the fins, outside of the "mesh" area; is more than adequate for stable flight with no contribution from inner "tube" areas, or the base drag.
[ Though a swing test in the parking lot, standing on the scissors lift, would make the neighbors curious. The neighbors are the county sheriff department... ]
The delay time is not important (I want it long.), since the Eggtimer Apogee is the primary deployment means. Motor is backup only.
After the first couple flights with data from the altimiters (Apogee, and Flightsketch Mini, and maybe an Eggtimer Ion.) I will compare to the sim, and adjust the overrides for SIM to match the REAL DATA.
I am not worried about stability, the main part of the fins, outside of the "mesh" area; is more than adequate for stable flight with no contribution from inner "tube" areas, or the base drag.
[ Though a swing test in the parking lot, standing on the scissors lift, would make the neighbors curious. The neighbors are the county sheriff department... ]
The delay time is not important (I want it long.), since the Eggtimer Apogee is the primary deployment means. Motor is backup only.
After the first couple flights with data from the altimiters (Apogee, and Flightsketch Mini, and maybe an Eggtimer Ion.) I will compare to the sim, and adjust the overrides for SIM to match the REAL DATA.
