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sure beats having to remove bumpers and quarter panels
3D Printing What Are You Printing Today?
- Thread starter DRAGON64
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Can I ask -- what are some of the general settings that you changed to get a lighter print? I have a BT-55 VK 5-1 that weighs in at 1.6 oz. When I use the 1.6 oz weight in Rocksim, my rocket flies well but is UNSTABLE. When I reduce the weight of the nosecone in half, the CG moves to the aft and the rocket flies very well and shows STABLE. Clearly, I want to reduce the weight of my nosecone. Thoughts?
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HUh?
Thinner walls, less mass and/or not as much infill.
But really, CG should move FWD with a heavier nose cone instead of backwards which should increase stability
Thinner walls, less mass and/or not as much infill.
But really, CG should move FWD with a heavier nose cone instead of backwards which should increase stability
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>> When I reduce the weight of the nosecone in half, the CG moves to the aft and the rocket flies very well and shows STABLE.
Usually you put more weight in the nose to make a rocket stable, as the point is to move your CG forward, not aft. Stability in calipers is the relationship of CG and CP, as expressed by the formula (CP-CG)/DIA, where CP and CG are measured from the nose, and DIA is the diameter of the airframe. You want at least 1 caliper (diameter) for the rocket to be stable. CG should always be ahead of CP.
But apart from whether you should be lightening it to make it stable, you can change some print settings, such as a thinner wall, or some lighter fill. I prefer the 3D cubic fills as being both light and strong. These may weaken your nose cone somewhat. I go with about a 10% fill in nose cones.
I've been experimenting with a foaming filament, a PLA that foams about 100% when it passes thru the hothead of the printer. Makes for very light constructions, but with less strength. You have to slow the print down, as well, so prints take a lot more time.
Usually you put more weight in the nose to make a rocket stable, as the point is to move your CG forward, not aft. Stability in calipers is the relationship of CG and CP, as expressed by the formula (CP-CG)/DIA, where CP and CG are measured from the nose, and DIA is the diameter of the airframe. You want at least 1 caliper (diameter) for the rocket to be stable. CG should always be ahead of CP.
But apart from whether you should be lightening it to make it stable, you can change some print settings, such as a thinner wall, or some lighter fill. I prefer the 3D cubic fills as being both light and strong. These may weaken your nose cone somewhat. I go with about a 10% fill in nose cones.
I've been experimenting with a foaming filament, a PLA that foams about 100% when it passes thru the hothead of the printer. Makes for very light constructions, but with less strength. You have to slow the print down, as well, so prints take a lot more time.
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Apologies. I had myself all confused and backwards. Right now, this is what RS shows me:
Nose Cone Mass: 1.6oz
CG: 14.7518 in.
CP: 20.5474 in.
Margin: 4.37 Overstable
When I just arbitrarily change the weight of the nosecone from 1.6oz to 0.8 oz, RS shows me:
Nose Cone Mass: 0.8 oz
CG: 16.7553 in.
CP: 20.5474 in.
Margin: 2.86 Overstable
My thought was that reducing the weight of the nose cone would make the rocket less susceptible to wind gusts.
Nose Cone Mass: 1.6oz
CG: 14.7518 in.
CP: 20.5474 in.
Margin: 4.37 Overstable
When I just arbitrarily change the weight of the nosecone from 1.6oz to 0.8 oz, RS shows me:
Nose Cone Mass: 0.8 oz
CG: 16.7553 in.
CP: 20.5474 in.
Margin: 2.86 Overstable
My thought was that reducing the weight of the nose cone would make the rocket less susceptible to wind gusts.
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Aha, I understand now what you're after. A lighter nose cone will make a rocket less susceptible to wind cocking, but a stability margin of 5 isn't that bad.
I'm assuming these margins are with a motor loaded, not an empty rocket. If not, load a motor you are planning to use, and see what the stability margin is.
One of my most stable rockets was an 4" upscale of an Aerotech Mustang. It could catch some wind with those four big fins, but it was arguably the most stable and reliable rockets in my stall for many years. If it was windy, I just used a fast burning motor, and it's magically less susceptible to wind cocking.
I'm assuming these margins are with a motor loaded, not an empty rocket. If not, load a motor you are planning to use, and see what the stability margin is.
One of my most stable rockets was an 4" upscale of an Aerotech Mustang. It could catch some wind with those four big fins, but it was arguably the most stable and reliable rockets in my stall for many years. If it was windy, I just used a fast burning motor, and it's magically less susceptible to wind cocking.
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Nose cone should be mostly wall.
This
I make NCs out of walls only. The only place I have infill in a NC is at the tip unless there is an extra feature I've added inside the NC (like a shock cord attachment point, an embedded T-nut, etc). If I want it lighter I reduce the number of walls but this also reduces part strength. Most of the NCs (MPR & HPR) I have printed utilize 4 or 5 walls. I think I printed one for my kid with 2 walls once but that was for LPR. Only NC failures I've had were from failed chute deployments.
Do doubt about it.
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...load the heaviest motor you are ever likely to use...
rharshberger
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I disagree with that because a 3 grain 54 J will require more noseweight than a 6 or more grain 38mm J in some (especially short fat) rockets as the long motor becomes part of the weight forward of the CG, its a good idea to sim with a large number of motors INCLUDING the largest motor you are likely to ever fly.
1 wall and 15% infill. so it becomes two walls and 15% between them.
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Well finished the RunCam6 mount... the mount itself, the cap, and then the attachment that goes inside the body tube to allow the mount to screw to.
Finishing up the enclosure mods to my Flashforge Adventurer 5M so I can install the Acrylic sides, top and door to print ASA and ABS.
I also printed the Gemini Joe and will be launching this when the weather breaks. Printed in PETG @15% Gets paint soon and then the body wrap.
very nice
rharshberger
Well-Known Member
Flew the saucer today 4 times...first flight on a D12-3 perfect flight, then three times on E9-6's just to tempt fate...all perfect flights so the design is validated with at least those two motors.
View attachment Untitled video - Made with Clipchamp.mp4
Last year, I created a builder's kit called the Betamax, currently on my Printables page. It's a 4-fin Estes Alpha clone. This year, I took that same form factor and created the RedMiniMax. Same body tube (just much shorter) and the nosecones, and fin cans are interchangeable. They all use an 18mm motor tube as a liner with a retaining ring and cap. They also include a launch lug and a baffle for those who would rather use a BT-50 body tube. I'll be working on a Goblin and a WAC Corporal version soon.
Pictured in the rear are my RedMax/Goblin 29mm variants from my Extreme series. These are roughly the same size as the Estes models on a BT-60 body tube. They just need recovery gear and rigging and they are ready to go.
I will be releasing all these models on my Printables page as soon as I get them tested, this coming Saturday. Once they are tested, I'll do a detailed build thread for each. Looks like I'll be starting my season with a bit of fun with the kiddos.
Pictured in the rear are my RedMax/Goblin 29mm variants from my Extreme series. These are roughly the same size as the Estes models on a BT-60 body tube. They just need recovery gear and rigging and they are ready to go.
I will be releasing all these models on my Printables page as soon as I get them tested, this coming Saturday. Once they are tested, I'll do a detailed build thread for each. Looks like I'll be starting my season with a bit of fun with the kiddos.
Off topic,
but I printed some yard "art" for our chicken run.... The little dinosaurs seem to like it.
but I printed some yard "art" for our chicken run.... The little dinosaurs seem to like it.
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Good call. I had nothing but troubles with small rockets and ejection charges even with PETG - just maybe ASA might help, but not sure. Used a motor tube with the motor as a buffer, but ejection charges just caused the tubes to melt.
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Just got my new Bambu P1S with AMS delivered last night. Only had time last night to get it all set up and the various calibrations run and printed a Benchy. Dang this thing is FAST!
What are you comparing it to?
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Ender 3 pro with Sonic pad, dual Z screws, and a whole host of the other 'normal upgrades'. I was able to max mine out at 120mm/sec profiles with acceptable quality, but I slow it down to 100mm/sec profiles for most thing as the quality and reliability rises to slightly better than the old Marlin 50mm/sec profiles.
Hopefully no more spending 3 days finding a screw 1/2 turn loose just to get something to print.......as I'm sure you know, maintaining an Ender 3 is a full time hobby in and of itself.
I'm just over 'maintenance and calibration as a hobby', and bought the Bambu to use as a tool to make things. In that regard, the Ender was a great learning tool and my experience with it (Marlin and Klipper) informed my decision to move up. Not that I at all believe that the Bambu won't need maintenance and some tuning, but so far most user experience that I've seen has been hugely positive.
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Last Friday, my new Comgrow T300 landed. I spent the weekend getting it setup and tuned. Churned out the provided Benchie in 12m and the quality was decent. They must have done the input shaping at the factory b/c there was no ringing whatsoever. The overhangs were nice.
I pushed out a couple Betamax and RedMiniMax prints and I have to say, it was worth it for me. Average print times are about 1/3 the time of my modded Ender3 v2 Neo. Printing a Scout Trooper helmet for my son who has been bugging me for a year.
I pushed out a couple Betamax and RedMiniMax prints and I have to say, it was worth it for me. Average print times are about 1/3 the time of my modded Ender3 v2 Neo. Printing a Scout Trooper helmet for my son who has been bugging me for a year.
That is why I bought the FlashForge Adventurer 5M tired of leveling with paper and looking for a loose something trying to figure out why one day the CR-10 prints good and the next terrible. Good Luck I love my new printer.
I am printing a heat insert press
That's on my list of projects this year. Which one are you printing?
Making Mini Alpha lightweight nose cone test designs on the FDM and finals on the SLA.
I finished the design of the RedMax Mini Builder's Kit. I have printed a few but I completed three for my son, my nephew, and me! I was going to maiden them this Saturday but we just 14 inches of snow and it's still coming, so I suspect the launch will be cancelled.
Anyways, the builder's kit is up on Printables. It includes the nosecone, body tube, fincan, and retainer. I also added the .3mf and OpenRocket files. It should be a fun park flyer with almost 500ft on a B4-4 and the C6-7 simmed at over 1000 ft! I'm not too sure about that one, so you know I am obligated to try it. The RMS 18/20 with a D24-10 sims at 2,280ft. I will NOT try that (until I can figure out how to find it). Since I'm snowed in for the weekend, I'll do a build thread for it, in case anyone is interested.
Anyways, the builder's kit is up on Printables. It includes the nosecone, body tube, fincan, and retainer. I also added the .3mf and OpenRocket files. It should be a fun park flyer with almost 500ft on a B4-4 and the C6-7 simmed at over 1000 ft! I'm not too sure about that one, so you know I am obligated to try it. The RMS 18/20 with a D24-10 sims at 2,280ft. I will NOT try that (until I can figure out how to find it). Since I'm snowed in for the weekend, I'll do a build thread for it, in case anyone is interested.
