Hanging out in desert cantinas after the launch and mindsiming, also betting on pod racing. A real motley crew. Always trying to fly wider spaced pods and other tractor powered abominations!
Hive Ship
- Thread starter DrewW
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So I realized I’ve never tested my planned ejection scheme. So I built the hive pod to do a demo flight. nearly ready, just need the 3D printer to finish something else before I have something I can put in place.
pod on the left is for the full size hive pod, pod on the right will be the test article.
if you note the inner fill of the nosecone (seen on the left) I’m expecting the gasses to vent through one side to the other without popping the nosecone off. At the same time I’m hoping it will baffle the hot debris. Hoping for a rear eject rather than spontaneous unplanned disassembly.
pod on the left is for the full size hive pod, pod on the right will be the test article.
if you note the inner fill of the nosecone (seen on the left) I’m expecting the gasses to vent through one side to the other without popping the nosecone off. At the same time I’m hoping it will baffle the hot debris. Hoping for a rear eject rather than spontaneous unplanned disassembly.
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If unobtanium was involved, it would be fine, it would float...
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I would use either 1) MJG Tech's BP starters or 2) Estes starters dipped in Testor's silver paint and then BP (while the paint is wet). They will light. Videos attached. 1st video is (L to R) - stock Estes starter, Estes dipped in Testor's, Estes dipped in Testor's & BP, Estes dipped in Testor's and magnesium shavings. 2nd video is of 3 paint & BP dipped starters (simulating a cluster ignition). Both vids are slo-mo. In real time they ignite immediately (12V LSA battery).
(The tone is the slo-mo sound of my relay launcher "power is on" piezo buzzer.)
View attachment 20210525_130315_1_1.mp4
View attachment 20210525_132013_1_1_1_1.mp4
Would you consider doing this with 3 pods / wings in a triangular configuration? The reason this does not sim stable is simply because there is nothing to affect CP along the one plane. Why not eliminate that issue with 3 pods/wings so you can really assess the aerodynamics of the central tube?
I really like the honeycomb look -- are you doing that with infill and 0 top layers? I also think this is crying for a ramjet style nose cone to finish the nose.
I am also skeptical about whether the long tube will channel much air and thus whether the tail cone will work as a grid fin. Maybe if you put a fan in there it would work like a ducted fan.
I really like the honeycomb look -- are you doing that with infill and 0 top layers? I also think this is crying for a ramjet style nose cone to finish the nose.
I am also skeptical about whether the long tube will channel much air and thus whether the tail cone will work as a grid fin. Maybe if you put a fan in there it would work like a ducted fan.
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FWIW -- there are a few designs of the Liberator for free in STL files. For example: https://www.thingiverse.com/thing:56376
Seems difficult to make stable with those side pods being shifted so far forward but with enough nose weight maybe... at least it has a triangular configuration.
Doesn't look anything like a Thales Starstreak......???!!!
I got distracted, though in my defense I was just able to pick up some parts last night for a jig I made just for the starstreak.
probably won’t consider 3 pods, both for aesthetics and that it would further destabilize the design.The CP of each wing and pod has a bad influence on the static stability I think I’ve settled on the least bad situation but looking at either adding a few additional grams of nose weight or maybe something Like a ring fin.
For the honeycomb I actually took a stab at parametric modelling in Fusion360 so I could vary the shape parameters until I got something I thought was visually appealing. Though the 0 top/bottom layers would also have been a possibility. Actually taking that approach right now with the hive pod grid fin, two sizes are printing right now
Alright I think I’m going with the bigger grid fin. Probably going to do a quick vinyl wrap in something easy to see and then finish anchoring everything in place.
Has the overall design changed from the earlier rendering?
If you put those big draggy components on the rear by the engines it will definitely help with stability...
If you put those big draggy components on the rear by the engines it will definitely help with stability...
this is just a small demo rocket, the "hive pod", to verify the ejection method has a chance of working on the larger rocket.
Grills are awesome.
@BigMacDaddy Just tried to slice a solid version of the tailcone in prusaslicer 2.4 suppressing top, bottom, and side walls in the inner volume and got a garbage output. For now, still happy with going parametric. Looks like the slicer has trouble when one surface is highly sloped.
Yes, it interprets angles as sides... I use the no top and no bottom layers approach when I want to create really thin cross-hatch patterns for n-scale model train walkways. I have also used that approach to hollow out complex shaped rocket parts -- 3 side layers, 0 top layers, 0 bottom layers, and 0% infill.
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Well first time wrapping so I’m sure I’ll have to work on those skills later, but otherwise Hive Pod is ready to test out ideas for Hive Ship
Tonight I even remembered to put a launch lug on it! Have to wait a weekend or three to launch. But big Hive Ship will need to progress in the mean time.
Aren't you? I thought you were member number two or three.
boomtube-mk2
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I wish I had some photos of the Boomtube, my namesake rocket.
A 3" airframe with three 24mm engines set OOO with the outer two BT-50s running the length of the 36" airframe. These two had nosecones and contained the two parachutes.
The middle motor was a D12-0 that lit the "Sustainer" which was a second rocket held within the 3" tube using it as a "flying launch tower".
The 3" tube had no nosecone.
A 3" airframe with three 24mm engines set OOO with the outer two BT-50s running the length of the 36" airframe. These two had nosecones and contained the two parachutes.
The middle motor was a D12-0 that lit the "Sustainer" which was a second rocket held within the 3" tube using it as a "flying launch tower".
The 3" tube had no nosecone.
The new OpenRocket just released so I immediately did terrible things to it. Simmed the Hive Ship which was giving issues to RS and here's what I find...
I don't 100% believe the outcome, but it's also not terribly far out of bed with my mental math. Two C5-3s with exquisite ignition timing or maybe something better time balanced like a D10 or D21. Ultimately, even if I derate the stability by 50% (which I don't think is called for) I would mentally be fine if I added a few grams of nose weight and ran as a heads up flight.
I don't 100% believe the outcome, but it's also not terribly far out of bed with my mental math. Two C5-3s with exquisite ignition timing or maybe something better time balanced like a D10 or D21. Ultimately, even if I derate the stability by 50% (which I don't think is called for) I would mentally be fine if I added a few grams of nose weight and ran as a heads up flight.
Definitely a club I would join
Well its been a little while since I last updated. I've been running very busy at work and in the midst of more windy weather than desired, but today I finally got out to a small field to fly the hive pod. I'll say if you're planning a rocket that is oblong, aim for 2+ cal of stability. I had ~1.1cal stability for flight but found a combination of moderate wind (~8mph) and asymmetric thrust made for an exciting flight with not nearly enough restoring force on the grid fin.
All that said, I did successfully deploy my chute through my baffle system so ultimately I can still call this experiment a success for the purpose it was created for, verifying the method of deployment for the Hive Ship.
All that said, I did successfully deploy my chute through my baffle system so ultimately I can still call this experiment a success for the purpose it was created for, verifying the method of deployment for the Hive Ship.
Congrats. Video or pics?
Well dang. Work got a little out of hand there for a while, but today I've been able to progress a few rocket projects including this one. Side pods mounted. Need to get my 3D printer back in working order if I'm going to finish this up anytime soon.
lakeroadster
When in doubt... build hell-for-stout!
OK Drew... it's time. Kick the tires, but don't light the fires. Set your camera up on a tripod, throw some motors and the laundry in the pods, then tie a string around the main fuselage and do a swing test.
Inquiring mindsim's want some actual pre-flight stability test data.
OK Drew... it's time. Kick the tires, but don't light the fires. Set your camera up on a tripod, throw some motors and the laundry in the pods, then tie a string around the main fuselage and do a swing test.
Inquiring mindsim's want some actual pre-flight stability test data.
Alright, I got around to a swing test in the least conservative configuration this past weekend, and sure enough, it settled into flying the wrong end forward. Need to get my 3D printer back online to create some extra aerodynamic features and need to look at adding some nose weight.
lakeroadster
When in doubt... build hell-for-stout!
Sometimes oddroc's can be cantankerous. Kudos to you for doing the test.
Was it stable flying backwards? I mean, was it porpoising, pointing down, pointing up, generally no sense of being level? If it flies level, but backwards, that means you're close.
Watching with great interest and trepidation. Hope all goes well with all the work you’ve put into this one.
Use a bunker for launch control.
Use a bunker for launch control.
Thanks for the info, first swing test I’ve ever done. It was stable in flight just pointed the wrong direction, which I figured would violate the pointy end up principle.
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